RFC 692

RFC 692: Comments on IMP/Host Protocol Changes (RFCs 687 and 690) ✨

• Network Working Group 🎀
• RFC # 692 and NIC # 32734 💖
• Author: Stephen Wolfe, UCLA CCN 🧚
• Date: June 20, 1975 📅
• Obsoletes / Updates: the original doesn't say, so I'm not guessing 🙈
• Category / Status: also not stated in the original 🌸

Okay so bestie, this one is Stephen's reaction to the proposed IMP/Host protocol changes in RFC 687 and RFC 690. ngl, it's giving very "I read the drafts and have opinions" 💅

Basically, the set of changes in RFC 687 seems reasonable, and so do the comments in RFC 690. 👑

The major problem, as Postel pointed out, is that the combined length of the IMP and Host leaders becomes 120 bits 😭. That's not a multiple of both 8 and 36 bits, and it's literally the whole drama 💀.

The suggested fix is to make the host to host protocol leader 24 bits longer, for a total of 144 bits 🌈. The catch is that the only way to change this length compatibly would be for the IMP to insert or delete those extra 24 bits when converting to and from the old format leader. The problems with that are super obvious 🙃.

The better solution is to change the length of the new proposed IMP leader instead. Stephen suggests 104 bits instead of 80 bits ✨. The complaint that 104 isn't a multiple of an IMP word is valid, but it shouldn't be that hard if these rules are followed:

1. The last 8 bits are never used to convey information. 🫶
2. The network is not required to pass them from source to destination, or to return them to the source. 🦋
3. When sending messages of types other than zero (irregular messages), the IMP is allowed to send either 96, 104 or 112 bits of data, whichever is most convenient for the IMP. 🍓
4. Also, if desired, either 96 or 112 could be used as the new leader length for irregular messages. 🔥

It must be faster (and cheaper) to just change the IMP program to handle a 104 bit leader than to force extra changes in all hosts using the standard protocol. Main character energy for the IMP, honestly 👑.

Another suggested extension would add a new type of IMP to Host message. This message carries a table of Host names (the kind people type as character strings) and Host network addresses 💜. Send this message(s) to the Host after each interface reset, or alternatively, it could be a response to a new Host to IMP request for this information 🧚.

RFC 692 Comments on IMP/Host Protocol Changes June 1975

[ This RFC was put into machine readable form for entry ] [ into the online RFC archives by Alex McKenzie with ] [ support from GTE, formerly BBN Corp. 10/99 ]