3 ms·
A Cisco Catalyst 6506 can handle 330 Mpps, so you need to have a guaranteed lookup time of about 3ns. This router was released in 2005, back when a CPU was luc
by crote 3y ago
A Cisco Catalyst 6506 can handle 330 Mpps, so you need to have a guaranteed lookup time of about 3ns.
This router was released in 2005, back when a CPU was lucky to have 2MB of L2 cache which had a 10ns access time. So no, you can't just have the routing table in cache. Considering a random read from memory takes in the order of 200 nanoseconds, you're not going to be able to handle that with commodity hardware.
It might be doable in 2023 - but 2023 routers are able to handle way more packages too.
- dfox 3y agoCisco specifies Sup720 as being capable of “up to 400Mpps*” routed IPv4 with the footnote implying that this is in dCEF mode. With dCEF, each linecard has its own forwarding logic, so the lookup time deadline has to be multiplied by number of linecards (ie. 4 for 6506 chassis). One implication of dCEF is that you end up replicating somewhat expensive ASICs across the system to gain more performance, which gets real expensive real fast. Not that it changes much about your point.