[c-nsp] OK, what is a cheap and dirty hack to test a port

Roy r.engehausen at gmail.com
Wed Oct 15 10:35:58 EDT 2008


Just because its a point to point circuit doesn't mean one side has to
have internal clocking.  This is only true if the circuit is copper all
the way.   There are lots of reasons that the telco would have its own
equipment installed on the circuit and you would need network timing.

Roy

Luan Nguyen wrote:
> Is it a Verizon circuit?
> We have a T1 circuit with Verizon and have the same problem.  We have a
> point to point circuit, so one side has clocking set to internal to provide
> the clocking and the other side feeds from the line.
> I wrote the problem up at http://ccie-security.blogspot.com/
> But basically, it will be up for a some hours then down, then I call them to
> test and it's good again.  Sometime it's good just by unplug the cable and
> plug it back.  Like you, we changed everything and that didn't help. 
> Finally, we talked to a knowledgeable Verizon tester and he mentioned the
> rate on the line is ~17 which is high.  It should be around 0 or negative.
> He said that's because of mismatch clocking between our hardware and the
> central office crossover equipment. The normal tester won't look at this,
> they only do the loopback pattern testing, so you should ask them about the
> rate of your line.
> They swapped one smart jack, but that didn't help, so they will swap the
> other today.  Hopefully that will do it.
> Good information here about troubleshooting T1
> http://www.informit.com/library/content.aspx?b=Troubleshooting_Remote_Access
> &seqNum=61
>
>
> Luan Nguyen
> Chesapeake NetCraftsmen, LLC.
> www.NetCraftsmen.net
>
> ...
>   



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