Backbone for Catlyst Switching

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Aug 11th, 2008
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Hi to all,

We have six Catalyst 2950 switches. We would like to install a Backbone switch for these switches.

Which device do you think that would be the most appropiate? Maybe a 3750 switch would be enough?


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dominic.caron Mon, 08/11/2008 - 10:10
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The 3750 has 2 16Gbps backplane between it's ports ASIC, it's more thant enought to handle six 2950. (If you only need a Layer 2 backbone)

srue Mon, 08/11/2008 - 11:36
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unless you need the stacking capabilities of the 3750, go with a 3560 24port 10/100 or 10/100/1000. configure etherchannel between the 2950's and the 3560 with at least two links. force the 3560 as the STP root. add another cable between each of the 2950's for redundancy.

Joseph W. Doherty Mon, 08/11/2008 - 15:59
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"Which device do you think that would be the most appropiate? Maybe a 3750 switch would be enough?"

Depends on what particular model 2950 you have, and whether you need your backbone to support L3.

For instance, if you only need L2 and copper ports on the backbone switch, the 2960G-8TC-L might work for you if your 2950s have gig copper uplinks.

If you need L3, and again assuming gig copper uplinks, you could use either a 3560G or 3750G, or might even be able to use a 3560-8PC with the above 2960G-8TC-L. (The 2960G-8TC-L ties together the six 2950s, and the 3560-8PC in a "router on a stick" configuration.)

FernandoSP Tue, 08/12/2008 - 05:22
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Thanks to all,

Customer has given me more info. Actually they are working with these 6 2960 switches stacked. Now, they want to connect everyone of these switches to a backbone switch, between their fiber ports.

So I would need a switch with at least 6 possibly fiber ports.


PD: I only need L2 capabilities

tdrais Tue, 08/12/2008 - 05:58
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If it must be fiber they you are into the 4500 line. Would be nice if cisco made a small switch that could take more than 4 optical connections but I have not seen one.

Your best option if you can is to not use the fiber. You could if you have to replace the optics in the 2960 with copper but if these are 10/100/1000 switches then just use any port for your uplink.

If fiber is being used for distance issues then you have very limited choices.

FernandoSP Tue, 08/12/2008 - 06:06
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And what about two 3560 or 3760 switches stacked? It would give to me the possibility to work with 8 fiber ports?


tdrais Tue, 08/12/2008 - 08:09
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That will work and if you used stacked 3700 you would have very close a single backbone switch.

Its really too bad they don't make a 8 port 2960 with all SFP ports since all you want is a layer 2 fiber consolidation point.

Joseph W. Doherty Tue, 08/12/2008 - 08:48
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Can't stack the 3560s.

Yes, you could obtain 8 SFP ports if you stack two 3750s with 4 SFP ports each. Note, some 3750s only have 2 SFP ports. Also if you go this route, you might want to obtain the non-"G" version to reduce cost.

Another switch to consider is the 3750G-12S, which offers 12 SFP ports. This might allow dual Etherchannel links to the existing six switches. It also, I believe, is the only 3750 model that offers a special aggregation configuration template.

Since you're not interested in L2, if you use either a 3560 or 3750, use the basic featured version, again to minimize cost.


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