[ntp:questions] Re: tinker step 0 (always slew) and kernel time discipline

Jan Ceuleers janspam.ceuleers at skynet.be
Sun Sep 24 11:26:02 UTC 2006

Hal Murray wrote:
> Anybody know if I can get a good frequency off a DSL line?
> Assume I'm willing to hack a wire into my modem/router.

Since the advent of Ethernet or IP DSLAMs they are no longer necessarily 
synchronised with the rest of the network. Only a DSLAM which has an ATM 
(or in any case SDH/SONET encapsulated) uplink necessarily is. 
Ethernet/IP DSLAMs may still have BITS interfaces but their use would be 
optional (and needed only if this DSLAM is being used for things like 
circuit emulation on G.shdsl access lines).

So: the clock frequency you would derive from a DSL line may or may not 
be synchronised with the (presumably high-quality) network clock. Unless 
you have detailed knowledge of your operator's network you cannot be 

Regards, Jan

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