The use of portchannels in VoIP

Answered Question
May 26th, 2009
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I am working on an access switch that has two gig ports configured as a single port channel going back to the core. In my mind, I would think that the implications of this set up would be the same as configuring VoIP packets to go accross a bonded T1 circuit without the benefit of interleaving. In my experience, if interleaving is not used on a bonded T1 circuit the audio quality suffers greatly as packets arrive out of order across the multiple circuits and are consequently dropped. Should this not happen with port channels as well?

Correct Answer by paolo bevilacqua about 8 years 4 days ago

With etherchannel, nothing guarantees that links will be used equally.


Seems like you put in doubt the ability of etherchannel designers to prevent out of order arrival.


Educate yourself at:

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

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paolo bevilacqua Tue, 05/26/2009 - 11:28
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Since ether-channel works at L2 level, packets are never sent out of order.


Depending on your application, you may find that one only or both ports are used for VoIP.

shikamarunara Tue, 05/26/2009 - 11:40
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L2 data, or frames, are never sent out of order? At layer 2, transmissions are still considered to be unreliable, how can it be said that they "are never sent out of order"?

paolo bevilacqua Tue, 05/26/2009 - 11:42
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etherchannel doesn't care abut reliable or unreliable.


As indicated above, the port to use is chosen based on MAC addresses, consequently packets pertaining to flows between same devices, are always sent on the same port, and never out of order.

shikamarunara Tue, 05/26/2009 - 11:47
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MAC being associated with a port-channel makes sense, but if you have multiple links configured for a single etherchannel and the links are used equally, how can you say that frames can not arrive out of order? Do you have documentation to back this up?

shikamarunara Tue, 05/26/2009 - 12:07
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This is what I was originally looking for, but your first post was misleading. This answers my question, thanks.

James Hawkins Tue, 05/26/2009 - 12:03
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|Removed post as p.bevilacqua has already answered.



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