Switch to avoid (was Re: NIC to avoid...?)

Michael Sowka msowka at doe.carleton.ca
Tue Aug 28 09:54:40 PDT 2001

Felix Rauch wrote:

>On Tue, 28 Aug 2001, Michael Sowka wrote:
>>Performance is the key as we're blowing a fair amount of money and a
>>Cisco Catalist 3500 Switch....
>I certainly don't want to stop you blowing money and I don't know
>anything about Catalist 3500 switches, but since you said performance
>is the key I thought I'd share some experiences we had with a Catalyst
>We had to compare the performance of two switches, one of them beeing
>the Catalyst 2900XL. We basically beat that thing into pieces. The
>experiment was performed with an extended version of our cloning tool
>Dolly [1]. This version just sends data as fast as it can from one
>node to the next and from there at the same time to the next and so
>on. It sends data around in a virtual TCP ring, so every used port of
>the switch has to send and receive data with full speed. Pretty tough
>for some switches, it seems, but a realistic scenario in our case.
>The result was that the Catalyst 2900XL (which was a 24 port switch)
>could sustain full performance at about 11 MB/s for the data stream up
>to 12 nodes [2,3]. For more than 12 nodes it went to its knees, beging
>for mercy. For 15 nodes it sustained only 2.5 MB/s!
>An Allied Telesyn Centrecom 742i 24 port switch had no problems handling the
>load [4,5] up to 15 nodes (we don't have more).
>As I said, I don't know the differences between the Catalists 3500 and
>2900XL, but if you need full bandwith on many ports, then you'd
>probably better benchmark that switch (reading the specifications
>doesn't necessarily help. We recently benchmarked an Enterasys Matrix E7
>with 128 nodes and this thing also didn't fulfill the specs, although
>it didn't fail as bad as the 2900XL).
>- Felix
>[1] http://www.cs.inf.ethz.ch/CoPs/patagonia/
>[2] http://www.cs.inf.ethz.ch/~rauch/tmp/FE.Catalyst2900XL.Stream.pdf
>[3] http://www.cs.inf.ethz.ch/~rauch/tmp/FE.Catalyst2900XL.Agg.pdf
>[4] http://www.cs.inf.ethz.ch/~rauch/tmp/FE.CentreCom742i.Stream.pdf
>[5] http://www.cs.inf.ethz.ch/~rauch/tmp/FE.CentreCom742i.Agg.pdf
Ouch... now I don't know what to do! We don't have the luxury of 
benchmarking a variaty of switches... I was sort of going on the 
recomendation of our resident network admin. It would have seemed that 
he knows his stuff, but I'll look into this further,
P.S. now how about that NIC anyone?

|      Mike Sowka                       o      _     _         _         |
| An Aspiring Engi"Nerd"        _o     /\_   _ \\o  (_)\__/o  (_)        |
|  Carleton University        _< \_   _>(_) (_)/<_    \_| \   _|/' \/    |
| msowka at doe.carleton.ca     (_)>(_) (_)        (_)   (_)    (_)'  _\o_  |
| (home msowka at home.com)                                                 |

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