[c-nsp] DWDM Optics use

[Brandon Applegate]

On Sat, 4 Jun 2011, Keegan Holley wrote:

> I'm struggling with a use for DWDM optics.  I understand the concept of
> DWDM/CWDM and phase shifting to create more links over a single fiber.  Once
> that is done the ASIC/FPGA bandwidth allocated to the port remains the same,
> correct?  So if I create multiple 1G connections on a single port with these
> magic sfp's am I still limited by the 1g/2g chip in the device.  Are all the
> logical connections forced to be sub-rate?  I know the larger equipment
> handles this differently, so I'm only concerned with the 3750/3560 size
> boxes.
>

Hmm, I may be misunderstanding - but I think you are misunderstanding how 
DWDM tuned optics works.  A 1g or 10g DWDM optic is still a singe 1 or 10 
interface.  It's just that that transmit laser is tuned to a channel (i.e. 
1546.12).

Router#sh int tenGigabitEthernet 7/1 | inc media
   Full-duplex, 10Gb/s, media type is DWDM-46.12

The reason you may need this is to connect this port directly to a 
(R)OADM.  There are (at least) two ways on the DWDM transport side to 
handle this:

a) Use a *sponder (transponder = 1:1, muxponder = n:1, etc).  You can use 
'grey' optics now (i.e. good ole SX/LX etc).  These cards on the DWDM side 
are expensive though.

or

b) Buy DWDM optics, and go directly into the mux/demux on the DWDM.

We are doing option b) in parts of our network because the cost of a) was 
too much, and these links aren't going to do any moving around or going 
away any time soon.

Again, apologies if I've misunderstood you.

--
Brandon Applegate - CCIE 10273
PGP Key fingerprint:
7407 DC86 AA7B A57F 62D1 A715 3C63 66A1 181E 6996
"SH1-0151.  This is the serial number, of our orbital gun."