As I mentioned in another thread, I am currently doing an apprenticeship program in a business with lots of Cisco switches and routers.
One of the employee, tried to connect 2 switches between each other using the Gigabit interfaces and using the module GLC-SX-MM for fiber. The result was no connection and the interfaces KO. As I am here to learn more about cisco... I set up 2 switches in lab to reproduce exactly the same situation.
1. 1x Switch 3750 and 1x Switch 2960.
2. I did the trunking using and ethernet cable and everything worked fine and could make the pings....
3. I then set up the modules GLC-SX-MM and inserted the fiber. At the point everything was KO. I tried again with the ethernet cable and it was OK.
4. The interfaces are up, the config is correct.... I tried with other modules and still KO.
5 What is interesting is that they have other 3750 and 2960 on their network and everything is OK.
Any ideas ?
thanks a lot.