ADDRESS TABLES

Attached is a copy of a revision to Appendix A of BBN Report No. 1822; the revised version of the Appendix is our first attempt to make the list of sites attached to the ARPA Network prospective rather than retrospective. We are adopting this approach because of the large number of sites scheduled for attachment in the near future, and because many Hosts apparently require a site's address to be in some local table before their NCPs will permit communication with the site. Therefore, we urge such Hosts to add the new sites to their lists of addresses as soon as possible. Also, please note the address change which will be made at BBN on exactly September first.

Incidentally, it seems to us that it is irrational for an NCP to discard otherwise valid messages, simply because the sender's address doesn't appear in a local table. Similarly, it seems almost as irrational for an NCP to prevent a local user from trying to communicate with a remote site, the address of which is known to the user but not stored in the NCP's tables.

Report No. 1822 Bolt Beranek and Newman Inc.

APPENDIX A

IMP AND HOST SITE IDENTIFICATION

Bit 9-16 of the leader of most Host-to-IMP or IMP-to-Host messages define a network address related to the message (these bits are not meaningful for message types 1, 2, and 4). In a Host-to-IMP message the network address identifies a particular Host to which the message should be delivered. In an IMP-to-Host message the network address identifies the Host from which the message originated.

A network address consists of six bits (bits 11-16 of the leader) which specify an IMP number, preceded by two bits (bits 9-10 of the leader) which specify the Host number of a particular Host connected to that IMP. The table below gives the decimal values of IMP number, Host number, and network address for each Host currently connected to the ARPA Network or scheduled for connection in the near future. Scheduled installation dates are also shown for Hosts not currently connected; these dates, however, are subject to change without notice.

    IMP      SITE     HOST                    NETWORK    SCHEDULED
   NUMBER    NAME    NUMBER       HOST        ADDRESS   INSTALLATION
   ------    ----    ------       ----        -------   ------------
     1       UCLA      0       SIGMA-7           1
                       1       IBM 360/91       65
     2       SRI       0       PDP-10 (NIC)      2
                       1       PDP-10 (Al)      66
     3       UCSB      0       IBM 360/75        3
     4       UTAH      0       PDP-lO            4
     5       BBN       0       DDP-516           5  )   See Note 1
                       1       PDP-10 (A)       69  )
                       2       PDP-1O (B)      133

Note 1: Prior to September 1, 1971 the BBN PDP-1O (A) will be Host number 0 (network address 5) and the BBN DDP-516 will be Host number 1 (network address 69). The address change is to be made during the day on 9/1/71.

 IMP       SITE       HOST                      NETWORK     SCHEDULE
NUMBER     NAME      NUMBER      HOST           ADDRESS   INSTALLATION
------     ----      ------      ----           -------   ------------
  6        MIT          0       Honeywell 645        6
                        1       PDP-10              70
  7        RAND         O       360/65               7
                        1       PDP-1O              71
  8        SDC          O       IBM 360/75           8
  9        HARVARD      O       PDP-1O               9
                        1       PDP-1               73
                        2       PDP-11             137
 10        LINCOLN      O       IBM 360/67          10
                        1       TX2                 74
 11        STANFORD     O       PDP-1O              11
 12        ILLINOIS     O       PDP-11              12
 13        CASE         O       PDP-1O              13
 14        CARNEGIE     O       PDP-1O              14
 15        PAOLI        O       B6500               15
 16        NASA/AMES    O       IBM 360/67          16      8/3/71
                        2       TIP                144
 17        MITRE        2       TIP                145      8/31/71
 18        RADC         O       H 635/645           18      10/5/71
                        2       TIP                146
 19        NBS          O       PDP-11              19      11/2/71
 20        ETAC         2       TIP                148      11/30/71
 21        TINKER       O       418 III             21      1/4/71
 22        McCLELLAN    O       418 III             22      2/1/72
 23        USC          0       IBM 360/44          23      2/29/72
                        2       TIP                151
 24        GWC          2       TIP                152      3/14/72
 25        NCAR         O       CDC 7600            25      3/28/72
                        2       TIP                153
 30        BBN/TIP      2       TIP                158