3850 and sfp problems

[1977bjorn]

Hi all,

I have never come across a problem like this before. We got new 3850 switches with NM2-10 as well as NM4-10 as well as native modular ports. We first started out with LRM sfp:s as theese where available. Connected everyting with various links including etherchannels with LACP. During troubleshooting we reloaded one of the switch stacks, and one of the etherchannel groups never came back. The module shows up in the "show interface status, but it says "notconnect"

We exchanged the sfp:s to SFP-10G-SR-S, same problem. During a service window, i fiddled around with the connections and I noticed that I could get a link on them. Separating the fibers and connecting one link at a time with some delay (maybee 2 seconds) brings the link up. Once the link is up, I can disconnect and reconnct the fiber successfully. For the SFP-10G-SR-S we are using the recommended OM3 patch cable (50/125), it also works with OM1, but I just wanted to rule out any cable issues.

It seems to me, a hardware timing of some kind.

I tried all sorts of configuration, including non-etherchannel configurations, speed auto, speed nonegotiate, udld off, udld aggressive etc...

Anyone seen this before?

Running on 16.3.3 by the way

//Bjorn

[Julio E. Moisa]

Hi

I have not experienced the problem, have you tried shutdown the ports, create the Etherchannel and then enable the ports using range?.

[1977bjorn]

Hi, Thanks for your reply

No, have not tried that, but the problem persists even with no etherchannel configuration.

Once I get it "to work" I can disconnect and reconnect cables in the current ether channel group with no problem. But a reload, will brake it again...

[Julio E. Moisa]

That is not a normal behavior, you also could open a case with the Cisco TAC to verify the hardware performance. 

[1977bjorn]

Yeah, I guess so :-)

Just wanted to see if anyone had seen it before

[Reza Sharifi]

Hi,

Have you cleaned the fiber tips with alcohol? Sometimes brand new fiber patches have issues connecting. The SFP should work with OM1-OM4.  

HTH

[1977bjorn]

Hi, thanks for input.

Seems HIGHLY unlikely, but sure, I think I got some sambucca laying around...

Coudl test of course, but I seriously doubt thats the problem :-)

[Leo Laohoo]

Kindly check the Release Notes for the 16.3.3.  I have seen several "exotic" SFP/SFP+ bugs for the 3850.  The bugs should be found in the OPEN Caveats.  

Another option is to downgrade to 3.7.X and see if this issue persist.