[c-nsp] ASR9k CWDM Optics

[Matt Addison]

On Sun, Oct 16, 2011 at 05:42, Gert Doering <gert at greenie.muc.de> wrote:
> Because you might need individual attenuation / amplification per Lambda,
> and because it gives you more detailed monitoring.  At least that's what
> I've been told...

You can't amp per lambda, the amp is an all or nothing deal, mostly
you attenuate when adding channels to the system to make sure the
added channel power matches the express per channel power (great
reason to get a spectrum analyzer if working on passive systems). This
gets really trivial if you preamp everywhere since all the express
channels should be at +0, but if you have purely passive add/drop
nodes you'll need to meter to figure out the express power.

In an active (Infinera DTN, Ciena CoreDirector) system you're
effectively pre-amping everywhere because every node is a regen, this
raises costs per node significantly when compared with a 'passive'
amplified system (Infinera ATN, Cisco EWDM). But because you have that
active equipment at every node you do get a lot more monitoring out of
it (since you have a power meter, and FEC, on every lambda in every
direction).

To add to the core discussion, it's probably going to be cheaper to
pay your Cisco tax than buy transponders from your WDM transport
vendor once you hit 3+ DWDM channels per blade if you have a passive
network you can put alien wavelengths into.

~Matt