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Trunking between 2960X and 3560G

Level 1
Level 1

I am trying to trunk between a Cisco 2960X and a 3560G switch. The 2960X has a 10gig (SFP) interface and the 3560G has a 1gig (SFP) interface. Can I do this with 1gig SFP modules? If so what is the configuration on both switches because I can't get them to come up. This what I have.


2960X config

interface TenGigabitEthernet3/0/2
 switchport mode trunk


3560G config

interface GigabitEthernet0/28
 switchport trunk encapsulation dot1q
 switchport mode trunk


12 Replies 12

Level 3
Level 3


 switchport nonegotiate


to both interfaces (this will disable DTP but not the ports ability as a trunk)

Ok I just tried that but that did not work. It is still not trunking. I guess my first question is can I do this with 1gig SFP modules. Specifically in the 2960X that has a 10gig sft port?

what type of SFP is connected in the 2960 port

Cisco GLC-SX-MM (1Gig SFP).

Looks like the 10Gb fiber interface is fixed to 10Gb, this is not possible.

Yes you are correct. The 1Gig modules are not supported. 

I think you are in the wrong Compatibility Matrix.

In that list, the SFP+-models of the 2960-X are listed with 1Gig SFPs like GLC-SX-MM.

Hi Karsten

I've just sent you a PM with a quick query.

If you get the time can you have a quick look ?



So just to be clear. What I am trying to do is take a 2960X with 10Gig module slots (2 qty) and insert a 1gig SFP (GLC-SX-MM) in the 2960X and then connect it to a 3560G with 1Gig module slots (2 qty) with another 1gig SFP (GLC-SX-MM) and get trunking over these fiber modules.

BTW I also tried a 10Gig SFP (SFP-10G-SR)in the 2960X and I still can't get the trunking to work. I also checked the transmit and receive on the fiber cable and they are correct.

Yes, thats clear, ant I think that when you use a 1Gig SFP it should work.

You can try to darken the room and look into the laser with the camera of a mobile. Can you see light on the transmitter? And what happens in a different slot? I recently had a 2900-X at a customer site where the SFP didn't work in the first slot but it did in the second.

Yes I can see the light through the fiber, so it is transmitting. I tried a different slot and SFP as well. I ended up connecting the 3560G to a 3750G via the SFP and it worked fine. I was able to trunk the ports just fine. I am pretty sure that the 2960X with 10Gig module slots will not work. It can't reduce down to 1Gig. Anyhow I got it working and I know now that it does not work. Thanks for the suggestions.

I looked at my 2960X, but I don't have one that has a 1Gig-Module in a SFP+ slot. But at least it is documented to work:

The SFP+ slots support both SFP and SFP+ modules

Are you sure you don't have just a send/receive mismatch? Sometimes the easy things are the hardest to find ... ;-)

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