🚀 go-pugleaf

In <2rcskl$jqj@inferno.mpx.com.au> jhonan@jolt.mpx.com.au (Jamie Honan) writes:

>Amongst the most popular cards in Europe are the Diehl (German). There
>are Linux driver's for these. I'm not sure if these are dumb or smart
>cards (or if they have a range).

To my recollection, diehl isdn GmBh offers both intelligent and passive
ISDN cards. Could check out some glossy brochures if anyone wants me to.

>Just to round off this long-winded article: I don't recommend external
>TA's. You lose too much bandwidth in 'framing'.

That depends on what kind of line protocol the TA uses. Currently, the
most popular (that I'm aware of, anyway) is V.110, which is a non-framing
rate adaption protocol, and V.120, which is a framing/multiplexing protocol.

V.110 is nice to use bacause of its simplicity and lack of overhead, the down
side is that it is not defined for R interface speeds above 19k2bps. At least
it wasn't the last time I checked. Several manufacturers, including us, do,
however, offer V.110 for speeds up to 64kbps. We've tested it for interopera-
bilty between several brands of TA's, and it seems to work nicely.

V.120 offers increased functionality over V.110, at the cost of some framing
overhead.

In the case of a PC card, I believe that some framing technique is employed
whenever one bonds 2 B-channels for increased bandwidth. This may be 
necessary because of the possibility of path differences (and consecutive
differences in transmission delay) between the two B-channels.

Regards,

Ragnar

Ragnar Nielsen
Technical Manager
ID Communication as