I'm a little confused as to what the options are for connecting T1s to Cisco routers, as I come from a Commonwealth country (where we use E1s instead).
Where my questions lie is the role that CSU/DSUs play in connecting T1 circuits to routers -- specifically, the way that Cisco integrates the CSU/DSU functionality into their WICs (if that's what they're actually doing!). I have a 2516 and a 2610 router, both of which have full T1s connected to them but appear to be configured entirel differently:
For the 2516 router, there is a Paradyne CSU/DSU box mounted on a wall. It connects to the 2516's built-in serial port with a thick serial cable, with what I presume is a V35 connector. For the 2610 router, there is only a punch-down block mounted on a wall. It connects to a WIC-1DSU-T1 on the 2610 with a cat5 cable & RJ45 connector.
So my question is, what advantages does the WIC-1DSU-T1 provide? Am I right in saying that it integrates the CSU/DSU functionality into the WIC itself, thus eliminating the need for an extra box (i.e. the external CSU/DSU) to stick on the wall and thus eliminating a potential point of failure? I'm looking to upgrade my 2516 to a 2610 or 2620XM, as the 2516s are no longer eligible for SMARTnet coverage. However, looking at the 2610 that I already have, does it completely do away with the need for an external CSU/DSU?
My other question is concerning the other type of T1 WIC from Cisco, the WIC-1T (and 2T). They do not appear to provide CSU/DSU functionality, so am I correct in presuming that an external CSU/DSU is required if you use one of these WICs? The connector on the WIC-1T/2T is different to what's built-in to a 2516 though; the 2516 appears to have a full V35 connector on it whereas the 1T/2Ts have a much smaller connector (which I think Cisco call a "smart serial" connector).
TIA and HAND!
Chris