[c-nsp] 6500/7600 TCAM Usage

Mack McBride mack.mcbride at viawest.com
Fri Jun 3 11:51:48 EDT 2016

One solution that is available on 6500s and 7600s in newer code is Selective Route Download.
There are a lot of deaggregates in the table.  Depending on the location of the device in the
Routing path and where those routes point you can remove a lot of deaggregates.
This helps with RAM utilization as well.  We are in the process of deploying it to devices where
We have downstreams with full tables but only symmetric upstream devices.  Ie. Traffic all
goes one direction upstream across multiple identical devices.  This allows us to prune a lot.
Where routers actually need to make a decision the amount of pruning is going to be a lot less
And you need to have some kind of default.  This works best for deaggregates that are far away
Network wise.  Think China for US based or Comcast for Chinese based.


That link is for S code but it is also available in SY.

Mack McBride | Senior Network Architect | ViaWest, Inc.
O: 720.891.2502 | C: 303.720.2711 | mack.mcbride at viawest.com | www.viawest.com

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of James Bensley
Sent: Friday, June 03, 2016 9:35 AM
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] 6500/7600 TCAM Usage

On 3 June 2016 at 07:50, Patrick M. Hausen <hausen at punkt.de> wrote:
> Is it possible to e.g. have a TCAM with timestamps associated to
> entries, so one can employ a TCAM as a route cache in LRU fashion and
> process-switch everything new/unknown?

This will penalise stable prefixes.

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