Cisco 9300 connected CIsco 3750G

[beconnect]

HI

we changed a old switch CIsco 2960 to a new Cisco 9300.

Sw9300 connects to the existing Cisco 3750G via SFP Fiber.

this a test flat envirorment with only one vlan and some servers .

Everything was working prior to this change.

Now On the CIsco 9300 log,   i see the tengigabit port flapping sometimes.

 today only arises a flap up an down at 4 pm and goes for 4 seconds.

 I had ping a server for  more than 2 hours without any ping loss.

Could it be any mismatch between old and new switch?

If it was a problem on STP protocol we should see more events of port disabling.

Thanks in advanced

[marce1000]

  - Check the interface counters on those interfaces who are flapping and look at the logs from the 3750G too ,

  M.

[beconnect]

Will do. Thanks

[Richard Burts]

With the limited information provided it is difficult to give good advice. The logs that are shown in the post show 4 events:

- at 11:19 G1/0/23 goes down. There is no indication that it came back up.

- at 11:20 exec timer expired. There is no way to know whether this is related to the previous message or is something else. 

- at 15:41 G1/0/10 goes down. There is no indication that it came back up.

- at 16:22 TenG1/1/2 goes down and almost immediately comes back up.

Your post focuses on the last event, and tells us that it had been working for 2 hours before it failed. Based on this we do not have enough information to identify the issue. Are there log messages on the 3750 at this time? Do the G1/0/x and the TenG1/1/x both connect to the same device?

It might be helpful if you would provide configuration details from both devices. It might also be helpful if you would provide the output of show cdp neighbor detail from both devices. 

[beconnect]

Hi Richard. 
indeed you are correct. 

but the reason ignore those gigabit events, its because 1/0/23 was my PC. I was at site today to check on the putty log and also I connect my pC. 

the strange behaviour is that on the old 2960 , with the same connections everything was fine

At port gigabit 1/0/5 we have another cisco 9300 connected by copper to another floor

so if you do cdp neighbors you will see cisco 3750g and cisco9300 also. 

regards

[Joseph W. Doherty]

I presume, although 9300 is using a 10g port, connection is gig (unless you're using the rather rare 3750G that has one built-in 10g port).

In addition to what @Richard Burts already requested, what SFP transceivers are being used, the kind of fiber, and end-to-end fiber length?

[beconnect]

Hi Joseph. 
be aware that this setup was working on the old 2960. 
I will check the configs later and get back to you guys

[Joseph W. Doherty]

be aware that this setup was working on the old 2960.

Yup, got that.

Sometimes (rarely), different hardware, supporting the same hardware specs, can "interpret" the spec a bit differently.

This seems to be most common with optical transceivers, which is one reason why Cisco only supports their own brand of transceivers that have been specifically declared supported for a specific platform and IOS.

So although, logically, you wouldn't expect this upgrade to matter, you did change hardware, so it can matter.

Understand, it's much to soon to say this is the root issue, but sometimes it is and it can be easily overlooked.  So, just want to make you aware of it.

[Leo Laohoo]

4 seconds from the lights going up to down?  I think this is error-disable behaviour. 

Post the complete output to the command "sh interface status error" from both switches.

[beconnect]

Hi. Will send you the output Monday. 

But err disable isn’t related to STP ?

[MHM Cisco World]

Show plat pm interface-flaps ×/× <<- in Monday please also share output of above command 

MHM

[marce1000]

@beconnect  For err disabled port reasons check the output from :

  show logging | inc err

 M.

[Leo Laohoo]

---

@beconnect wrote:
But err disable isn’t related to STP ?

---

No, it is totally different.  

[marce1000]

   - @Leo Laohoo                                       .>....No, it is totally different.  
                         ????       What about BPDU guard violations,  Root guard, Loop guard,....

  M.

[Leo Laohoo]

I have never seen an error-disable reason due to "STP" or Spanning-Tree Protocol.

True, I have seen error-disable reasons due to many things, such as, loopback failure, BPDU Guard, etc.  But STP?