[c-nsp] 6500/7600 TCAM Usage

[James Bensley]

Hi All,

In a similar vein to the concurrently running thread about a SUP-2T-XL
thinking it is out of TCAM space...

What are realistic usage levels for TCAM on 6500 and 7600s RSPs? We've
got some 7600s running RSP720-3CXL-10GEs and they are at nearly 80%
utilisation (74%-78% off the top of my head).

Ignoring the fact that one can partition a certain percentage for IPv4
or IPv6 or multicast space. I mean overall can we actually use 1
million TCAM entries?

I have asked TAC and they said the TCAM can be 100% used, not until we
have 1,024,000 entries in TCAM will we start of see the syslog
messages for failing to install a prefix. I am certain that one CAN
NOT use 100% of the TCAM space, I'm sure I read somewhere that at
around 90% utilisation we start so process switch / drop packets /
fail to install routes.

I obviously can’t find any Cisco documentation on saying we can’t use
100% of the TCAM. TAC have said we can use 100% of the TCAM. I still
don’t believe this, I’m so certain I have read somewhere that we
can’t.

Has anyone had any experiences relating to this they can comment on?

Cheers,

James.