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I know it probably does not make sense, but can you reuse port-channel number on a LAN?


Switch 1 -----po1----- Switch 2 -----po2----- Switch 3 -----po1----- Switch 4

I would not do this, but this will help with an argument...

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up vote 3 down vote accepted


In fact - there is nothing wrong about it. Switch A might be using Port-Channel 1 to Switch B, and Port-Channel 2 to Switch C, while Switch B and switch C both use port-channel 1. It's quite normal, we do it here.

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Thanks for the feed back – mrlayance May 29 '12 at 13:03

It's actually fairly common practice to keep channel group numbers consistent along a chain, but it's not necessary. The PC number is only significant to the switch - so you could have different port channel numbers on either side of a given connection (i.e. po1 on switch A connects to po2 on switch B), while these switches use otherwise overlapping numbers for other connections.

Consider the case of twenty access switches connecting to a pair of aggregation switches. For convenience's sake the access switches are identically configured such that po1 corresponds to aggregation switch A while po2 connects to aggregation switch B. On aggregation A a decision is made to number the port channels 101-120 (i.e. 100 + switch number). The same setup is used on the B switch. The aggregation switches have a crossover channel that is numbered po2 on both sides. Each also has a po1 that connects to a VPC trunk on a Nexus core switch (or MLAG on another vendor). Complete overlap of numbering in a fairly typical enterprise configuration.

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