[ih] TCP/IP routing

[william yeager]

Oppas .. CHAOS byte order was host net rather than net host.

> On May 5, 2026, at 4:10 PM, william yeager via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> 
>> On May 5, 2026, at 12:19 PM, Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
>> 
>> On a 3MB Ethernet, which used 8 bit host numbers, no. (Although I didn't
>> realize CHAOS protocol was ever run over 3MB Ethernet; it's news to me that
>> it was.) CHAOS protocol on 10MB Ethernet did, of course, use ARP.
> 
> My error. What my router did is route CHAOS packets on 3mbps networks. This was often the shortest or only route to the 10mbps network on which the target systems were hosted. This was easy because the CHAOS network was one byte. This was identical to the PUP network’s network abeit that in the CHAOS packet the byte order was reversed, ie, network, host or low ender. There is a funny story about this at the end of this discussion. 
> 
> We actually had a two twisted pair network between our machine room and the then Welch Road offices where at the majority of TI explorers were hosted on a 10mbps ethernet. We used the Andy Becholscheim 3mbps ethernet interface. We had to modify it to send packets on this twisted pair connection. The modification required replacing the two crystals between each of two FIFOs. We had no idea what the bandwidth would be. This required testing until packets were sent error free. The final bandwidth was 1.52 mpbs. A T1 line. We of course called this the twisted net. 
> 
> Our genious hardware fellow, Nick Veizades made his “blue box” that converted the ethernet square waves so that so that 0s and 1s would be sent on one of the twisted pairs alternating as appropriate. That way an output twisted pair would be an input twisted pair at the other end. 
> 
> My network OS mananged this beautifully without buffer loss from the 10mbps input side. 
> 
> Funny story: One day a Cisco software phoned me and asked if I would help him debug their CHAOS net router. When Cisco did a rewrite of my software they removed it.
> 
> I said sure. He stopped by my office and telneted via the Cisco VPN and we edit the source code. Ends up he didn’t know the reverse order of the CHAO packet’s fields. Thus, used net as host, and host as net and well … simple fix. The thanked me and left. 
> 
> Those were indeed the days.
> 
> Bill
> 
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————打🎾————
马年快乐🐎
<Happy year of the horse>
保佑众生 🙏🐘🌲🦋🏃‍♀️🐳
<Bless & Protect all living things>