[nsp] OC3 interfaces for 7xxx vs. other OC12 transport options

[Mike Lewinski]

While we have always had services delivered to us via OC-3 and OC-12, 
they have always been terminated on carrier-owned and maintained 
equipment, and muxed out as DS3 on coax or DS1 on copper to us.

So as preface let me say I've got little experience with fiber and none 
with OC transport.

We are now venturing into terminating an OC service ourselves and have a 
couple paths. The primary service we are considering is a Qwest OC-3 via 
a standard sonet interface in a point-to-point terminal configuration (1 
+ 1 protected) delivered on single-mode fiber (standard 1310nm signal) 
with FC connectors. This would tie back into an ICDF colo at the Qwest 
CO where a Loop Mux Combo (LMC) would interconnect DS1 tail circuits for 
data and VOIP services to client sites. The Qwest technician who will do 
this installation advises he is using FLM150s on his side.

The primary use for these OC3s will be terminating client T1s and that's 
all we ever expect to use them for. So the ability to peel off a single 
DS1 in the router is important. I understand that in this type of 
configuration, Qwest does not do the channelization for us, but that the 
product itself is capable of channelization and we are responsible for 
keeping track of the correspondences between the OC3 and LMC (they give 
us a circuit ID w/ CFA which is the channel on the OC3 and an APOT which 
specifies the DS3 termination, as I understand it).

Cisco has a number of OC3 interfaces for a 72xx or 75xx (we have both 
and my preference is to probably use the 75xx so that widens my choices 
I believe). It's not at all clear to me which interface is really 
appropriate and I'm hoping someone here is doing something similiar 
enough to give me good guidance. Additionally, I assume that for the 1 + 
1 protection what I really want are two separate interfaces in case of 
failure (and there's just one entrance facility into this building so I 
understand what will happen when the backhoes dig it up).

We are also considering an OC12 but I realize the 7xxx backplanes never 
had enough bandwidth to justify making an OC12 interface and so I'm 
looking at buying a 12xxx series in order to support it directly. But I 
wonder also if anyone has advice on a standalone device to (relatively 
cheaply) terminate an OC12 and mux out OC3s to the aforementioned Ciscos 
7xxxs...

TIA,

Mike