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

[Luan Nguyen]

-----Original Message-----
From: Ted Mittelstaedt [mailto:tedm at toybox.placo.com] 
Sent: Wednesday, October 15, 2008 12:01 PM
To: Luan Nguyen; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] OK, what is a cheap and dirty hack to test a port



> -----Original Message-----
> From: Luan Nguyen [mailto:luan at netcraftsmen.net]
> Sent: Wednesday, October 15, 2008 7:22 AM
> To: 'Ted Mittelstaedt'; cisco-nsp at puck.nether.net
> Subject: RE: [c-nsp] OK, what is a cheap and dirty hack to test a port
>
>
> 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.

Luan,

  We have several spans going through Verizon.  One thing I have
found is that Verizon uses different make and model of NIUs at the
remote sites.  The newest make and model of NIU they use (I have it
documented somewhere but I cannot find it) is not compatible with
certain make and model of CSU/DSUs.  I found that out with one
of our customer spans that was the first span delivered through
one of these newer NIUs.  We fortunately never standardized on
DSU/CSUs (I get them off Ebay nowadays for cents on the dollar)
and I have always favored use of -external- DSU's coupled to a
serial port on the router rather than the integrated Cisco WIC
with DSU.  So with that span I had 5 different
make and model DSU's to experiment with.

  The problem I believe is that certain DSU's are particular
on the frequency clock they slave to.  If the clock is too far
off frequency from what the CSU/DSU thinks it is supposed to be,
even if the CSU is set to slave clock from the span, it will slip
anyway.

  Unfortunately I wish it were that simple with my own problem.
In my instance, the spans are actually going into a m13 mux
from the DSU bank (most are, at any rate)  So it is consistent
environment on all spans going into the router.

Ted


Ted,

I was also told by one of the tech that their NIU isn't compatible with the
VWIC card we have in the router.
But our circuit has been working for years.  I tested 4 different types of
Wan Interface Cards and none worked.
Verizon somehow agreed to replace their NIUs at both ends.  And that seems
to work so far. 3 hours and counting...

Luan Nguyen
Chesapeake NetCraftsmen, LLC.
www.NetCraftsmen.net