Path: utzoo!utgpu!CUNYVM!IBMTCP-L Date: Wed, 21 Feb 90 22:00:11 EST Reply-To: IBM TCP/IP For VM List Sender: IBM TCP/IP For VM List From: Stephen Brown Subject: Confused/confusing VM TCP/IP To: UofToronto LAN redistribution Message-ID: <90Feb22.001145est.58704@ugw.utcs.utoronto.ca> Newsgroups: list.ibmtcp-l Distribution: ut Approved: devnull@gpu.utcs.toronto.edu We've recently experienced problems with VM becoming confused about it's default gateway and it's own Ethernet address. We suspect that an uninformed users cranked-up an incorrectly configured Mac TCP/IP, some how the Mac convinced VM that it's Ethernet address was that of the Mac. Thus while Sniffing, VM would respond to ARPs for it's IP address with the Ethernet address of the Mac; the bad information travelled quickly and soon all the users started sending SYNs to the Mac. IMLing VM TCP/IP solved the problem, I assume by clearing the ARP entry for VM. Does VM consult it's ARP table before the hard-coded configuration? I would not expect this behavior with the IP address AND Ethernet address both being in the config. Secondly, in a separate incident, VM began sending ALL packets to it's default gateway. The cisco router, which is the default gateway, ignored the packets since they were arriving on the network which they were destined. My understanding of the cisco is that global ICMP redirects are not possible, I'm not sure VM would correct the problem even if it received a redirect. There's nothing complicated about the GATEWAY statement: if it's 129.219.0.0 send it direct, otherwise send to 129.219.16.1. Is this known behavior? What can we do to avoid this in the future. Help!? =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Stephen Brown (602) 965-5922 Arizona State University, Tempe, AZ 85287-0201 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=