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From: lim@slc6.INS.CWRU.Edu (Hock Koon Lim)
Subject: Re: Cabletron Repeater Problems
Message-ID: <1991Jun24.195346.633@usenet.ins.cwru.edu>
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Organization: Case Western Reserve Univ. Cleveland, Ohio, (USA)
References: <1991Jun20.203445.12130@unhd.unh.edu> <1991Jun21.212938.29822@usenet.ins.cwru.edu> <1991Jun24.000210.4759@qualcomm.com>
Date: Mon, 24 Jun 91 19:53:46 GMT
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In article <1991Jun24.000210.4759@qualcomm.com> antonio@qualcom.qualcomm.com (Franklin Antonio) writes:
>
>Thank you for this report.  Now that we know that the Cabletron statistics
>CAN work, we just have to figure out how to make them work for us.
>
>
>I just look at the total number of collisions reported for a port, and
>divide by the number of packets on that port.  We often have these numbers
>in the 10% to 15% range on Cabletron repeater ports which have nothing
>but a single Shiva FastPath on them.   
>
  Did you try to connect other devices beside Shiva FastPath?  I pick up a few ports
on my network which connect to the Sun4/490 files servers, the packet collision is 
about 3%.  These servers provide many services to our network and the network utilization
on this MMAC8/IRM is about 10-30% in the day time.  I do not have a Shiva FastPath on 
hand to verify the number.

>
>I guess i didn't make myself clear enough.  We dedicate one Cabletron
>repeater port to each Shiva FastPath, even tho the FastPath's are only
>about 2ft away from the repeater.  These particular Cabletron repeater
>ports have one each Shiva FastPath, and _nothing_ _else_ on them.
>

   How is you thinwire terminated?  You might want to make sure that the cable
is terminated only at one end but not on the THIN-MIM side.   

>Now, given that, which ports on the MMAC should i use?  Are all repeater
>ports created equal?  If i pull some cables from the front of the THN-MIMs
>and plug them in different ports -- this is _just_ a _permutation_ of ports!
>-- i would expect all the collision statistics to remain the same.
>(of course now reported on different port numbers, because i have moved
>the "interesting" traffic to different repeater ports)
>What we seem to have discovered is that all repeater ports are _not_ 
>created equal.  The worst choice seems to be to plug those cables from
>the FastPaths into ports all on one THN-MIM card.  Still one repeater
>port per FastPath, and nothing else on those ports.  The best choice seems
>to be to plug the cables from the FastPaths into ports chosen one per
>each THN-MIM card.  Still one repeater port per FastPath, and nothing else
>on those ports.  This doesn't make sense at all for any reasonable 
>functioning of the repeaters.
>

   I also check the number with the IRBM(similar to IRM-2), the collision rate is
about 0.3% to 1 % on a particular building.  All repeater ports on the THIN-MIM is
created equal.  I would suggest you try to connect other devices beside the
Shiva FastPath and see what happan.

>No way will i believe that permuting the cables at the front panel of
>the repeater should change the performance of my network.
>
>Thanks again for your thoughts tho.  I'm pleased to know that someone
>is haveing good luck with Cabletron's repeaters.  I was beginning to 
>think we just made a really bad decision when we decided to go with them.
>
>I still have my network problems... and i'm still interested to hear
>from anyone who has Shiva FastPath boxes successfully working with
>Cabletron repeaters.

-- 
Hock-Koon Lim, Information Network services
Case Western Reserve University; Cleveland, Ohio, USA  44106   
(216) 368-2982        lim@ins.cwru.edu