[c-nsp] full routing table / provider-class chassis

[Kevin Loch]

Phil Mayers wrote:
> Kevin Loch wrote:
> 
>>>
>>> Unfortunately, Cisco's partners are useless.  They propose 6509s 
>>> without the DFCs, which we know will fall over.  
>>
>> Well that depends...
>>
>> The DFC's only do next-hop (tcam) lookups and netflow.  All packets are
>> switched on the centralized PFC.  Each line card has two 20Gbit/s
> 
> Łukasz has already addressed this; suffice to say he's right, and the 
> above is not correct. A TCAM lookup *is* the forwarding operation, and 
> the DFC has all information required locally to switch the packet (via 
> the fabric) to the output linecard, and does so.

After re-reading this:

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper0900aecd80673385.html

I shouldn't have said PFC. The fabric is on the supervisor card itself
not the PFC.  What I meant was the packet is always sent to the
centralized switch fabric on the active supervisor card regardless of
where the lookups/acl are done.

The important point is that the lookup limitations (mpps) are
different than the fabric bandwidth limitations (gbps) because of how
these functions are separated on the cef720/dcef720 platform.

A 6509 should not "fall over without DFC's" unless you are doing more
than 30mpps.  That is 15gbit/s of 64 byte packets or 360gbit/s of
1500 byte packets.

- Kevin