Xref: utzoo alt.sys.sun:4309 comp.dcom.lans:8441 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!slc6!lim From: lim@slc6.INS.CWRU.Edu (Hock Koon Lim) Newsgroups: alt.sys.sun,comp.dcom.lans Subject: Re: Cabletron Repeater Problems Message-ID: <1991Jun21.212938.29822@usenet.ins.cwru.edu> Date: 21 Jun 91 21:29:38 GMT References: <1991Jun7.200603.9378@ns.network.com> <1991Jun20.075328.6540@qualcomm.com> <1991Jun20.203445.12130@unhd.unh.edu> Sender: lim@po.cwru.edu Reply-To: lim@po.CWRU.Edu Organization: Case Western Reserve Univ. Cleveland, Ohio, (USA) Lines: 72 Nntp-Posting-Host: slc6.ins.cwru.edu >>In article <1991Jun20.075328.6540@qualcomm.com> antonio@qualcom.qualcomm.com (Franklin Antonio) writes: >> >>isolate problems to a particular port? We've recently implemented >>Remote-Lanview, so we can see all these statistics for all the repeaters >>remotely. This SOUNDS great, but since all the collision statistics are >>unreliable, all this provides is a very fancy Windows program to display >>random numbers. I expect these statistics should be a TOOL i can use to >>diagnose my network. Do i ask too much? You are not asking too much. Remote-Lanview(PCOV) has helped me solve many problems on our network. It is great to have thoese statistics on every single ports of the multiport repeater. We have more that 50 MMAC-8 concentrators, 30 NB25E and many many Cabletron Ethernet cards ( > 2000+ )on our network and the network statistics report by the Remote-Lanview did show a pretty accurate result. For example, one of the port show high number of the CRC Errors counts, and base on the information given by the PCOV, we manage to track down the offender. We used the cabletron IRM and IRBM on the MMAC-8. >>We've had better luck when we use one repeater port for EACH Shiva >>FastPath. That's the way we've been running for a long time. We still >>get lots of collisions on these ports, sometimes 10% or 15%, but the >>network still seems to work. Just a few days ago we made yet another What do you mean by 10% to 15 %? PCOV give the collision percentage as %port/Board and %Port/MMAC on the IRM. The defination of the %Port/MMAC is the percentage of collisions of which the port is responsible, based on total MMAC activity. i.e. total port collisions count/total MMAC collision count * 100%. It is not = total port collision count/total packet that the MMAC is transmit * 100 %. So if PCOV report that 60% collision on Port 1/ Board 1 of you Thin-MIM and you only have two ports active on you MMAC, then it mean that 60% of the collision the MMAC has is from port 1. It does not mean 60 percent of the packets transmit result in collision. >>discovery. We can reduce the number of collisions by choosing WHICH >>Cabletron ports we wire up to the Shiva FastPaths. We used to take the >>first THN-MIM card in the MMAC, and dedicate it to the FastPaths. >>Now we find that we get many fewer collisions if we spread out the >>ports which connect to FastPaths, putting no more than one FastPath >>on each THN-MIM card, then using the other 7 ports on each THN-MIM for >>anything else. I'm not sure exactly what to conclude from this. >>Sure looks like this has uncovered some kind of timing problem in the >>MMAC design, but that's just one possibility. It make perfect sense here. If you put less devices on the THN-MIM port the less collision percentage it will display on the PCOV. You you have done is using more ports on you THN-MIM at the same time, you have just distribute the collision packet transmission per port. The total collision percentage of the THN-MIM bord still remain the same but the percentage per port will be much smaller now - see the defination. > > >>Anybody else got Cabletron collision bogosity? >>Anybody out there using Cabletron's collision statistics AND finding >>them meaningful? > Yes, it is meaningful only if you read them correctly. I have based on the PCOV to help me to manage our network for the last two years - it has save my life many time since. I also have start using the new Cabletron Spectrum network management software here and it is powerful. -- Hock-Koon Lim, Information Network services Case Western Reserve University; Cleveland, Ohio, USA 44106 (216) 368-2982 lim@ins.cwru.edu