USC/Information Sciences Institute
C. Villamizar
Avici Systems
E. Gerich
At Home Network
D. Kessens
Qwest Communications
D. Meyer
University of Oregon
T. Bates
Cisco Systems
D. Karrenberg
RIPE NCC
M. Terpstra
Bay Networks
June 1999
Routing Policy Specification Language (RPSL)
Status of this Memo
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This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
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Copyright © The Internet Society (1999). All Rights Reserved.
Abstract
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RPSL allows a network operator to be able to specify routing policies at various levels in the Internet hierarchy; for example at the Autonomous System (AS) level. At the same time, policies can be specified with sufficient detail in RPSL so that low level router configurations can be generated from them. RPSL is extensible; new routing protocols and new protocol features can be introduced at any time.
Table of Contents
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1 Introduction 3 2 RPSL Names, Reserved Words, and Representation 4 3 Contact Information 7 3.1 mntner Class . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 person Class . . . . . . . . . . . . . . . . . . . . . . . . 10 3.3 role Class . . . . . . . . . . . . . . . . . . . . . . . . . 11 4 route Class 12 5 Set Classes 13 5.1 as-set Class . . . . . . . . . . . . . . . . . . . . . . . . 14 5.2 route-set Class. . . . . . . . . . . . . . . . . . . . . . . 15 5.3 Predefined Set Objects . . . . . . . . . . . . . . . . . . . 17 5.4 Filters and filter-set Class . . . . . . . . . . . . . . . . 17 5.5 rtr-set Class. . . . . . . . . . . . . . . . . . . . . . . . 22 5.6 Peerings and peering-set Class . . . . . . . . . . . . . . . 24 6 aut-num Class 27 6.1 import Attribute: Import Policy Specification . . . . . . . 27 6.1.1 Action Specification . . . . . . . . . . . . . . . . . . 28 6.2 export Attribute: Export Policy Specification . . . . . . . 29 6.3 Other Routing Protocols, Multi-Protocol Routing Protocols, and Injecting Routes Between Protocols . . . . . . . . . . . . 29 6.4 Ambiguity Resolution . . . . . . . . . . . . . . . . . . . . 31 6.5 default Attribute: Default Policy Specification . . . . . . 33 6.6 Structured Policy Specification. . . . . . . . . . . . . . . 33 7 dictionary Class 37 7.1 Initial RPSL Dictionary and Example Policy Actions and Filters. . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 8 Advanced route Class 45 8.1 Specifying Aggregate Routes. . . . . . . . . . . . . . . . . 45 8.1.1Interaction with policies in aut-num class. . . . . . . . 49 8.1.2Ambiguity resolution with overlapping aggregates. . . . . 50 8.2 Specifying Static Routes . . . . . . . . . . . . . . . . . . 52 9 inet-rtr Class 52 10 Extending RPSL 54 10.1 Extensions by changing the dictionary class . . . . . . . . 54 10.2 Extensions by adding new attributes to existing classes . . 55 10.3 Extensions by adding new classes . . . . . . . . . . . . . 55 10.4 Extensions by changing the syntax of existing RPSL attributes. . . . . . . . . . . . . . . . . . . . . . . . . . 55 11 Security Considerations 56 12 Acknowledgements 56 References 56 A Routing Registry Sites 59 B Grammar Rules 59 C Changes from RFC 2280 67 D Authors' Addresses 68 Full Copyright Statement 69
1 Introduction
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This memo is the reference document for the Routing Policy Specification Language (RPSL). RPSL allows a network operator to be able to specify routing policies at various levels in the Internet hierarchy; for example at the Autonomous System (AS) level. At the same time, policies can be specified with sufficient detail in RPSL so that low level router configurations can be generated from them. RPSL is extensible; new routing protocols and new protocol features can be introduced at any time.
RPSL is a replacement for the current Internet policy specification language known as RIPE-181 [6] or RFC-1786 [7]. RIPE-81 [8] was the first language deployed in the Internet for specifying routing policies. It was later replaced by RIPE-181 [6]. Through operational use of RIPE-181 it has become apparent that certain policies cannot be specified and a need for an enhanced and more generalized language is needed. RPSL addresses RIPE-181's limitations.
RPSL was designed so that a view of the global routing policy can be contained in a single cooperatively maintained distributed database to improve the integrity of Internet's routing. RPSL is not designed to be a router configuration language. RPSL is designed so that router configurations can be generated from the description of the policy for one autonomous system (aut-num class) combined with the description of a router (inet-rtr class), mainly providing router ID, autonomous system number of the router, interfaces and peers of the router, and combined with a global database mappings from AS sets to ASes (as-set class), and from origin ASes and route sets to route prefixes (route and route-set classes). The accurate population of the RPSL database can help contribute toward such goals as router configurations that protect against accidental (or malicious) distribution of inaccurate routing information, verification of Internet's routing, and aggregation boundaries beyond a single AS.
RPSL is object oriented; that is, objects contain pieces of policy and administrative information. These objects are registered in the Internet Routing Registry (IRR) by the authorized organizations. The registration process is beyond the scope of this document. Please refer to [1, 17, 4] for more details on the IRR.
In the following sections, we present the classes that are used to define various policy and administrative objects. The "mntner" class defines entities authorized to add, delete and modify a set of objects. The "person" and "role" classes describes technical and administrative contact personnel. Autonomous systems (ASes) are specified using the "aut-num" class. Routes are specified using the
"route" class. Sets of objects can be defined using the "as-set", "route-set", "filter-set", "peering-set", and "rtr-set" classes. The "dictionary" class provides the extensibility to the language. The "inet-rtr" class is used to specify routers. Many of these classes were originally defined in earlier documents [6, 13, 16, 12, 5] and have all been enhanced.
This document is self-contained. However, the reader is encouraged to read RIPE-181 [7] and the associated documents [13, 16, 12, 5] as they provide significant background as to the motivation and underlying principles behind RIPE-181 and consequently, RPSL. For a tutorial on RPSL, the reader should read the RPSL applications document [4].
2 RPSL Names, Reserved Words, and Representation
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Each class has a set of attributes which store a piece of information about the objects of the class. Attributes can be mandatory or optional: A mandatory attribute has to be defined for all objects of the class; optional attributes can be skipped. Attributes can also be single or multiple valued. Each object is uniquely identified by a set of attributes, referred to as the class "key".
The value of an attribute has a type. The following types are most widely used. Note that RPSL is case insensitive and only the characters from the ASCII character set can be used.
<object-name>
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Many objects in RPSL have a name. An <object-name> is made up of letters, digits, the character underscore "_", and the character hyphen "-"; the first character of a name must be a letter, and the last character of a name must be a letter or a digit. The following words are reserved by RPSL, and they can not be used as names:
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any as-any rs-any peeras
and or not
atomic from to at action accept announce except refine networks into inbound outbound
Names starting with certain prefixes are reserved for certain object types. Names starting with "as-" are reserved for as set names. Names starting with "rs-" are reserved for route set names. Names starting with "rtrs-" are reserved for router set names. Names starting with "fltr-" are reserved for filter set names. Names starting with "prng-" are reserved for peering set names.
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<as-number> An AS number x is represented as the string "ASx". That
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is, the AS 226 is represented as AS226.
<ipv4-address> An IPv4 address is represented as a sequence of four
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integers in the range from 0 to 255 separated by the character dot ".". For example, 128.9.128.5 represents a valid IPv4 address. In the rest of this document, we may refer to IPv4 addresses as IP addresses.
<address-prefix> An address prefix is represented as an IPv4 address
followed by the character slash "/" followed by an integer in the range from 0 to 32. The following are valid address prefixes: 128.9.128.5/32, 128.9.0.0/16, 0.0.0.0/0; and the following address prefixes are invalid: 0/0, 128.9/16 since 0 or 128.9 are not strings containing four integers.<address-prefix-range> An address prefix range is an address prefix
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followed by an optional range operator. The range operators are:
^- is the exclusive more specifics operator; it stands for the more
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specifics of the address prefix excluding the address prefix itself. For example, 128.9.0.0/16^- contains all the more specifics of 128.9.0.0/16 excluding 128.9.0.0/16.
^+ is the inclusive more specifics operator; it stands for the more
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specifics of the address prefix including the address prefix itself. For example, 5.0.0.0/8^+ contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8.
^n where n is an integer, stands for all the length n specifics of
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the address prefix. For example, 30.0.0.0/8^16 contains all the more specifics of 30.0.0.0/8 which are of length 16 such as 30.9.0.0/16.
^n-m where n and m are integers, stands for all the length n to
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length m specifics of the address prefix. For example, 30.0.0.0/8^24-32 contains all the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as 30.9.9.96/28.
Range operators can also be applied to address prefix sets. In this case, they distribute over the members of the set. For example, for a route-set (defined later) rs-foo, rs-foo^+ contains all the inclusive more specifics of all the prefixes in rs-foo.
It is an error to follow a range operator with another one (e.g. 30.0.0.0/8^24-28^+ is an error). However, a range operator can be applied to an address prefix set that has address prefix ranges in it (e.g. {30.0.0.0/8^24-28}^27-30 is not an error). In this case, the
outer operator ^n-m distributes over the inner operator ^k-l and becomes the operator ^max(n,k)-m if m is greater than or equal to max(n,k), or otherwise, the prefix is deleted from the set. Note that the operator ^n is equivalent to ^n-n; prefix/l^+ is equivalent to prefix/l^l-32; prefix/l^- is equivalent to prefix/l^(l+1)-32; {prefix/l^n-m}^+ is equivalent to {prefix/l^n-32}; and {prefix/l^n- m}^- is equivalent to {prefix/l^(n+1)-32}. For example, {128.9.0.0/16^+}^- == {128.9.0.0/16^-} {128.9.0.0/16^-}^+ == {128.9.0.0/16^-} {128.9.0.0/16^17}^24 == {128.9.0.0/16^24} {128.9.0.0/16^20-24}^26-28 == {128.9.0.0/16^26-28} {128.9.0.0/16^20-24}^22-28 == {128.9.0.0/16^22-28} {128.9.0.0/16^20-24}^18-28 == {128.9.0.0/16^20-28} {128.9.0.0/16^20-24}^18-22 == {128.9.0.0/16^20-22} {128.9.0.0/16^20-24}^18-19 == {}<date>
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A date is represented as an eight digit integer of the form YYYYMMDD where YYYY represents the year, MM represents the month of the year (01 through 12), and DD represents the day of the month (01 through 31). All dates are in UTC unless otherwise specified. For example, June 24, 1996 is represented as 19960624.
<email-address>is as described in RFC-822 [10].
<dns-name>is as described in RFC-1034 [17].
<nic-handle> is a uniquely assigned identifier word used by routing,
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address allocation, and other registries to unambiguously refer to contact information. Person and role classes map NIC handles to actual person names, and contact information.
<free-form>is a sequence of ASCII characters.
<X-name> is a name of an object of type X. That is <mntner-name> is a
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name of a mntner object.
<registry-name> is a name of an IRR registry. The routing registries
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are listed in Appendix A.
A value of an attribute may also be a list of one of these types. A list is represented by separating the list members by commas ",". For example, "AS1, AS2, AS3, AS4" is a list of AS numbers. Note that being list valued and being multiple valued are orthogonal. A multiple valued attribute has more than one value, each of which may or may not be a list. On the other hand a single valued attribute may have a list value.
An RPSL object is textually represented as a list of attribute-value pairs. Each attribute-value pair is written on a separate line. The attribute name starts at column 0, followed by character ":" and followed by the value of the attribute. The attribute which has the same name as the object's class should be specified first. The object's representation ends when a blank line is encountered. An attribute's value can be split over multiple lines, by having a space, a tab or a plus ('+') character as the first character of the continuation lines. The character "+" for line continuation allows attribute values to contain blank lines. More spaces may optionally be used after the continuation character to increase readability. The order of attribute-value pairs is significant.
An object's description may contain comments. A comment can be anywhere in an object's definition, it starts at the first "#" character on a line and ends at the first end-of-line character. White space characters can be used to improve readability.
An integer can be specified using (1) the C programming language notation (e.g. 1, 12345); (2) sequence of four 1-octet integers (in the range from 0 to 255) separated by the character dot "." (e.g. 1.1.1.1, 255.255.0.0), in this case a 4-octet integer is formed by concatenating these 1-octet integers in the most significant to least significant order; (3) sequence of two 2-octet integers (in the range from 0 to 65535) separated by the character colon ":" (e.g. 3561:70, 3582:10), in this case a 4-octet integer is formed by concatenating these 2-octet integers in the most significant to least significant order.
3 Contact Information
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The mntner, person and role classes, admin-c, tech-c, mnt-by, changed, and source attributes of all classes describe contact information. The mntner class also specifies authenticaiton information required to create, delete and update other objects. These classes do not specify routing policies and each registry may have different or additional requirements on them. Here we present the common denominator for completeness which is the RIPE database implementation [16]. Please consult your routing registry for the latest specification of these classes and attributes. The "Routing Policy System Security" document [20] describes the authenticaiton and authorization model in more detail.
3.1 mntner Class
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The mntner class specifies authenticaiton information required to create, delete and update RPSL objects. A provider, before he/she can create RPSL objects, first needs to create a mntner object. The attributes of the mntner class are shown in Figure 1. The mntner class was first described in [13].
