gbic loop on catalyst 2960

tquero · ‎08-13-2009

Hello,

I would like to know if there is a way to validate that a SFP type 1000baseLX is working properly on catalyst 2960.

I am looking for the loop feature that is available on routers.... but not on switches.

The topology is 2 catalyst 2960 switches with both SFP type 1000baseLX connected together with a fiber. This was working find but actually, the two interfaces are down/down.

The idea is to be sure that the problem is on the fiber and not on one of the SFP....

Thank You for your help.

Marvin Rhoads · ‎08-13-2009

UniDirectional Link Detection (UDLD) addresses your concern regarding the fiber. See http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/12.2_46_se/configuration/guide/swudld.html for more information.

For the SFPs themselves, you might want to review http://www.cisco.com/en/US/products/hw/modules/ps4999/products_tech_note09186a00807a30d6.shtml for more information.

Hope this helps.

viyuan700 · ‎08-13-2009

You can also use hard loop means take a patchcord and connect transmitter to receiver (in LX you can connect directly but if you have a attenuator would be nice)similarly you can check your card at other end.

IF both cards are working, Now only fiber is left , you can loop the 2 fiber at other end and check whether your fiber have problems.

tquero · ‎08-13-2009

Hi,

Thank You for your updates.

That means that there is no way to perform this loop in software mode with the IOS :-(

I thought about the possibility to physically loop with a patchcord but I am afraid to break the Rx LED of the SFP.

I will have a look on the LX specification to check the minimal distance.

The UDLD will not help me in this situation because both interfaces of both sides are in down/down status.

Anyway, thank you for your updates.

Regards,

Thomas Quero

viyuan700 · ‎08-13-2009

Hi Thomas,

U can try LAN switching board to check if anybody else knows loop in software but you can use physical loop for GLC-LH-SM (I think this is the card u have). As Max Transmit power is -3dBm and Max Receive power is also -3dBm so shd not be a problem.

http://www.cisco.com/en/US/docs/routers/12000/gsr_linecards/enet_lc/installation/guide/enet_lc.html#wp476232