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SFP is getting damaged

Hi All,

I have two catalyst 4500 model switch, connecting a trunk of fiber. At one end, there is '4510 with SFP (WS-X4516) module' and at another end there is '4510 with GBIC (GLC-SX-MM) module'. But the problem is, our SFP module is getting damaged on regular basis each after 5/6 months. Can anyone guide whether it's the compatibility issue or anything else? What change can prevent this damage?

6 Replies 6

Level 10
Level 10

Damaged how? Do you mean the link drops and stays down (forever)?

If someone tried connecting the GigE fiber into the 10GigE port, the laser could damage the receiver on the GigE side.

When the module fails, does it go away slowly (intermittent errors that get worse until total failure) or does it just die?

You might want to verify the SFP/GBIC at each end and make sure they are the same. Longer range fiber optic modules use a much stronger transmitter source, and could require optical attenuation (or risk burning out the receiver on the short-haul side).

Let us know

Good Luck


Thanks bro!

>>>Damaged how? Do you mean the link drops and stays down (forever)?

---yes, the link drops suddenly and found it's damaged. We didn't get any warning of packet loss or % error packet received at any end, it suddenly goes dead.

>>>Longer range fiber optic modules use a much stronger transmitter source, and could require optical attenuation

---distance between them is couple of meters (like 10/12 meters), i don't know whether the models i have specified are for long distance link, are those? if yes, then what are the suitable models for short distance?

And both of them are GigE ports.

The GLC-SX-MM is a GigE, short reach, multimode fiber transceiver. Is the other end of the link the same?

The model you provided, WS-X4516, is a supervisor engine card that the transceiver plugs into.

Take a look again at what transceivers are installed. This will help to determine if they are mismatched or not.


Level 5
Level 5


Since your GLC-SX-MM is working at 850nm and your link is working, so i am assuming that 10Gb Optical transmistter on your WS-X4516 is Cisco X2-10GB-SR(as i dinot find any other 10G card working at 850nm).

Though both are short haul card but have different Transmit & receive levels, i think can be the problem.


Cisco X2-10GB-SR

Transmit power is -1.2**(Max) -7.3(Min)

Receive -1.0(Max) -9.9(Min)

Whereas GLC-SX-MM

Optical transmit 9.5 dBm (Min) -3 dBm (Max)

Receive -17 dBm (Min) 0 dBm (Max)

Though they power level are within limits like 10G is transmitting at -1.2dBm and Max for GLC-SX-MM receive is 0dBm will have atleast one patch chord which will have loss.

But sometimes Transmit levels can be more than the specified, so check the transmit level of your cards before connecting as you are connecting over 10-12meter dsitance.

Also there is warning with 10G card see the link below

"The launch power shall be the lesser of the class 1 safety limit or the maximum receive power."

Sometime back there was a message where we were trying to get an answer for the above statement. So check your Optical Power level before connecting.

Hi, I have found the model number of GBIC, it's WS-G5484. So, the combination is '4510 with WS-G5484' at one end & '4510 with GLC-SX-MM' at other end. So can you please help me out?

Can I control the optical power level? any reference doc for that please?

WS-G5484 & GLC-SX-MM both are shor haul optics and same specs.

You cannot control the Optical power with a command but you can use Optical attenuator.

As per link below if you are getting the Max Transmit power which is -3dBm and with some patch cable loss, you are within range (Since both are 10-15meters away so cable loss is very less). As max receive level is 0dBm.

But you can check with an Optical power meter what is output power of both Transreceiver. Possible that any one is transmitting more than the specified limit.

If you find that power is more than -3dBm short term solution is to use some optical attenuator like 3-5dB to make it within receive level i.e 0 to -17dBm .

Right solution if power is more then -3dBm , is to call Cisco and find what is wrong with Transreceiver.