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WLC Port Channel Host Flapping

mark shuford
Beginner
Beginner

Hello,

I have setup LAG for one of our 5508 controllers and have connected 4 of the 8 ethernet ports to a 4507 switch. After configuring 2 port channels on the switch we are receiving a host flapping error between the port channels and it seems to be causing a serious slowdown on the switch. When I shutdown one of the port channels the error goes away and traffic returns to normal. I have the same configuration at other locations with the only difference being the switches used are 3750G-12S and I do not see the host flapping error. It appears to only be a problem with modular switches.

One other thing of note: I read a Cisco white paper on LAG and it suggested creating the port channels over 2 different modules. For example, put ports G4/24 and G5/24 in port channel 1 and G4/25 and G5/25 in port channel 2. I tried this but I still got the host flapping error.

I searched the forum and found a few threads on the subject but no resolution. Any insight on a fix will be greatly appreciated.

Thanks

Mark

1 Accepted Solution

Accepted Solutions

That is correct.  One port channel on the switch, but the ports can be across multiple blades.

HTH,

Steve

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HTH,
Steve

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Please remember to rate useful posts, and mark questions as answered

View solution in original post

4 Replies 4

Stephen Rodriguez
Cisco Employee
Cisco Employee

Mark,

     Just to double check.  You configured two port channels on the switch, and connected these to the WLC?

If that is the case, that is currently not a supported config.  You can split the ports across the modules, but you can't link two different etherchannels to the WLC.

HTH,

Steve

----------------------------------------------------------------------------------------------------------

Please remember to rate helpful posts or to mark the question as answered so that it can be found later.

HTH,
Steve

------------------------------------------------------------------------------------------------
Please remember to rate useful posts, and mark questions as answered

Thanks for the response Steve.

So you are saying that all 4 of the ports that I used from the controller should be assigned to one port channel on the switch?

Thanks

Mark

That is correct.  One port channel on the switch, but the ports can be across multiple blades.

HTH,

Steve

----------------------------------------------------------------------------------------------------------

Please remember to rate helpful posts or to mark the question as answered so that it can be found later.

HTH,
Steve

------------------------------------------------------------------------------------------------
Please remember to rate useful posts, and mark questions as answered

Thanks for the help Steve. I have rated your post and and marked the question answered.

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