The mntner attribute is mandatory and is the class key. Its value is an RPSL name. The auth attribute specifies the scheme that will be used to identify and authenticate update requests from this maintainer. It has the following syntax:
auth:
<scheme-id> <auth-info>
E.g.
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auth:
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NONE Attribute Value Type mntner <object-name> mandatory, single-valued, class key descr <free-form> mandatory, single-valued auth see description in text mandatory, multi-valued upd-to <email-address> mandatory, multi-valued mnt-nfy <email-address> optional, multi-valued tech-c <nic-handle> mandatory, multi-valued admin-c <nic-handle> optional, multi-valued remarks <free-form> optional, multi-valued notify <email-address> optional, multi-valued mnt-by list of <mntner-name> mandatory, multi-valued changed <email-address> <date> mandatory, multi-valued source <registry-name> mandatory, single-valued
Figure 1: mntner Class Attributes
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auth: CRYPT-PW dhjsdfhruewf auth: MAIL-FROM .*@ripe\.netThe <scheme-id>'s currently defined are: NONE, MAIL-FROM, PGP-KEY and CRYPT-PW. The <auth-info> is additional information required by a particular scheme: in the case of MAIL-FROM, it is a regular expression matching valid email addresses; in the case of CRYPT-PW, it is a password in UNIX crypt format; and in the case of PGP-KEY, it is a pointer to key-certif object [22] containing the PGP public key of the user. If multiple auth attributes are specified, an update request satisfying any one of them is authenticated to be from the maintainer.
The upd-to attribute is an email address. On an unauthorized update attempt of an object maintained by this maintainer, an email message will be sent to this address. The mnt-nfy attribute is an email address. A notification message will be forwarded to this email address whenever an object maintained by this maintainer is added, changed or deleted.
The descr attribute is a short, free-form textual description of the object. The tech-c attribute is a technical contact NIC handle. This is someone to be contacted for technical problems such as misconfiguration. The admin-c attribute is an administrative contact NIC handle. The remarks attribute is a free text explanation or clarification. The notify attribute is an email address to which notifications of changes to this object should be sent. The mnt-by attribute is a list of mntner object names. The authorization for changes to this object is governed by any of the maintainer objects referenced. The changed attribute documents who last changed this object, and when this change was made. Its syntax has the following form:
changed:
<email-address> <YYYYMMDD> E.g. changed: johndoe@terabit-labs.nn 19900401
The <email-address> identifies the person who made the last change. <YYYYMMDD> is the date of the change. The source attribute specifies the registry where the object is registered. Figure 2 shows an example mntner object. In the example, UNIX crypt format password authentication is used.
mntner: RIPE-NCC-MNT descr: RIPE-NCC Maintainer admin-c: DK58 tech-c: OPS4-RIPE upd-to: ops@ripe.net mnt-nfy: ops-fyi@ripe.net auth: CRYPT-PW lz1A7/JnfkTtI mnt-by: RIPE-NCC-MNT changed: ripe-dbm@ripe.net 19970820 source: RIPE
Figure 2: An example mntner object.
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The descr, tech-c, admin-c, remarks, notify, mnt-by, changed and source attributes are attributes of all RPSL classes. Their syntax, semantics, and mandatory, optional, multi-valued, or single-valued status are the same for for all RPSL classes. Only exception to this is the admin-c attribute which is mandatory for the aut-num class. We do not further discuss them in other sections.
3.2 person Class
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A person class is used to describe information about people. Even though it does not describe routing policy, we still describe it here briefly since many policy objects make reference to person objects. The person class was first described in [15].
The attributes of the person class are shown in Figure 3. The person attribute is the full name of the person. The phone and the fax-no attributes have the following syntax:
phone: +<country-code> <city> <subscriber> [ext. <extension>]
E.g.:
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phone:
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- 20 12334676
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Attribute Value Type person <free-form> mandatory, single-valued nic-hdl <nic-handle> mandatory, single-valued, class key address <free-form> mandatory, multi-valued phone see description in text mandatory, multi-valued fax-no same as phone optional, multi-valued e-mail <email-address> mandatory, multi-valued
Figure 3: person Class Attributes
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phone: +44 123 987654 ext. 4711
Figure 4 shows an example person object.
person: Daniel Karrenberg address: RIPE Network Coordination Centre (NCC) address: Singel 258 address: NL-1016 AB Amsterdam address: Netherlands phone: +31 20 535 4444 fax-no: +31 20 535 4445 e-mail: Daniel.Karrenberg@ripe.net nic-hdl: DK58 changed: Daniel.Karrenberg@ripe.net 19970616 source: RIPE
Figure 4: An example person object.
3.3 role Class
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The role class is similar to the person object. However, instead of describing a human being, it describes a role performed by one or more human beings. Examples include help desks, network monitoring centers, system administrators, etc. Role object is particularly useful since often a person performing a role may change, however the role itself remains.
The attributes of the role class are shown in Figure 5. The nic-hdl attributes of the person and role classes share the same name space. The trouble attribute of role object may contain additional contact information to be used when a problem arises in any object that references this role object. Figure 6 shows an example role object.
Attribute Value Type role <free-form> mandatory, single-valued nic-hdl <nic-handle> mandatory, single-valued, class key trouble <free-form> optional, multi-valued address <free-form> mandatory, multi-valued phone see description in text mandatory, multi-valued fax-no same as phone optional, multi-valued e-mail <email-address> mandatory, multi-valued
Figure 5: role Class Attributes
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role: RIPE NCC Operations trouble: address: Singel 258 address: 1016 AB Amsterdam address: The Netherlands phone: +31 20 535 4444 fax-no: +31 20 545 4445 e-mail: ops@ripe.net admin-c: CO19-RIPE tech-c: RW488-RIPE tech-c: JLSD1-RIPE nic-hdl: OPS4-RIPE notify: ops@ripe.net changed: roderik@ripe.net 19970926 source: RIPE
Figure 6: An example role object.
4 route Class
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Each interAS route (also referred to as an interdomain route) originated by an AS is specified using a route object. The attributes of the route class are shown in Figure 7. The route attribute is the address prefix of the route and the origin attribute is the AS number of the AS that originates the route into the interAS routing system. The route and origin attribute pair is the class key.
Figure 8 shows examples of four route objects (we do not include contact attributes such as admin-c, tech-c for brevity). Note that the last two route objects have the same address prefix, namely 128.8.0.0/16. However, they are different route objects since they are originated by different ASes (i.e. they have different keys).
Attribute Value Type route <address-prefix> mandatory, single-valued, class key origin <as-number> mandatory, single-valued, class key member-of list of <route-set-names> optional, multi-valued see Section 5 inject see Section 8 optional, multi-valued components see Section 8 optional, single-valued aggr-bndry see Section 8 optional, single-valued aggr-mtd see Section 8 optional, single-valued export-comps see Section 8 optional, single-valued holes see Section 8 optional, multi-valued Figure 7: route Class Attributes route: 128.9.0.0/16 origin: AS226 route: 128.99.0.0/16 origin: AS226 route: 128.8.0.0/16 origin: AS1 route: 128.8.0.0/16 origin: AS2 Figure 8: Route Objects
5 Set Classes
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To specify policies, it is often useful to define sets of objects. For this purpose we define as-set, route-set, rtr-set, filter-set, and peering-set classes. These classes define a named set. The members of these sets can be specified either directly by listing them in the sets' definition, or indirectly by having member objects refer to the sets' names, or a combination of both methods.
A set's name is an rpsl word with the following restrictions: All as-set names start with prefix "as-". All route-set names start with prefix "rs-". All rtr-set names start with prefix "rtrs-". All filter-set names start with prefix "fltr-". All peering-set names start with prefix "prng-". For example, as-foo is a valid as-set name.
Set names can also be hierarchical. A hierarchical set name is a sequence of set names and AS numbers separated by colons ":". At least one component of such a name must be an actual set name (i.e. start with one of the prefixes above). All the set name components of an hierarchical name has to be of the same type. For example, the following names are valid: AS1:AS-CUSTOMERS, AS1:RS-EXPORT:AS2, RS- EXCEPTIONS:RS-BOGUS.
The purpose of an hierarchical set name is to partition the set name space so that the maintainers of the set X1 controls the whole set name space underneath, i.e. X1:...:Xn-1. Thus, a set object with name X1:...:Xn-1:Xn can only be created by the maintainer of the object with name X1:...:Xn-1. That is, only the maintainer of AS1 can create a set with name AS1:AS-FOO; and only the maintainer of AS1:AS-FOO can create a set with name AS1:AS-FOO:AS-BAR. Please see RPS Security Document [20] for details.
5.1 as-set Class
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The attributes of the as-set class are shown in Figure 9. The as-set attribute defines the name of the set. It is an RPSL name that starts with "as-". The members attribute lists the members of the set. The members attribute is a list of AS numbers, or other as-set names.
Attribute Value Type as-set <object-name> mandatory, single-valued, class key members list of <as-numbers> or optional, multi-valued <as-set-names> mbrs-by-ref list of <mntner-names> optional, multi-valued
Figure 9: as-set Class Attributes
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Figure 10 presents two as-set objects. The set as-foo contains two ASes, namely AS1 and AS2. The set as-bar contains the members of the set as-foo and AS3, that is it contains AS1, AS2, AS3. The set as- empty contains no members.
as-set: as-foo as-set: as-bar as-set: as-empty members: AS1, AS2 members: AS3, as-foo
Figure 10: as-set objects.
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The mbrs-by-ref attribute is a list of maintainer names or the keyword ANY. If this attribute is used, the AS set also includes ASes whose aut-num objects are registered by one of these maintainers and whose member-of attribute refers to the name of this AS set. If the value of a mbrs-by-ref attribute is ANY, any AS object referring to the AS set is a member of the set. If the mbrs-by-ref attribute is missing, only the ASes listed in the members attribute are members of the set.
as-set: as-foo members: AS1, AS2 mbrs-by-ref: MNTR-ME aut-num: AS3 aut-num: AS4 member-of: as-foo member-of: as-foo mnt-by: MNTR-ME mnt-by: MNTR-OTHER Figure 11: as-set objects.Figure 11 presents an example as-set object that uses the mbrs-by-ref attribute. The set as-foo contains AS1, AS2 and AS3. AS4 is not a member of the set as-foo even though the aut-num object references as-foo. This is because MNTR-OTHER is not listed in the as-foo's mbrs-by-ref attribute.
5.2 route-set Class
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The attributes of the route-set class are shown in Figure 12. The route-set attribute defines the name of the set. It is an RPSL name that starts with "rs-". The members attribute lists the members of the set. The members attribute is a list of address prefixes or other route-set names. Note that, the route-set class is a set of route prefixes, not of RPSL route objects.
Attribute Value Type route-set <object-name> mandatory, single-valued, class key members list of <address-prefix-range> or optional, multi-valued <route-set-name> or <route-set-name><range-operator> mbrs-by-ref list of <mntner-names> optional, multi-valued
Figure 12: route-set Class Attributes
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Figure 13 presents some example route-set objects. The set rs-foo contains two address prefixes, namely 128.9.0.0/16 and 128.9.0.0/24. The set rs-bar contains the members of the set rs-foo and the address prefix 128.7.0.0/16.
An address prefix or a route-set name in a members attribute can be optionally followed by a range operator. For example, the following set:
route-set: rs-foo members: 128.9.0.0/16, 128.9.0.0/24 route-set: rs-bar members: 128.7.0.0/16, rs-foo
Figure 13: route-set Objects
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route-set: rs-bar members: 5.0.0.0/8^+, 30.0.0.0/8^24-32, rs-foo^+
contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8, all the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as 30.9.9.96/28, and all the more specifics of address prefixes in route set rs-foo.
The mbrs-by-ref attribute is a list of maintainer names or the keyword ANY. If this attribute is used, the route set also includes address prefixes whose route objects are registered by one of these maintainers and whose member-of attribute refers to the name of this route set. If the value of a mbrs-by-ref attribute is ANY, any route object referring to the route set name is a member. If the mbrs-by- ref attribute is missing, only the address prefixes listed in the members attribute are members of the set.
route-set: rs-foo mbrs-by-ref: MNTR-ME, MNTR-YOU route-set: rs-bar members: 128.7.0.0/16 mbrs-by-ref: MNTR-YOU route: 128.9.0.0/16 origin: AS1 member-of: rs-foo mnt-by: MNTR-ME route: 128.8.0.0/16 origin: AS2 member-of: rs-foo, rs-bar mnt-by: MNTR-YOU
Figure 14: route-set objects.
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Figure 14 presents example route-set objects that use the mbrs-by-ref attribute. The set rs-foo contains two address prefixes, namely 128.8.0.0/16 and 128.9.0.0/16 since the route objects for 128.8.0.0/16 and 128.9.0.0/16 refer to the set name rs-foo in their member-of attribute. The set rs-bar contains the address prefixes 128.7.0.0/16 and 128.8.0.0/16. The route 128.7.0.0/16 is explicitly listed in the members attribute of rs-bar, and the route object for 128.8.0.0/16 refer to the set name rs-bar in its member-of attribute.
Note that, if an address prefix is listed in a members attribute of a route set, it is a member of that route set. The route object corresponding to this address prefix does not need to contain a member-of attribute referring to this set name. The member-of attribute of the route class is an additional mechanism for specifying the members indirectly.
