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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The thing I dislike the most about the 79xx phones is that
in DHCP mode, they expect the DHCP server to tell them their TFTP server
address. They won’t let you set it manually. So if I don’t have
DHCP server that gives TFTP server info, which is most of the DHCP servers at
out there, then the phone won’t be able to download any updates made to
the SIP000*.cnf file. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Using dhcpd on my full blown linux, I’ve added:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> next-server 10.5.5.1;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> option tftp-server-name "10.5.5.1";<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>to dhcpd.conf and that makes the phones take it fine.
Initially I only needed the “next-server” option, but I found the
oldest firmware’s of the 79xx sometimes ignored this parameter, I added “option
tftp-server-name” and that seems to have fixed the problem. It’s
probably only in my head, but you never know.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Anyways, I’m playing with the LinkSys WRT54G router
now with OpenWRT installed. I’m trying to use dnsmasq to give the same
parameters. In dnsmasq.conf I’ve added:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>“dhcp-option=66,10.5.5.1”<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>But the Cisco phones are ignoring it. According to RFC2132,
DHCP Option/Code 66 is the TFTP server name. But the Cisco 79xx phones I’ve
tested are ignoring this.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>My question is this, does the Cisco 79xx IP Phones use a
different DHCP Code (other than 66) to define its TFTP server?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Also, does the Cisco 79xx honor DHCP Option 42, which
defines the NTP server? Or does it only honor the “sntp_server=”
option in its config file?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Maybe there’s a way to query the dhcp server on my
Linux server and figure out which DHCP codes it’s offering. I can then
mimick it with dnsmasq?<o:p></o:p></span></font></p>
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