[Asterisk-Users] T1 Sync clarification

[Rich Adamson]

> > Think we're trying to make this more difficult then what it really is.
> 
> [ lengthy and accurate text snipped ]
> 
> I think you're oversimplifying.  There is *no* need to have individual T1 
> spans synchronized to each other unless you're trying to aggregate the data 
> on those individual spans.  DS2/DS3 takes care of this with 'slop' bits in 
> which the individual DS1 frames can "float around" in.  
> 
> We're not talking about aggregating the data though.  We're talking about 
> four individual T1/E1 framers -- Maybe my telco design has slipped a little 
> over the years but I see no necessity for the requirement that the four T1s 
> on a TE410P be in sync with each other.  

I don't have a TE410P, but I'd bet a small amount there is only one clock
on the board, and since that clock will be in sync with something (probably
the telco), all four ports are in sync (by design, not by option).

> As soon as you come out the ass 
> end of the framer you're running on internal card bus and more than likely 
> on PCI time, which has nothing at all to do with the T1s you started with.
> 
> So while you are absolutely correct in that for an overall network you need 
> to have everyone agree on a single clock source, it's often not going to 
> happen if you're running with different providers.  And if you're doing 
> this in anything other than a backup situation, you need to be able to sync 
> to both of these sources.  Whether that means you need two T100P cards 
> since they can individually sync, or some form of T1 buffer which will sync 
> to two clocks to satisfy this requirement... well that's up to the design 
> spec.  
> 
> Which brings me back to my original question:  Can I sync to the telco, and 
> then have my channel banks synchronized to the TE410P, which I've 
> synchronized to the telco?

Yes, and I agree with everything that you've noted above.

Rich