[c-nsp] TCAM refresher

[Phil Bedard]

We have a core that is currently running off of Sup2s and it works  
right now,
but is being upgraded to something that can do at least 1M entries  
(could be
RSP720, could be a different vendor).   I would suggest anyone  
thinking of handling
full tables do the 3BXL or RSP720.

Taking two full feeds plus a lot of peering, we have about 550k BGP  
routes coming
into the busiest box, but the FIB TCAM right now is at about 217k  
routes.

Phil

On Mar 14, 2007, at 12:20 PM, TCIS List Acct wrote:

>
>
> Justin M. Streiner wrote:
>> Someone I know is considering upgrading the core network device in  
>> their
>> data center to a 6500/Sup2/MSFC2.  They take three full BGP feeds  
>> from
>> their transit providers.  My initial caution to them about going  
>> with the
>> Sup2 instead of a Sup720/3BXL was that the Sup2 is limited to  
>> about 250k
>> TCAM entries assuming they're not running uRPF.  Given the size of  
>> a full
>> Internet routing table these days, that allows them a little bit of
>> headroom, but not much, plus this doesn't take into account their  
>> existing
>> access-lists, policies, local routes, multicast, Netflow, NAT, etc...
>> That said, it would seem that a Sup2 would work for now, but it  
>> won't be
>> very long before it would need to be upgraded, i.e. they'd be  
>> better off
>> going with the 720/3BXL straight out of the gate.
>
> We are in a similar situation -- considering a 6500/Sup2/MSFC2 for  
> core.  Am I
> to understand that, if we take three full BGP feeds (lets say at  
> 200K routes a
> piece, for a total of 600K routes), that the number of BGP routes  
> does not
> translate 1:1 -- meaning that only 1 route will be chosen and used  
> by the TCAM
> at a time, so as long as the number of total routes from any one  
> BGP feed does
> not exceed ~240K, we will be OK?
>
> --Mike
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Phil Bedard
philxor at gmail.com