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

[Clayton Zekelman]

If you're going to be terminating DS1 services from the OC3, then you'll likely need a SONET MUX of some sort.  AFAIK, Cisco does not have an OC3 interface that supports DS1 channelization on the 7XXX series router.  The only OC3 interfaces I know of are the Port Adapters that support OC3c (concatenated) services such as Packet over Sonet or ATM.

What we use is a Positron Fiber Systems (www.positronnetworks.com) OSIRIS optical mux.  The system presents a UPSR protected interface to the carrier, then peels of DS3's from the STS streams within the OC3.  You can then take that directly into a Channelized DS3 Port Adapter, which appears to the router as 28 serial T1 interfaces.

You have to be careful though - if Qwest is mapping the channels into VT1.5's then this arrangement won't work without a "transmux" to convert to DS3 M13 mapping.  Positron used to sell a transmux product called the "MIST", but I'm not sure if they still do.  The best option is to have Qwest make sure they use DS3/M13 format.  

If they insist on using VT1.5's then you'll have to put the DS1 mappers into the SONET Mux itself, then come out at the DSX-1 level, and into DS1 ports on the router (or a Channelized T3 PA front ended with a M13 mux such as a Carrier Access Widebank/28 http://www.carrieraccess.com/products/index.cfm/fuseaction/default_prod/cat_id/16.htm).

I'm sure if you look at any of Cisco's channelized OC12 products on the bigger routers, the price will curl your toenails.


BTW - we've used the Positron gear to do an optical handoff with SBC who was using an FLM150 on their end.  We've also used the OC12 variety of Positron equipment to handoff with SBC using an FLM600.

Some various vendors of SONET muxes you might want to check out:

Positron Networks (http://www.positronnetworks.com) We use these.  I have 8 units.
Fujitsu (http://www.fujitsu.com/services/telecom/optical/interoffice/category_inter-office.html) They make the FLM series.
White Rock Networks (http://www.whiterocknetworks.com) Integrated transmux - higher end applications.



>
>Subject: [nsp] OC3 interfaces for 7xxx vs. other OC12 transport options
>   From: Mike Lewinski <mike at rockynet.com>
>   Date: Mon, 12 Jul 2004 11:21:40 -0600
>     To: cisco-nsp at puck.nether.net
>
>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
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