Aastra Telecom 41-001343-02 manual Hostfile.txt

Advanced Operational Features

In the following example, both the priority and weight fields are used to provide a combination of load balancing and backup service.

Example

sip dns srv1 name: _sip._udp.example.com

sip dns srv1 priority: 10

sip dns srv1 weight: 60

sip dns srv1 port: 5060

sip dns srv1 target: bigbox.example.com

sip dns srv2 name: _sip._udp.example.com

sip dns srv2 priority: 10

sip dns srv2 weight: 20

sip dns srv2 port: 5060

sip dns srv2 target: smallbox1.example.com

sip dns srv3 name: _sip._udp.example.com

sip dns srv3 priority: 10

sip dns srv3 weight: 20

sip dns srv3 port: 5060

sip dns srv3 target: smallbox2.example.com

sip dns srv4 name: _sip._udp.example.com

sip dns srv4 priority: 20

sip dns srv4 weight: 10

sip dns srv4 port: 5060

sip dns srv4 target: backupbox.example.com

The first three records (SRV 1, 2, and 3) share a priority of 10, so the weight field's value is used by the phones to load bal- ance across the three target host names.

Bigbox will get 60% of the load, and smallbox1 and smallbox2 will each get 20% load.

If all three servers with priority 10 are unavailable, the next highest priority record is selected, in this case backupbox. This could be a server in another physical location.

The server entries in the aastra.cfg file can use DNS hostnames or can use IP addresses. If hostnames are used, any pre- cached DNS A records via the host file mechanism are used before resorting to live DNS query if there is no local match.

For example, the following hostfile.text uses IP addresses that are used in the DNS server queries:

hostfile.txt

192.168.2.3 bigbox.example.com 192.168.3.4 smallbox1.example.com 192.168.8.1 smallbox2.example.com 47.28.05.69 backupbox.example.com

Use the following procedure in the configuration files to configure DNS server query support for the phones.

Configuration Files

For the specific parameter you can set in the configuration files, see Appendix A, the section, “DNS Server Query” on page A-214.

Use the following procedure to configure DNS SRV record pre-caching.

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