Problems with Etherchannel

[Jose Martin Villanueva Mauricio]

Hi CISCO Guys:

I'm having some problems with an Etherchannel. I have only 2 switches 2960 and these switches are connected through an Etherchannel (at both ends of the Etherchannel de ports that form de bundle are F0/11 and F0/12). When I Issue the following configuration in both Switches the Etherchannel works fine:

SW1 and SW2 Configuration

**********************************

interface Port-channel1
switchport mode trunk

!

!

interface FastEthernet0/11
switchport mode trunk
channel-group 1 mode desirable
!
interface FastEthernet0/12
switchport mode trunk
channel-group 1 mode desirable

But when I try to change the duplex and speed of the Etherchannel (at both ends) It comes down

SW1 and SW2 Configuration

**********************************

interface Port-channel1
switchport mode trunk

duplex full

speed 100

!

!

interface FastEthernet0/11
switchport mode trunk
channel-group 1 mode desirable

duplex full

speed 100
!
interface FastEthernet0/12
switchport mode trunk
channel-group 1 mode desirable

duplex full

speed 100

The question here is: Can I set de duplex and speed in an Etherchannel or It only will work in speed an duples auto?

Thanks a Lot Guys

[Leo Laohoo]

Can I set de duplex and speed in an Etherchannel or It only will work in speed an duples auto?

And why would you want to set "speed 100" on a FastEthernet port?  I wouldn't.

[Jose Martin Villanueva Mauricio]

Hi

According with my experience it is always the best practice in a trunk between 2 switches set the duplex and speed manually to avoid problems with the automatic negotation. That's why I'm setting the speed and duplex in all the ports at both ends of the Etherchannel.

[Reza Sharifi]

Jose,

As Leo noted, you don't need to set the duplex specially when things are working the way the supposed to.  If the 2 switches are Fast-e then they will both be Fast-e

[Leo Laohoo]

According with my experience it is always the best practice in a trunk between 2 switches set the duplex and speed manually to avoid problems with the automatic negotation.

Hey Jose,

Please don't be offended when I say that philosophy is "old school".  I agree with you when you say that your switch is a 2900/3500XL or 2940/2950/2955 switches.  But with 2960?  You're going to land into more trouble than fixing things.  Avoid hardcoding speed and duplex.  Keep It Simple!