FTP Software, Inc.
June 1993
The Definitions of Managed Objects for
the IP Network Control Protocol of
the Point-to-Point Protocol
Status of this Memo
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This RFC specifies an IAB standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Abstract
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This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in TCP/IP-based internets. In particular, it describes managed objects used for managing the IP Network Control Protocol on subnetwork interfaces using the family of Point-to-Point Protocols [8, 9, 10, 11, & 12].
Table of Contents
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1. The Network Management Framework ...................... 1 2. Objects ............................................... 2 2.1 Format of Definitions ................................ 2 3. Overview .............................................. 2 3.1 Object Selection Criteria ............................ 2 3.2 Structure of the PPP ................................. 2 3.3 MIB Groups ........................................... 3 4. Definitions ........................................... 4 5. Acknowledgements ...................................... 8 6. Security Considerations ............................... 8 7. References ............................................ 8 8. Author's Address ...................................... 9
1. The Network Management Framework
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The Internet-standard Network Management Framework consists of three components. They are:
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STD 16/RFC 1155 which defines the SMI, the mechanisms used for describing and naming objects for the purpose of management. STD 16/RFC 1212 defines a more concise description mechanism, which is wholly consistent with the SMI.
STD 17/RFC 1213 which defines MIB-II, the core set of managed objects for the Internet suite of protocols.
STD 15/RFC 1157 which defines the SNMP, the protocol used for network access to managed objects.
The Framework permits new objects to be defined for the purpose of experimentation and evaluation.
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2. Objects
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Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. Objects in the MIB are defined using the subset of Abstract Syntax Notation One (ASN.1) [3] defined in the SMI. In particular, each object type is named by an OBJECT IDENTIFIER, an administratively assigned name. The object type together with an object instance serves to uniquely identify a specific instantiation of the object. For human convenience, we often use a textual string, termed the descriptor, to refer to the object type.
2.1. Format of Definitions
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Section 4 contains the specification of all object types contained in this MIB module. The object types are defined using the conventions defined in the SMI, as amended by the extensions specified in [5,6].
3. Overview
3.1. Object Selection Criteria
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To be consistent with IAB directives and good engineering practice, an explicit attempt was made to keep this MIB as simple as possible. This was accomplished by applying the following criteria to objects proposed for inclusion:
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(1) Require objects be essential for either fault or
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configuration management. In particular, objects for which the sole purpose was to debug implementations were explicitly excluded from the MIB.
(2) Consider evidence of current use and/or utility.
(3) Limit the total number of objects.
(4) Exclude objects which are simply derivable from others in
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this or other MIBs.
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3.2. Structure of the PPP
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This section describes the basic model of PPP used in developing the PPP MIB. This information should be useful to the implementor in understanding some of the basic design decisions of the MIB.
The PPP is not one single protocol but a large family of protocols. Each of these is, in itself, a fairly complex protocol. The PPP protocols may be divided into three rough categories:
Control Protocols
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The Control Protocols are used to control the operation of the PPP. The Control Protocols include the Link Control Protocol (LCP), the Password Authentication Protocol (PAP), the Link Quality Report (LQR), and the Challenge Handshake Authentication Protocol (CHAP).
Network Protocols
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The Network Protocols are used to move the network traffic over the PPP interface. A Network Protocol encapsulates the datagrams of a specific higher-layer protocol that is using the PPP as a data link. Note that within the context of PPP, the term "Network Protocol" does not imply an OSI Layer-3 protocol; for instance, there is a Bridging network protocol.
Network Control Protocols (NCPs)
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The NCPs are used to control the operation of the Network Protocols. Generally, each Network Protocol has its own Network Control Protocol; thus, the IP Network Protocol has its IP Control Protocol, the Bridging Network Protocol has its Bridging Network Control Protocol and so on.
This document specifies the objects used in managing one of these protocols, namely the IP Network Control Protocol.
3.3. MIB Groups
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Objects in this MIB are arranged into several MIB groups. Each group is organized as a set of related objects.
These groups are the basic unit of conformance: if the semantics of a group are applicable to an implementation then all objects in the group must be implemented.
The PPP MIB is organized into several MIB Groups, including, but not limited to, the following groups:
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o The PPP Link Group
o The PPP LQR Group
o The PPP LQR Extensions Group
o The PPP IP Group
o The PPP Bridge Group
o The PPP Security Group
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This document specifies the following group:
The PPP IP Group
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The PPP IP Group contains configuration, status, and control variables that apply to the operation of IP over PPP.
