> -----Original Message----- > From: Luan Nguyen [mailto:[EMAIL PROTECTED] > Sent: Wednesday, October 15, 2008 7:22 AM > To: 'Ted Mittelstaedt'; [email protected] > 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 _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
