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Ethernet Switches & Routers

Frequent Visitor
Posts: 1
Registered: ‎09-20-2016

can someone explain loop-detection in LAG ports%3F

I'm upgrading a ICX6650 to ICX7750 from code 8.0.30c to code 8.0.40.c.

while copying configuration from ICX6650 to ICX7750, I noticed ports configured with the following:






lag "abc1" dynamic id 7

 ports ethernet 1/1/17

 primary-port 1/1/17

 lacp-timeout short


 port-name Uplink ethernet 1/1/17




interface ethernet 1/1/17

 port-name Uplink


 speed-duplex 1000-full-master


According to "show loop-detection status", the port is "tagged, UP"



However, when I try to copy the configuration to ICX7750, I first get an error message when I configured the port first then tried to configure the lag






interface ethernet 1/1/17
 port-name Uplink
 speed-duplex 1000-full


lag "abc1" dynamic id 7

 ports ethernet 1/1/17  (when I type this line, I get the below error)


Error - Port 1/1/17 has loop detect enabled on it


LAG ports adding validation failed
Error - Command could not be executed



When I remove "loop-detection" from the ethernet 1/1/17, then I can add the port to the lag.  Then, I was able to go back to the ethernet 1/1/17 and put the "loop-detection" command back in.



Can someone explain whether it is a best practice to add "loop-detection" on a port which is a member of a LAG?


Posts: 66
Registered: ‎02-25-2016

Re: can someone explain loop-detection in LAG ports%3F

I am very sure, the reason is that the dynamic LAG has its own loop detection frames, that are recognized as control frames and keeps the ports up, else you would shut down the port e/1/1/17.

Adding "loop-detection" to a lag member afterwards, seems more like a "bug". Does it even show with "show loop-detection status "?

Jörg Kost

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