[nsp] What WIC to use with E1 service

Gert Doering gert at greenie.muc.de
Sat May 8 11:56:19 EDT 2004


Hi,

On Sat, May 08, 2004 at 09:55:58AM -0400, Krzysztof Adamski wrote:
> > Other carriers (COLT, for example) usually deliver "unframed" only
> > anyway...
> 
> The circuit is being delivered in Belgium by FranceTelecom.

I have no experience with them.  Sorry.

> On my end it is delivered by 360, and it looks like the people that I'm
> dealing with have not done this before, so extracting recommendations from
> them is difficult. Every answer has "this should work" instead of "this
> will work".

Expect "it will not work, and nobody can tell you how it was supposed to
work in the first place" :-(

> Here are the options that 360 told are available:
> 
> E1: G.703/G.704 framed or G.703 unframed
> hence framing options: CRC4 or NO-CRC4
> coding: AMI or HDB3 (HDB3 most common for data)
> 
> The E1 will be used just for data and will terminate on a T1 on my end.
> The other mystery is how will the E1 be changed into T1 on my end?

Now this is interesting.  I have no idea how this is planned, but they
might try something like this:

The E1, when run with G.703/G.704 framing, has 32 timeslots, 64kbit/s
each.  Of those, *up to* 31 can be used for data - on a VWIC-Interface, 
this is configured as, for example

contr e1 0/0
  channel-group 0 timeslot 1-31

to use 1984 kbit/s (the maximum for E1 / framed - ts 0 is used for frame
sync).

T1 has 23 timeslots.  So it *might* work if you just use
"channel-group 0 timeslot 1-23"
on the E1 end, and the telco has some multiplexing device that takes
23 individual DS0's from the E1 side, and feeds them into the T1 side.

All of this is guesswork, of course.  You need hard data how they
do the E1/T1 conversion to decide how to configure your end.

gert

-- 
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de


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