5.3 Predefined Set Objects
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In a context that expects a route set (e.g. members attribute of the route-set class), an AS number ASx defines the set of routes that are originated by ASx; and an as-set AS-X defines the set of routes that are originated by the ASes in AS-X. A route p is said to be originated by ASx if there is a route object for p with ASx as the value of the origin attribute. For example, in Figure 15, the route set rs-special contains 128.9.0.0/16, routes of AS1 and AS2, and routes of the ASes in AS set AS-FOO.
route-set: rs-special members: 128.9.0.0/16, AS1, AS2, AS-FOO
Figure 15: Use of AS numbers and AS sets in route sets.
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The set rs-any contains all routes registered in IRR. The set as-any contains all ASes registered in IRR.
5.4 Filters and filter-set Class
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The attributes of the filter-set class are shown in Figure 16. A filter-set object defines a set of routes that are matched by its filter. The filter-set attribute defines the name of the filter. It is an RPSL name that starts with "fltr-".
Attribute Value Type filter-set <object-name> mandatory, single-valued, class key filter <filter> mandatory, single-valued
Figure 16: filter Class Attributes
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filter-set: fltr-foo filter: { 5.0.0.0/8, 6.0.0.0/8 } filter-set: fltr-bar filter: (AS1 or fltr-foo) and <AS2>
Figure 17: filter-set objects.
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The filter attribute defines the set's policy filter. A policy filter is a logical expression which when applied to a set of routes returns a subset of these routes. We say that the policy filter matches the subset returned. The policy filter can match routes using any BGP path attribute, such as the destination address prefix (or NLRI), AS-path, or community attributes.
The policy filters can be composite by using the operators AND, OR, and NOT. The following policy filters can be used to select a subset of routes:
ANY
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The keyword ANY matches all routes.
Address-Prefix Set This is an explicit list of address prefixes
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enclosed in braces '{' and '}'. The policy filter matches the set of routes whose destination address-prefix is in the set. For example:
{ 0.0.0.0/0 } { 128.9.0.0/16, 128.8.0.0/16, 128.7.128.0/17, 5.0.0.0/8 } { }An address prefix can be optionally followed by a range operator (i.e.
{ 5.0.0.0/8^+, 128.9.0.0/16^-, 30.0.0.0/8^16, 30.0.0.0/8^24-32 }contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8, all the more specifics of 128.9.0.0/16 excluding 128.9.0.0/16, all the more specifics of 30.0.0.0/8 which are of length 16 such as 30.9.0.0/16, and all the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as 30.9.9.96/28.
Route Set Name A route set name matches the set of routes that are members of the set. A route set name may be a name of a route-set object, an AS number, or a name of an as-set object (AS numbers and as-set names implicitly define route sets; please see Section 5.3). For example:
-
aut-num: AS1
import: from AS2 accept AS2
import: from AS2 accept AS-FOO
import: from AS2 accept RS-FOO
The keyword PeerAS can be used instead of the AS number of the peer AS. PeerAS is particularly useful when the peering is specified using an AS expression. For example:
as-set: AS-FOO members: AS2, AS3 aut-num: AS1 import: from AS-FOO accept PeerASis same as:
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aut-num: AS1
import: from AS2 accept AS2
import: from AS3 accept AS3
A route set name can also be followed by one of the operators '^-', '^+', example, { 5.0.0.0/8, 6.0.0.0/8 }^+ equals { 5.0.0.0/8^+, 6.0.0.0/8^+ }, and AS1^- equals all the exclusive more specifics of routes originated by AS1.AS Path Regular Expressions
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An AS-path regular expression can be used as a policy filter by enclosing the expression in `<' and `>'. An AS-path policy filter matches the set of routes which traverses a sequence of ASes matched by the AS-path regular expression. A router can check this using the AS_PATH attribute in the Border Gateway Protocol [19], or the RD_PATH attribute in the Inter-Domain Routing Protocol [18].
AS-path Regular Expressions are POSIX compliant regular expressions over the alphabet of AS numbers. The regular expression constructs are as follows:
ASN
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where ASN is an AS number. ASN matches the AS-path that is of length 1 and contains the corresponding AS number (e.g. AS-path regular expression AS1 matches the AS-path "1").
The keyword PeerAS can be used instead of the AS number of the peer AS.
AS-set
-
where AS-set is an AS set name. AS-set matches the AS-paths that is matched by one of the ASes in the AS-set.
.
-
matches the AS-paths matched by any AS number.
[...]
-
is an AS number set. It matches the AS-paths matched by the AS numbers listed between the brackets. The AS numbers in the set are separated by white space characters. If a `-' is used between two AS numbers in this set, all AS numbers between the two AS numbers are included in the set. If an as-set name is listed, all AS numbers in the as-set are included.
[^...]
-
is a complemented AS number set. It matches any AS-path which is not matched by the AS numbers in the set.
^
-
Matches the empty string at the beginning of an AS-path.
$
-
Matches the empty string at the end of an AS-path.
We next list the regular expression operators in the decreasing order of evaluation. These operators are left associative, i.e. performed left to right.
Unary postfix operators * + ? {m} {m,n} {m,} For a regular expression A, A* matches zero or more occurrences of A; A+ matches one or more occurrences of A; A? matches zero or one occurrence of A; A{m} matches m occurrence of A; A{m,n} matches m to n occurrence of A; A{m,} matches m or more occurrence of A. For example, [AS1 AS2]{2} matches AS1 AS1, AS1 AS2, AS2 AS1, and AS2 AS2. Unary postfix operators ~* ~+ ~{m} ~{m,n} ~{m,} These operators have similar functionality as the corresponding operators listed above, but all occurrences of the regular expression has to match the same pattern. For example, [AS1 AS2]~{2} matches AS1 AS1 and AS2 AS2, but it does not match AS1 AS2 and AS2 AS1.Binary catenation operator
-
This is an implicit operator and exists between two regular expressions A and B when no other explicit operator is specified. The resulting expression A B matches an AS-path if A matches some prefix of the AS-path and B matches the rest of the AS-path.
Binary alternative (or) operator | For a regular expressions A and B, A | B matches any AS-path that is matched by A or B.Parenthesis can be used to override the default order of evaluation. White spaces can be used to increase readability.
The following are examples of AS-path filters:
<AS3>
<^AS1>
<AS2$>
<^AS1 AS2 AS3$>
<^AS1 .* AS2$>.The first example matches any route whose AS-path contains AS3, the second matches routes whose AS-path starts with AS1, the third matches routes whose AS-path ends with AS2, the fourth matches routes whose AS-path is exactly "1 2 3", and the fifth matches routes whose AS-path starts with AS1 and ends in AS2 with any number of AS numbers in between.
Composite Policy Filters The following operators (in decreasing order of evaluation) can be used to form composite policy filters:
NOT Given a policy filter x, NOT x matches the set of routes that
-
are not matched by x. That is it is the negation of policy filter x.
AND Given two policy filters x and y, x AND y matches the intersection
-
of the routes that are matched by x and that are matched by y.
OR Given two policy filters x and y, x OR y matches the union of the routes that are matched by x and that are matched by y.Note that an OR operator can be implicit, that is `x y' is equivalent to `x OR y'.
E.g.
NOT {128.9.0.0/16, 128.8.0.0/16} AS226 AS227 OR AS228 AS226 AND NOT {128.9.0.0/16} AS226 AND {0.0.0.0/0^0-18}The first example matches any route except 128.9.0.0/16 and 128.8.0.0/16. The second example matches the routes of AS226, AS227 and AS228. The third example matches the routes of AS226 except 128.9.0.0/16. The fourth example matches the routes of AS226 whose length are not longer than 18.
Routing Policy Attributes Policy filters can also use the values of other attributes for comparison. The attributes whose values can be used in policy filters are specified in the RPSL dictionary. Please refer to Section 7 for details. An example using the the BGP community attribute is shown below:
aut-num: AS1
export: to AS2 announce AS1 AND NOT community(NO_EXPORT)Filters using the routing policy attributes defined in the dictionary are evaluated before evaluating the operators AND, OR and NOT.
Filter Set Name
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A filter set name matches the set of routes that are matched by its filter attribute. Note that the filter attribute of a filter set, can recursively refer to other filter set names. For example in Figure 17, fltr-foo matches { 5.0.0.0/8, 6.0.0.0/8 }, and fltr-bar matches AS1'S routes or { 5.0.0.0/8, 6.0.0.0/8 } if their as path contained AS2.
5.5 rtr-set Class
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The attributes of the rtr-set class are shown in Figure 18. The rtr-set attribute defines the name of the set. It is an RPSL name that starts with "rtrs-". The members attribute lists the members of the set. The members attribute is a list of inet-rtr names, ipv4_addresses or other rtr-set names.
Attribute Value Type rtr-set <object-name> mandatory, single-valued, class key members list of <inet-rtr-names> or optional, multi-valued <rtr-set-names> or <ipv4_addresses> mbrs-by-ref list of <mntner-names> optional, multi-valued
Figure 18: rtr-set Class Attributes
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Figure 19 presents two rtr-set objects. The set rtrs-foo contains two routers, namely rtr1.isp.net and rtr2.isp.net. The set rtrs-bar contains the members of the set rtrs-foo and rtr3.isp.net, that is it contains rtr1.isp.net, rtr2.isp.net, rtr3.isp.net. rtr-set: rtrs-foo rtr-set: rtrs-bar members: rtr1.isp.net, rtr2.isp.net members: rtr3.isp.net, rtrs-foo
Figure 19: rtr-set objects.
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The mbrs-by-ref attribute is a list of maintainer names or the keyword ANY. If this attribute is used, the router set also includes routers whose inet-rtr objects are registered by one of these maintainers and whose member-of attribute refers to the name of this router set. If the value of a mbrs-by-ref attribute is ANY, any inet-rtr object referring to the router set is a member of the set. If the mbrs-by-ref attribute is missing, only the routers listed in the members attribute are members of the set.
rtr-set: rtrs-foo members: rtr1.isp.net, rtr2.isp.net mbrs-by-ref: MNTR-ME inet-rtr: rtr3.isp.net local-as: as1 ifaddr: 1.1.1.1 masklen 30 member-of: rtrs-foo mnt-by: MNTR-ME Figure 20: rtr-set objects. Figure 20 presents an example rtr-set object that uses the mbrs-by- ref attribute. The set rtrs-foo contains rtr1.isp.net, rtr2.isp.net and rtr3.isp.net.
5.6 Peerings and peering-set Class
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The attributes of the peering-set class are shown in Figure 21. A peering-set object defines a set of peerings that are listed in its peering attributes. The peering-set attribute defines the name of the set. It is an RPSL name that starts with "prng-".
Attribute Value Type peering-set <object-name> mandatory, single-valued, class key peering <peering> mandatory, multi-valued
Figure 21: filter Class Attributes
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The peering attribute defines a peering that can be used for importing or
---------------------- ---------------------- | 7.7.7.1 |-------| |-------| 7.7.7.2 | | | ======== | | | AS1 | EX1 |-------| 7.7.7.3 AS2 | | | | | | 9.9.9.1 |------ ------| 9.9.9.2 | ---------------------- | | ---------------------- =========== | EX2 ---------------------- | | 9.9.9.3 |--------- | | | AS3 | ----------------------Figure 22: Example topology consisting of three ASes, AS1, AS2, and
AS3; two exchange points, EX1 and EX2; and six routers.
-
exporting routes.
-
In describing peerings, we are going to use the topology of Figure 22. In this topology, there are three ASes, AS1, AS2, and AS3; two exchange points, EX1 and EX2; and six routers. Routers connected to the same exchange point peer with each other and exchange routing information. That is, 7.7.7.1, 7.7.7.2 and 7.7.7.3 peer with each other; 9.9.9.1, 9.9.9.2 and 9.9.9.3 peer with each other.
The syntax of a peering specification is:
<as-expression> [<router-expression-1>] [at <router-expression-2>] | <peering-set-name>-
where <as-expression> is an expression over AS numbers and AS sets using operators AND, OR, and EXCEPT, and <router-expression-1> and <router-expression-2> are expressions over router IP addresses, inet-rtr names, and rtr-set names using operators AND, OR, and EXCEPT. The binary "EXCEPT" operator is the set subtraction operator and has the same precedence as the operator AND (it is semantically equivalent to "AND NOT" combination). That is "(AS1 OR AS2) EXCEPT AS2" equals "AS1".
This form identifies all the peerings between any local router in <router-expression-2> to any of their peer routers in <router- expression-1> in the ASes in <as-expression>. If <router- expression-2> is not specified, it defaults to all routers of the local AS that peer with ASes in <as-expression>. If <router- expression-1> is not specified, it defaults to all routers of the peer ASes in <as-expression> that peer with the local AS.
If a <peering-set-name> is used, the peerings are listed in the corresponding peering-set object. Note that the peering-set objects can be recursive.
Many special forms of this general peering specification is possible. The following examples illustrate the most common cases, using the import attribute of the aut-num class. In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2.
(1) aut-num: AS1
import: from AS2 7.7.7.2 at 7.7.7.1 accept { 128.9.0.0/16 }In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and 7.7.7.3.
(2) aut-num: AS1
import: from AS2 at 7.7.7.1 accept { 128.9.0.0/16 } In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and 7.7.7.3, and 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2.(3) aut-num: AS1
import: from AS2 accept { 128.9.0.0/16 }In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2 and 9.9.9.3.