Implementation of this group is mandatory for all implementations of PPP that support IP over PPP.
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4. Definitions
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PPP-IP-NCP-MIB DEFINITIONS ::= BEGIN
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IMPORTS
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Counter FROM RFC1155-SMI ifIndex FROM RFC1213-MIB OBJECT-TYPE FROM RFC-1212 ppp FROM PPP-LCP-MIB;-
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-- The PPP IP Group.
-- Implementation of this group is mandatory for all -- PPP implementations that support operating IP over PPP.
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pppIp OBJECT IDENTIFIER ::= { ppp 3 }
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pppIpTable OBJECT-TYPE SYNTAX SEQUENCE OF PppIpEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "Table containing the IP parameters and statistics for the local PPP entity." ::= { pppIp 1 } pppIpEntry OBJECT-TYPE SYNTAX PppIpEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "IPCP status information for a particular PPP link." INDEX { ifIndex } ::= { pppIpTable 1 } PppIpEntry ::= SEQUENCE { pppIpOperStatus INTEGER, pppIpLocalToRemoteCompressionProtocol INTEGER, pppIpRemoteToLocalCompressionProtocol INTEGER, pppIpRemoteMaxSlotId INTEGER, pppIpLocalMaxSlotId INTEGER } -- The following object reflect the values of the option -- parameters used in the PPP IP Control Protocol -- pppIpLocalToRemoteCompressionProtocol -- pppIpRemoteToLocalCompressionProtocol -- pppIpRemoteMaxSlotId -- pppIpLocalMaxSlotId -- These values are not available until after the PPP Option -- negotiation has completed, which is indicated by the link -- reaching the open state (i.e., pppIpOperStatus is set to -- opened). -- -- Therefore, when pppIpOperStatus is not opened -- the contents of these objects is undefined. The value -- returned when accessing the objects is an implementation -- dependent issue. pppIpOperStatus OBJECT-TYPE SYNTAX INTEGER {opened(1), not-opened(2)} ACCESS read-only STATUS mandatory DESCRIPTION "The operational status of the IP network protocol. If the value of this object is up then the finite state machine for the IP network protocol has reached the Opened state." ::= { pppIpEntry 1 } pppIpLocalToRemoteCompressionProtocol OBJECT-TYPE SYNTAX INTEGER { none(1), vj-tcp(2) } ACCESS read-only STATUS mandatory DESCRIPTION "The IP compression protocol that the local PPP-IP entity uses when sending packets to the remote PPP-IP entity. The value of this object is meaningful only when the link has reached the open state (pppIpOperStatus is opened)." ::= { pppIpEntry 2 } pppIpRemoteToLocalCompressionProtocol OBJECT-TYPE SYNTAX INTEGER { none(1), vj-tcp(2) } ACCESS read-only STATUS mandatory DESCRIPTION "The IP compression protocol that the remote PPP-IP entity uses when sending packets to the local PPP-IP entity. The value of this object is meaningful only when the link has reached the open state (pppIpOperStatus is opened)." ::= { pppIpEntry 3 } pppIpRemoteMaxSlotId OBJECT-TYPE SYNTAX INTEGER(0..255) ACCESS read-only STATUS mandatory DESCRIPTION "The Max-Slot-Id parameter that the remote node has advertised and that is in use on the link. If vj-tcp header compression is not in use on the link then the value of this object shall be 0. The value of this object is meaningful only when the link has reached the open state (pppIpOperStatus is opened)." ::= { pppIpEntry 4 } pppIpLocalMaxSlotId OBJECT-TYPE SYNTAX INTEGER(0..255) ACCESS read-only STATUS mandatory DESCRIPTION "The Max-Slot-Id parameter that the local node has advertised and that is in use on the link. If vj-tcp header compression is not in use on the link then the value of this object shall be 0. The value of this object is meaningful only when the link has reached the open state (pppIpOperStatus is opened)." ::= { pppIpEntry 5 }-
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--
-- The PPP IP Configuration table.
-- This is a separate table in order to facilitate -- placing these variables in a separate MIB view.
