Wednesday, November 9, 2011

Autoprovision Aastra SIP Phones using mDNS

If you are unable to change the DHCP options on your DHCP server to allow for Option 66 there is a relatively undocumented alternative, mDNS (bounjour).  There is a blurb about it in the manual which tells you this exists, but it doesn't give you any direction, and there isn't much about it on the internet.  I managed to get it to work and am simply posting my solution, hopefully it works for you.

This is the snippet about mDNS in the Aastra Admin Guide:
The IP phones can perform an auto-discovery of all servers on a network using
mDNS. When the IP phone discovers a TFTP server, it is automatically
configured by that TFTP server.
An unconfigured phone (phone right out of the box) added to a network, attempts
to auto-discover a configuration server on the network without any end-user
intervention. When it receives DHCP option 66 (TFTP server), it automatically
gets configured by the TFTP server.
An already configured phone (either previously configured by auto-discovery or
manually configured) added to a network, uses its predefined configuration to
boot up.
1. Configuration parameters received via DHCP do not constitute
configuration information, with the exception of a TFTP server.
Therefore, you can plug a phone into a DHCP environment, still use the
auto-discovery process, and still allow the use of the TFTP server
parameter to set the configuration server.
2. DHCP option 66 (TFTP server details) overrides the mDNS phase of
the auto-discovery. Therefore, the DHCP option takes priority and the
remaining process of auto-discovery continues.
3. As the phone performs auto-discovery, all servers in the network
(including the TFTP server), display in the phone window. However, only
the server configured for TFTP automatically configures the phone.

There isn't any other information to be found, and I spent a lot of time trying to get this feature to work.  My final solution was to use avahi-daemon to do be the mDNS responder.  One thing to note is if there is a DHCP server sending out option 66 that will override this and the phone will listen to the DHCP option 66 instead.

The installation and configuration is incredibly simple.  On Debian I installed the daemon and the utilities.  I did this directly on my phone system in order to create an all in one type of appliance where I didn't need access to the DHCP server or be at the mercy of the configuration options available in that device.

apt-get install avahi-daemon avahi-discover avahi-utils 

Next, we need to configure avahi for the Aastra phones.  We need to create
This is the config file that tells avahi-daemon to listen for aastra phones and tell the phone to use tftp to boot.


<?xml version="1.0" standalone="no"?>
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<name replace-wildcards="yes">Aastra self-configuration on %h</name>

And that's it.  Reboot your phone and it should auto discover the tftp server and grab the aastra.cfg and mac.cfg files from there.

I've tested this with the following phones:
Aastra 6757i
Aastra 6739i
Aastra 6731i

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