Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Attention: The Community will be in read-only mode on 12/14/2017 from 12:00 am pacific to 11:30 am.

During this time you will only be able to see content. Other interactions such as posting, replying to questions, or marking content as helpful will be disabled for few hours.

We apologize for the inconvenience while we perform important updates to the Community.

New Member

New fiber install

Hey folks - I have a new install comming up that I am pretty sure I will need a ZX transceiver for. Ill be connecting a remote 3560-E to a 6513 using SFP connectors. I am pretty positive Ill be using a GLC-ZX-SM on both ends, but I am not sure how to determine 1) if I need attenuation, 2) how much to use, and finally 3) does cisco sell these, or will i need a 3rd party vendor?

I need to re-scan the fibers again with a power meter and OTDR, because I seem to recall getting massivly different distance readings from each end - one side said 19 miles, the other said 32. Either way, I am positive I am going to be over the (approximate) 6 miles for LH, right?


Re: New fiber install

If your one side is 32 miles then certainly you need ZX or even if it is 19 then also ZX.

Yes you need to check your fiber if fiber length is differnt in both direction. While this testing check what is loss between both ends.

1) if I need attenuation

I think you want to know whether you need Attenuator. As the GLC-ZX-SM has Max Trasmit level +5dBm and Max Receive Level is -3dBm. Before connecting just check what power level you are receiving if it is more than -3 then you dont need attenuator. But i am positive that even with 19 miles you will have power less than -3.

see the followinglink for power level

But if you connect it to nearby distance or in same office then take a 10dB attenuator.

You can buy from cisco or third partyanything is fine i think there will be price difference thats it

Re: New fiber install

If your link is between 19 and 31 miles, you won't need any attenuation.

All you are trying to do is make sure the light level at the receive ends falls between the Receiver's Minimum and Maximum specification.

The attached document may help you calculate your losses and understand when to use attenuation.

Let us know if you have additional questions.

Re: New fiber install

If you ever do need attenuators, In the USA, I have used Fiber Instrument Sales (FIS). They are a good source for ancillary fiber optic products.

You will want LC/UPC attenuators.

Fiber Optic Attenuators


CreatePlease to create content