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Calculating TCAM Usage with PBR on 3750

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Apr 9th, 2009
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Hi Folks,

Does anyone have guidance on how much PBR config can be possible on a 3750 with the routing template?

Also what are the impacts on traffic and the number of users sending traffic through the box?

Is it a simple case of testing whether the TCAM utilization has not reached a limit and expect that any level of traffic from the ACL entries will never exhaust TCAM?


TIA


Alan

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Giuseppe Larosa Thu, 04/09/2009 - 12:07
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Hello Alan,

actually PBR can be implemented in a very efficient way in TCAM: in the action field a pointer to the PBR next hop is used.

So actually redirection doesn't use more TCAM resources then standard forwarding


Hope to help

Giuseppe


alanwright1 Sat, 04/11/2009 - 11:17
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Hi Giuseppe,

If that is the case, if I add say two networks like 10.1.0.0/16 and 10.16.0.0/16. Will each user of these ranges use TCAM memory? or will all users of each range share the same lookup entry (in this case only two lookups)?

Giuseppe Larosa Sat, 04/11/2009 - 21:59
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Hello Alan,

with the routing template all users in a range should share a single lookup entry


Hope to help

Giuseppe


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