Number of VLAN, STP and CPU Utilization

Unanswered Question
Nov 8th, 2009

Hi,

In a campus setup with around 20 L2 switches and only one L3 - 3560 switch. To this L3 switch servers are connected, this L3 swicth will be doing inter VLAN routing, STP is running by default. Total number of VLAN are 20. If we run all these proceses on the L3 switch which is connected to servers will it affect the server connectivity performance?

Please share the experience.

any link on the cisco.com

Thanks in advance.

Subodh

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Joseph W. Doherty Sun, 11/08/2009 - 04:53

"If we run all these proceses on the L3 switch which is connected to servers will it affect the server connectivity performance? "

It really shouldn't. If you had much traffic between the servers (e.g. server backups), such traffic could be kept from the L3 switch if the servers were on another switch and the traffic was L2 on that switch. However, if traffic is going to be between servers and other subnets, it would need to transit your L3 switch anyway although then the uplink from a server switch might be the bottleneck vs. the fabric of the L3 switch if the servers are connected to it. (This becomes even more relevant if the servers are running at gig and uplink is only gig vs. 10 gig.)

Personally, in a small topology like yours, I prefer the servers attached to the core switch. However, I would also prefer usage of a 3750 stack with enough excess ports that loss of a single core L3 switch doesn't take down your whole network and that at least "critical" servers can be repatched (or already dual patched) into the stacked switches.

bapatsubodh Sun, 11/08/2009 - 14:15

hi Josephdoherty

Thanks for you valuable inputs.

This topology with approximately 20 L2 and one L3 switch. with 20 VLANs and no major traffif running between trunks, can we say it ok to have inter vlan routing and servers connected to single L3 switch.

Thanks again.

Subodh

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