Portchannel config not inherited to physical ports?

FrankGuthrie

So If have a port channel which currently consist of 2 physical port. The portchannel is a trunk config, but If I change this to the portchannel to being an access port, the config on the psychical port still show this:

interface Ethernet2/2

switchport trunk encapsulation dot1q
switchport mode trunk
duplex auto
channel-group 34 mode active
end


interface Ethernet2/3
switchport trunk encapsulation dot1q

switchport mode trunk

duplex auto
channel-group 34 mode active

end


The NEW portchannel has the following config:

interface Port-channel34

switchport
switchport access vlan 10
switchport mode access
end


The OLD config before was:
interface Ethernet2/3

switchport trunk encapsulation dot1q

switchport mode trunk
duplex auto
channel-group 34 mode active
end



I was under the impression that the physical ports would take over the config I made on the portchannel. Am I wrong in that assumption...Why is the NEW config not inherited?

NetworkNewb

From Cisco's website:

When the interface joins a port channel, the following individual parameters are replaced with the values on the port channel:

• Bandwidth
• MAC address
• Spanning Tree Protocol

FrankGuthrie

Yeah, I know that already..... Asking why it did not take the the config from the portchannel....

networker050184

Might need to remove them and readd them or shut all the ports down before making the change. I have seen some weird behavior when making changes in the past.

FrankGuthrie

It might be weirder form me as I'm using IOU. I tough this might be different on real hardware, but seems, even in real hardware it behaves strangly..

EdTheLad

Port-channels are buggy, always have been, slowly getting better over time, but i generally find at least one issue on every ios/ios-xr i test.
This is common knowledge in the industry, so if you ever see a design with port-channels, know that's were most issues will be.

NetworkNewb

FrankGuthrie wrote: »

Yeah, I know that already..... Asking why it did not take the the config from the portchannel....

because switchport mode and vlan aren't listed as parameters that get replaced by the Portchannel config?

Also just an FYI, I haven't configured anything with portchannel so I'm just going by the information I've read about portchannels. I have read on one site that someone needed to shut all ports down before making any changes like networker said though. So that might just be issue. Let us know if that works, I'm definitely curious!

FrankGuthrie

NetworkNewb wrote: »

because switchport mode and vlan aren't listed as parameters that get replaced by the Portchannel config?

That might be an excellent suggestion. I will try this in Packet tracer, and maybe on 2 real Cisco 3560 which I have laying around. I'll let you know the outcome.

Hondabuff

EdTheLad wrote: »

Port-channels are buggy, always have been, slowly getting better over time, but i generally find at least one issue on every ios/ios-xr i test.
This is common knowledge in the industry, so if you ever see a design with port-channels, know that's were most issues will be.

100% this. If you change the Port Channel then do the same on the interfaces belonging to the port channel. Had that happen with Vlan pruning before and found out the hard way why it wasn't working. Cisco says if you change it on the Port Channel then it will change the physical interfaces also. Not so much.

FrankGuthrie

Hondabuff wrote: »

100% this. If you change the Port Channel then do the same on the interfaces belonging to the port channel. Had that happen with Vlan pruning before and found out the hard way why it wasn't working. Cisco says if you change it on the Port Channel then it will change the physical interfaces also. Not so much.

The plot thickens....Looks like there is nothing wrong with IOU, but the facts portchannels behave strangely.