Port Channels Traffic Control Catalyst 4500 Series

[Israel Logan]

Alright, so I am replacing an old 4507 with a new 4507.  The goal is to utilize redundant uplinks to the core for seamless port/interface migration from the old switch to the new switch.

The old switch has 2 redundant uplinks on a Port Channel connecting the old switch to the core.  So let's just say interface 1/1 on the old switch is connected to int 1/1 on the core switch and interface 1/2 on the old switch is connected to interface 1/2 on the core.  We cloned the old switch config to the new switch config.  There are a few SVI's and I haven't changed any IPs there because it seems like the traffic should flow to the source it came from and not lose packets on the new switch that doesn't have clients attached yet.  I think I should be able to connect the uplink interface 1/2 on the new switch to 1/2 on the core and that traffic on the 1/1 uplink would continue without a problem, right?  Or, is there some way to force preference for traffic to use 1/1 such as adjusting the interface delay setting higher on 2/2?  

I ask this because I started off by taking the 1/2 line from the old switch and accidentally put it on to 1/1 on the new switch which had adverse affects and I'm hoping that moving the 1/2 line of the old switch to the 1/2 of the new switch would work fine.  I think the problem with moving the 1/2 line from the old switch to the 1/1 interface on the new switch is that when comms would go from 1/1 on the old switch the core would see two paths back to 1/1 (one on the old switch and one on the new) so it would choose the one that had less traffic load (obviously the new switch because nothing is attached)

This is not LACP or PAGP, plain old "channel-group 1 mode on"

[Jon Marshall]

I am not really following what you are doing here. 

You cannot have an etherchannel on the core switch where the member ports terminate on different 4500 switches assuming you are not running VSS between the 4500 which you aren't by the sounds of it. 

What exactly do you want to do ?

Jon

[Joseph W. Doherty]

What do you mean by "seamless port/interface migration" especially as you've noted "We cloned the old switch config to the new switch config." If you mean, you want to disconnect your existing 4507 from the core, and they connect your new 4507 to the core, that should be doable. I.e. your core will see the same "logical" switch drop off-line and then come back on-line.

if you're looking to have both switches connected to the core, at the same time, with old using one of the core port channel links, and new using the other core port channel link, that would indeed cause issues, unless as Jon notes, your old and new 4507 were a VSS pair. Even though your port channel is manual, it still expects only one (logical) device use the port channel links. "Cloning" the old to new config, isn't enough.

[Israel Logan · Accepted solution]

 Nevermind... We've done this before.  Just been a while and I forgot.  2 Trunk ports.  Easy peasy lemon squeezy.  I just got thrown off by the port channel that was configured here.