Cisco SFP-10G-ER - Is attenuator is must for < 20km

[raghav.rai]

Hello,

I am planning to use Cisco ER SFP's (SFP-10G-ER) to connect a point-to-point circuit which is less than 10KM. I read in the datasheet SFP-10G-ER supports upto 40KM but it would require an attenuator to support less than 20km distance. Is it mandatory to have an attenuator? what will be the impact if I dont use attenuator ? pleas advise

Tks,

Raghavendra

[marce1000]

 - Check first actual reply from : https://www.reddit.com/r/networking/comments/5igacx/fibre_attenuators_how_do_to_figure_what_to_use/
                                    Personally I  would try without (first)

 M.

[Joseph W. Doherty]

"Is it mandatory to have an attenuator?"

Depends on how you mean "mandatory".

"what will be the impact if I dont use attenuator ?'

You receivers might receive a signal stronger than spec.  This may lead to data corruption.  Possibly if too, too strong a laser signal, transceiver Rx might be damaged.

Chances of the foregoing should depend how far you stray from spec.  So, for example, less risk for 19 Km vs. 1 Km.

[raghav.rai]

Thank you both!.

in my case in the current scenario this circuit is terminated on a XENPAK-10G-ER+ module on a 6509.  We are refreshing 6509 with 9606R and the wan interface module will be SFP-10G-ER. I did check the received power on the current set-up which looks to be less which is -5db

                             Optical   Optical
            Temperature  Voltage  Current   Tx Power  Rx Power
Port        (Celsius)    (Volts)  (mA)      (dBm)     (dBm)
----------  -----------  -------  --------  --------  --------
Te1/1         32.8       0.00      89.4 --    0.9      -5.0

and on the other side is a juniper device with 10G ER SFP transmits only 0.34db

  Laser output power                        :  1.0810 mW / 0.34 dBm

We dont know the exact fibre running distance. am I safe to assume power is less so it should work without attenuator? appreciate your spport