Cisco CRS-1 1-Port OC-768C/STM-256C Tunable WDMPOS

Unanswered Question
Aug 12th, 2009


I suppose there are four data streams coming out of the port oc-768c because there is a DWDM function inside the module. Am I right?

What is the format of each data stream? Is it OC-192c?

Can this module talk to Juniper 4-PORT OC-192 PIC configured at OC-768c via inverse multiplex.



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viyuan700 Thu, 08/13/2009 - 07:34

Hi George,

Yes you are right there are 4 streams of Oc-192 (10G). In this card OC 768 (40G )is converted to 4 10G. As 40G have few problems when it is carried over long distances. Like inverse multiplexing in Juniper.

Yes this module can talk to Juniper 4-PORT OC-192 PIC. Only problem i see is that Juniper port are not DWDM ports there are 3 interfaces one at 1300nm other 2 at 1550. So you will need some transponder at juiper end which can give DWDM wavelength in C Band. You cisco module is tunable so can be tuner to any wavelength over C Band.

gespitia@uninor... Mon, 08/17/2009 - 05:51

Hi, can two CRS-4 be interconnected via 110Km length dark-fiber and get 40G, without ONS 15454 MPST?


Gustavo Espitia

Tom Randstrom Tue, 08/18/2009 - 05:19


According to the Cisco CRS-1 1-Port OC-768C/STM-256C Tunable WDMPOS data sheet, the modules can be directly connected to your fiber, with the following fiber path lengths:

Path length (fiber type):

80 km (G.652/G.655)

100 km (G.653)*

*Proper system design required; network may require Dispersion Compensating Units (DCUs).

It would be difficult to say if you could reach 110km without a thorough review of the particular network. Your network would be operating at its limits (if at all) and any system impairment may result in an outage. It would surprise me if Cisco would support this network length, given they have to support you installation after the sale. You would have to speak directly with a Cisco sales engineer.

Module Spec Sheet:


Tom Randstrom Fri, 08/14/2009 - 05:26


Are you discussing the following OC-768 module?


Reviewing the data sheet it indicates this is a single 40G stream, not 4 x 10G. The 40G signal is compatible with 10G DWDM systems by inserting the signal directly into the optical filters (no transponder). You might be able to connect the output of this card to an OC-768 POS interface from Juniper (depending on modulation used), but not an OC-192 interface.

If you need to connect to a Juniper OC-192 interface, then selecgt the appropriate Cisco CRS-1 OC-192 interface card.

georgechen2101 Tue, 08/18/2009 - 02:04

Thank viyuan700 and baileyshbr.

These days I read more technical documents and understand that OC-768c with DWDM has just one data stream only. There are three products for OC-768, which are 1OC768-POS-SR, 1OC768-ITU/C and 1OC768-DPSK/C. But the difference among them is the modulation of optical transponder. The modulations are NRZ for 1OC768-POS-SR and DPSK for 1OC768-DPSK/C. Anybody knows the modulation for 1OC768-ITU/C?

If one end uses 1OC768-ITU/C, what is the compitable product other than 1OC768-ITU/C at the other end?



viyuan700 Tue, 08/18/2009 - 07:46

Hi George,

I apologize for the confusion over no. of ports in OC 768. I saw only one port but was diverted by ur message about 4 ports (means i took in different way the first message) & 100G implementation. Where they are trying to take 1 100G over 10 wavelength & combine again.

I think you will be able to connect to other products of OC 768 if it in single channel mode (if both are as per ITU standard). Also either you will be having CRS on both places or Juniper high end router on other side which donot have single OC 768. Do you have any other thing which you want to connect to other side and have one prot 768.

But in DWDM mode where the signal can go to 1000Km 1OC768-ITU/C & 2000Km 1OC768-DPSK/C without 3R regenration, you need same kind of card as there will be some properitery EFEC to get that kind of distance.

georgechen2101 Tue, 08/18/2009 - 17:09

Thanks, Viyuan

The word 'properitery EFEC' in your message catches my eyes. We are considering to develop a product which can passively get the traffic data between two routers. The properitery EFEC makes the idea impossible, right?


viyuan700 Tue, 08/18/2009 - 19:57

The properitery EFEC makes the idea impossible, right?

I think will be difficult to develop such thing where u have no idea how the things are working. If you have not read the link,go through the paper discussing something similar.


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