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
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