Fast Etherchannel on 4507R

Unanswered Question
Jul 9th, 2008
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I have installed a 4402 Wireless Controller with LAG. The controller has multiple VLANs.

The two ports of the controller connect to a single module on a Catalyst 4507R. I have tried to set up Fast Etherchannel on the two ports of the 4507R with no success.

The config is:

Interface Port-channel2


Interface GigabitEthernet7/47

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 2 mode desirable

Interface GigabitEthernet7/48

switchport trunk encapsulation dot1q

switchport mode trunk

channel-group 2 mode desirable

I tried making the trunk on the port-channel interface instead of the physical interfaces but nothing seems to work.

What am I doing wrong?

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Overall Rating: 5 (1 ratings)
mahmoodmkl Wed, 07/09/2008 - 04:43
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i dnot think the WLC supports ether-channel.



ibrydon Thu, 07/10/2008 - 06:58
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Thanks Mahmood

I think the WLC when using LAG does support connection to devices using Etherchannel to bundle their interfaces. The WLC Release Config guide even provides some guidance on how to set etherchannel up on the Catalyst switch; however, only 6500 and 3750 are mentioned not the 4500.


glen.grant Thu, 07/10/2008 - 07:58
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Etherchannel setup is pretty much the same across all IOS boxes , a 4500 should be the same as a 3750 as far as etherchannel setup goes. I would try forcing the etherchannel on for the switch side instead of using PAGP . found some info .

Note When a 4404 controller or WiSM controller module LAG port is connected to a Catalyst 3750G or 6500 channel group employing load balancing, note the following:

•LAG requires the etherchannel to be configured for the "on" mode on both the controller and the Catalyst switch.

•Once the etherchannel is configured as "on," at both ends of the link, it does not matter if the Catalyst switch is configured with either Link Aggregation Control Protocol (LACP) or Cisco proprietary Port Aggregation Protocol (PAgP) because no channel negotiation is done between the controller and the switch. Additionally, LACP and PAgP are not supported on the controller.

•However, the load-balancing method configured on the Catalyst switch must be a load-balancing method that terminates all IP datagram fragments on a single controller port. Not following this recommendation may result in problems with access point association.

•The recommended load-balancing method for Catalyst switches is src-dest-ip (Command line interface command: port-channel load-balance src-dest-ip).

•If the recommended load-balancing method cannot be configured on the Catalyst switch, then configure the LAG connection as a single member link or disable LAG on the controller.

ibrydon Fri, 07/11/2008 - 05:59
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Thanks for that.

Setting the mode to 'on' instead of 'desirable' cured the problem.



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