[c-nsp] N7K tcam handling

[Tony Varriale]

----- Original Message ----- 
From: "Tim Stevenson" <tstevens at cisco.com>
To: "Tim Durack" <tdurack at gmail.com>
Cc: <cisco-nsp at puck.nether.net>
Sent: Tuesday, March 09, 2010 12:59 PM
Subject: Re: [c-nsp] N7K tcam handling


> Hi Tim,
>
> Sorry about that, assumed you were talking about ACL TCAM, but you are 
> referring to FIB TCAM.
>
> In the scenario you mention, prefixes are installed in the FIB TCAM on a 
> first come first served basis. Packets not matching a prefix in the FIB 
> TCAM are punted to the CPU, but such traffic is heavily rate limited (to 
> protect the inband/CPU), so your routing will be considerably hosed. 
> Obviously we syslog such events.
>
> As you probably know, n7k today has a 128K FIB TCAM, inadequate to hold 
> full routes anyway. Near-term we will have an XL card that holds 900K 
> prefixes. In that case, you should not run out of FIB TCAM in the case you 
> describe, but as always, you should be sure not to "miss" configuring 
> route limits & filters to avoid issues, that's clearly best practice.
>
> Hope that helps,
> Tim

And I believe you are going to allow configurable allocation between ipv4 
and ipv6 space.

tv