tdd@convex.cl.msu.edu (Thomas D. Davis) (10/31/90)
We have a number of Retix 2255M bridges on our campus ethernet (we have DEC and Crosscomm bridges as well) that seem to have intermittent problems. The symptom that we've experienced which points to bridge trouble is basically the loss of connectivity (NFS block read errors, ping failures) to machines on the far side of the bridge. After checking out as many variables as we have the capability to test, we have pointed an accusing finger at these bridges. It "feels" like the bridge is getting its forwarding tables upset, although I am definitely going on a hunch here. Like everyone else, our net traffic has increased substantially over the past months which may be a contributing factor (shouldn't bridges keep up with a loaded network?). Has anyone else had problems like this? I know of no way to tell for sure that the bridge is to blame other than to swap it out with another and see if the problem recurs (yuck!). How do other people debug such problems? -- Tom Davis | The above statement shall be construed, Network Software Services | interpreted, and governed by me alone. Michigan State University | EMail: tdd@convex.cl.msu.edu
tjc@ecs.soton.ac.uk (Tim Chown) (10/31/90)
In <1990Oct30.210914.23429@msuinfo.cl.msu.edu> tdd@convex.cl.msu.edu (Thomas D. Davis) writes: >We have a number of Retix 2255M bridges on our campus ethernet (we have DEC >and Crosscomm bridges as well) that seem to have intermittent problems. The >symptom that we've experienced which points to bridge trouble is basically >the loss of connectivity (NFS block read errors, ping failures) to machines >on the far side of the bridge. After checking out as many variables as we >have the capability to test, we have pointed an accusing finger at these >bridges. It "feels" like the bridge is getting its forwarding tables upset, >although I am definitely going on a hunch here. Like everyone else, our net >traffic has increased substantially over the past months which may be a >contributing factor (shouldn't bridges keep up with a loaded network?). >Has anyone else had problems like this? I know of no way to tell for sure >that the bridge is to blame other than to swap it out with another and see >if the problem recurs (yuck!). How do other people debug such problems? We have two 2265Ms which had similar problems. What appears to be happening is that they lock up on certain combinations of short/long packets or CRC errors, which can occur. Retix announced in April that such bridges *must* be upgraded to firmware revision E (which has corrections for these bugs) while we in fact only had revision D. It may well be the same for your 2255Ms. A handy tip here is to get a portable ether analyser, which can be found for under #1000 in the UK. Well worth the expense, I feel. Cheers, Tim.
network@zeus.unomaha.edu (11/01/90)
In article <1990Oct30.210914.23429@msuinfo.cl.msu.edu>, tdd@convex.cl.msu.edu (Thomas D. Davis) writes: > We have a number of Retix 2255M bridges on our campus ethernet (we have DEC > and Crosscomm bridges as well) that seem to have intermittent problems. The > symptom that we've experienced which points to bridge trouble is basically > the loss of connectivity (NFS block read errors, ping failures) to machines > on the far side of the bridge. <stuff deleted> > Has anyone else had problems like this? I know of no way to tell for sure > that the bridge is to blame other than to swap it out with another and see > if the problem recurs (yuck!). How do other people debug such problems? We don't have Retix bridges (have had a demo unit). But we did have this problem with our older Dec Fiber Bridge 100's. Their address entry tables would fill up and then do a poor job of cleaning out the old entries and things would get weird at odd times. Resetting them all would fix the problem for a day or two. Digital has upgrade chips that fix this problem that we installed with no problems. So yes, we have seen this problem, but not with Retix stuff. Unless you have a network analyzer it's a real shadow of the ghost type of problem to nail down. If you can catch the problem 'as it happens' then try to reset the bridge(s) between the two devices and see if it fixes it. Also make sure that any transceivers and transceiver cables connected to the retix bridges are 802.3 stuff. Steven Lendt Network Manager University of Nebraska at Omaha Bitnet: NETWORK@UNOMA1 Internet: NETWORK@ZEUS.UNOMAHA.EDU