[c-nsp] Router/Switch Sizing terms

[Sami Joseph]

So Pete when you want to compare a switch/router performance to another,
which numbers do you look at ?

When you are also trying to size your needs, how would you calculate this ?


On 1/8/07, Pete Templin <petelists at templin.org> wrote:
>
> Sami Joseph wrote:
>
> > 1) Backplane:
>
> The <thingy> across which packets are flung from ingress to egress.
>
> > 2) Switch Fabric
>
> In switches or switch-like routers, this is another term for the
> backplane.
>
> > 3) Switching Capacity
>
> L2 devices switch packets from ingress to egress.  L3 devices route, and
> then switch packets from ingress to egress.  Either method requires an
> appropriate (L2, L3, etc.) lookup, one time per packet regardless of
> packet payload size, and therefore most switches and routers are
> performance-limited by the number of frames/packets they can perform
> switching/routing lookups on (and then switch the packet to the egress
> port).
>
> > 4) Forwarding performance
>
> Often a measure of switching capacity multiplied by minimum, average,
> weighted, and/or maximum packet size.  Used to differentiate between
> devices that can only fill their ports if maximum-sized packets are
> used, and devices that can fill their ports if minimum-sized packets are
> used.
>
> pt
>