Cisco CPAK 100GBASE-ER4 Lite Module

[M. G.]

Hi all, 

I am looking in the data sheet for the Cisco CPAK 100GBASE-ER4 Lite Module as it says that supports distance up to 15 miles (25 km). 

As well, it is stated by Cisco :"The module can be used over longer distances in engineered links with CPAK-100G-ER4L modules at both ends."

Does anybody have any real life experience that does it mean "longer distance" in this context? For example, if you connect two modules over 25 miles (40k) would it still work? Will I face degraded perfomace in terms of speed of packets will start dropping as well?

Best regards, 
M.G.

[xthuijs]

hi mg,

the key thing to the "lite" module is the fact that it has lesser transmit power then the "full" version. the rated distance is upto 25km. for the full version that can go upto 40km it is required to run (e)FEC to enhance the signal interpretation and using correction algorithms.

it also depends on what FEC mode you use and the chipset of the card that is or is not able to enhance the signal.

this picture shows a bit what FEC can do for the signal enhancement.

note that the ipodwdm card for asr9k has a special cisco chip (ETNA) that can improve long haul transmissions.

xander

[M. G.]

Hi  xthuijs, 

Thank you very much for your asnwer, appreciated. 

I am just a bit confused as cisco data sheet says differnet thing than what you mention, even though your post make more sense to me. 

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-728110.html

The LR4 module is IEEE 802.3ba-compliant and supports link lengths of up to 10 km over standard SMF, G.652.

The ER4 Lite module is compatible with the 100GBASE-ER4 standard and supports link lengths up to about 25 km over standard SMF, G.652. 

Data sheet says that normal module goes up to 10km whilc ER4 Lite goes up to 25km. 

The MPA I am using is A9K-MPA-2X100GE and cannot find any resources that  says if I use it over 40km  (and which transciever module to use) will it work, even if it is degraded for 10-20% it is still fine by me. 

In the same Dath Sheet it states for the ER4 Lite:"The module can be used over longer distances in engineered links with CPAK-100G-ER4L modules at both ends. "

Not clear what does this mean...
Best regards, 

mg

[alaincaillet]

Hello,

What is the FEC default configuration in ASR9K for CPAK ER4-L ? 

RP/0/RSP0/CPU0:xxxxxxxx(config-if)#fec ?
base-r Enable BASE-R FEC
none Disable any FEC enabled on the interface
standard Enable the standard (Reed-Solomon) FEC

But any of this configuration is possible (100G LAN port). May be it's not supported ?

I run version 6.1.4