We experience packet loss on one of our 4 Tengigabit interfaces bundled in portchannel between 2 VSS.

[george-tonev]

We experienced packet loss on the one of our 4 Tengigabit interfaces bundled in port channel between 2 VSS. Both VSS are not connected directly via the respective 4 links which are building the channel. Between them exist an Intrusion Prevention System which is working in transparent mode. What could cause that issue?

[Robert Falconer]

Has the IPS always been there? Has the packet loss always been there?

Have you replaced the optic and/or cable? I recently had an issue with an optic that caused something similar.

[george-tonev]

1 month ago there was a network failure by partial packet loss, which can only be eliminated by switching off one of the 4 links. There was / is no sign why packets are lost, the solution could only be found by trial + error. We could assume that the IPS has always been there.

[Robert Falconer]

So have you replaced the optics and cable on the single link that's causing the problem? Since it's in a port channel, as long as you can get by on 30gb temporarily, it should be non-disruptive.

[george-tonev]

Well,

I need to clarify that with my colleague.

I believe on Monday I will know much more than now.

[WILLIAM STEGMAN]

If the IPS is inline, have you checked the interfaces statistics of the IPS ports that make up the inline interface?  Are your switch interfaces reporting any errors?