[3283] in North American Network Operators' Group
Re: Telco discussions
daemon@ATHENA.MIT.EDU (Rob Gutierrez)
Wed Jun 26 22:05:48 1996
From: rmg@ranma.com (Rob Gutierrez)
To: dhirsch@bbn.com (Douglas Hirsch)
Date: Wed, 26 Jun 1996 16:00:38 -0700 (PDT)
Cc: oliveira@bbnplanet.com, nanog@merit.edu
In-Reply-To: <199606261853.OAA22722@foggy.bbn.com> from "Douglas Hirsch" at Jun 26, 96 02:53:15 pm
> >This is because most vendors still believes that T1 circuits are provision
> >as D4/AMI..:-) Digital Link Encore csu/dsu by default has it setup as
> >ESF/B8ZS.
>
> I'm evaluating the new cisco 2524 with internal CSU/DSU, and it looks
> like the default is ESF/B8ZS on this box too. Maybe there's hope for
> the vendors catching up with reality on this front afterall.
I haven't touched a 2524 yet. Is the DSU options set on the command line?
> Anyone have experience mixing different vendor CSU/DSUs and getting
> things like remote loopback to work?
In-band and out-of-band lookpback codes should work fine. The differences
I've seen are with in-band codes. Some CSUs need to see the loop-up
code unframed, and some will respond to the loop-up code framed.
Rememeber that you can't send an out-of-band loop-up code unless
(a) you're ESF framed, and (b) the CSU is optioned to acknowledge
any o-o-b request.
An Out-Of-Band code is also known as an ESF code. The loop-up or loop-
down requests are sent in the 4kbps ESF channel instead of the actual data
channel/path.
Also remember that CSU and NIU (Network Interface Units) codes are
different. Make sure you're sending a CSU code. An NIU code is
technically called a Facility-2 code (FAC-2).
Since one mfgr's unit can't be configured to send a framed or unframed
loop-up/down (it doesn't tell you), you're at their mercy. Same if you
want to send an in-band or out-of-band code.
With a test set, though, I've never run across a CSU or NIU that I couldn't
loop up or down. You can virtually set a test set to do _anything_.
rob.
p.s...I have the data sheet scanned in. I'm gonna html it.