(4) as-set: AS-FOO members: AS2, AS3 aut-num: AS1 import: from AS-FOO at 9.9.9.1 accept { 128.9.0.0/16 } In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2 and 9.9.9.3, and 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and 7.7.7.3.(5) aut-num: AS1
import: from AS-FOO accept { 128.9.0.0/16 }In the following example AS1 imports 128.9.0.0/16 from AS3 at router 9.9.9.1
(6) aut-num: AS1
-
import:
from AS-FOO and not AS2 at not 7.7.7.1 accept { 128.9.0.0/16 }This is because "AS-FOO and not AS2" equals AS3 and "not 7.7.7.1" equals 9.9.9.1.
In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2 and 9.9.9.3.
(7) peering-set: prng-bar peering: AS1 at 9.9.9.1 peering-set: prng-foo peering: prng-bar peering: AS2 at 9.9.9.1 aut-num: AS1 import: from prng-foo accept { 128.9.0.0/16 }
6 aut-num Class
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Routing policies are specified using the aut-num class. The attributes of the aut-num class are shown in Figure 23. The value of the aut-num attribute is the AS number of the AS described by this object. The as-name attribute is a symbolic name (in RPSL name syntax) of the AS. The import, export and default routing policies of the AS are specified using import, export and default attributes respectively.
Attribute Value Type aut-num <as-number> mandatory, single-valued, class key as-name <object-name> mandatory, single-valued member-of list of <as-set-names> optional, multi-valued import see Section 6.1 optional, multi valued export see Section 6.2 optional, multi valued default see Section 6.5 optional, multi valued
Figure 23: aut-num Class Attributes
6.1 import Attribute: Import Policy Specification
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In RPSL, an import policy is divided into import policy expressions. Each import policy expression is specified using an import attribute. The import attribute has the following syntax (we will extend this syntax later in Sections 6.3 and 6.6):
import: from <peering-1> [action <action-1>] . . . from <peering-N> [action <action-N>] accept <filter>The action specification is optional. The semantics of an import attribute is as follows: the set of routes that are matched by <filter> are imported from all the peers in <peerings>; while importing routes at <peering-M>, <action-M> is executed.
E.g.
aut-num: AS1 import: from AS2 action pref = 1; accept { 128.9.0.0/16 }This example states that the route 128.9.0.0/16 is accepted from AS2 with preference 1. We already presented how peerings (see Section 5.6) and filters (see Section 5.4) are specified. We next present how to specify actions.
6.1.1 Action Specification
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Policy actions in RPSL either set or modify route attributes, such as assigning a preference to a route, adding a BGP community to the BGP community path attribute, or setting the MULTI-EXIT-DISCRIMINATOR attribute. Policy actions can also instruct routers to perform special operations, such as route flap damping.
The routing policy attributes whose values can be modified in policy actions are specified in the RPSL dictionary. Please refer to Section 7 for a list of these attributes. Each action in RPSL is terminated by the semicolon character (';'). It is possible to form composite policy actions by listing them one after the other. In a composite policy action, the actions are executed left to right. For example,
aut-num: AS1 import: from AS2 action pref = 10; med = 0; community.append(10250, 3561:10); accept { 128.9.0.0/16 }sets pref to 10, med to 0, and then appends 10250 and 3561:10 to the BGP community path attribute. The pref attribute is the inverse of the local-pref attribute (i.e. local-pref == 65535 - pref). A route with a local-pref attribute is always preferred over a route without one.
aut-num: AS1 import: from AS2 action pref = 1; from AS3 action pref = 2; accept AS4The above example states that AS4's routes are accepted from AS2 with preference 1, and from AS3 with preference 2 (routes with lower integer preference values are preferred over routes with higher integer preference values).
aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; from AS2 action pref = 2; accept AS4The above example states that AS4's routes are accepted from AS2 on peering 7.7.7.1-7.7.7.2 with preference 1, and on any other peering with AS2 with preference 2.
6.2 export Attribute: Export Policy Specification
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Similarly, an export policy expression is specified using an export attribute. The export attribute has the following syntax:
export: to <peering-1> [action <action-1>] . . . to <peering-N> [action <action-N>] announce <filter> The action specification is optional. The semantics of an export attribute is as follows: the set of routes that are matched by <filter> are exported to all the peers specified in <peerings>; while exporting routes at <peering-M>, <action-M> is executed.E.g.
aut-num: AS1 export: to AS2 action med = 5; community .= { 70 }; announce AS4In this example, AS4's routes are announced to AS2 with the med attribute's value set to 5 and community 70 added to the community list.
Example:
aut-num: AS1 export: to AS-FOO announce ANYIn this example, AS1 announces all of its routes to the ASes in the set AS-FOO.
6.3 Other Routing Protocols, Multi-Protocol Routing Protocols, and
Injecting Routes Between Protocols
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The more complete syntax of the import and export attributes are as follows:
import: [protocol <protocol-1>] [into <protocol-2>] from <peering-1> [action <action-1>] . . . from <peering-N> [action <action-N>] accept <filter> export: [protocol <protocol-1>] [into <protocol-2>] to <peering-1> [action <action-1>] . . . to <peering-N> [action <action-N>] announce <filter>Where the optional protocol specifications can be used for specifying policies for other routing protocols, or for injecting routes of one protocol into another protocol, or for multi-protocol routing policies. The valid protocol names are defined in the dictionary. The <protocol-1> is the name of the protocol whose routes are being exchanged. The <protocol-2> is the name of the protocol which is receiving these routes. Both <protocol-1> and <protocol-2> default to the Internet Exterior Gateway Protocol, currently BGP.
In the following example, all interAS routes are injected into RIP.
aut-num: AS1
import: from AS2 accept AS2
export: protocol BGP4 into RIP-
-
to AS1 announce ANY
-
In the following example, AS1 accepts AS2's routes including any more specifics of AS2's routes, but does not inject these extra more specific routes into OSPF.
aut-num: AS1
import: from AS2 accept AS2^+
export: protocol BGP4 into OSPF-
-
to AS1 announce AS2
-
In the following example, AS1 injects its static routes (routes which are members of the set AS1:RS-STATIC-ROUTES) to the interAS routing protocol and appends AS1 twice to their AS paths.
aut-num: AS1 import: protocol STATIC into BGP4 from AS1 action aspath.prepend(AS1, AS1); accept AS1:RS-STATIC-ROUTESIn the following example, AS1 imports different set of unicast routes for multicast reverse path forwarding from AS2:
aut-num: AS1
import: from AS2 accept AS2
import: protocol IDMR-
-
from AS2 accept AS2:RS-RPF-ROUTES
-
-
6.4 Ambiguity Resolution
-
It is possible that the same peering can be covered by more that one peering specification in a policy expression. For example:
aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 2; from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; accept AS4This is not an error, though definitely not desirable. To break the ambiguity, the action corresponding to the first peering specification is used. That is the routes are accepted with preference 2. We call this rule as the specification-order rule.
Consider the example:
aut-num: AS1 import: from AS2 action pref = 2; from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; dpa = 5; accept AS4where both peering specifications cover the peering 7.7.7.1-7.7.7.2, though the second one covers it more specifically. The specification order rule still applies, and only the action "pref = 2" is executed. In fact, the second peering-action pair has no use since the first peering-action pair always covers it. If the intended policy was to accept these routes with preference 1 on this particular peering and with preference 2 in all other peerings, the user should have specified:
aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; dpa = 5; from AS2 action pref = 2; accept AS4It is also possible that more than one policy expression can cover the same set of routes for the same peering. For example:
aut-num: AS1
import: from AS2 action pref = 2; accept AS4
import: from AS2 action pref = 1; accept AS4In this case, the specification-order rule is still used. That is, AS4's routes are accepted from AS2 with preference 2. If the filters were overlapping but not exactly the same:
aut-num: AS1
import: from AS2 action pref = 2; accept AS4
import: from AS2 action pref = 1; accept AS4 OR AS5the AS4's routes are accepted from AS2 with preference 2 and however AS5's routes are also accepted, but with preference 1.
We next give the general specification order rule for the benefit of the RPSL implementors. Consider two policy expressions:
aut-num: AS1 import: from peerings-1 action action-1 accept filter-1 import: from peerings-2 action action-2 accept filter-2
The above policy expressions are equivalent to the following three expressions where there is no ambiguity:
aut-num: AS1 import: from peerings-1 action action-1 accept filter-1 import: from peerings-3 action action-2 accept filter-2 AND NOT filter-1 import: from peerings-4 action action-2 accept filter-2
where peerings-3 are those that are covered by both peerings-1 and peerings-2, and peerings-4 are those that are covered by peerings-2 but not by peerings-1 ("filter-2 AND NOT filter-1" matches the routes that are matched by filter-2 but not by filter-1).
Example:
aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 2; accept {128.9.0.0/16} import: from AS2 action pref = 1; accept {128.9.0.0/16, 75.0.0.0/8}Lets consider two peerings with AS2, 7.7.7.1-7.7.7.2 and 9.9.9.1- 9.9.9.2. Both policy expressions cover 7.7.7.1-7.7.7.2. On this peering, the route 128.9.0.0/16 is accepted with preference 2, and the route 75.0.0.0/8 is accepted with preference 1. The peering 9.9.9.1-9.9.9.2 is only covered by the second policy expressions. Hence, both the route 128.9.0.0/16 and the route 75.0.0.0/8 are accepted with preference 1 on peering 9.9.9.1-9.9.9.2.
Note that the same ambiguity resolution rules also apply to export and default policy expressions.
6.5 default Attribute: Default Policy Specification
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Default routing policies are specified using the default attribute. The default attribute has the following syntax:
default: to <peering> [action <action>] [networks <filter>] The <action> and <filter> specifications are optional. The semantics are as follows: The <peering> specification indicates the AS (and the router if present) is being defaulted to; the <action> specification, if present, indicates various attributes of defaulting, for example a relative preference if multiple defaults are specified; and the <filter> specifications, if present, is a policy filter. A router only uses the default policy if it received the routes matched by <filter> from this peer.
In the following example, AS1 defaults to AS2 for routing.
aut-num: AS1 default: to AS2
In the following example, router 7.7.7.1 in AS1 defaults to router 7.7.7.2 in AS2.
aut-num: AS1 default: to AS2 7.7.7.2 at 7.7.7.1
In the following example, AS1 defaults to AS2 and AS3, but prefers AS2 over AS3.
aut-num: AS1
default: to AS2 action pref = 1;
default: to AS3 action pref = 2;In the following example, AS1 defaults to AS2 and uses 128.9.0.0/16 as the default network.
aut-num: AS1 default: to AS2 networks { 128.9.0.0/16 }
6.6 Structured Policy Specification
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The import and export policies can be structured. We only reccomend structured policies to advanced RPSL users. Please feel free to skip this section.
The syntax for a structured policy specification is the following:
<import-factor> ::= from <peering-1> [action <action-1>] . . . from <peering-N> [action <action-N>] accept <filter>; <import-term> ::= <import-factor> | LEFT-BRACE <import-factor> . . . <import-factor> RIGHT-BRACE <import-expression> ::= <import-term> | <import-term> EXCEPT <import-expression> | <import-term> REFINE <import-expression> import: [protocol <protocol1>] [into <protocol2>] <import-expression>Please note the semicolon at the end of an <import-factor>. If the policy specification is not structured (as in all the examples in other sections), this semicolon is optional. The syntax and semantics for an <import-factor> is already defined in Section 6.1.
An <import-term> is either a sequence of <import-factor>'s enclosed within matching braces (i.e. `{' and `}') or just a single <import- factor>. The semantics of an <import-term> is the union of <import- factor>'s using the specification order rule. An <import-expression> is either a single <import-term> or an <import-term> followed by one of the keywords "except" and "refine", followed by another <import- expression>. Note that our definition allows nested expressions. Hence there can be exceptions to exceptions, refinements to refinements, or even refinements to exceptions, and so on.
The semantics for the except operator is as follows: The result of an except operation is another <import-term>. The resulting policy set contains the policies of the right hand side but their filters are modified to only include the routes also matched by the left hand side. The policies of the left hand side are included afterwards and their filters are modified to exclude the routes matched by the right hand side. Please note that the filters are modified during this process but the actions are copied verbatim. When there are multiple levels of nesting, the operations (both except and refine) are performed right to left.
Consider the following example:
import: from AS1 action pref = 1; accept as-foo; except { from AS2 action pref = 2; accept AS226; except { from AS3 action pref = 3; accept {128.9.0.0/16}; } }where the route 128.9.0.0/16 is originated by AS226, and AS226 is a member of the as set as-foo. In this example, the route 128.9.0.0/16 is accepted from AS3, any other route (not 128.9.0.0/16) originated by AS226 is accepted from AS2, and any other ASes' routes in as-foo is accepted from AS1.
