Subject: Re: Clock synchronization with ISDN
To: Wolfgang Solfrank <>
From: Christian Kuhtz <>
List: tech-kern
Date: 02/17/1997 19:17:14
On Mon, 17 Feb 1997 20:22:18 +0100, (Wolfgang Solfrank) wrote:
> > The timestamp is coming over the 16Kbit/s D channel, which is designed to
> > be a very low latency out-of-band signaling channel.
> >
> > Why would latency be high on the D channel? Assuming you're not abusing it
> > for something like a low volume X.25 channel, by definition, there should
> > never be any significant latency.
> Since by design the D channel may carry a "low volume" X.25 channel (it's
> running effectively as a 9600 baud X.25 line), why would anyone bother to
> make the clock particularly accurate, esp. more accurate than can be
> guarranteed over this channel?

Come on.  This is ridiculous.  How many people configurations have you seen  
which actually *do* configure a X.25 link over a signalling channel?!

Over the last 7 yrs I have seen exactly... two, out of hundreds of ISDN  
installations around the world.

D channel is primarily out-of-band signaling, and nothing else.  And it is by  
design low latency.  If this bickering goes much longer, I'll actually go and  
dig for the ISDN specs which are somewhere around here.

Christian Kuhtz <> (work),   <> (personal)
UNIX/Network Specialist,   "A German in the U.S., speaking for himself *gasp*"
Paranet, Inc. Rocky Mountain Branch,  MIME/NeXTmail Ok