<div class="gmail_quote">On Fri, Feb 27, 2009 at 7:49 PM, Jared Smith <span dir="ltr"><<a href="mailto:jsmith@digium.com" target="_blank">jsmith@digium.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div>On Fri, 2009-02-27 at 14:07 -0700, Brandon B. wrote:<br>
> As of yet, I am unwilling to change the LBO to 0 to where it probably<br>
> should be because the system is working and I'm not sure exactly what<br>
> the LBO does. I'm aware some changes were made to deal with low audio<br>
> levels.<br>
<br>
</div>LBO stands for Line Built Out... it's essentially a measurement of the<br>
distance between your demarcation point (d-marc/smart jack/NIU) and your<br>
Asterisk box. As you can see from a sample system.conf (from DAHDI) or<br>
zaptel.conf (from Zaptel), it's an integer value from the following<br>
table:<br>
<br>
0: 0 db (CSU) / 0-133 feet (DSX-1)<br>
1: 133-266 feet (DSX-1)<br>
2: 266-399 feet (DSX-1)<br>
3: 399-533 feet (DSX-1)<br>
4: 533-655 feet (DSX-1)<br>
5: -7.5db (CSU)<br>
6: -15db (CSU)<br>
7: -22.5db (CSU)<br>
<br>
As I understand it, the LBO is effectively an attenuation value, with a<br>
higher number meaning less attenuation. This way, you don't get too hot<br>
of a signal with a short cable, or two low of a signal on long cable.<br>
<br>
Just how far is your Asterisk box from the demarcation point?</blockquote><div><br>This system is connected to a CSU in the same room that provides the physical T1 line. I've always set the LBO setting at 0 for this because I've never had a long line to deal with. Since 0 works for me, I'm going to assume it's the correct setting with the demarc point (i.e. the Paradyne CSU) in the same room -- right? It's slightly confusing with settings 5,6,7 labelled CSU and no description as to when to use those levels. Could you provide any suggestion for when levels 5,6,7 would be appropriate?<br>
<br>From what you say an LBO setting of 5 would boost the signal level, which could be "hot". Is there any chance this would cause the card to fail after a while? It appears this site just had 4 port Digium card fail today.<br>
<br>
</div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div>> Also, I am trying to cross connect with another Asterisk system with<br>
> the normal LBO setting (i.e. span=1,1,0,esf,b8zs) but as of yet the<br>
> systems aren't seeing each other at all. Could the side with the high<br>
> LBO be confusing the other side somehow?<br>
<br>
</div>Shouldn't be... you did use a T1-crossover cable to cross-connect the<br>
two Asterisk boxes, right? I've got a little T1 cross-connect diagram<br>
at <a href="http://www.asteriskdocs.org/cables/" target="_blank">http://www.asteriskdocs.org/cables/</a> if you need a reference.<br>
</blockquote><div><br>Yes, it's a T1 cross over and this problem was resolved after plugging into a working Digium card on the other end.<br> </div>Brandon B.<br></div><br>