does etherchannel require lacp or pagp

[axfalk]

I need to configure an etherchannel and was wondering if either lacp or pagp have to be configured in conjunction with it?

Thanks.

[Georg Pauwen]

Hello,

you do not need PAgP (Cisco-proprietary) or LACP (IEEE 802.3ad standard), when you set your channel to:

channel-group 1 mode on

PAgP and LACP are disabled.

Here are the available channel modes:

On

--> PAgP and LACP disabled (no negotiation)

Desirable

--> Actively negotiate PAgP

Auto

--> Passively listen for PAgP

Active

--> Actively negotiate LACP

Passive

--> Passively listen for LACP

The following combinations for both sides will result in successfully establishing the channel:

On -- On

Desirable -- Desirable

Desirable -- Auto

Active -- Active

Active -- Passive

HTH,

GP

[glen.grant]

If you have cisco on both sides just run pagp with both sides set to desirable. If you have mixed gear then you need to runn lacp . The general cisco recomendation is to set both sides as desirable.

[axfalk]

Thanks for everybody's responses. What is the upside of using or downside of not using pagp/lacp.

Thanks again

[Georg Pauwen]

Hello,

the main difference is that PAgP is Cisco-proprietary, while LACP is IEEE defined (802.3ad), AFAIK, the protocols are quite similiar, with a few exceptions, e.g. LACP does not support half-duplex links.

HTH,

GP

[axfalk]

Thanks. I guess what I am really trying to understand is the rational of creating an etherchannel without either PAgP or LACP. Would would be the downside? Thanks.

[Georg Pauwen]

Hello,

I guess it can be compared to duplex and speed autonegotiatin in Ethernet environments. Setting speed and duplex to a fixed value on both sides is preferable when you are sure that either side will never be used for anything else than the device it is connected to. So, I would always disable negotiation if possible...

HTH,

GP

[Aaron Harrison]

Hi

Just thought I'd throw in another bit of info... if you're using 3750s and want to do FEC to two switches in a stack you need to manually configure it using the 'channel-group 1 mode on' command on the ports as opposed to using PAgP or LACP.

Which is handy sometimes.

Aaron