Can someone clarify the concept of route once, switch many? Does that mean within a local area network you should be two hops at most between any other system? I'm having a hard time seeing how this works in large networks with separate access, distribution, and core layers. It seems like the distribution and core layers would all communicate on a separate VLAN to pass data, thus creating more logical hops.
Or am I over thinking this?
The basic issue has to due with the delay imposed by a router on packet forwarding - if you can minimize the number of times that datagram headers have to be parsed in order to forward them to the appropriate end destination, the result will be a reduction in the total system delay and an improvement in throughput.
This is especially useful in a packet train or data flow between two peers -- determine the route, then disseminate the path info to the (layer-2) switches so that minimal processing occurs, minimizing delay.
Sincerely,
Brad Reese
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