[Asterisk-Users] Beyond T1

Glenn Dalgliesh asterisk at techhat.com
Thu Sep 16 10:35:23 MST 2004


Well, you might be better off at that scale to use a cisco as5850 or equiv
with SER and Asterisk. I might not work so well with 672 calls going thru 1
asterisk box.

ds3 <-> Cisco as5850 <-> Asterisk (Possible multiple depending on actual
config and use)


----- Original Message ----- 
From: "Marcelo Pacheco" <marcelo at macp.eti.br>
To: "Asterisk Users Mailing List - Non-Commercial Discussion"
<asterisk-users at lists.digium.com>
Sent: Thursday, September 16, 2004 12:52 PM
Subject: Re: [Asterisk-Users] Beyond T1


> I'm no E1 expert, but as I understand one channel is wasted with framing,
so
> it is as 2048000 bps link, where one 64000 bps channel is wasted with
> signalling. So there's 31 channels left. If you use E&M, FXS or FXO, you
> could get 31 voice channels, with PRI or MFC/R2D you get 30 voice
channels.
>
> I now that from the fact that a full E1 with EuroISDN gives you 30 voice
> channels.
>
> An a full E1 with Brazilian R2D also gives you 30 voice channels, as one
> channel is used for signalling as CAS (Channel Associated Channeling),
where
> each 4 bits is used for each channel.
>
> The only situation where you get closer to actual 2mbps out of an E1
channel
> is when you run SyncPPP, Frame Relay or another bit synchronous protocol
on
> the full trunk/link, where you throw away the channelling and use the
whole
> link as one big synchronous bit pipe.
>
> Marcelo Pacheco
>
> Em Qui 16 Set 2004 13:26, Andrew Kohlsmith escreveu:
> > On Thursday 16 September 2004 12:17, Andrew Thompson wrote:
> > > Depending on where you using the circuits, you might try an E1. It
uses
> > > the same total bandwidth as a T1(I think), but splits the channels at
> > > 56K instead of 64K, yielding more channels. (And now I can't remember
> > > the number.)
> >
> > uh, no.  This is definitely NOT correct.
> >
> > T1 is 24 8-bit channels + 1 framing bit sent 8000 times a second.
24*8+1 =
> > 193 bits per frame * 8000 = 1554000bps.
> >
> > E1 is 32 8-bit channels + 1 framing bit sent 8000 times a second.
32*8+1 =
> > 2056000bps.
> >
> > (my E1 knowlege is poor, I hope I am not furthering the misinformation
> > here)
> >
> > In both cases you get 64kbit clean channels unless you're doing
robbed-bit
> > (inband) signalling.
> >
> > -A.
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