GLC-LH-SM module in 2960G

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May 16th, 2010
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Hi, GLC-LH-SM transceiver module is not functioning (no red led in module) in GB uplink ports of 2960G but GLC-SX-MM module is wokring (immediate red led in module) without any configuration on port. does GLC-LH-SM required any port configuration?

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Leo Laohoo Sun, 05/16/2010 - 01:38
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does GLC-LH-SM required any port configuration?

No.   It should work.  What is your setup like?  Is it GLC-LH on both sides?  Are you using single-mode cable?  What is the result of the output "sh inventory" or "sh interface status"?
aleemuddin Sun, 05/16/2010 - 09:53
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thanks. yes i am using GLC-LH-SM on both sides. fiber cable is Single Mode. fiber patch cords are also single mode. actualy the problem is before i connect patch cord to module which is in switches, i should be able to see red led inside module but not appears and if i put GLC-SX-MM module then red led appears. I replaced GLC-LH-SM with new doubting faulty but new results same no red led. all switches are new.

okay if i consider that there will be no red led in GLC-LH-SM and if i connect to another end (Switch) then connection must come between them but its not like that no connection.regards

Reza Sharifi Sun, 05/16/2010 - 10:30
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Hi,


Have you tried crossing the fiber patch cord between the switches (red blue and blue red)?


Reza

Leo Laohoo Sun, 05/16/2010 - 16:08
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i should be able to see red led inside module

Firstly, unlike SX, you can't see the laser in LH.  Secondly, if you value your eyes, DO NOT DO THIS. 


If you want to test the integrity of your fibre optic links you get a SFP loopback plug and/or a Optical TDR tester.

sashxx Sun, 05/16/2010 - 11:05
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aleemuddin wrote:


Hi, GLC-LH-SM transceiver module is not functioning (no red led in module) in GB uplink ports of 2960G but GLC-SX-MM module is wokring (immediate red led in module) without any configuration on port. does GLC-LH-SM required any port configuration?



What do you mean by 'red light'?

If you mean the TX laser, then you just can't see it, because LH (or LX) transceivers work at a higher wavelength (1270-1355 nm, which is in the infra-red band) than SX modules (850nm, red).


You should be carefull and not look directly into the laser beam - although LH and SX transceivers are laser class 1 devices.


Be sure to use monomode fibers. You may use multimode or monomode with SX, but you can't use multimode with LH.


You may try to connect RX and TX of this one transceiver with one fiber. You should see - at least for a short time - a link (the port may shut down because of the loop, but this is a hint that there was actually a link).

aleemuddin Sun, 05/16/2010 - 12:21
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hi, thanks. yes i mean laser beam which appears only in GLC-SX-MM and not in GLC-LH-SM. (i observe this before i connect patch cord to module or to patch pannel)


while i am using singlemode cable, single mode fiber connectorts on patch pannel i mean all SM then i cannot use GLC-SX-MM, so its clear i have to use GLC-LH-SM ok fine.


for test: i used GLC-SX-MM moudles on two switches and connected them directly using multimode patch cord (not thru patch pannel but direct switch to switch)-->>then its works fine there is connection between them.


second test: i used GLC-LH-SM modules on two switches and connected them directly (using Singlemode patch cord)-- then no connection.

pls advise..if this not work then i have to change all cabling to Multimode..which is around 200metes..

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