08-20-2010 05:03 AM - edited 03-06-2019 12:34 PM
Hello,
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.
Manu
08-20-2010 05:20 AM
Did you cross your TX and RX fibers on the other switch? I've been burned by that before. Also, if the SFP ports are dual purpose (either RJ-45 or SFP), try to define the media type under the interface config. I believe the command is media-type rj45|sfp
08-20-2010 06:41 AM
Thanks a lot for your answer.
For the 2960 : the media type worked or I could say that I manage to run that command.
For the 3750 : this command doesn't exist. I did go into the config mode for the Interface Gigabit 1/0/1 but I can't run the media type ?
Thanks again.
Manu
08-20-2010 06:55 AM
Yeah, that command only works if the ports are dual-purpose.
Did you verify that the TX fiber from one switch was going to RX on the other and vice versa?
08-20-2010 07:15 AM
Hello,
Yes I checked the fiber to make sure it was fine on both end. I even tried it the other way aroun lol to see if I was doing it wrong. Well this is the WE here in France, so I am going out to take a walk and get my mind working for me.
thanks again and hopefully I will find the answer soon !!! and thanks for your advices again.
manu
08-20-2010 06:58 AM
Me, again !! well I checked the interface and it is in SFP for the 3750 but still KO between both switches. I tried with the ethernet cable and it is OK. ??
I have to study more things it looks like. If anyone has more idea, it would be appreciated.
Thanks again.
Manu
08-24-2010 01:51 AM
Hello again,
So I manage to make it work with the module fiber. It was a problem with the configuration.
But now I have another question.
I want to order some GLC-SX-MM to use on the switches which will be enough for the distance... I have some spares here that I am using in lab for testing but they don't work ???? when I use the GLC-LH-SM, everything is fine. I thought that maybe the GLC-SX-MM was KO but I have 10 of them and I don't think that all of them are KO.
Is there a difference between them or something I should do on the switches ??? (except the differences in distance...). Weird as this is working with the LH-SM, so it should also work with the SX-MM ???
Thanks.
Manu
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