On Wed, 2013-07-24 at 12:49 +1000, Shanawaz Batcha wrote: > Lets assume I have a WS-2960G-48 model switch. The advertised > backplane capacity for this platform is 32G. That is 32Gbps for 48 > ports, so I assume straightaway that its a blocking (as in > not-non-blocking) switch
Correct. All the C2k and C3k switches are (blocking) store-and-forward switches. > 1) Does traffic within the ASIC hit the backplane and count towards > the backplane 32 gbps capacity? Does say traffic from port Gi0/29 > to Gi0/30 (both in Asic 8) reach the backplane or simply switched > locally at ASIC level? AFAIK the ASICs perform forwarding decisions themselves and will not send traffic destined for a local port towards the switch fabric. > 2) If the answer to the above is yes, and assuming all ports are > transmitting at the same time at 1 Gbps, then presumably we can > call this a line-rate switch provided the right connections are in > the right places? if the answer is no, and assuming all ports are > transmitting at the same time at 1 Gbps, then there will be about > ~16 gbps worth of drops? Yes on both counts. Even with locally switched traffic you can easily imagine a scenario where all traffic has to cross the switch fabric. The 2960S has no ingress QoS but I don't know about "plain" 2960. Without ingress QoS you can't work around an overloaded backplane with e.g. priority queueing. If you need line-rate the 2960 (non-S) probably doesn't fit your needs. Take a look at BRKARC-3437 from 2011. It touches on 2960 a bit though it does not answer your specific question in any exact way. -- Peter _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
