Calculating TCAM Usage with PBR on 3750

alanwright1 · ‎04-09-2009

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

Giuseppe Larosa · ‎04-09-2009

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 · ‎04-11-2009

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 · ‎04-11-2009

Hello Alan,

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

Hope to help

Giuseppe