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channel protocol command

is channel protocol command mandatory ?

if not, what is the purpose of this command?



Re: channel protocol command

channel protocol is not mandatory. (do you mean pagp?) (do you mean LACP?)

if you're talking about pagp specifically then this protocol is used to facilitate the auto creation of ether channels by exchanging packets between ethernet ports. pagp is used for ports in Auto or Desirable modes only. pagp is not exchanged between on or off mode ports.

LACP supports the auto creation of etherChannels by exchanging packets between ports. lacp is used for ports in passive & active modes.

etherChannels can be used for portAggregation to facilitate link redundancy, increased link bandwidth and load balancing.

see these following links for more info:

if you have no etherChannels defined/configured, the pagp or lacp protocols are not operating by default.

Community Member

Re: channel protocol command

if we dont use channel protocol command, can we create etherchannel just using channel group command.

i still dont get the point anyway

Community Member

Re: channel protocol command

for example:

which one is correct ? what is the different?

sw(config-if)#channel-group 1 mode auto


sw(config-if)#channel-protocol 1 pagp

sw(config-if)#channel-group 1 mode auto


Re: channel protocol command

by default, the above is basically the same configuration.

channel-group 1 mode auto

(this is a pagp default config)

channel-protocol 1 pagp

channel-grouop 1 mode auto

(this specifies the port can only talk pagp, not lacp)

basically, both examples achieve the same results, a PAGP etherChannel in Auto mode. (the auto mode places the lan port into a passive negotiating state. the port responds to pagp packets it receives but does not initiate pagp negotiation. this is default behavior)

Community Member

Re: channel protocol command

im sorry, i still dont get the point,

why need to restrict to PAGP

while we know 'mode auto' already responds to PAGP only ?


Re: channel protocol command

So you should use channel-protocol command when you would like use some dynamic method to establis etherchannel, I mean that you don't define the etherchannel with "on" option. So when you want to use some dynamic option to establish the eteherchannel you need define the protocol, if your switch support more etherechannel protocol - Cisco 2950 only support PagP (Cisco solution).

If your switch support only PagP next command is enough since channel-protocol is pagp in default:

sw1(config-if)#channel-group 1 mode auto

sw2(config-if)#channel-group 1 mode desireable

You can't use boths side auto...

I case of when switch support both LACP and PagP you should use channel-protcol command to define what kind of protocol you want use.



Please rate me if I helped.


Re: channel protocol command

how to configure an etherChannel depends on the switch type/IOS/CATos you have.

the channel-group command is configured at the interface level. it defines the channel-group that the interface belongs to. this allows you to add 2 or more links to the same channel-group, there by creating a logical link of 2 or more lan ports.

the channel-protocol command is optional. it restricts the channel-group command to the etherChannel protocol configured with the channel-protocol command. in other words, it makes the specified lan port accept only one of the two channel protocols, ie: pagp or lacp.

the configuration steps vary depending on if you are creating a Layer2 etherChannel or a Layer3 etherChannel.

see the following link for steps and configuration example(s):

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