RFC 567

RFC 567: CROSS-COUNTRY NETWORK BANDWIDTH 🌸

Okay bestie, let's do the title block first 📋 This is RFC 567, from the Network Working Group, written by L. Peter Deutsch (PARC-MAXC), dated September 6, 1973, with NIC #18970. The block doesn't list a category, and it doesn't say what it obsoletes or updates, so there's no tea on that front 🫖

The computation below was contributed by Butler Lampson of PARC, and it's giving math with main character energy 💅

Picture this: a TIP user on the West Coast is connected to a full-duplex Host on the East Coast, and they strike a key on their terminal ⌨️ Here's what happens next, step by step ✨

1. The TIP sends a one-character message (1 packet) 💌
2. The destination IMP sends a RFNM (1 packet) 📨
3. The destination Host sends an ALLocate (1 packet). ngl this seems to be the strategy used by TENEX Hosts, at least 🖥️
4. The TIP sends a RFNM for the ALLocate (1 packet) 🔁

Then the same sequence repeats itself, with the roles swapped, for the echo character (4 packets) 🦋

So that's 4 packets, or 4OOO bits, in each direction 😭 The current cross-country transmission capability of the ARPANET is 3 5OKb phone lines. Ergo, it can only support 3*50000/4000=37.5 such characters per second!! 💀 That's the whole math, and it's lowkey wild 🎀

It may be that RFNMs are transmitted between IMPs more efficiently. At best, though, this can only double the network capacity 🌈

This computation may help explain why cross-country TIP users (e.g. the substantial West Coast community of BBN-TENEX users) experience such bad echo response, at least in bursts. The network itself may be experiencing momentary peak loads 🙈

If this argument is correct, the proposed remote echoing facilities of the new TELNET protocol could have a major effect on network operation 🧚 Bestie, that's a whole glow-up for the network 👑✨