ISDN / BT home highway

Mark Ovens marko at freebsd.org
Fri Oct 6 00:32:09 BST 2000


On Tue, Oct 03, 2000 at 06:37:44PM +0100, Brian Somers wrote:
> 
> 
> A TA that does the MP stuff itself isn't a great deal of use with 
> standard 115200bps UARTs - link bandwidth is higher than DTR 
> bandwidth.
> 

Is this not true of external modems as well though? I've got an internal
one and can regularly exceed 115200bps:

   PPP ON parish> show phy
   Name: deflink
    State:           open (with carrier)
    Device:          /dev/cuaa2
    Link Type:       interactive
    Connect Count:   1
    Physical outq:   0
    Queued Packets:  0
    Phone Number:    1234567890

   Defaults:
    Device List:     "/dev/cuaa2"
    Characteristics: 115200bps, cs8, no parity, CTS/RTS on
    CD check delay:  device specific

   Connect time: 1:00:51
   10416974 octets in, 164815 octets out
     overall     2898 bytes/sec
     currently    115 bytes/sec in, 51 bytes/sec out (over the last 5 secs)
     peak       23908 bytes/sec on Thu Oct  5 23:57:40 2000
   PPP ON parish> 

That's 239080bps (at 10bits/byte including the stop bits), over double the
rate of a 16650 UART, so if this was an external modem what would happen?
Reduced transfer rates or would the modem buffer the data?

> The only way to go is ppp(8), either with two serial connections to 
> two TA ports (I guess mpd would work in this scenario) or via an ISDN 
> card (the best way) IMHO :-)
> 
> > Neil.
> > -- 
> > Neil C. Ford
> > neil at ourshack.com / neil at binky.demon.co.uk
> > Sent using Pronto! - http://www.muhri.net/pronto
> 
> -- 
> Brian <brian at Awfulhak.org>                        <brian@[uk.]FreeBSD.org>
>       <http://www.Awfulhak.org>                   <brian@[uk.]OpenBSD.org>
> Don't _EVER_ lose your sense of humour !
> 
> 
> 
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