cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
448
Views
0
Helpful
4
Replies

connecting two VSS pair using channel-group mode on

Hou Qiming
Level 1
Level 1
sorry for my poor english 
 
I'm trying add two links for my old system.
4506E vss----4500X vss
using channel group mode on(old config,cant change to lacp by now)
4506E(ten1/5/10,2/5/10)-------4500X(ten1/1/1,2/1/1)
 
and i have test the new links using L3 mode singlely.that works well.
 
the i shutdown the new ports,config it an doing no shut.
the first link add successful.when i no shut the 2nd one,
it join the port-channel,and in P flag in show etherchannel summary.
but all my traffic corrupted.the port-channel looks like didnt forward any data.
 
no errlog,the only log i can found is etherchannel join logs.
 
because our maintenance windows is too short I can just unplug the 2nd link.
 
anyone can tell me why this happen?
 
the new link is crossed,that make this happen?
attachment is the old and new topology.
four links in one channel-group,using mode on

4 Replies 4

Reza Sharifi
Hall of Fame
Hall of Fame

According to your diagram and description you are trying to establish VSS between a 4500x and 4506E.  This is not possible, as for VSS to work the platforms need to be the same. 2 4500x or 2 4506E.

HTH

no,i have two vss pair

4506E vss and 4500-X vss

i have connecting them with MEC,now we need adding two 10G link into this MEC.

after adding the fourth link the port-channel stop work. but no errors in the system message

Paul Chapman
Level 4
Level 4

Hi Hou -

This is the problem with an unconditional EtherChannel (mode on).  There will be no errors to troubleshoot and any misconfiguration on either side will result in traffic drop.

Since you have uptime requirements, I suggest that you reduce your connections between your 2 VSS pairs to 1, then build a brand new LACP EtherChannel.  This will result in a STP controlled dual-link between the switches.  To ensure that you do not get unintended forwarding across the new PortChannel (EtherChannel) while you are building it, make sure that the STP cost for the single link will always be lower than the PC (you will likely need the STP path cost method set to long).  When you are ready, turn off the single link and STP will move all traffic over to the PC.

PSC

thank you i will try this next maintenance windows

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Innovations in Cisco Full Stack Observability - A new webinar from Cisco