We can come to the same conclusion using the algebra defined above. Consider the inner exception specification:
from AS2 action pref = 2; accept AS226; except { from AS3 action pref = 3; accept {128.9.0.0/16}; } is equivalent to { from AS3 action pref = 3; accept AS226 AND {128.9.0.0/16}; from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16}; }Hence, the original expression is equivalent to:
import: from AS1 action pref = 1; accept as-foo; except { from AS3 action pref = 3; accept AS226 AND {128.9.0.0/16}; from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16}; }which is equivalent to
import: {
-
from AS3 action pref = 3; accept as-foo AND AS226 AND {128.9.0.0/16}; from AS2 action pref = 2; accept as-foo AND AS226 AND NOT {128.9.0.0/16}; from AS1 action pref = 1; accept as-foo AND NOT (AS226 AND NOT {128.9.0.0/16} OR AS226 AND {128.9.0.0/16}); }Since AS226 is in as-foo and 128.9.0.0/16 is in AS226, it simplifies to:
import:
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{ from AS3 action pref = 3; accept {128.9.0.0/16}; from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16}; from AS1 action pref = 1; accept as-foo AND NOT AS226; } In the case of the refine operator, the resulting set is constructed by taking the cartasian product of the two sides as follows: for each policy l in the left hand side and for each policy r in the right hand side, the peerings of the resulting policy are the peerings common to both r and l; the filter of the resulting policy is the intersection of l's filter and r's filter; and action of the resulting policy is l's action followed by r's action. If there are no common peerings, or if the intersection of filters is empty, a resulting policy is not generated.Consider the following example:
import: { from AS-ANY action pref = 1; accept community(3560:10); from AS-ANY action pref = 2; accept community(3560:20); } refine { from AS1 accept AS1; from AS2 accept AS2; from AS3 accept AS3; }Here, any route with community 3560:10 is assigned a preference of 1 and any route with community 3560:20 is assigned a preference of 2 regardless of whom they are imported from. However, only AS1's routes are imported from AS1, and only AS2's routes are imported from AS2, and only AS3's routes are imported form AS3, and no routes are imported from any other AS. We can reach the same conclusion using the above algebra. That is, our example is equivalent to:
import: { from AS1 action pref = 1; accept community(3560:10) AND AS1; from AS1 action pref = 2; accept community(3560:20) AND AS1; from AS2 action pref = 1; accept community(3560:10) AND AS2; from AS2 action pref = 2; accept community(3560:20) AND AS2; from AS3 action pref = 1; accept community(3560:10) AND AS3; from AS3 action pref = 2; accept community(3560:20) AND AS3; }Note that the common peerings between "from AS1" and "from AS-ANY" are those peerings in "from AS1". Even though we do not formally define "common peerings", it is straight forward to deduce the definition from the definitions of peerings (please see Section 5.6).
Consider the following example:
import: {
from AS-ANY action med = 0; accept {0.0.0.0/0^0-18}; } refine { from AS1 at 7.7.7.1 action pref = 1; accept AS1; from AS1 action pref = 2; accept AS1; }where only routes of length 0 to 18 are accepted and med's value is set to 0 to disable med's effect for all peerings; In addition, from AS1 only AS1's routes are imported, and AS1's routes imported at 7.7.7.1 are preferred over other peerings. This is equivalent to:
import: {
from AS1 at 7.7.7.1 action med=0; pref=1; accept {0.0.0.0/0^0-
18} AND AS1;
from AS1 action med=0; pref=2; accept {0.0.0.0/0^0-
18} AND AS1;
}
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The above syntax and semantics also apply equally to structured export policies with "from" replaced with "to" and "accept" is replaced with "announce".
7 dictionary Class
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The dictionary class provides extensibility to RPSL. Dictionary objects define routing policy attributes, types, and routing protocols. Routing policy attributes, henceforth called rp- attributes, may correspond to actual protocol attributes, such as the BGP path attributes (e.g. community, dpa, and AS-path), or they may correspond to router features (e.g. BGP route flap damping). As new protocols, new protocol attributes, or new router features are introduced, the dictionary object is updated to include appropriate rp-attribute and protocol definitions.
An rp-attribute is an abstract class; that is a data representation is not available. Instead, they are accessed through access methods. For example, the rp-attribute for the BGP AS-path attribute is called aspath; and it has an access method called prepend which stuffs extra AS numbers to the AS-path attributes. Access methods can take arguments. Arguments are strongly typed. For example, the method prepend above takes AS numbers as arguments.
Once an rp-attribute is defined in the dictionary, it can be used to describe policy filters and actions. Policy analysis tools are required to fetch the dictionary object and recognize newly defined rp-attributes, types, and protocols. The analysis tools may approximate policy analyses on rp-attributes that they do not understand: a filter method may always match, and an action method may always perform no-operation. Analysis tools may even download code to perform appropriate operations using mechanisms outside the scope of RPSL.
We next describe the syntax and semantics of the dictionary class. This description is not essential for understanding dictionary objects (but it is essential for creating one). Please feel free to skip to the RPSL Initial Dictionary subsection (Section 7.1).
The attributes of the dictionary class are shown in Figure 24. The dictionary attribute is the name of the dictionary object, obeying the RPSL naming rules. There can be many dictionary objects, however there is always one well-known dictionary object "RPSL". All tools use this dictionary by default.
Attribute Value Type dictionary <object-name> mandatory, single-valued, class key rp-attribute see description in text optional, multi valued typedef see description in text optional, multi valued protocol see description in text optional, multi valued
Figure 24: dictionary Class Attributes
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The rp-attribute attribute has the following syntax:
rp-attribute: <name>
<method-1>(<type-1-1>, ..., <type-1-N1> [, "..."]) ... <method-M>(<type-M-1>, ..., <type-M-NM> [, "..."])where <name> is the name of the rp-attribute; and <method-i> is the name of an access method for the rp-attribute, taking Ni arguments where the j-th argument is of type <type-i-j>. A method name is either an RPSL name or one of the operators defined in Figure 25. The operator methods with the exception of operator() and operator[] can take only one argument.
operator= operator== operator<<= operator< operator>>= operator> operator+= operator>= operator-= operator<= operator*= operator!= operator/= operator() operator.= operator[]
Figure 25: Operators
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An rp-attribute can have many methods defined for it. Some of the methods may even have the same name, in which case their arguments are of different types. If the argument list is followed by "...", the method takes a variable number of arguments. In this case, the actual arguments after the Nth argument are of type <type-N>.
Arguments are strongly typed. A <type> in RPSL is either a predefined type, a union type, a list type, or a dictionary defined type. The predefined types are listed in Figure 26.
integer[lower, upper] ipv4_address real[lower, upper] address_prefix enum[name, name, ...] address_prefix_range string dns_name boolean filter rpsl_word as_set_name free_text route_set_name email rtr_set_name as_number filter_set_name peering_set_name
Figure 26: Predefined Types
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The integer and the real predefined types can be followed by a lower and an upper bound to specify the set of valid values of the argument. The range specification is optional. We use the ANSI C language conventions for representing integer, real and string values. The enum type is followed by a list of RPSL names which are the valid values of the type. The boolean type can take the values true or false. as_number, ipv4_address, address_prefix and dns_name types are as in Section 2. filter type is a policy filter as in Section 6. The value of filter type is suggested to be enclosed in parenthesis.
The syntax of a union type is as follows:
union <type-1>, ... , <type-N>
where <type-i> is an RPSL type. The union type is either of the types <type-1> through <type-N> (analogous to unions in C[14]).
The syntax of a list type is as follows:
list [<min_elems>:<max_elems>] of <type>
In this case, the list elements are of <type> and the list contains at least <min_elems> and at most <max_elems> elements. The size specification is optional. If it is not specified, there is no restriction in the number of list elements. A value of a list type is represented as a sequence of elements separated by the character "," and enclosed by the characters "{" and "}".
The typedef attribute in the dictionary defines named types as follows:
typedef:
<name> <type>
where <name> is a name for type <type>. typedef attribute is paticularly useful when the type defined is not a predefined type (e.g. list of unions, list of lists, etc.).
A protocol attribute of the dictionary class defines a protocol and a set of peering parameters for that protocol (which are used in inet- rtr class in Section 9). Its syntax is as follows:
protocol: <name>
MANDATORY | OPTIONAL <parameter-1>(<type-1-1>,..., <type-1-N1> [,"..."]) ... MANDATORY | OPTIONAL <parameter-M>(<type-M-1>,..., <type-M-NM> [,"..."])where <name> is the name of the protocol; MANDATORY and OPTIONAL are keywords; and <parameter-i> is a peering parameter for this protocol, taking Ni many arguments. The syntax and semantics of the arguments are as in the rp-attribute. If the keyword MANDATORY is used, the parameter is mandatory and needs to be specified for each peering of this protocol. If the keyword OPTIONAL is used, the parameter can be skipped.
7.1 Initial RPSL Dictionary and Example Policy Actions and Filters
dictionary: RPSL
rp-attribute: # preference, smaller values represent higher preferences
pref
operator=(integer[0, 65535])
rp-attribute: # BGP multi_exit_discriminator attribute
med
# to set med to 10: med = 10;
# to set med to the IGP metric: med = igp_cost;
operator=(union integer[0, 65535], enum[igp_cost])
rp-attribute: # BGP destination preference attribute (dpa)
dpa
operator=(integer[0, 65535])
rp-attribute: # BGP aspath attribute
aspath
# prepends AS numbers from last to first order
prepend(as_number, ...)
typedef: # a community value in RPSL is either
# - a 4 byte integer (ok to use 3561:70 notation)
# - internet, no_export, no_advertise (see RFC-1997)
community_elm union
integer[1, 4294967295],
enum[internet, no_export, no_advertise],
typedef: # list of community values { 40, no_export, 3561:70 }
community_list list of community_elm
rp-attribute: # BGP community attribute
community
# set to a list of communities
operator=(community_list)
# append community values
operator.=(community_list)
append(community_elm, ...)
# delete community values
delete(community_elm, ...)
# a filter: true if one of community values is contained
contains(community_elm, ...)
# shortcut to contains: community(no_export, 3561:70)
operator()(community_elm, ...)
# order independent equality comparison
operator==(community_list)
rp-attribute: # next hop router in a static route
next-hop
# to set to 7.7.7.7: next-hop = 7.7.7.7;
# to set to router's own address: next-hop = self;
operator=(union ipv4_address, enum[self])
rp-attribute: # cost of a static route
cost
operator=(integer[0, 65535])
protocol: BGP4
# as number of the peer router
MANDATORY asno(as_number)
# enable flap damping
OPTIONAL flap_damp()
OPTIONAL flap_damp(integer[0,65535],
# penalty per flap
integer[0,65535],
# penalty value for supression
integer[0,65535],
# penalty value for reuse
integer[0,65535],
# halflife in secs when up
integer[0,65535],
# halflife in secs when down
integer[0,65535])
# maximum penalty
protocol: OSPF
protocol: RIP
protocol: IGRP
protocol: IS-IS
protocol: STATIC
protocol: RIPng
protocol: DVMRP
protocol: PIM-DM
protocol: PIM-SM
protocol: CBT
protocol: MOSPF
Figure 27: RPSL Dictionary
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Figure 27 shows the initial RPSL dictionary. It has seven rp- attributes: pref to assign local preference to the routes accepted; med to assign a value to the MULTI_EXIT_DISCRIMINATOR BGP attribute; dpa to assign a value to the DPA BGP attribute; aspath to prepend a value to the AS_PATH BGP attribute; community to assign a value to or to check the value of the community BGP attribute; next-hop to assign next hop routers to static routes; and cost to assign a cost to static routes. The dictionary defines two types: community_elm and community_list. community_elm type is either a 4-byte unsigned integer, or one of the keywords internet, no_export or no_advertise (defined in [9]). An integer can be specified using two 2-byte integers seperated by ":" to partition the community number space so that a provider can use its AS number as the first two bytes, and assigns a semantics of its choice to the last two bytes. The initial dictionary (Figure 27) defines only options for the Border Gateway Protocol: asno and flap_damp. The mandatory asno option is the AS number of the peer router. The optional flap_damp option instructs the router to damp route flaps [21] when importing routes from the peer router.
It can be specified with or without parameters. If parameters are missing, they default to:
flap_damp(1000, 2000, 750, 900, 900, 20000)
That is, a penalty of 1000 is assigned at each route flap, the route is suppressed when penalty reaches 2000. The penalty is reduced in half after 15 minutes (900 seconds) of stability regardless of whether the route is up or down. A supressed route is reused when the penalty falls below 750. The maximum penalty a route can be assigned is 20,000 (i.e. the maximum suppress time after a route becomes stable is about 75 minutes). These parameters are consistent with the default flap damping parameters in several routers.
Policy Actions and Filters Using RP-Attributes
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The syntax of a policy action or a filter using an rp-attribute x is as follows:
x.method(arguments)
x "op" argumentwhere method is a method and "op" is an operator method of the rp- attribute x. If an operator method is used in specifying a composite policy filter, it evaluates earlier than the composite policy filter operators (i.e. AND, OR, NOT, and implicit or operator).
