Route table growth and hardware limits...talk to the filter

Bora Akyol bora.akyol at aprius.com
Thu Sep 20 23:07:48 UTC 2007




On 9/20/07 2:03 PM, "Jon Lewis" <jlewis at lewis.org> wrote:

> 
> On Thu, 20 Sep 2007, Matt Liotta wrote:
> 
>> I was playing with a sup2 adding in extra routes to the point that it ran out
>> of memory. Unfortunately, it didn't just drop routes like I thought it would.
>> CEF disabled itself as well, which on a busy box would be a disaster.
>> 
>> Is this what people expect will happen in a few months to people using sup2s?
>> Or am I missing something else?
> 
> That's not good.  What software version was it running?


While it is not good, the alternative approach would leave an indeterminate
routing table in hardware. Would you like the packets to go to randomized
directions?

The box is trying to do the right thing by turning off CEF and switching
everything in software since in this case software is the only entity in the
system with a consistent FIB.

An alternate would be to use the hardware forwarding tables as a limited
size cache (similar but not exactly as in the 7000 router). I am sure that
this is a large software effort and whether the hardware can support this is
questionable.

SUP2 was a great RP with a really long life, but maybe it is time to move on
to a SUP720 with the large table option and then grab a cold one ;-)

Cheers,

Bora




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