--
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pppIpConfigTable OBJECT-TYPE SYNTAX SEQUENCE OF PppIpConfigEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "Table containing configuration variables for the IPCP for the local PPP entity." ::= { pppIp 2 } pppIpConfigEntry OBJECT-TYPE SYNTAX PppIpConfigEntry ACCESS not-accessible STATUS mandatory DESCRIPTION "IPCP information for a particular PPP link." INDEX { ifIndex } ::= { pppIpConfigTable 1 }-
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PppIpConfigEntry ::= SEQUENCE {
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pppIpConfigAdminStatus INTEGER, pppIpConfigCompression INTEGER } pppIpConfigAdminStatus OBJECT-TYPE SYNTAX INTEGER {open(1), close(2)} ACCESS read-write STATUS mandatory DESCRIPTION "The immediate desired status of the IP network protocol. Setting this object to open will inject an administrative open event into the IP network protocol's finite state machine. Setting this object to close will inject an administrative close event into the IP network protocol's finite state machine." ::= { pppIpConfigEntry 1 } pppIpConfigCompression OBJECT-TYPE SYNTAX INTEGER { none(1), vj-tcp(2) } ACCESS read-write STATUS mandatory DESCRIPTION "If none(1) then the local node will not attempt to negotiate any IP Compression option. Otherwise, the local node will attempt to negotiate compression mode indicated by the enumerated value. Changing this object will have effect when the link is next restarted." REFERENCE "Section 4.0, Van Jacobson TCP/IP Header Compression of RFC1332." DEFVAL { none } ::= { pppIpConfigEntry 2 } END -
5. Acknowledgements
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This document was produced by the PPP working group. In addition to the working group, the author wishes to thank the following individuals for their comments and contributions:
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Bill Simpson -- Daydreamer
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Glenn McGregor -- Merit Jesse Walker -- DEC Chris Gunner -- DEC -
6. Security Considerations
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The PPP MIB affords the network operator the ability to configure and control the PPP links of a particular system, including the PPP authentication protocols. This represents a security risk.
These risks are addressed in the following manners:
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(1) All variables which represent a significant security risk
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are placed in separate, optional, MIB Groups. As the MIB Group is the quantum of implementation within a MIB, the implementor of the MIB may elect not to implement these groups.
(2) The implementor may choose to implement the variables
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which present a security risk so that they may not be written, i.e., the variables are READ-ONLY. This method still presents a security risk, and is not recommended, in that the variables, specifically the PPP Authentication Protocols' variables, may be easily read.
(3) Using SNMPv2, the operator can place the variables into
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MIB views which are protected in that the parties which have access to those MIB views use authentication and privacy protocols, or the operator may elect to make these views not accessible to any party. In order to facilitate this placement, all security-related variables are placed in separate MIB Tables. This eases the identification of the necessary MIB View Subtree.
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7. References
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[1] Rose M., and K. McCloghrie, "Structure and Identification of Management Information for TCP/IP-based internets", STD 16, RFC 1155, Performance Systems International, Hughes LAN Systems, May 1990. [2] McCloghrie K., and M. Rose, Editors, "Management Information Base for Network Management of TCP/IP-based internets", STD 17, RFC 1213, Performance Systems International, March 1991. [3] Information processing systems - Open Systems Interconnection - Specification of Abstract Syntax Notation One (ASN.1), International Organization for Standardization, International-
Standard 8824, December 1987.
[4] Information processing systems - Open Systems Interconnection - Specification of Basic Encoding Rules for Abstract Notation One (ASN.1), International Organization for Standardization, International Standard 8825, December 1987. [5] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions", STD 16, RFC 1212, Performance Systems International, Hughes LAN Systems, March 1991. [6] Rose, M., Editor, "A Convention for Defining Traps for use with the SNMP", RFC 1215, Performance Systems International, March 1991. [7] McCloghrie, K., "Extensions to the Generic-Interface MIB", RFC 1229, Hughes LAN Systems, Inc., May 1991. [8] Simpson, W., "The Point-to-Point Protocol for the Transmission of Multi-protocol Datagrams over Point-to-Point Links, RFC 1331, Daydreamer, May 1992. [9] McGregor, G., "The PPP Internet Protocol Control Protocol", RFC 1332, Merit, May 1992. [10] Baker, F., "Point-to-Point Protocol Extensions for Bridging", RFC 1220, ACC, April 1991. [11] Lloyd, B., and W. Simpson, "PPP Authentication Protocols", RFC 1334, L&A, Daydreamer, October 1992. [12] Simpson, W., "PPP Link Quality Monitoring", RFC 1333, Daydreamer, May 1992. -
8. Author's Address
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Frank Kastenholz
FTP Software, Inc.
2 High Street
North Andover, Mass 01845 USAPhone: (508) 685-4000 EMail: kasten@ftp.com