Router backplane issues

[rmargiotta1]

I have recently heard that when using a 4 port switch module on a router that you need to connect one of the ports directly to one of the router ports in order to bypass the backplane as there is a known issue of packets being dropped when you use the backplane directly.  Is this true?  If so, why?

[ghostinthenet]

I haven't heard of this sort of thing at all. In almost all cases, you want to use the backplane because it will provide more aggregate bandwidth to the switch ports and won't waste two physical ports. I have hundreds of installations using four-port switch modules and all of them work well without any connectivity issues.

[Joseph W. Doherty]

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Posting

It would depend on the switch module, router and router port.  Many ISRs, especially older series, have limited backplanes but they also often have bandwidth limitations to their module ports (generally not well documented).

That noted, unsure connected a module interface port to a router port (especially if not a built-in port).