Service Failover and Load Balancing

DIDWW provides mechanisms for failover and load balancing between its system and customer equipment. These mechanisms include the DNS SRV protocol and Trunk Groups.


DNS SRV

The DNS SRV mechanism is fully supported by the DIDWW system. Using DNS SRV, calls can be directed to a customer-defined DNS SRV record, which specifies multiple destinations and their respective priorities for failover.

How It Works

For UDP SIP transport, the system resolves the following record:

_sip._udp.<customer.domain>

For TCP SIP transport, the system resolves the following record:

_sip._tcp.<customer.domain>

In both cases, <customer.domain> represents the trunk host value.

Enabling DNS SRV for SIP Trunks

To enable the DNS SRV mechanism for SIP trunks, leave the port field empty.

The DNS SRV mechanism operates on the SIP transaction layer. In case of failover, a new Call Detail Record (CDR) is generated for each attempt.


Trunk Groups

Trunk Groups allow customers to bundle multiple SIP trunks, distributing traffic for DID numbers across multiple gateways. This feature provides flexible configuration options for failover and load balancing.

Configuration Options

You can configure the following parameters to manage Trunk Groups effectively:

  • Priority and Weight: Specify the order and distribution of calls among trunks.

  • Ringing Timeout: Set the maximum time to wait for a response from a trunk.

  • Re-routing Disconnect Rules: Define conditions for redirecting calls.

  • Capacity: Limit the number of simultaneous calls per trunk.

CDR Generation

For each call termination attempt within a Trunk Group, DIDWW generates a separate CDR. The following fields track these attempts:

By leveraging DNS SRV and Trunk Groups, you can implement robust failover and load-balancing strategies for your DID numbers.