Path: utzoo!utgpu!ugw.utcs.utoronto.ca!CUNYVM!IBMTCP-L Date: Sat, 3 Feb 90 22:53:45 EST Reply-To: IBM TCP/IP For VM List Sender: IBM TCP/IP For VM List From: Nick Gimbrone Subject: Re: Loopback problems To: UofToronto LAN redistribution References: Message of Wed, 31 Jan 90 08:54:49 PST from Message-ID: <90Feb3.230253est.57494@ugw.utcs.utoronto.ca> Newsgroups: list.ibmtcp-l Distribution: ut Approved: devnull@gpu.utcs.toronto.edu On Wed, 31 Jan 90 08:54:49 PST Mike Friedman said: >So, if NETSTAT is to be believed, there is no data transfer going on. >Why is this? As I said in an earlier note, if I connect to LOOPBACK, >instead of cmsa.Berkeley.EDU, I have no trouble. Also, since putting >the 8232 into production Sunday, I'm not aware of any file transfer >problems between us and a different host. LOOPBACK is a software transfer (the IP packets never leave the TCPIP server, who pretends to send them on the network and then pretends to recieve them from the network by simply moving the packet from the IP output queue to the IP input queue... basicly speaking...). Use of either the host name or IP address will cause the same code paths as use of another host name or IP address (i.e. IP packets actually hit the network attachment box). With both 7170s and 8232s (I don't know about other boxes) these packets will actually be sent on the real network and then recieved by the sender... So, could it be that you have a hardware problem with your 8232's network card? Some cards can't recieve data from themselves reliably... yet they can talk to others just fine... seems to match your symptoms. (Hum, must be a software type... blaming the hardware again! :-)