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New Member

Etherchannel sequence

Hi Experts,

I would like to know the Etherchannel sequence.

If I have 2 ports in EtherChannel, for example, port 1 and port 2.  Source and destination mac is my load balance method.  I would like to know when the first packet goes to the Etherchannel, which port that the 1st packet will go, port 1 or port 2.

I am sure it would only go by one port for each session, and I wonder which port it would take when the first packer arrives. 

Thank you,

Aries

6 REPLIES
New Member

Etherchannel sequence

Hi Aries,

Nice question.

I just now did three experiments on this and at the three times... the first frame has passed throught the port with the lowest number.

For ex:

My first port-channel has Fa0/1 and Fa0/2 ,,, the first frame passed through Fa0/2.

My second port channel ex: There were two ports already in channel they were Fa0/14,Fa0/15... fa0/15 was first added to the channel... but the frame chose Fa0/14 for the first time.

My third ex: There were Fa0/15 and Fa0/14 channels... then after i added Fa0/1... the first frame chose Fa0/1.

Regards,
Chandu

Regards, Chandu
Cisco Employee

Etherchannel sequence

which platform is it?

its not like the first packet goes here and the 2nd packet goes there.. it calculates a hash value based on the load-balance method and based on the hash value outcome, it chooses the egress interface.

New Member

Etherchannel sequence

Hi Ali,

I've checked it on 2960 switches.

Regards,
Chandu

Regards, Chandu
Cisco Employee

Etherchannel sequence

I think we should be able to find the egress interface for a specific flow (src mac / dst mac) using this command in 3750 (i belive same applies to 2960 - havent tested).

test etherchannel load-balance interface port-channel

New Member

Etherchannel sequence

Ali,

I've tested with the load balance method of src-dst-mac.

Regards,
Chandu

Regards, Chandu
New Member

Etherchannel sequence

Hi Ali & Chandu,

I was talking about 3750 actually.  We can test it and find out which port it is going, that is no problem.  However, I am just thinking why it takes this port as first path.  I am not sure if it uses hash algorithm to do so.  I keep searching.

regards,

Aries

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