bruce@THINK.COM.UUCP (02/21/87)
Oh, I forgot to mention another problem which I first noticed last weekend. We are unable to send segments to SRI-NIC.ARPA of size MTU. This time NIC is the only host with which I have observed the problem. If I kludge our tcp to negotiate a slightly smaller MSS, everything works fine. On this end, we appear to be getting RFMNs from the long packet, but NIC evidently isn't seeing it. The connection stays alive: we retransmit the long packet, and they retransmit the previous ack. This is not the standard 4.2/4.3 driver bug of not allocating buffers at least one greater than MTU. That was fixed long ago. But the symptoms are exactly the same. This is a NEW problem, and we haven't changed any tcp/ip code here recently. Evidently we can RECEIVE mtu-sized packets from the NIC. --Bruce Nemnich, Thinking Machines Corporation, Cambridge, MA bruce@think.com, seismo!think!bruce, bjn@mitvma.bitnet; +1 617 876 1111