Cisco ASR1002 and Cisco 3750G SW- router-on-stick but switch gig port doesn't come up

[m-abooali]

Hi folks,

I have connected a Cisco ASR 1002 router via a sub-Int gi0/0/1.1 [has an IP] to a Cisco 3750G switch. vlan id and dot1q taggs are in place under sub-int and port on switch gi1/0/25 (the uplink) is trunk. the switch port is not connecting. the router side has a link and I can ping router's sub-int IP while on router. the switch has IPservices K9 image on it.

i cannot hard code speed and duplex on the gig sw port since its a gig switchport. I have nonegiciation under this switch port.

I am running out if tricks trying to find out what this switch uplink (trunk at switch side but subint at router side) not coming up.

your help and would be greatly appreciated.

Best Regards,

Masood

[Richard Burts]

Masood

You give us a general description but not much detail to help us identify the issue. A good next step would be to post the output from the switch of the command show interface status. Also please identify which switch port is connected to router.

HTH

Rick

[m-abooali · Accepted solution]

Thank you. Problem was a bad SFP.

It felt like a physical Layer issue. I had to swap 4 SFPs before link came up.

Thank you for writing back.

Best Regards,
Masood

[Richard Burts]

Masood

Thanks for the update. Glad to know that you resolved the issue and that it was bad SFP. If there is a lesson to be learned from this discussion it is the reminder that even though our first reaction to a problem is to look for configuration issues, that sometimes the problem is in the hardware.

HTH

Rick

[m-abooali]

Hi Rick,

You are exactly right! Physical layer problem. I changed 3 SFPs before I posted my discussion here however, all three SFPs were not new but used ones. The 4th one did the trick.

Thanks again for writing back.

Best Regards,
Masood