[c-nsp] 6500/7600 TCAM Usage

[Pete Templin]

+1 on what Gert said. You'll get log entries at the 90% threshold within 
a region, but the badness only happens when you tickle the 100% threshold.


On 5/31/2016 11:45 AM, Gert Doering wrote:
> Hi,
>
> On Tue, May 31, 2016 at 07:19:22PM +0100, James Bensley wrote:
>> 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.
> You can use 100% of what you have partitoned for - so if you partion for
> 512k IPv4, you'll blow up at 512*1024 IPv4 routes (minus a few, I'd
> assume).  Been there, done that - not at 512k but at something like 200k
> on non-XLs, years ago.
>
> That "at 90% utilization bad things will happen" sounds like an urban
> legend from the BNC ethernet times...  it's TCAM, there is nothing magic
> about 90% - either a route can be poked in there, then it will work,
> or not, then all excess routes will be process switch (and subject to
> rate-limiting)
>