The pref rp-attribute can be assigned a positive integer as follows:
pref = 10;
The med rp-attribute can be assigned either a positive integer or the word "igp_cost" as follows:
med = 0;
med = igp_cost;The dpa rp-attribute can be assigned a positive integer as follows:
dpa = 100;
The BGP community attribute is list-valued, that is it is a list of 4-byte integers each representing a "community". The following examples demonstrate how to add communities to this rp-attribute:
community .= { 100 }; community .= { NO_EXPORT }; community .= { 3561:10 };In the last case, a 4-byte integer is constructed where the more significant two bytes equal 3561 and the less significant two bytes equal 10. The following examples demonstrate how to delete communities from the community rp-attribute:
community.delete(100, NO_EXPORT, 3561:10);
Filters that use the community rp-attribute can be defined as demonstrated by the following examples:
community.contains(100, NO_EXPORT, 3561:10); community(100, NO_EXPORT, 3561:10); # shortcut
The community rp-attribute can be set to a list of communities as follows:
community = {100, NO_EXPORT, 3561:10, 200}; community = {};In this first case, the community rp-attribute contains the communities 100, NO_EXPORT, 3561:10, and 200. In the latter case, the community rp-attribute is cleared. The community rp-attribute can be compared against a list of communities as follows:
community == {100, NO_EXPORT, 3561:10, 200}; # exact matchTo influence the route selection, the BGP as_path rp-attribute can be made longer by prepending AS numbers to it as follows:
aspath.prepend(AS1); aspath.prepend(AS1, AS1, AS1);
The following examples are invalid:
med = -50; # -50 is not in the range med = igp; # igp is not one of the enum values med.assign(10); # method assign is not defined community.append(AS3561:20); # the first argument should be 3561
Figure 28 shows a more advanced example using the rp-attribute community. In this example, AS3561 bases its route selection preference on the community attribute. Other ASes may indirectly affect AS3561's route selection by including the appropriate communities in their route announcements.
aut-num: AS1 export: to AS2 action community.={3561:90}; to AS3 action community.={3561:80}; announce AS1 as-set: AS3561:AS-PEERS members: AS2, AS3 aut-num: AS3561 import: from AS3561:AS-PEERS action pref = 10; accept community(3561:90) import: from AS3561:AS-PEERS action pref = 20; accept community(3561:80) import: from AS3561:AS-PEERS action pref = 20; accept community(3561:70) import: from AS3561:AS-PEERS action pref = 0; accept ANY Figure 28: Policy example using the community rp-attribute.
8 Advanced route Class
8.1 Specifying Aggregate Routes
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The components, aggr-bndry, aggr-mtd, export-comps, inject, and holes attributes are used for specifying aggregate routes [11]. A route object specifies an aggregate route if any of these attributes, with the exception of inject, is specified. The origin attribute for an aggregate route is the AS performing the aggregation, i.e. the aggregator AS. In this section, we used the term "aggregate" to refer to the route generated, the term "component" to refer to the routes used to generate the path attributes of the aggregate, and the term "more specifics" to refer to any route which is a more specific of the aggregate regardless of whether it was used to form the path attributes.
The components attribute defines what component routes are used to form the aggregate. Its syntax is as follows:
components: [ATOMIC] [[<filter>] [protocol <protocol> <filter> ...]]
where <protocol> is a routing protocol name such as BGP4, OSPF or RIP (valid names are defined in the dictionary) and <filter> is a policy expression. The routes that match one of these filters and are learned from the corresponding protocol are used to form the aggregate. If <protocol> is omitted, it defaults to any protocol. <filter> implicitly contains an "AND" term with the more specifics of the aggregate so that only the component routes are selected. If the keyword ATOMIC is used, the aggregation is done atomically [11]. If a <filter> is not specified it defaults to more specifics. If the components attribute is missing, all more specifics without the ATOMIC keyword is used.
route: 128.8.0.0/15 origin: AS1 components: <^AS2> route: 128.8.0.0/15 origin: AS1 components: protocol BGP4 {128.8.0.0/16^+} protocol OSPF {128.9.0.0/16^+}
Figure 29: Two aggregate route objects.
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Figure 29 shows two route objects. In the first example, more specifics of 128.8.0.0/15 with AS paths starting with AS2 are aggregated. In the second example, some routes learned from BGP and some routes learned form OSPF are aggregated.
The aggr-bndry attribute is an AS expression over AS numbers and sets (see Section 5.6). The result defines the set of ASes which form the aggregation boundary. If the aggr-bndry attribute is missing, the origin AS is the sole aggregation boundary. Outside the aggregation boundary, only the aggregate is exported and more specifics are suppressed. However, within the boundary, the more specifics are also exchanged.
The aggr-mtd attribute specifies how the aggregate is generated. Its syntax is as follows:
aggr-mtd: inbound
| outbound [<as-expression>]
where <as-expression> is an expression over AS numbers and sets (see Section 5.6). If <as-expression> is missing, it defaults to AS-ANY. If outbound aggregation is specified, the more specifics of the aggregate will be present within the AS and the aggregate will be formed at all inter-AS boundaries with ASes in <as-expression> before export, except for ASes that are within the aggregating boundary (i.e. aggr-bndry is enforced regardless of <as-expression>). If inbound aggregation is specified, the aggregate is formed at all inter-AS boundaries prior to importing routes into the aggregator AS. Note that <as-expression> can not be specified with inbound aggregation. If aggr-mtd attribute is missing, it defaults to "outbound AS-ANY".
route: 128.8.0.0/15 route: 128.8.0.0/15 origin: AS1 origin: AS2 components: {128.8.0.0/15^-} components: {128.8.0.0/15^-} aggr-bndry: AS1 OR AS2 aggr-bndry: AS1 OR AS2 aggr-mtd: outbound AS-ANY aggr-mtd: outbound AS-ANY
Figure 30: Outbound multi-AS aggregation example.
-
Figure 30 shows an example of an outbound aggregation. In this example, AS1 and AS2 are coordinating aggregation and announcing only the less specific 128.8.0.0/15 to outside world, but exchanging more specifics between each other. This form of aggregation is useful when some of the components are within AS1 and some are within AS2.
When a set of routes are aggregated, the intent is to export only the aggregate route and suppress exporting of the more specifics outside the aggregation boundary. However, to satisfy certain policy and topology constraints (e.g. a multi-homed component), it is often required to export some of the components. The export-comps attribute equals an RPSL filter that matches the more specifics that need to be exported outside the aggregation boundary. If this attribute is missing, more specifics are not exported outside the aggregation boundary. Note that, the export-comps filter contains an implicit "AND" term with the more specifics of the aggregate.
Figure 31 shows an example of an outbound aggregation. In this example, the more specific 128.8.8.0/24 is exported outside AS1 in addition to the aggregate. This is useful, when 128.8.8.0/24 is multi-homed site to AS1 with some other AS.
route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY export-comps: {128.8.8.0/24} Figure 31: Outbound aggregation with export exception.The inject attribute specifies which routers perform the aggregation and when they perform it. Its syntax is as follow:
inject:
[at <router-expression>] ... [action <action>] [upon <condition>]where <action> is an action specification (see Section 6.1.1), <condition> is a boolean expression described below, and <router- expression> is as described in Section 5.6.
All routers in <router-expression> and in the aggregator AS perform the aggregation. If a <router-expression> is not specified, all routers inside the aggregator AS perform the aggregation. The <action> specification may set path attributes of the aggregate, such as assign a preferences to the aggregate.
The upon clause is a boolean condition. The aggregate is generated if and only if this condition is true. <condition> is a boolean expression using the logical operators AND and OR (i.e. operator NOT is not allowed) over:
HAVE-COMPONENTS { list of prefixes }
EXCLUDE { list of prefixes }
STATICThe list of prefixes in HAVE-COMPONENTS can only be more specifics of the aggregate. It evaluates to true when all the prefixes listed are present in the routing table of the aggregating router. The list can also include prefix ranges (i.e. using operators ^-, ^+, ^n, and ^n- m). In this case, at least one prefix from each prefix range needs to be present in the routing table for the condition to be true. The list of prefixes in EXCLUDE can be arbitrary. It evaluates to true when none of the prefixes listed is present in the routing table. The list can also include prefix ranges, and no prefix in that range should be present in the routing table. The keyword static always evaluates to true. If no upon clause is specified the aggregate is generated if an only if there is a component in the routing table (i.e. a more specific that matches the filter in the components attribute).
route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY inject: at 1.1.1.1 action dpa = 100; inject: at 1.1.1.2 action dpa = 110; route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY inject: upon HAVE-COMPONENTS {128.8.0.0/16, 128.9.0.0/16} holes: 128.8.8.0/24
Figure 32: Examples of inject.
-
Figure 32 shows two examples. In the first case, the aggregate is injected at two routers each one setting the dpa path attribute differently. In the second case, the aggregate is generated only if both 128.8.0.0/16 and 128.9.0.0/16 are present in the routing table, as opposed to the first case where the presence of just one of them is sufficient for injection.
The holes attribute lists the component address prefixes which are not reachable through the aggregate route (perhaps that part of the address space is unallocated). The holes attribute is useful for diagnosis purposes. In Figure 32, the second example has a hole, namely 128.8.8.0/24. This may be due to a customer changing providers and taking this part of the address space with it.
8.1.1 Interaction with policies in aut-num class
-
An aggregate formed is announced to other ASes only if the export policies of the AS allows exporting the aggregate. When the aggregate is formed, the more specifics are suppressed from being exported except to the ASes in aggr-bndry and except the components in export-comps. For such exceptions to happen, the export policies of the AS should explicitly allow exporting of these exceptions.
If an aggregate is not formed (due to the upon clause), then the more specifics of the aggregate can be exported to other ASes, but only if the export policies of the AS allows it. In other words, before a route (aggregate or more specific) is exported it is filtered twice, once based on the route objects, and once based on the export policies of the AS.
route: 128.8.0.0/16 origin: AS1 route: 128.9.0.0/16 origin: AS1 route: 128.8.0.0/15 origin: AS1 aggr-bndry: AS1 or AS2 or AS3 aggr-mtd: outbound AS3 or AS4 or AS5 components: {128.8.0.0/16, 128.9.0.0/16} inject: upon HAVE-COMPONENTS {128.9.0.0/16, 128.8.0.0/16} aut-num: AS1 export: to AS2 announce AS1 export: to AS3 announce AS1 and not {128.9.0.0/16} export: to AS4 announce AS1 export: to AS5 announce AS1 export: to AS6 announce AS1
Figure 33: Interaction with policies in aut-num class.
-
In Figure 33 shows an interaction example. By examining the route objects, the more specifics 128.8.0.0/16 and 128.9.0.0/16 should be exchanged between AS1, AS2 and AS3 (i.e. the aggregation boundary). Outbound aggregation is done to AS4 and AS5 and not to AS3, since AS3 is in the aggregation boundary. The aut-num object allows exporting both components to AS2, but only the component 128.8.0.0/16 to AS3. The aggregate can only be formed if both components are available. In this case, only the aggregate is announced to AS4 and AS5. However, if one of the components is not available the aggregate will not be formed, and any available component or more specific will be exported to AS4 and AS5. Regardless of aggregation is performed or not, only the more specifics will be exported to AS6 (it is not listed in the aggr-mtd attribute).
When doing an inbound aggregation, configuration generators may eliminating the aggregation statements on routers where import policy of the AS prohibits importing of any more specifics.
8.1.2 Ambiguity resolution with overlapping aggregates
-
When several aggregate routes are specified and they overlap, i.e. one is less specific of the other, they must be evaluated more specific to less specific order. When an outbound aggregation is performed for a peer, the aggregate and the components listed in the export-comps attribute for that peer are available for generating the next less specific aggregate. The components that are not specified in the export-comps attribute are not available. A route is exportable to an AS if it is the least specific aggregate exportable to that AS or it is listed in the export-comps attribute of an exportable route. Note that this is a recursive definition.
route: 128.8.0.0/15 origin: AS1 aggr-bndry: AS1 or AS2 aggr-mtd: outbound inject: upon HAVE-COMPONENTS {128.8.0.0/16, 128.9.0.0/16} route: 128.10.0.0/15 origin: AS1 aggr-bndry: AS1 or AS3 aggr-mtd: outbound inject: upon HAVE-COMPONENTS {128.10.0.0/16, 128.11.0.0/16} export-comps: {128.11.0.0/16} route: 128.8.0.0/14 origin: AS1 aggr-bndry: AS1 or AS2 or AS3 aggr-mtd: outbound inject: upon HAVE-COMPONENTS {128.8.0.0/15, 128.10.0.0/15} export-comps: {128.10.0.0/15}
Figure 34: Overlapping aggregations.
-
In Figure 34, AS1 together with AS2 aggregates 128.8.0.0/16 and 128.9.0.0/16 into 128.8.0.0/15. Together with AS3, AS1 aggregates 128.10.0.0/16 and 128.11.0.0/16 into 128.10.0.0/15. But altogether they aggregate these four routes into 128.8.0.0/14. Assuming all four components are available, a router in AS1 for an outside AS, say AS4, will first generate 128.8.0.0/15 and 128.10.0.0/15. This will make 128.8.0.0/15, 128.10.0.0/15 and its exception 128.11.0.0/16 available for generating 128.8.0.0/14. The router will then generate 128.8.0.0/14 from these three routes. Hence for AS4, 128.8.0.0/14 and its exception 128.10.0.0/15 and its exception 128.11.0.0/16 will be exportable.
For AS2, a router in AS1 will only generate 128.10.0.0/15. Hence, 128.10.0.0/15 and its exception 128.11.0.0/16 will be exportable. Note that 128.8.0.0/16 and 128.9.0.0/16 are also exportable since they did not participate in an aggregate exportable to AS2.
Similarly, for AS3, a router in AS1 will only generate 128.8.0.0/15. In this case 128.8.0.0/15, 128.10.0.0/16, 128.11.0.0/16 are exportable.
