After 3 weeks delay (because of the smoke clouds),  a new switch has arrived and is ok, I have tested and work fine.

Yesterday after a short outage the switches (2XSLM2048) did not worked correctly(uplink ok, but no traffic. Also did not work if i had moved the wire to other ports).

I have also a SLM2024 (this one is better than 2048, worked flowless)

  After restart was ok. (Are sensitive to short outages)

Hi,

Thanks for participating in the Community. My name is Nico Muselle from Cisco Sofia STAC.

The problem with ports not passing traffic is a known issue and currently a new firmware version is being tested which would resolve this issue.

However, while waiting for the time to release, there is a workaround which could help your switch ports from going down.

If your network topology allows it, and no redundant links are implemented, you could disable STP globally on the switch. At the same time, as a security measure, I would implement port security, so nobody can accidently create a loop in the network and bring it down. You could even disable non-used ports.

If you cannot disable STP, please configure all ports connecting to clients and not to other switches with PortFast, this should also prevent them from suffering the issue that you currently experience.

Would you need any assistance with this configuration, please do not hesitate to contact me or your nearest local Small Business Support Center.

Best regards,

Nico Muselle

Sr. Network Engineer - CCNA