inquiry on using POS

Hi, there;

First of all, thanks you all for your unintended and unnoticed help what
I¡¯ve got from nanog.

I¡¯m looking for a reference case of a point-to-point POS link.

My potential customer asked me to configure their nodes using 40G POS
interface cards.

The distance of their nodes is between 10 km to 50 km.

They are considering Cisco CRS for their core router.

I¡¯ve found that CRS has 2 kinds of POS card. One support only up to 2km.
so, this one is out.

From the datasheet, the other one can support point-to-point connection up

to 80km using this DCU. Dispersion compensating unit.

I¡¯ve talked about this configuration with people and no one would
recommend those kind of things.

Personally, I prefer 10G Ethernet with XENPAK ZR optics.

Here is what I want to know.

Is there anyone who are using POS with DCUs (without DWDM or something like
that) between nodes of less than 80km apart?

If there, would you recommend it to others?

Jinwha Chung

CCIE#11776

u-Eng'g Team | u-Telecom Global Business Unit | SK Engineering &
Construction Co. Ltd

South Korea

TEL 82-2-3700-8822

FAX 82-2-3700-8999

From the datasheet, the other one can support point-to-point connection up

to 80km using this DCU. Dispersion compensating unit.

I��ve talked about this configuration with people and no one would
recommend those kind of things.

There is nothing saying this won't work. I'd gladly implement this (if you by this mean the DPSK or dunobinary cards with g.709).

The advantage of this is that you get FEC and can see what margin you have until the link starts to give post-FEC errors.

Personally, I prefer 10G Ethernet with XENPAK ZR optics.

If dark fiber is available, this is much much cheaper, but then you have to load balance and the customer traffic might not be possible to load balance properly on 4x10GE, but if it is, this is definitely a viable option.

Middle ground would be the 4 port 10GE g.709 card with FEC if you really feel you need indications of error rate constantly. It's cheaper than the 40G card, but most likely more expensive than a 4 port 10GE card with ZR optics.