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New Member

Link usage of etherchannel

For etherchannel of 2 links on a 3750 switch, if 1 link ever gets saturated, will the other link be used as well if the excess traffic is part of the same flow?

Or that excess traffic will simply be dropped?

I just can't get such infromation in any cisco document.

Everyone's tags (3)
4 REPLIES
Cisco Employee

Link usage of etherchannel

Hello,

In my understanding, EtherChannel by its definition works by hashing the address fields of transmtted frames (optionally of packets and even segments) to produce a single number that indicates the egress port to send the frame. The actual load of this port is not taken into account. This means even if a port in EtherChannel is saturated, the EtherChannel will not move the traffic to another port. As a result, the excess traffic will be buffered and possibly dropped.

Best regards,

Peter

New Member

Link usage of etherchannel

Thanks for your reply Peter. Are you aware of any cisco document talking about this? Many thanks.

Cisco Employee

Link usage of etherchannel

Hello,

Sadly, no, no document I know says this plainly. The only document I really liked about EtherChannels is this one:

http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml

My answer is in part based on the facts from this document.

Best regards,

Peter

Super Bronze

Link usage of etherchannel

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Posting

My understanding is the same as Peter's, which is also why choice of hashing algorithm can be crucial for optimal Etherchannel load balancing.

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