2821 - Etherchannel

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Overall Rating: 5 (2 ratings)
thotsaphon Mon, 06/15/2009 - 07:43


As far as I know is that Etherchannel doesn't support on the built-in ethernet interface. You may try to use Ethernet switch module to accomplish this.



Paolo Bevilacqua Mon, 06/15/2009 - 08:26

Beside working or not, what exactly ether channel with gigabit buys you on a 2821 ?

A 2821 is unable to handle one wire speed gigabit, not to mention multiple ones.

And link redundancy on LAN links is never a real issue.

Paolo Bevilacqua Mon, 06/15/2009 - 08:42

Doh, it agrees with what I was saying before...

Cfr second paragraph of "Applications".

Gotta love that "performance is at a premium" phrasing.

Joseph W. Doherty Mon, 06/15/2009 - 12:21

"Doh, it agrees with what I was saying before... "

Paolo, actually, according to our timestamps on our posts, it's what you were saying after. ;)

However, you're quite right, not a useful technique for gig Ethernet bandwidth on a 2821.

On redundancy, also agree there are other ways to address this, such as your mention of BVI and STP in your later post. However, ISR Etherchannel can also provide link/port redundancy, and although it increases device configuration complexity, can simplify the L2 or L3 topology in some situations, e.g. those dealing with a switch stack or different line cards on a chassis switch.

Paolo Bevilacqua Mon, 06/15/2009 - 10:04

You do not gain any redundancy from switch failure with etherchannel, because all links must go to the same switch.

If you are really worried about switch failure (and you should not not be), use a BVI config with links going to different switches. Note that will block one link due to STP.

thotsaphon Mon, 06/15/2009 - 10:14


Thanks for pointing the document. I just read it. The first release of IOS that supports embedded interface to do Layer3 Etherchannel is 12.4(17.6).

As I mentioned,there are a lot of network modules can support this feature. Yes,document says that as well.

I used to test this once. It did't work. I did search from http://www.cisco.com/go/fn with an "etherchannel" keyword. Haven't seen ISR showing up there. I give you 5P! anyway (grin)

Nick, Please let us know how things work out.

Paolo, BVI is a good idea as well. STP will come into play. No more load-balancing. 5P! for sure


thotsaphon Mon, 06/15/2009 - 12:14


Many thanks, I will lab it up tomorrow. Please let me know which ios version you did test.


Joseph W. Doherty Mon, 06/15/2009 - 12:35

Toshi, not certain, it was some time back. I think version 12.4(18) or 12.4(19). Whatever was highest available with 12.4 at the time.

huangedmc Thu, 06/18/2009 - 03:28

Keep in mind w/ distributed either-channel on 3750's you can only do static or LACP; PAgP isn't supported.


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