Etherchannel - CDP, STP

[bapatsubodh]

hi,

If we configure Etherchannel between two interfaces of two switches each.

( {Fa1/1 + fa 1/2} ---> {fa1/1 + fa 1/2} ).

If both switches are Cisco will CDP messages will be exchanged from all interfaces and will STP messages ( BPDUs) will be exchanged?

If we configure IEEE standard LACP, in this case will STP messages will be generated?

Please share the experience.

Any link on Cisco.com

Thanks in advance.

Subodh

[Thotsaphon Lueangwattanaphong · Accepted solution]

Subodh,

If both switches are Cisco will CDP messages will be exchanged from all interfaces and will STP messages( BPDUs) will be exchanged?

Yes, They still exchange CDP and STP packets. Note: STP will use a logical interface(Port-Channel) for calculating spanning tree

If we configure IEEE standard LACP, in this case will STP messages will be generated?

Yes, They still exchange STP packets. Note: STP will use a logical interface(Port-Channel) for calculating spanning tree.

HTH,

Toshi

[iyde]

To elaborate a little: You will see a CDP neighbor for each physical connection but as Toshi notes STP will use the PortChannel when calculating Spanning Tree. This means that both physical links will be transmitting data because they are by Spanning Tree and other protocols seen as one logical interface (i.e. even though it's two links connected between the same two devices it's not a loop).

HTH.

[kishan1984]

By default both cdp and stp(bpdu) will be exchanged,but you can turn off cdp messages,if you are forcefully configuring the trunk.