C9500-40X fails port negotiation

[mauricio2099]

Hello people, I have a pair of C9500-40X running SVL in a 24/7 environment. Once connecting a server using TWINAX cables didn't worked, there was no link on the ports. This was not the first server connected to the 9500s. Due to the urgency the server was connected using ethernet cables to another switch.

Later I found a port for a Standby firewall was not coming up (when a failover was needed).
Firewall is connected to the 9500s with an GLC-TE RJ45 SFP but ports doesn't come up. Tried different speed/duplex combinations. The best was getting 10M-Half. Then if you remove the cable. The port on the switch remains solid green and active on the IOS. 

The SFP was replaced and also the cable. And also tested on other ports and on both switches but had same results.
Also the problem happens if you attach a laptop instead. 
SFPs are recognized but ports doesn't come up.

Actually there are other SFPs same type and twinax working fine on other ports.

The switch was restarted but no luck.

[mauricio2099]

Upgrade was successful, and then went back to the original problem.

I checked the current port where the standby FW was left, it was in a half duplex state (because duplex full was hardcoded on the switch). Instead of removing duplex full from the port I asked local person to put it on its original port (trying to keep symmetric ports for the 2 firewalls)....but it didn't come up. It resulted that he can't remove the SFP from the port. It is stuck the bracket/clip is broken. Then this port is damaged.

We don't have any other SFP to test on another port but we will get one and test. We tested with different SFP and port before and didn't work but now the expectation is that work with the upgraded IOS. And i will let you know.

I have another question derived from this activity. I saw on the release notes that In Service Software Upgrade with Cisco StackWise Virtual is possible but only when upgrading from Amsterdam 17.3.1 to another Amsterdam 17.3.X.

Can you redirect me to a guide on how to do this types of upgrade (which can let me know the principles of how this work, etc)? For my case maybe If I went through more software jumps I could be able to do ISSU?

I understand there is no traffic interruption with ISSU (is this true?) . There were troubles with Servers and Storage during this upgrade as the switch had to reboot.

:'(  I don't have more words to say excuse me but maybe can be prepared for future scenarios.

[Leo Laohoo]

I am not recommending ISSU, FSU/eFSU in production.   

ISSU, FSU/eFSU only works in "corner cases" like labs but, in production, when ISSU, FSU/eFSU fails, it will fail spectacularly.  

Anyone who wants to do an upgrade using ISSU, FSU/eFSU must have proactive TAC on standby because TAC would want to "witness" when it fails.