4500-X VSS and Dual-Active detection PAgP, using 2960-X access stacks

[rfawns]

Hi.

I think this may have been asked before but its not clear to me.

I have 2 4500-X configured as a VSS pair, so a VSL link of 2 x 10Gig between them.

I have a number of Access stacks, built from 2600-X's

I have tried to configure dual active detection, which from what I read it is to use ePAgP or Dual-Active Fast hello Packets.

I do not have any additional SFP's to connect the 4500's together using Fast Hello, so ePAgP appears my only option

When I try and configure the access stack with an Etherchannel across 2 switches using PAgP I get the error -

command rejected by the 2960-x stack

%With PAgP enabled, all ports in the Channel should belong to the same switch

Command rejected (Port-channel11, Te1/0/1): Invalid etherchnl mode

From what I have read, PAgP cannot be configured across a stack, and people are recommending LACP as the method to configure the Etherchannnel, but How does that work with Dual-Active detection PAgP?

When I configuring Dual-Active detection PAgP, and made a couple of the MEC's trusted and configure using LACP active, then tried failing the VSL between the 4500's, each stack went into err disable on the trunk connections.

Question is! Does dual active detection PAgP work over an Etherchannel configured as LACP? or what's my options

Thanks for any help.

[Reza Sharifi · Accepted solution]

Hi,

Question is! Does dual active detection PAgP work over an Etherchannel configured as LACP? or what's my options

No, you can't use LACP for ePAGP detection.  One option is to break one of the stacks in your access layer and use the switch you want to use for dual active detection individually (not part of a stack) and uplink it to both 4500X switches. This way, you know that the single switch is used for ePAgP detection.

HTH

[rfawns]

Hi Reza,

Exactly what I thought. Need a single switch that I can configure the PAgP MEC on. back to the design team and customer.

Thanks

Rod

[Reza Sharifi]

That is correct Rod.

Good Luck and thanks for the rating!

BTW, if you can, I would purchase the additional 2 SFPs and use fast-hello instead of PAgP.

I think, using fast-hello its just easier to deploy and understand. That is just my opinion.

HTH