2910AL - 4500G 10G Link unstable

[MikeMolto]

We just expanded our Network that mainly consists of 4500G and 45010G switches with 3 2910AL Switches.

All the 45xx switches are connected via either 10G Cu or 10G XFP-SR which worked flawlessly for years.

The new 2910AL switches should be connected with SFP+ 10G-SR to XFPs on the 4500 side.

This connection is unstable.

It works in the first place but we see packet loss while pinging and we loose the connection after some minutes. It comes back once in a while.

Link is OM3 less than 20m and we already checked different fibres. Also the 4500G stack perfectly over the same fibre.

STP is turned of on the 2910AL and we do not have rings in the topology so far.

Thank you very much for your help!

Mike

[Matcol]

I guess the first place to start are the logs.

Do some "show int" on the ports that are giving you trouble.

Enable STP and check your STP design to ensure the topology is sensible.