Dual Homing (Link Aggregation) Servers

gavin.mckee · ‎09-28-2006

Hi,

I have been following the document

http://www.cisco.com/application/pdf/en/us/guest/netsol/ns304/c649/cdccont_0900aecd800ea162.pdf

We are moving our network to a data center this is why I am reading this document. I have found an interesting point in this doument.

Page 18 (Link Aggregation Modes) states:

"The main disadvantage of the link aggregation modes is that all team members need to be connected to

the same access switch which is a single point of failure."

See my attached diagram.

If you look I have proposed a way of getting around the Link Failure by using a Cisco 3750 switch. If I use this switch am I right in saying that I have overcome the single point of failure while still preserving the ability to use Gigabit Etherchannel between the server and access layer switch?

Any comments will be rated.

Thanks

Aaron Harrison · ‎09-28-2006

Hi

Yes - you can do etherchannel on a stacked set of 3750s to work around the issue highlighted.

Versions SEE and above support dynamic aggregation protocols, earlier ones you need to configure with

channel-group XX mode on

Regards

Aaron

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Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

gavin.mckee · ‎09-28-2006

Aaron

When you say that version SEE and above support dynamic aggregation protocols what exactly do you mean? The 3750G switches I would be ordering to do this job would most likely have the EMI image. I just assumed that dynamic aggregation protocols would be supported.

Thanks

Gavin

Aaron Harrison · ‎09-28-2006

Sorry - current version is 12.2(25) but they have a suffix e.g.

12.2(25)SEB2

12.2(25)SEB3

12.2(25)SEB4

12.2(25)SED

12.2(25)SEE

etc...

The last shipping version i saw was a 12.2(25)SEB4 I think, so you'd need to upgrade to 12.2(25)SEC or later to take advantage of what's listed in the release notes linked below as 'cross-stack etherchannel'...

http://www.cisco.com/en/US/products/hw/switches/ps5023/prod_release_note09186a00804cc6aa.html#wp89520

I've configured Etherchannel on earlier versions, it works, you just don't get LACP/PAGP...

Aaron

Please rate helpful posts...

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

gavin.mckee · ‎09-28-2006

thanks for that, i'll have a look into doing cross stack etherchannel.

Gavin