In cisco.external.nanog you write:
not to make this too cisco specific, but...
the number of entries in the forwarding cache on the sse is generally more than the number of routes in the bgp rib (because of the way the cache handles more-specifics of over-lapping aggregates). so in addition to the raw number of routes in the rib, the efficiency (and scope) of aggregation are also important data points
now a question. what does an sse do when its cache fills? it used to(*) bring down the whole sse, which doesn't really make much sense given that it's a cache and therefore it's normal operation for it to be incomplete. anyone know an answer to that one?
SSE memory usage is monitored and if it falls below a particular threshold, the ager will become more aggressive in aging entries.. --ravi
/jws
(*) -- "used to" implies that it happened before, which it did. but that was largely due to the ineffeciency of the data structures, and the problem was solved such that 2 years (and counting) was added to its life
Hmm, it's not news for us. 45K can hold core routing only as inter-back-bone router, not more.
But why, why this crasy CISCO could not predict future when they designed 45K routers? It was not difficult for them develop this box to cary 64 or 128MB RAM.
Looks like the 45k mark was reached:
Folks with 7000's and SSE's should start monitoring their memory utilization via "show sse summary".
There's a couple of comments here:
First, 45k is not the limit. More like 60k. You'll pardon me for being cautious.
The limitation is not DRAM. It's the 64k words of SRAM that the SSE uses for its high speed forwarding table. You don't want to pay for 64Mbytes of SRAM. ;-)
When cisco's engineers designed the SSE, we knew very well what was happening. We expected to be given the opportunity to produce subsequent hardware which implemented the SSE in an ASIC. If, by that time, CIDR hadn't killed off the exponential growth, we would have expanded the address space. Unfortunately, cisco management decided that the SSE ASIC should not be implemented (a mistake which, to my knowledge, cisco has not corrected). Thus, the 7500 exists without an SSE.
Tony