question in pagp protocol !

[Dr.X]

hi , i read from cisco press book about pagp that :

if changes in one of the bundled ports , that change will be reflected on all ports in bundle .

but i tried this on cisco 3550 and it failed !

i  mean that the correct info is :

<<< Configuration changes made on the port-channel interface apply to all physical ports assigned to the portchannel interface.>>

plz correctt me if i understood info from cisco press uncorrectly .

regards

.

[Giuseppe Larosa]

Hello,

your understanding is correct:

before the bundle is created all member interface need to have the same configuration for several aspects.

Once the bundle is operational changes have to be done at the port-channel level in order to have them automatically propagated to all member ports at the same time.

Hope to help

Giuseppe

[Dr.X]

so , its wrong to say that if we changed config of a port in the bundle , this change will be applied on all other physical ports .

am i right ?

[Giuseppe Larosa]

Hello,

yes changing configuration of a member port after the bundle is operational is a source of issues a bridging loop can form even if the switches are C6500 devices. (if for example the list of permitted vlans is changed without any additional command for protection of bundle misconfiguration)

After the bundle is up all changes must be done on the port-channel interface. this is the rule

Hope to help

Giuseppe