Introduction

Configuring SIP Trunk Failover is crucial for maintaining the reliability and availability of VoIP services. This guide outlines the steps and configurations required to set up SIP Trunk Failover in ADTRAN Operating System (AOS) voice products. It covers both the default and validated methods for failover, detailing the necessary CLI commands, example configurations, and monitoring techniques.

1. SIP Trunk Failover Overview

SIP trunk failover ensures that your VoIP connections remain active even when primary SIP servers become unreachable. It’s a critical feature for any enterprise relying on SIP for voice communications, as it provides redundancy and prevents loss of connectivity.

There are two primary methods for configuring SIP trunk failover in AOS:

• Default SIP Trunk Failover: This method uses a prioritized list of SIP servers. If the primary server fails, the system automatically tries the next server in the list.
• Validated SIP Trunk Failover: This method adds an extra layer of control by validating servers through successful SIP registration before using them.

2. Hardware and Software Requirements

To use SIP Trunk Failover features, your AOS voice product must meet specific hardware and software requirements:

• Firmware Version: AOS firmware A5.01 or later is required for basic failover, while R10.9.0 or later is needed for SIP trunk failover recovery delay.
• Compatibility: Ensure that your device is compatible by checking the AOS Product Feature Matrix.

3. Configuring SIP Trunk Failover Behavior

Configuring SIP trunk failover behavior involves several steps, starting with global settings and moving to specific trunk configurations.

3.1 Global Settings for SIP Trunk Failover

1. Set the Round Trip Time (RTT) and Maximum Retransmit Interval:

   (config)# ip sip timer T1 750
   (config)# ip sip timer T2 6000

2. Configure the Rollover Timer:

   (config)# ip sip timer rollover 4

3. Set the Register Rollover Time:

   (config)# ip sip timer rollover register 8

4. Set the Registration Failure Retry Interval:

   (config)# ip sip timer registration-failure-retry 30

3.2 SIP Trunk Failover Configuration

After setting the global parameters, configure the specific SIP trunks:

1. Specify Registration Expiration Time:

   (config-T01)# registrar expire-time 1800

2. Set Maximum Concurrent Registration Requests:

   (config-T01)# registrar max-concurrent-reg 2

3. Configure the Registration Renewal Threshold:

   (config-T01)# registrar threshold percentage 5

4. Configure Failover Behavior:

   (config-T01)# sip-server rollover service-unavailable-or-timeout

4. SIP Trunk Failover Configuration Example

Below is an example configuration that includes both default and validated failover settings:

Default SIP Trunk Failover Configuration

(config)# voice trunk t01 type sip
(config-T01)# registrar expire-time 1800
(config-T01)# registrar max-concurrent-reg 2
(config-T01)# registrar threshold percentage 5
(config-T01)# sip-server primary as1.adtran.com
(config-T01)# sip-server secondary as2.adtran.com
(config-T01)# sip-server rollover service-unavailable-or-timeout
(config-T01)# snmp trap registration failures 3 interval 3600

Validated SIP Trunk Failover Configuration

(config)# voice trunk t01 type sip
(config-T01)# registrar expire-time 1800
(config-T01)# registrar max-concurrent-reg 2
(config-T01)# registrar threshold percentage 5
(config-T01)# sip-server primary as1.adtran.com
(config-T01)# sip-server secondary as2.adtran.com
(config-T01)# sip-server rollover service-unavailable-or-timeout
(config-T01)# sip-server validation register
(config-T01)# sip-server monitor
(config-T01-monitor)# recover delay 1800
(config-T01-monitor)# no shutdown

5. Monitoring SIP Trunk Failover

To monitor SIP trunk failover, you can enable SNMP traps that will alert you to registration failures. The following command sets up SNMP traps:

(config-T01)# snmp trap registration failures 3 interval 3600

Conclusion

Configuring SIP trunk failover is essential for maintaining robust and reliable VoIP communications. By following the steps outlined in this guide, you can ensure that your SIP trunks are configured for optimal failover behavior, minimizing the impact of server failures on your network.

For more detailed information and troubleshooting, refer to the AOS Command Reference Guide available on the ADTRAN support forums.