[c-nsp] Channelized DS3 over SM fiber handoff

Jay Hennigan jay at west.net
Fri May 1 19:08:53 EDT 2009

Michael Ulitskiy wrote:
> Hello,
> We will need to terminate channelized DS3 circuit in 7200VXR router. 
> The problem is that DS3 is given to us by telco (Verizon) as a single-mode fiber.
> I have no experience with this kind of setup and actually limited experience with DS3 circuits.
> Has anybody done this before? How it's usually done?
> Is there a DS3 PA with fiber interface for 7200 routers (I don't see any) or I should use
> a media converter with PA-MC-T3? If so, can you recommend one?
> It seems that many media converters use proprietary DS3 encoding scheme and must be used in pairs
> (or at least I've been told so), but telco is unable to give us any recommendation on how
> we should terminate it on our end. 
> If anyone could share the experience on terminating DS3 over fiber handoff from Verizon, East Coast,
> I'd greatly appreciate it. Any pointers to appropriate documentation/tutorials/howtos/etc are also very welcome.
> Thanks a lot,

I've never seen a telco hand off a DS-3 as fiber.  Always a pair of 
75-ohm coaxial cables on BNC connectors.  Typically it comes in to the 
customer premise as a SONET fiber connection and a carrier-owned MUX and 
NID is installed with the customer handoff as co-ax.

You would need to know the exact make and model of the hardware at the 
other end of the link to procure a compatible media converter if they 
are really terminating a DS-3 this way.  And good luck when you have a 
case of trouble, the blame game on this one will not be fun.

Are you sure they're finished with the provisioning and that there isn't 
another group scheduled to install equipment?

Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV

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