8.2 Specifying Static Routes
-
The inject attribute can be used to specify static routes by using "upon static" as the condition:
inject:
[at <router-expression>] ... [action <action>] upon staticIn this case, the routers in <router-expression> executes the <action> and injects the route to the interAS routing system statically. <action> may set certain route attributes such as a next-hop router or a cost.
In the following example, the router 7.7.7.1 injects the route 128.7.0.0/16. The next-hop routers (in this example, there are two next-hop routers) for this route are 7.7.7.2 and 7.7.7.3 and the route has a cost of 10 over 7.7.7.2 and 20 over 7.7.7.3.
route: 128.7.0.0/16 origin: AS1 inject: at 7.7.7.1 action next-hop = 7.7.7.2; cost = 10; upon static inject: at 7.7.7.1 action next-hop = 7.7.7.3; cost = 20; upon static
9 inet-rtr Class
Routers are specified using the inet-rtr class. The attributes of the inet-rtr class are shown in Figure 35. The inet-rtr attribute is a valid DNS name of the router described. Each alias attribute, if present, is a canonical DNS name for the router. The local-as attribute specifies the AS number of the AS which owns/operates this router.
-
Attribute Value Type inet-rtr <dns-name> mandatory, single-valued, class key alias <dns-name> optional, multi-valued local-as <as-number> mandatory, single-valued ifaddr see description in text mandatory, multi-valued peer see description in text optional, multi-valued member-of list of <rtr-set-names> optional, multi-valued
Figure 35: inet-rtr Class Attributes
-
The value of an ifaddr attribute has the following syntax:
<ipv4-address> masklen <integer> [action <action>]
The IP address and the mask length are mandatory for each interface. Optionally an action can be specified to set other parameters of this interface.
Figure 36 presents an example inet-rtr object. The name of the router is "amsterdam.ripe.net". "amsterdam1.ripe.net" is a canonical name for the router. The router is connected to 4 networks. Its IP addresses and mask lengths in those networks are specified in the ifaddr attributes.
inet-rtr: Amsterdam.ripe.net alias: amsterdam1.ripe.net local-as: AS3333 ifaddr: 192.87.45.190 masklen 24 ifaddr: 192.87.4.28 masklen 24 ifaddr: 193.0.0.222 masklen 27 ifaddr: 193.0.0.158 masklen 27 peer: BGP4 192.87.45.195 asno(AS3334), flap_damp() Figure 36: inet-rtr ObjectsEach peer attribute, if present, specifies a protocol peering with another router. The value of a peer attribute has the following syntax:
<protocol> <ipv4-address> <options> | <protocol> <inet-rtr-name> <options> | <protocol> <rtr-set-name> <options> | <protocol> <peering-set-name> <options>
where <protocol> is a protocol name, <ipv4-address> is the IP address of the peer router, and <options> is a comma separated list of peering options for <protocol>. Instead of the peer's IP address, its inet-rtr-name can be used. Possible protocol names and attributes are defined in the dictionary (please see Section 7). In the above example, the router has a BGP peering with the router 192.87.45.195 in AS3334 and turns the flap damping on when importing routes from this router.
Instead of a single peer, a group of peers can be specified by using the <rtr-set-name> and <peering-set-name> forms. If <peering-set- name> form is being used only the peerings in the corresponding peering set that are with this router are included. Figure 37 shows an example inet-rtr object with peering groups.
rtr-set: rtrs-ibgp-peers members: 1.1.1.1, 2.2.2.2, 3.3.3.3 peering-set: prng-ebgp-peers peering: AS3334 192.87.45.195 peering: AS3335 192.87.45.196 inet-rtr: Amsterdam.ripe.net alias: amsterdam1.ripe.net local-as: AS3333 ifaddr: 192.87.45.190 masklen 24 ifaddr: 192.87.4.28 masklen 24 ifaddr: 193.0.0.222 masklen 27 ifaddr: 193.0.0.158 masklen 27 peer: BGP4 rtrs-ibgp-peers asno(AS3333), flap_damp() peer: BGP4 prng-ebgp-peers asno(PeerAS), flap_damp() Figure 37: inet-rtr Object with peering groups
10 Extending RPSL
-
Our experience with earlier routing policy languages and data formats (PRDB [2], RIPE-81 [8], and RIPE-181 [7]) taught us that RPSL had to be extensible. As a result, extensibility was a primary design goal for RPSL. New routing protocols or new features to existing routing protocols can be easily handled using RPSL's dictionary class. New classes or new attributes to the existing classes can also be added.
This section provides guidelines for extending RPSL. These guidelines are designed with an eye toward maintaining backward compatibility with existing tools and databases. We next list the available options for extending RPSL from the most preferred to the least preferred order.
10.1 Extensions by changing the dictionary class
-
The dictionary class is the primary mechanism provided to extend RPSL. Dictionary objects define routing policy attributes, types, and routing protocols.
We recommend updating the RPSL dictionary to include appropriate rp- attribute and protocol definitions as new path attributes or router features are introduced. For example, in an earlier version of the RPSL document, it was only possible to specify that a router performs route flap damping on a peer, but it was not possible to specify the parameters of route flap damping. Later the parameters were added by changing the dictionary.
When changing the dictionary, full compatibility should be maintained. For example, in our flap damping case, we made the parameter specification optional in case this level of detail was not desired by some ISPs. This also achieved compatibility. Any object registered without the parameters will continue to be valid. Any tool based on RPSL is expected to do a default action on routing policy attributes that they do not understand (e.g. issue a warning and otherwise ignore). Hence, old tools upon encountering a flap damping specification with parameters will ignore the parameters.
10.2 Extensions by adding new attributes to existing classes
-
New attributes can be added to any class. To ensure full compatibility, new attributes should not contradict the semantics of the objects they are attached to. Any tool that uses the IRR should be designed so that it ignores attributes that it doesn't understand. Most existing tools adhere to this design principle.
We recommend adding new attributes to existing classes when a new aspect of a class is discovered. For example, RPSL route class extends its RIPE-181 predecessor by including several new attributes that enable aggregate and static route specification.
10.3 Extensions by adding new classes
-
New classes can be added to RPSL to store new types of policy data. Providing full compatibility is straight forward as long as existing classes are still understood. Since a tool should only query the IRR for the classes that it understand, full compatibility should not be a problem in this case.
Before adding a new class, one should question if the information contained in the objects of the new class could have better belonged to some other class. For example, if the geographic location of a router needs to be stored in IRR, it may be tempting to add a new class called, say router-location class. However, the information better belongs to the inet-rtr class, perhaps in a new attribute called location.
10.4 Extensions by changing the syntax of existing RPSL attributes
-
If all of the methods described above fail to provide the desired extension, it may be necessary to change the syntax of RPSL. Any change in RPSL syntax must provide backwards compatibility, and should be considered only as a last resort since full compatibility may not be achievable. However, we require that the old syntax to be still valid.
11 Security Considerations
-
This document describes RPSL, a language for expressing routing policies. The language defines a maintainer (mntner class) object which is the entity which controls or "maintains" the objects stored in a database expressed by RPSL. Requests from maintainers can be authenticated with various techniques as defined by the "auth" attribute of the maintainer object.
The exact protocols used by IRR's to communicate RPSL objects is beyond the scope of this document, but it is envisioned that several techniques may be used, ranging from interactive query/update protocols to store and forward protocols similar to or based on electronic mail (or even voice telephone calls). Regardless of which protocols are used in a given situation, it is expected that appropriate security techniques such as IPSEC, TLS or PGP/MIME will be utilized.
12 Acknowledgements
-
We would like to thank Jessica Yu, Randy Bush, Alan Barrett, Bill Manning, Sue Hares, Ramesh Govindan, Kannan Varadhan, Satish Kumar, Craig Labovitz, Rusty Eddy, David J. LeRoy, David Whipple, Jon Postel, Deborah Estrin, Elliot Schwartz, Joachim Schmitz, Mark Prior, Tony Przygienda, David Woodgate, Rob Coltun, Sanjay Wadhwa, Ardas Cilingiroglu, and the participants of the IETF RPS Working Group for various comments and suggestions.
References
-
[1] Internet routing registry. procedures.
http://www.ra.net/RADB.tools.docs/, http://www.ripe.net/db/doc.html. [2] Nsfnet policy routing database (prdb). Maintained by MERIT Network Inc., Ann Arbor, Michigan. Contents available from nic.merit.edu.:/nsfnet/announced.networks/nets.tag.now by anonymous ftp. [3] Alaettinouglu, C., Bates, T., Gerich, E., Karrenberg, D., Meyer, D., Terpstra, M. and C. Villamizer, "Routing Policy Specification Language (RPSL)", RFC 2280, January 1998. [4] C. Alaettinouglu, D. Meyer, and J. Schmitz. Application of routing policy specification language (rpsl) on the internet. Work in Progress.[5] T. Bates. Specifying an `internet router' in the routing
registry. Technical Report RIPE-122, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994. [6] T. Bates, E. Gerich, L. Joncheray, J-M. Jouanigot, D. Karrenberg, M. Terpstra, and J. Yu. Representation of ip routing policies in a routing registry. Technical Report ripe-181, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994. [7] Bates, T., Gerich, E., Joncheray, L., Jouanigot, J-M., Karrenberg, D., Terpstra, M. and J. Yu, " Representation of IP Routing Policies in a Routing Registry", RFC 1786, March 1995.[8] T. Bates, J-M. Jouanigot, D. Karrenberg, P. Lothberg, and M.
-
Terpstra. Representation of ip routing policies in the ripe database. Technical Report ripe-81, RIPE, RIPE NCC, Amsterdam, Netherlands, February 1993.
[9] Chandra, R., Traina, P. and T. Li, "BGP Communities Attribute", RFC 1997, August 1996. [10] Crocker, D., "Standard for ARPA Internet Text Messages", STD 11, RFC 822, August 1982. [11] Fuller, V., Li, T., Yu, J. and K. Varadhan, "Classless Inter- Domain Routing (CIDR): an Address Assignment and Aggregation Strategy", RFC 1519, September 1993. [12] D. Karrenberg and T. Bates. Description of inter-as networks in the ripe routing registry. Technical Report RIPE-104, RIPE, RIPE NCC, Amsterdam, Netherlands, December 1993. [13] D. Karrenberg and M. Terpstra. Authorisation and notification of changes in the ripe database. Technical Report ripe-120, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994.[14] B. W. Kernighan and D. M. Ritchie. The C Programming Language.
-
Prentice-Hall, 1978.
[15] A. Lord and M. Terpstra. Ripe database template for networks and
persons. Technical Report ripe-119, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994. [16] A. M. R. Magee. Ripe ncc database documentation. Technical Report RIPE-157, RIPE, RIPE NCC, Amsterdam, Netherlands, May 1997. [17] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, November 1987. [18] Y. Rekhter. Inter-domain routing protocol (idrp). Journal of Internetworking Research and Experience, 4:61--80, 1993. [19] Rekhter Y. and T. Li, "A Border Gateway Protocol 4 (BGP-4)", RFC 1771, March 1995.[20] C. Villamizar, C. Alaettinouglu, D. Meyer, S. Murphy, and C.
-
Orange. Routing policy system security", Work in Progress.
[21] Villamizar, C., Chandra, R. and R. Govindan, "BGP Route Flap Damping", RFC 2439, November 1998. [22] J. Zsako, "PGP authentication for ripe database updates", Work in Progress.
A Routing Registry Sites
-
The set of routing registries as of November 1996 are RIPE, RADB, CANet, MCI and ANS. You may contact one of these registries to find out the current list of registries.
B Grammar Rules
-
In this section we provide formal grammar rules for RPSL. Basic data types are defined in Section 2. We do not provide formal grammar rules for attributes whose values are of basic types or list of basic types. The rules are written using the input language of GNU Bison parser. Hence, they can be cut and pasted to that program.
