> Hi! Thanks for answers.
> Below some additional info:
> > > We were using Cisco 2611 with 1 WIC 2A/S + Rad's Converter G.703
> > > 64kbps codirectional/V.35 + 3Com 16-port hub.
> > That sounds like a V.35 to G.703 Terminal Adapter that indeed operates
> > G.703 at 64kbps.
> RAD'Converter is SPD-703-1 model
> (http://www.veryComputer.com/,6583,16470,00.html). Does this clarify
> something for you?
Well, it makes me quite sure about the adapter beeing a pure 64kbps G.703
device. It's not feeding some single time slot in a G.703 E1, it is native
64kbps. If it needs to be muxed upwards the hierarchy, a "channel bank"
is required. This will probably mux up to 30 (or 31) such lines into a
PCM30 (which is a E1).
> > [...] You can use just one B-channel of the whole E1 to get
> > just 64kbps payload off the 1984kbps available in a G.704/G.703 E1
> > line. But that is sure not the same as a pure 64kbps line.
> > The cheapest way to get two times 64kbps out of a router is actually
> > a BRI. A real 64kbps line is not unlikely to be provisioned based on
> > ISDN anyway (dunno about .br, but at least here in .de its typical),
> > so the best way is to get the telco to strip their provisioning down
> > to the * I.430 circuit and then connect to it using a BRI in leased
> > line configuration.
> As I understand is possible to get a 64kbps slot time from a 2MB E1
> with VWIC, but not from a 64 kbps link alone... Think this 64 kbps
> link as a PCM Digital line...
I've been using PCM lines to some extend, some years ago. These were,
however, interfaced using ISDN (S0 compliant BRI) and looked just like
normal Basic Rate NTs. Plug them into a router's BRI, make it leased
and establish either 128kbps/144kbps L1 bundle (the two B-channels
aka timeslots they provide are octet synchronous) or use MP to bundle
the Bs on L2. Pretty robust stuff, came from ke/Quante. I realize, however,
that focusing that much on ISDN style interfaces is a german specialty
(yet a neat one, BRI *is* cheap, though not that cheap in Cisco world
if you need to buy a WIC-1B...).
Quote:> In fact we are linking SDH or PDH radios where there is a 64kbps
> digital service channel and its provided interface is 64kbps G.703
If it's a service channel that drops out some hierarchy mux/demux, there
is no easy way to get it as a BRI. 64kbps G.703 is probably one of the
simplest interfaces you can get for something like that - just two
twisted pairs and a trivial signaling. The drawback is that this inter-
face is not really common with routers, it's pure telco world - so you
have two options:
a) Use a TA (like the RAD one) that turns the 64kbps G.703 into something
serial you can terminate on a Cisco (you do that already), or
b) If you need a multitude of these, try to get telco equipment that can
mux a bunch of such 64kbps G.703 into one E1. It should allow for 30
or even 31 lines to be muxed into the E1, some just exclude time slot
16 for bizarre reasons (in PRI applications, 16 is used as the D-channel,
but this doesn't make it any special timeslot on a leased/muxed one).
To get b) into a router, just use the appropriate PRI interface in leased
line mode. We are doing this with E1s on PA-MC-8E1s, the german Telco
is providing us 64kbps and 128kbps leased lines (PCM) to a bunch of
customers muxed onto E1 lines this way. If they can buy that PCM stuff
somewhere, you sure can, too. On a 26xx, you'd need a PRI NM, though -
the VWICs cannot interface more than two channel groups, but you could
aggregate as much as 31. This, of course, only pays if you need more but
a handful of them, but then it's getting really chic.
The _S_anta _C_laus _O_peration
or "how to turn a complete illusion into a neverending money source"
-> Andre "ABPSoft" Beck +++ ABP-RIPE +++ Dresden, Germany, Spacetime <-