EtherChannel and LAN Design for new buildiing(s)

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May 9th, 2009
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What is the recommended best practice for EtherChannel size for a 3750G-12S stack? Will I benefit from stacking these with the StackWise cable on the backplane, or would it be better to run these independently back to the 4006 with individual EtheChannels?


The 3750G-12S stack will likely be 1 or 2 devices at distribution layer for upwards of 18 - 20 2960G-48 access layer switches and approximately 20 1242LAP AP's in addition to max capacity of end users attached to the switches.


I am considering implementing a 4 gig EtherChannel between the 3750's to the 4006 for this load. My limit is the number of available ports on the 4006 and obviously the max load of links on the EtherChannel.

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Joseph W. Doherty Sat, 05/09/2009 - 14:11
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Unsure there's a single "best practice" for stacking or not. Some advantages/disadvantages to both. Part of the decision might rest on whether the 3750s will be L2 or L3.


Stackwise could be a performance bottleneck if you believe there would be much traffic between switch ports, but if most will transit your 4006, your links to it would be the bottleneck.


What you might consider, a single 3750G-12S (four?) that can handle 2 links from each access switch, that are Etherchanneled and not connected to the same 3750 stack member. This with the 4 gig Etherchannel to the 4006, which again should be spread across stack members.

Giuseppe Larosa Sun, 05/10/2009 - 04:14
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Hello Timothy,

I would suggest another device for core C4006 may have the GE port density but the performance can be too low.


We have problems with these devices for examples linecards WS-C4548 have a fixed 8:1 oversubcription (8 GE ports share a single ASIC chip)


Using the stackwise cable could be a way to offload traffic from 4006 but all depends from traffic patterns.


Hope to help

Giuseppe


t_flacy Tue, 05/12/2009 - 16:20
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Thank you both (Joseph and Giuseppe) for your information.


I am stuck with the 4006 as my primary core distribution switch for now. I have not worked with the 3750 yet and was unsure of the limitiations or benefits.

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