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Port flapping between Offline and Initialization on ISL port-channel


Today i've tried to configure up a ISL port-channel between an older Nexus 5548 and a brand new MDS 9148t. 

Now, the issue/problem is that on one fabric, everything works perfectly, and the port-channel is up and running with it's 2 members.


On the second fabric, 1 out of 2 ports came up fine, and port-channel looked ok (though with only 1 member). The second was "flapping" between a status of Offline or Initializing. So, i replaced the SFP at both ends for the port that was having issues, and replaced the cable. just to try an eliminate that as a source for the error.


Then when i checked, both ports in that port-channel was now "flapping" between Offline and Initializing..... so now i'm confused... What could be wrong ? (and yes, i'm certain i replaced the SFP in the correct port)


Anyone have any good ideas or suggestions on things to try to get this link running like it should do ?


To summarise abit about the environment.

2 completely separate fabrics, where one works like expected, and the second have the above issues.

Each switch of the same type is running the exact same Software/OS.

Each fabrics consists of a Nexus 5548 with a module with 8 FC ports.

Each fabric consists of a MDS9148

Each fabric consists of a new MDS 9148t


So, before they were connected 5548 --> 9148 --> 9148t

Now, i'm trying to connect the 5548 directly to the 9148t, and i guess create a "ring", and once that is done successfully i'll then completely remove the old 9148.

Everyone's tags (1)

Re: Port flapping between Offline and Initialization on ISL port-channel



When i left last night, both ports where down, and 1 was in a port-channel, the other was outside. Arrived today, and both ports were operational.... so moved the port outside the port-channel into it (channel-group x on the interface) and lo and behold.... that port now starts flapping between offline and initilizing again ..... Wonder if it fixes itself if i leave it alone for 12-24 hours like last time ....

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