Please help edumacate me on T1 WICs

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

Reply to
Chris
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That's all about right. You'd find about the same situation with an E1 except that the outboard box is generally called a G.703 convertor and I don't know if Cisco provide a WIC with the same kind of convertor functionality (difficult physically since G.703 is often presented as

2xBNC connectors).

Yes. They provide an interface equivalent to the serial interface on the 2516. They can be used for E1 as well as T1.

In both cases Cisco provide a transition cable. The physical interface on the router can offer various interfaces to the network depending on how the cable is wired. The 2500 series and the WIC-1T have a 60-way D connector (approximately the same size as a 15-way D but with 4 rows of

15 tiny pins crammed in); the WIC-2T has the Smart Serial Connector which offers basically the same features but is smaller and obviously needs a different cable.

HTH, HAND

Sam

Reply to
Sam Wilson

Okay great, thanks Sam. My experience is more with SDH (I think it's called SONET in the U.S.), but I remember playing with a couple of G.703s.

Okay, good. I would probably rather go for the built-in CSU/DSU in the WICs, though; but I just wanted to make sure I knew what I was talking about. :-)

Yep, I found a list of cables on Cisco's site; which is where I found the name of the 'smart' cable. Thanks again!

Chris

Reply to
Chris

Actually, I still have one last question. What is physically required to go from using an external CSU/DSU to using an internal one? Will there be a cable from a punch-down block that goes to the external CSU/DSU that I can just 'move' into the Cisco, or will I actually need (or have my ISP) to re-terminate stuff on the premises?

Chris

Reply to
Chris

Ummm. Since I'm from a Commonwealth country that uses E1s rather than T1s I don't know. :-)

Sam Wilson Network Development Team, Infrastructure Services Division Computing Services, The University of Edinburgh Edinburgh, Scotland, UK

Reply to
Sam Wilson

I didn't know the answer, so I went to

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and
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and searched for: wic-1t

Each of them gave me THE SAME OR EQUIVALENT FIRST HIT, entitled 'Understanding the 1-Port Serial WAN Interface Card (WIC-1T)'. I followed the link, which led to a page within

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which stated:

The WIC-1T interface card does not have an integrated CSU/DSU. You need to use an external CSU/DSU.

Reply to
nospam

Depends on the CSU/DSU. In most cases, you'll fine basicly a cat5 patch cable RJ45 to RJ45 on both ends, which is exactly what the WIC-1DSU-T1 is expecting.

Some CSU/DSUs use a DB15, and sometimes the cable is the DB15 out to RJ45 on the other end. In this case, you most likely can replace it with a stock ethernet patch cord. Thats all Cisco supplies, a stock blue cat5 patch cord for hooking up the WIC-1DSU-T1.

Reply to
Doug McIntyre

When we upgraded to the Cisco routers, I too was unclear as to how they would physically connect to our T1s and some of these same questions came up for me. We were previously using external CSU/DSU Adtran boxes to handle the CAT5 connection to the provider's "smart jack" on the wall. The router would then connect to the Adtrans via the old V.35 serial interfaces. With the WIC cards in the new routers, now I take that CAT5 connection from the smart jack and plug it directly into the WIC card in the router. This is all you need to connect the T1. No additional baggage is required. Take the CAT5 running to your external CSU/DSUs and plug them into the WIC cards.

Some folks still opt to use the Adtrans as expensive lightning protection or for logging purposes in the event of problems. As far as I'm concerned, if it's not working, that's the provider's responsibility to figure it out.

Reply to
steve_nsi

I actually tried searching Cisco's site before I posted here, but that (as it often is) was fruitless. So, apologies...

Chris

Reply to
Chris

We have two different 2516s, one uses a Paradyne CSU/DSU (which is quite bulky) and the other uses an Adtran CSU/DSU (which looks less sophisticated). Both are connected with RJ45, though I haven't verified the pin-outs yet... but I can't imagine they're non-standard.

I haven't seen this on our equipment, luckily! It sounds like it should all be pretty simple for me, then.

Chris

Reply to
Chris

That sounds pretty much exactly like what we're doing here, one Adtran box and one Paradyne box are used for two different T1s. But I just want to use straight cat5 instead... the less boxes I have in this environment the better.

How did you go for timeslot information, encoding etc. in terms of configuring the Cisco to match whatever CSU/DSU settings you had?

I think I echo that sentiment of yours...

Chris

Reply to
Chris

Almost all data circuits installed in the last 8-10 years at the least have been very standard. B8ZS encoding, ESF framing. All 24 channels. These are the defaults on Cisco gear.

In my 15 years on WAN circuit installs, I really have only seen half a dozen (vs. many hundreds) data T1 circuits that varried from this setup. You'll be pretty safe going with the defaults.

Reply to
Doug McIntyre

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