SFP Trunk will not come up on Cisco 2960 switch

Trying to connect fiber from a 3750 to 2960 cisco devive and the 2960 trunk port never comes up not eevn with the no shutdown command

Here is trunk config on the 2960

nterface GigabitEthernet1/0/49
 description Uplink to Core 3750
 switchport trunk native vlan 98
 switchport mode trunk
 srr-queue bandwidth share 10 10 60 20
 queue-set 2
 priority-queue out
 mls qos trust dscp
 auto qos voip trust
tbartimAsked:
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koudryCommented:
Hello,

From the above posts, I assume you are using a fibre SFP. Can give the name / product code of the SFP?  I just need to check Cisco IOS and hardware compatibility.

If your SFP is fibre, what mode does it support, i.e. Multi mode (MMF) or Single Mode (SMF)? This will dictate what type of fibre cable you need to use.  

Also, if you are using SFP on both ends, are you using the same type of SFP? They need to be identical. If you are using SFP on only one end, which end, i.e. the 3750 end or the 2960 end?

Your problem is most likely to be the mode of fibre cable you are using, i.e. single mode SFP needs single mode fibre cable and multi mode SFP needs multi mode fibre cable and this must be from end to end.

Depending on the platform as well, you may need to issue the command "media-type SFP" to activate the SFP mode.  This is true for the Cisco 3825 where you have both RJ45 and SFP sitting on the same card and you use the media-type command to switch from one to the other.

Another easy way to test your SFPs and cable is to plug both SFP in the same machine, e.g. the 3750 and stick a cable between them to see if they come up. This should tell you where the problem is.


Thanks.
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Share-ITCommented:
Not too sure on the network switches but i often get this on SAN switches when our datacenter boys use x-over fiber cables!

Is the fiber the right way round? look in the transciever and check you have light going to dark and vice versa.
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tbartimAuthor Commented:
fiber cables are round
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Share-ITCommented:
what cables are you using? thought they could only use LC cables which are made up of a pair.
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tbartimAuthor Commented:
LC Cables which is a pair
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Share-ITCommented:
tbartim:
fiber cables are round


when you said that i though you meant you were using ST cables.

you can swap the left and right cables over. if they are "crossed" the link wont come up as you'll have TX to TX rather than TX to RX.

As i said, happens all the time at our DC with LC cables. I end up flipping the sides round (hurts your fingers) and all is well.

If that's not it and both transievers have light, the cables not broken and you've issued a "no shut" then no idea.

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tbartimAuthor Commented:
yes Ive tried swapping (reversing the cables ) with no luck

The transciervers (SFP modules have no link lights lit on the 2960 but on the 3750 they are lit with a solid green
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Share-ITCommented:
have you unplugged the fiber and looked inside the tranceiver on the 2960? you should see one side glowing red. if it's not then you probably have a duff/incompatible tranceiver. try swapping them between the switches. and see if they light then.
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tbartimAuthor Commented:
We Got the trunks going by turning off autonegotian and forcing full duplex on bothe the cisco 3750 and 2960

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koudryCommented:
Hello,

That's fantastic news. You must be very pleased.  These niggling things can be very frustrating.
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tbartimAuthor Commented:
"That's fantastic news. You must be very pleased.  These niggling things can be very frustrating"

Yes indeed I am thanks for everyones input
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Share-ITCommented:
Bizarre that Auto-Neg broke it. Glad you got it working in the end though.
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