Re: Etherchannel misconfig guard

Keegan.Holley_at_sungard.com wrote:
>
> If I remember correctly it only detects if you're negotiating and the
> other end is in the wrong channel group. The problem with removing
> the channel group and statically setting it on the other end is that
> there is no way for the switch to know that this is incorrect. If
> etherchannel is set statically on the other end and negotiation is
> turned off it looks the same as when etherchannel is not configured at
> all. Also, there are several devices which can channel but cannot
> negotiate.
>
>
> From: Dimitar Mojsovski <dimitar.mojsovski_at_gmail.com>
> To: ccielab_at_groupstudy.com
> Date: 11/22/2009 11:41 AM
> Subject: Etherchannel misconfig guard
> Sent by: <nobody_at_groupstudy.com>
>
>
> ------------------------------------------------------------------------
>
>
>
> Hello !
>
> Does anyone have any experience with the Etherchannel guard misconfig
> feature ?
>
> I have a setup with 2xCat6500 running in VSS and I have a a Cat2960
> connecting to both VSS nodes. Naturally, I bundle the ports to a
> port-channel and create a trunk. All is working fine.
> At this point I try to test the Etherchannel guard and see what happens.
> I deliberately misconfigure the 2960 interfaces (set them to default
> with no channel-group), and wait for some (about 5 mins) and I see no
> sign of the Etherchannel Misconfig detection. Instead, a bridging loop
> occured - which is expected to happen without this feature.
>
> I am able to kind-of escape this problem by negotiating the etherchannel
> (auto/desirable), but this is not what I'm trying to accomplish.
>
> Cisco documentation doesen't help me much
> Cat6500 etherchannel config guide warns about misconfig, but states no
> measure to avoid.
> Cat6500 spanning-tree config guide only says this feature exists and
> detects misconfigured etherchannels. On most switches it seems to be
> enabled by default. On my 6500 it was not.
>
> Thanx
>
>
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Hi Keegan,

Thank you for taking some time to reply, your answer totally makes sense.
However, I am still confused about this reading in the Cisco doc :
"If one switch is configured for EtherChannel and the other switch is
not configured for EtherChannel, the spanning tree process can shut down
the channeled ports on the side that isconfigured for EtherChannel" -
referring to the same feature.

Do you by any chance know where I can read details about how this works ?

Thanks

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Received on Mon Nov 23 2009 - 00:44:09 ART