[snip]  The MIT guys did ARP for ChaosNet which quickly migrated down the street to BBN for the 4.1 IP stack.  Remember that BBN had the contract to do IP for UNIX and that was the stack a number of us ran on our Vaxen for long time [IIRC - Sam actually did the routed and rcp stuff which the BBN stack, before Joy had rewritten it - created the sockets interface etc].