EWDM connectivity

Answered Question
Feb 20th, 2008
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Hi all,


I'm hoping I'm not the first to run into this issue.


I've recently purchased 2 EWDM MUX's to use with 10Gig Xenpak interfaces stuck into ws-6704-10ge blades on 6509-E chassis'.


There are three different frequency transceivers in each of the 6509-Es. I have single mode LC-SC patches connecting the transceiver with their partner inputs in the EWDM MUX.


I have both EWDM MUXs connected to each other via the 'Network' input using LC-LC single mode cable (this is a test bed). The cables are 2 meters long and I am using 5dB attenuators connected to the 'Network' input of one of the MUXs.


Porblem: I am not getting any link from my transceivers to each other, and I don't know why.

I was wondering if the attenuators weren't working, but I don't have any idea how to test those...



I am pretty sure I've got the setup correct (well as far as the installation guide that came with the mux tells me), but it won't be the first time I've missed something.


Can anyone here give me a clue or an idea of what to do to troubleshoot this?


Any help will be very much appreciated.


Brad

Correct Answer by Tom Randstrom about 9 years 4 months ago

Brad:


Do you have the LC-LC singlemode jumper cable between the AMP IN and AMP OUT ports on the MUXes. This is required to get signal from the DWDM input ports and the NETWORK ports.


If you test the two 6509s with a 2 meter patch cord (without the MUXes), you will need the 5dB attenuator. Once the MUXes are installed, no attenuation should be necessary.


Your 17km of singlemode fiber should have approx 4.25dB of loss (17km x .25dB loss per km) plus any splice losses (which can be significant if old mechanical connectors are used at in intermediate sites in the link). The link loss can be verified by using a simple optical power meter (fairly inexpensive these days to buy). An OTDR trace would allow you better visibility of any other fiber abnormalities and individual splice losses, again, to provide a baseline for future troubleshooting.


It is recommended that the fiber links be documented before final turn-up of the system. This allows a baseline for future issues that may arise and makes troubleshooting easier.


Tom


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Tom Randstrom Thu, 02/21/2008 - 07:27
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Brad:


Could you clarify, what is an EWDM mux and what is the model number (I've heard of DWDM and CWDM)?


Do you have any optical test equipment (power meter or other)?


What is your calculated link attenuation (muxes + interconnecting fiber) between the equipment?


Have you verified the Xenpack modules' wavelenghts are the same as the inputs to the muxes?


Have you tried to connect the 6059s together without the muxes to determine the system functions properly? You will need additional attenuation.


Challenging to diagnose without more detail.


Thanx!


Tom

bmcginn Thu, 02/21/2008 - 13:09
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Tom,


Thanks for responding.


The EWDM Mux (Enhanced Wave Division Multiplexing - EWDM-MUX8=) is a 10Gig version of DWDM I think.


Test Equipment: No, I don't have any optical testing equipment.


Calculated link attenuation: I've none of that either. doh! It's a two meter single mode connection for testing and will move to a 17km link for production. I don't know how to calculate the link attenuation. Is there a formula for that? Or do I need to get some expensive test equipment?


I have verified that the Xenpak modules wavelengths match up to the input in the mux.


I'll be trying to connect the 6509's up together today using a SC-SC single mode fibre patch cable and 5dB attenuators (I was told that 5dB attenuators would do the trick...do you think I will require more attenuation?)


Thanks loads for your help.

Correct Answer
Tom Randstrom Thu, 02/21/2008 - 15:06
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Brad:


Do you have the LC-LC singlemode jumper cable between the AMP IN and AMP OUT ports on the MUXes. This is required to get signal from the DWDM input ports and the NETWORK ports.


If you test the two 6509s with a 2 meter patch cord (without the MUXes), you will need the 5dB attenuator. Once the MUXes are installed, no attenuation should be necessary.


Your 17km of singlemode fiber should have approx 4.25dB of loss (17km x .25dB loss per km) plus any splice losses (which can be significant if old mechanical connectors are used at in intermediate sites in the link). The link loss can be verified by using a simple optical power meter (fairly inexpensive these days to buy). An OTDR trace would allow you better visibility of any other fiber abnormalities and individual splice losses, again, to provide a baseline for future troubleshooting.


It is recommended that the fiber links be documented before final turn-up of the system. This allows a baseline for future issues that may arise and makes troubleshooting easier.


Tom


bmcginn Thu, 02/21/2008 - 17:52
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Tom,


Thanks load Champ! I needed the SM fibre loopback on the amp input in the EWDM MUX.


It now works a treat.


Next time you're in Brisbane Australia I'll buy you a beer :)


Brad

scottmac Sat, 02/23/2008 - 06:33
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Did you check the output level with a power meter and compare it to the receiver spec to get the "5db" number?


Attenuators are generally place at the transmit end of the link (by convention. It doesn't really matter in a lab setup).


Make sure the optical connector ends are clean. With a diameter of 8.3 microns, it doesn't take much in the way of dirt/dust/debris to get in the way of the signal path.


Make sure the receptacles are also clean for the same reason.


Verify the configuration on each mux line-by-line for typos and mismatches.


Good Luck


Scott


Tom Randstrom Sat, 02/23/2008 - 09:09
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Scott:


I've typically seen the optical attenuators placed at the receive end of the link as this is where the final link power measurement is taken.


Just a matter of preference.


Tom

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