Cisco 6509 & 3750 error while etherchanneling

[Anand Narayana]

Hi,

we have cisco 6509(catOS) & 3750(IOS), while etherchanneling between them, ports are getting err-disabled in 3750, below are the configuration.

Cisco 3750

interface gig 1/0/1

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 1 mode on

interface gi 2/0/1

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 1 mode on

interface Port-channel1

switchport trunk encapsulation dot1q

switchport mode trunk

Cisco 6509

set port channel 3/4 445

set port channel 3/5 447

set trunk 3/4 on dot1q 1-1005,1025-4094

set trunk 3/5 on dot1q 1-1005,1025-4094

set port channel 3/4-5 mode on

with this configuration, when i connect, within a minute the ports gets err-disabled in 3750, any changes to be made in the above said configuration?

[ankurbhasin]

Hi Anand,

Can you confirm if your modules 3 on your cat6k is gig module or 10/100 module?

It is going into errdisable state due to some etherchannel problem and that can be due to negotiation also.

Regards,

Ankur

[Anand Narayana]

on cisco 6509 the 3rd module is WS-X6408A-GBIC which has got fiber, port is getting disabled only 3750 not on 6509.

[Anand Narayana]

Hi Ankur,

actually i resolved the problem, just because the admin group value is different it has disabled, when i made it as equal, it started working fine, i mean admin group ID i meade in cisco 6509. thanks for the effort

[clayhawks]

I'm pretty sure that the 2 ports on the 6509 have to be in the same admin group. In your example, the 2 ports are in seperate admin groups (445 and 447). Try configuring the admin group to be the same for the 2 interfaces.

6509

set port channel 3/4,3/5 448

I've never had much luck allowing the 6509 to put the ports into admin groups on it's own. I've had much better luck assigning the admin group explicitly.

[glen.grant]

I think if you had set up the channels as desirable and let the switches negotiate they would not have this problem , you only see this when channels are forced on. From what i have read it is best practice to set up the trunks and channels as desirable and let them negotiate the trunks and channels. I have never seen a problem with channel or trunk negotiation and myself try to avoid forcing them on .