[c-nsp] ONSs, DWDM SFPs, and the 3560/3750E

[Justin Shore]

Thanks for the reply, Eric.

Eric Van Tol wrote:
> I was in the same boat for the past year, so I feel your pain!
> 
> It doesn't sound like you are using dark fiber if your fiber is passing through your provier's electronics.  You're not going to be able to run DWDM over a lit pair that's handed off to you from a provider.  What you are describing is a lit service where they're handing off a p2p GE or 10GE to you.  Is this the case, or have I misunderstood?

I should have given more detail in my post.  We're the ILEC in the area 
and own all the fiber (including what our upstream come in on to our 
data center).  While we own all the fiber, it's also a limited resource 
and definitely isn't free (though don't we all wish).  So in our case I 
have unfettered access to the dark fiber itself without interference 
from other equipment.  That definitely helps.  WDM is definitely doable 
in our scenario thanks to that.  I agree though that if this was through 
another provider we'd end up in a lengthy dark fiber lease to do the 
same thing.

> See previous response.  You cannot run DWDM over copper or over an already lit fiber.  Your provider might be willing to sell you different wavelengths on their fiber and you can mux/aggregate multiple GEs or 10GEs at your switch, but you're not going to be able to mux/demux at the wavelength level yourself, unless you're the one generating the light.

Yeah, I should have been more specific earlier.  Since we own the fiber 
we're not having to integrate this into something our upstreams are 
doing.  They are just one of many Ethernet connections that I need to 
transport between 2 points without over-subscription.  My bad.

> Previous answers aside, I doubt there is any technical reason behind any Cisco switch from supporting any SFP.

That's along the same lines as my own thoughts.

> If you've already engaged your Cisco SE, I'm surprised that he/she has not mentioned to you that, with the physical setup you describe above, you're not going to be able to accomplish what you want.

:-)  Ok, ok.  I should definitely have been more specific earlier.  My 
fault.  :-)

> If you want to learn about Cisco-centric design and implementation, I suggest the Cisco Press book, "Optical Network Design and Implementation" (http://safari.ciscopress.com/1587051052).  It gives a very detailed, scientific overview of how WDM works, then provides some great info on the various optical platforms that Cisco offers, as well as case studies.

I have a copy.  Unfortunately it's packed away in a moving box and won't 
be accessible until after I move next week.  The last time I cracked it 
open (almost 2 years ago) it was well over my head with my very limited 
ONS knowledge.  Perhaps now it will make more sense.  I've been told 
that the ONSs really aren't that hard to learn.  I'm sure they would 
make much more sense to me if I could see them in action.  Maybe I 
should pay a visit to Cisco's optical lab in Dallas.

> If I have your setup correct, then doing L2/L3 redundancy is your only option at this point.  Unless you can get dark fiber from your providers, WDM is not going to work.  I can say that moving to dark fiber can be costly at first, especially if your provider is a major player, but the long term benefits and cost savings are huge, since WDM offers almost limitless possibilities.

Justin <-- *hangs head in digital shame*