//**** Generic Attributes **********************************************
changed_attribute: ATTR_CHANGED TKN_EMAIL TKN_INT
//**** aut-num class ***************************************************
//// as_expression /////////////////////////////////////////////////////
opt_as_expression:
| as_expression
as_expression: as_expression OP_OR as_expression_term
| as_expression_term
as_expression_term: as_expression_term OP_AND as_expression_factor | as_expression_term KEYW_EXCEPT as_expression_factor | as_expression_factor
as_expression_factor: '(' as_expression ')'
| as_expression_operand
as_expression_operand: TKN_ASNO
| TKN_ASNAME
//// router_expression /////////////////////////////////////////////////
opt_router_expression:
| router_expression
opt_router_expression_with_at:
| KEYW_AT router_expression
router_expression: router_expression OP_OR router_expression_term
| router_expression_term
router_expression_term: router_expression_term OP_AND
router_expression_factor
| router_expression_term KEYW_EXCEPT router_expression_factor
| router_expression_factor
router_expression_factor: '(' router_expression ')'
| router_expression_operand
router_expression_operand: TKN_IPV4 | TKN_DNS | TKN_RTRSNAME
//// peering ///////////////////////////////////////////////////////////
peering: as_expression opt_router_expression opt_router_expression_with_at
| TKN_PRNGNAME
//// action ////////////////////////////////////////////////////////////
opt_action:
| KEYW_ACTION action
action: single_action
| action single_action
single_action: TKN_RP_ATTR '.' TKN_WORD '(' generic_list ')' ';'
| TKN_RP_ATTR TKN_OPERATOR list_item ';'
| TKN_RP_ATTR '(' generic_list ')' ';'
| TKN_RP_ATTR '[' generic_list ']' ';'
| ';'
//// filter ////////////////////////////////////////////////////////////
filter: filter OP_OR filter_term
| filter filter_term %prec OP_OR
| filter_term
filter_term : filter_term OP_AND filter_factor
| filter_factor
filter_factor : OP_NOT filter_factor
| '(' filter ')'
| filter_operand
filter_operand: KEYW_ANY
| '<' filter_aspath '>'
| filter_rp_attribute
| TKN_FLTRNAME
| filter_prefix
filter_prefix: filter_prefix_operand OP_MS
| filter_prefix_operand
filter_prefix_operand: TKN_ASNO
| KEYW_PEERAS
| TKN_ASNAME
| TKN_RSNAME
| '{' opt_filter_prefix_list '}'
opt_filter_prefix_list:
| filter_prefix_list
filter_prefix_list: filter_prefix_list_prefix
| filter_prefix_list ',' filter_prefix_list_prefix
filter_prefix_list_prefix: TKN_PRFXV4
| TKN_PRFXV4RNG
filter_aspath: filter_aspath '|' filter_aspath_term
| filter_aspath_term
filter_aspath_term: filter_aspath_term filter_aspath_closure
| filter_aspath_closure
filter_aspath_closure: filter_aspath_closure '*'
| filter_aspath_closure '?'
| filter_aspath_closure '+'
| filter_aspath_factor
filter_aspath_factor: '^'
| '$'
| '(' filter_aspath ')'
| filter_aspath_no
filter_aspath_no: TKN_ASNO
| KEYW_PEERAS
| TKN_ASNAME
| '.'
| '[' filter_aspath_range ']'
| '[' '^' filter_aspath_range ']'
filter_aspath_range:
| filter_aspath_range TKN_ASNO
| filter_aspath_range KEYW_PEERAS
| filter_aspath_range '.'
| filter_aspath_range TKN_ASNO '-' TKN_ASNO
| filter_aspath_range TKN_ASNAME
filter_rp_attribute: TKN_RP_ATTR '.' TKN_WORD '(' generic_list ')'
| TKN_RP_ATTR TKN_OPERATOR list_item
| TKN_RP_ATTR '(' generic_list ')'
| TKN_RP_ATTR '[' generic_list ']'
//// peering action pair ///////////////////////////////////////////////
import_peering_action_list: KEYW_FROM peering opt_action
| import_peering_action_list KEYW_FROM peering opt_action
export_peering_action_list: KEYW_TO peering opt_action
| export_peering_action_list KEYW_TO peering opt_action
//// import/export factor //////////////////////////////////////////////
import_factor: import_peering_action_list KEYW_ACCEPT filter
import_factor_list: import_factor ';'
| import_factor_list import_factor ';'
export_factor: export_peering_action_list KEYW_ANNOUNCE filter
export_factor_list: export_factor ';'
| export_factor_list export_factor ';'
//// import/export term ////////////////////////////////////////////////
import_term: import_factor ';'
| '{' import_factor_list '}'
export_term: export_factor ';'
| '{' export_factor_list '}'
//// import/export expression //////////////////////////////////////////
import_expression: import_term
| import_term KEYW_REFINE import_expression
| import_term KEYW_EXCEPT import_expression
export_expression: export_term
| export_term KEYW_REFINE export_expression
| export_term KEYW_EXCEPT export_expression
//// protocol ///////////////////////////////////////////////////////////
opt_protocol_from:
| KEYW_PROTOCOL tkn_word
opt_protocol_into:
| KEYW_INTO tkn_word
//**** import/export attributes ****************************************
import_attribute: ATTR_IMPORT
| ATTR_IMPORT opt_protocol_from opt_protocol_into import_factor
export_attribute: ATTR_EXPORT
| ATTR_EXPORT opt_protocol_from opt_protocol_into export_factor
opt_default_filter:
| KEYW_NETWORKS filter
default_attribute: ATTR_DEFAULT KEYW_TO peering
filter_attribute: ATTR_FILTER filter
peering_attribute: ATTR_PEERING peering
//**** inet-rtr class **************************************************
ifaddr_attribute: ATTR_IFADDR TKN_IPV4 KEYW_MASKLEN TKN_INT opt_action
//// peer attribute ////////////////////////////////////////////////////
opt_peer_options:
| peer_options
peer_options: peer_option
| peer_options ',' peer_option
peer_option: tkn_word '(' generic_list ')'
peer_id: TKN_IPV4 | TKN_DNS | TKN_RTRSNAME | TKN_PRNGNAME
peer_attribute: ATTR_PEER tkn_word peer_id opt_peer_options
//**** route class *****************************************************
aggr_bndry_attribute: ATTR_AGGR_BNDRY as_expression
aggr_mtd_attribute: ATTR_AGGR_MTD KEYW_INBOUND
| ATTR_AGGR_MTD KEYW_OUTBOUND opt_as_expression
//// inject attribute //////////////////////////////////////////////////
opt_inject_expression:
| KEYW_UPON inject_expression
inject_expression: inject_expression OP_OR inject_expression_term
| inject_expression_term
inject_expression_term: inject_expression_term OP_AND
inject_expression_factor
| inject_expression_factor
inject_expression_factor: '(' inject_expression ')'
| inject_expression_operand
inject_expression_operand: KEYW_STATIC
| KEYW_HAVE_COMPONENTS '{' opt_filter_prefix_list '}'
| KEYW_EXCLUDE '{' opt_filter_prefix_list '}'
inject_attribute: ATTR_INJECT opt_router_expression_with_at opt_action
opt_inject_expression
//// components attribute //////////////////////////////////////////////
opt_atomic:
| KEYW_ATOMIC
components_list:
| filter
| components_list KEYW_PROTOCOL tkn_word filter
components_attribute: ATTR_COMPONENTS opt_atomic components_list
//**** route-set *******************************************************
opt_rs_members_list: /* empty list */
| rs_members_list
rs_members_list: rs_member
| rs_members_list ',' rs_member
rs_member: TKN_ASNO
| TKN_ASNO OP_MS
| TKN_ASNAME
| TKN_ASNAME OP_MS
| TKN_RSNAME
| TKN_RSNAME OP_MS
| TKN_PRFXV4
| TKN_PRFXV4RNG
rs_members_attribute: ATTR_RS_MEMBERS opt_rs_members_list
//**** dictionary ******************************************************
rpattr_attribute: ATTR_RP_ATTR TKN_WORD methods
| ATTR_RP_ATTR TKN_RP_ATTR methods
methods: method
| methods method
method: TKN_WORD '(' ')'
| TKN_WORD '(' typedef_type_list ')'
| TKN_WORD '(' typedef_type_list ',' TKN_3DOTS ')'
| KEYW_OPERATOR TKN_OPERATOR '(' typedef_type_list ')'
| KEYW_OPERATOR TKN_OPERATOR '(' typedef_type_list ',' TKN_3DOTS ')'
//// typedef attribute ////////////////////////////////////////////////
typedef_attribute: ATTR_TYPEDEF TKN_WORD typedef_type
typedef_type_list: typedef_type
| typedef_type_list ',' typedef_type
typedef_type: KEYW_UNION typedef_type_list
| KEYW_RANGE KEYW_OF typedef_type
| TKN_WORD
| TKN_WORD '[' TKN_INT ',' TKN_INT ']'
| TKN_WORD '[' TKN_REAL ',' TKN_REAL ']'
| TKN_WORD '[' enum_list ']'
| KEYW_LIST '[' TKN_INT ':' TKN_INT ']' KEYW_OF typedef_type
| KEYW_LIST KEYW_OF typedef_type
enum_list: tkn_word
| enum_list ',' tkn_word
//// protocol attribute ////////////////////////////////////////////////
protocol_attribute: ATTR_PROTOCOL tkn_word protocol_options
protocol_options:
| protocol_options protocol_option
protocol_option: KEYW_MANDATORY method
| KEYW_OPTIONAL method
//**** Token Definitions ***********************************************
//// flex macros used in token definitions /////////////////////////////
INT [[:digit:]]+
SINT [+-]?{INT}
REAL [+-]?{INT}?\.{INT}({WS}*E{WS}*[+-]?{INT})?
NAME [[:alpha:]]([[:alnum:]_-]*[[:alnum:]])?
ASNO AS{INT}
ASNAME AS-[[:alnum:]_-]*[[:alnum:]]
RSNAME RS-[[:alnum:]_-]*[[:alnum:]]
RTRSNAME RTRS-[[:alnum:]_-]*[[:alnum:]]
PRNGNAME PRNG-[[:alnum:]_-]*[[:alnum:]]
FLTRNAME FLTR-[[:alnum:]_-]*[[:alnum:]]
IPV4 [0-9]+(\.[0-9]+){3,3}
PRFXV4 {IPV4}\/[0-9]+
PRFXV4RNG {PRFXV4}("^+"|"^-"|"^"{INT}|"^"{INT}-{INT})
ENAMECHAR [^()<>,;:\\\"\.[\] \t\r]
ENAME ({ENAMECHAR}+(\.{ENAMECHAR}+)*\.?)|(\"[^\"@\\\r\n]+\")
DNAME [[:alnum:]_-]+
//// Token Definitions ////////////////////////////////////////////////
TKN_INT {SINT}
TKN_INT {INT}:{INT} if each {INT} is two octets
TKN_INT {INT}.{INT}.{INT}.{INT} if each {INT} is one octet
TKN_REAL {REAL}
TKN_STRING Same as in programming language C
TKN_IPV4 {IPV4}
TKN_PRFXV4 {PRFXV4}
TKN_PRFXV4RNG {PRFXV4RNG}
TKN_ASNO {ASNO}
TKN_ASNAME (({ASNO}|peeras|{ASNAME}):)*{ASNAME}\
(:({ASNO}|peeras|{ASNAME}))*
TKN_RSNAME (({ASNO}|peeras|{RSNAME}):)*{RSNAME}\
(:({ASNO}|peeras|{RSNAME}))*
TKN_RTRSNAME (({ASNO}|peeras|{RTRSNAME}):)*{RTRSNAME}\
(:({ASNO}|peeras|{RTRSNAME}))*
TKN_PRNGNAME (({ASNO}|peeras|{PRNGNAME}):)*{PRNGNAME}\
(:({ASNO}|peeras|{PRNGNAME}))*
TKN_FLTRNAME (({ASNO}|peeras|{FLTRNAME}):)*{FLTRNAME}\
(:({ASNO}|peeras|{FLTRNAME}))*
TKN_BOOLEAN true|false
TKN_RP_ATTR {NAME} if defined in dictionary
TKN_WORD {NAME}
TKN_DNS {DNAME}("."{DNAME})+
TKN_EMAIL {ENAME}@({DNAME}("."{DNAME})+|{IPV4})
C Changes from RFC 2280
-
RFC 2280 [3] contains an earlier version of RPSL. This section summarizes the changes since then. They are as follows:
- It is now possible to write integers as sequence of four 1-octet integers (e.g. 1.1.1.1) or as sequence of two 2-octet integers (e.g. 3561:70). Please see Section 2.
- The definition of address prefix range is extended so that an address prefix is also an address prefix range. Please see Section 2.
- The semantics for a range operator applied to a set containing address prefix ranges is defined (e.g. {30.0.0.0/8^24-28}^27-30). Please see Section 2.
- All dates are now in UTC. Please see Section 2.
- Plus ('+') character is added to space and tab characters to split an attribute's value to multiple lines (i.e. by starting the following lines with a space, a tab or a plus ('+') character). Please see Section 2.
- The withdrawn attribute of route class is removed from the language.
- filter-set class is introduced. Please see Section 5.4.
- rtr-set class is introduced. Please see Section 5.5.
- peering-set class is introduced. Please see Section 5.6.
- Filters can now refer to filter-set names. Please see Section 5.4.
- Peerings can now refer to peering-set, rtr-set names. Both local and peer routers can be specified using router expressions. Please see Section 5.6.
- The peer attribute of the inet-rtr class can refer to peering-set, rtr-set names. Please see Section 9.
- The syntax and semantics of union, and list types and typedef attribute have changed. Please see Section 7.
- In the initial dictionary, the typedef attribute defining the community_elm, rp-attribute defining the community attribute has changed. Please see Section 7.
- Guideliness for extending RPSL is added. Please see Section 10.
- Formal grammar rules are added. Please see Appendix B.
D Authors' Addresses
-
Cengiz Alaettinoglu
USC/Information Sciences InstituteEMail:
cengiz@isi.edu
Curtis Villamizar
Avici SystemsEMail:
curtis@avici.com
Elise Gerich
At Home NetworkEMail:
epg@home.net
David Kessens
Qwest CommunicationsEMail: David.Kessens@qwest.net
David Meyer
University of OregonEMail: meyer@antc.uoregon.edu
Tony Bates
Cisco Systems, Inc.EMail:
tbates@cisco.com
Daniel Karrenberg
RIPE NCCEMail:
dfk@ripe.net
Marten Terpstra
c/o Bay Networks, Inc.EMail:
marten@BayNetworks.com
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Acknowledgement
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Funding for the RFC Editor function is currently provided by the Internet Society.