3750E etherchannel only using 1 port

Unanswered Question
Aug 10th, 2009

I am using 3750E switch and configure with a 4 Port etherchannel to a GSR. The incoming traffic is load balance from GSR to 3750E but the traffic from 3750E to GSR is only travel via 1 Port. I have try different load balance method eg.scr-dst-ip, scr-dst-mac but still the same. Anyone got any suggestion?

I have this problem too.
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Lucien Avramov Mon, 08/10/2009 - 21:59

This sounds normal:

Port Channel doesn't do per packet load balancing. It does the load balancing based on the source and destination ip address of the packet (or MAC address). It basically does the hashing of source and destination ip addresses (or MAC) and chooses the output member interface based on that.

So in your network it might be happening that 80% of the packets' source and destination IP (or MAC) addresses are hashing to a specific interface and hence you are seeing this.

You may say that it is a limitation of portchannel. Port channel was not designed to do per packet load balancing.

marcochan Mon, 08/10/2009 - 22:55

yes I understand etherchannel is not load balance per packet but the result that I am getting it 600MB on 1 port and the other 3 port are >1MB.


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