How to configure Etherchannel(LACP)?

Unanswered Question
Feb 7th, 2009

Provide step by step how to configure Etherchannel(LACP)

I have this problem too.
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mahmoodmkl Sat, 02/07/2009 - 21:15


First make sure that the ports u want to use in the etherchannel are having indentical configs and after that.

for eg.

switch#conf t

switch(config)#interface range f0/1 - 2

switch(config-if)#switch port mode trunk

switch(config-if)#switchport truk encap dot1q

switch(config-if)#channel-group 1 mode active

this should be done on both the switches.



johnlloyd_13 Sat, 02/07/2009 - 22:25

there's a missing config line to be added here:

Switch(config-if)#channel-protocol lacp

glen.grant Sun, 02/08/2009 - 06:07

The channel protocol lacp is not absolutely needed it knows when you add channel-group x mode active that it is lacp . I don't know why they have that separate command , maybe someone else can chime in why thats even there .

Giuseppe Larosa Sun, 02/08/2009 - 00:54

Hello Vinoth,

here is a reference to chapter on config guide for c3750

I recommend if you need a trunk to provide an explicit list of needed vlans on the trunk with

switchport enc dot1q

swichport mode trunk

switchport trunk allowed vlan x,y,z-k,w

the same list has to be configured on both ends and on every member link.


Actually in newer releases the command to specify the protocol used looks like not necessary anymore for example in the document I've linked.

However, it shouldn't hurt and I agree it is necessary on older versions of code

Hope to help


babatunde_sanda Sun, 02/08/2009 - 17:59

Ok guys this is the simply explanation.

Pagp is Cisco proprietary. Port aggregation Protocol

Lacp is industry standard. Link aggregation protocol.

to enable PAGP

Go to the interfaces say i decide to group two interfaces together

Int range fa0/1 - 2

channel-group 1 mode ? (auto or desirable)

channel protocol pagp (Technically this command is not needed because the switch knows immediatelly from the previous command you are using Cisco PAGP protocol that has only auto or desirable)

to enable LACP

Int range fa0/1 - 2

channel-group 1 mode ? (active or passive)

channel protocol LACP (Technically this command is not needed because the switch knows immediately from the previous command you are using Cisco LACP protocol that has only active or passive)

Now I personally stay away from anything auto (If you want something done do it Hard code the thing). Personal choice. Alright auto on somethings are good at times.

Int range fa0/1 - 2

channel-group 1 mode on


All ports must have identical configurations.


Int range fa0/1 - 2

duplex full

speed 100

trunk or access ports

Now am sure we know that the opposite side must be configured the same way. For LACP Passive, active will form channel. You guessed it desirable and on will work not the other way round.

Pls Rate if this helps.


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