Mitel 6800 Series, Administrator'S Manual, Page: 636 / 1113

Mitel 6800 Series SIP Phone Release 4.2.0 SP2 Administrator Guide
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3.
Save the file as “
<filename>.txt
”. For example, “
hostfile.txt”
.
4.
Using a text-based editing application, open the
startup.cfg
file for the phone(s) for which
you want to apply the DNS hostfile.
5.
Enter the following parameter in the
startup.cfg
file followed by the host file name as the
value: sip dns host file: <filename>.txt
For example:
sip dns host file: hostfile.txt
6.
Save the file. Make sure the
startup.cfg
and the
hostfile.txt
files are on the configuration
server in your network before downloading to the phone(s).
7.
Restart the phone(s) in your network.
The phone(s) downloads the specified host text file and stores it locally on the phone’s
flash memory. Upon each subsequent boot of the phones, if the host text file is available
on the configuration server, it is downloaded to replace the locally cached copy; otherwise,
the previously cached copy is retained and used unchanged.
The configuration of the phone(s) can now use server1, server2, or server3 for SIP or other
services instead of using the IP addresses. The phones will continue resolving the host
names even if DNS on the network has conflicting or missing entries for server1, server2,
or server3, or if the local LAN DNS server fails to respond.
CONFIGURING DNS “SERVICE (SRV) RECORDS” PRE-CACHING
In addition to using a host file to resolve host names to IP addresses, an Administrator can also
configure DNS “SRV records” (Service Records) for geographic redundancy and failover
between application servers in the network.
The SIP registration and SIP proxy features on the phones previously allowed the use of server
queries only to live DNS servers. Using the host file and specific DNS SVR parameters extends
this mechanism to allow pre-configuration of server values in the
startup.cfg
file. The following
new parameters are used for this feature:
• sip dns srvX name
• sip dns srvX priority
• sip dns srvX weight (supported in a future release)
• sip dns srvX port
• sip dns srvX target
You can configure up to 4 DNS SRV records, with each server having a
priority
which tells the
phone which server to use, and a host name or
target
. The IP phone will use the DNS SRV
record with the lowest-numbered priority value first, and will only failover to other records if the
connection with this record's host fails. Thus a service may have a designated failover server,
which is only used if the primary server fails.
Note:
If using a text file on a PC to enter this value, you must enter a carriage return
(CR) after entering the host file name.
Note:
The “X” indicates a DNS SRV with a value from 1 to 4.