RFC 381 (rfc381) - Page 2 of 4
Three aids to improved network operation
Alternative Format: Original Text Document
RFC 381 Three Aids To Improved Network Operation 26 July 1972 2. IMP-to-Host Communication There have long been complaints that the IMP-to-Host error messages were not precise enough or were just plain ambiguous. In RFC #312 we proposed some additional error messages. These and other IMP-to-Host message changes will be made on August 14, 1972 and we encourage Hosts to modify their NCP's as appropriate by then. Unmodified NCPs will probably continue to work after this change, but each site should look into this question carefully. The table below lists all the IMP-to-Host messages and clearly indicates the changes which will be made. Type Old Meaning New Meaning 0 Regular Messages Same 1 Error without Error in Leader of Host-to- identification IMP Message Bits 31,32=00 - IMP's error flip-flop set on the first 32 bits of a Host-to-IMP message which the IMP therefore cannot identify Bits 31,32=01 - Host-to-IMP message too short (less than 32 bits) Bits 31,32=10 - illegal Host-to-IMP code 2 IMP Going Down IMP Going Down Bits 17-32 coded as follows: All bits zero - going down in 30 sec. Bits 17,18=01 - scheduled hardware PM Bits 17,18=10 - scheduled software reload Bits 17,18=11 - emergency reload or restart Bits 19-22 - how soon the IMP is going down - in 5 minute units Bits 23-32 - how long the IMP will be down - in 5 minute units 3 Blocked Link Unassigned Mc Quillan, et. al.
