Polycom V2IU Converged Network Appliance 6400-S - Manual (Page 38)

User Guide V 2 IU 6400-S Converged Network Appliance
5 - 8
Configuring VoIP survivability
Survivability features enable the 6400-S to extend the availability of VoIP
services. These features include:
• Support for redundant SIP softswitches
• Support for the Virtual Router Redundancy Protocol (VRRP), allowing a
backup 6400-S to take control for a master 6400-S in the event of a failure.
Configuring sofswitch survivability
If you will be using multiple SIP softswitches then you will need to enable
server redundancy and specify the time between DNS lookups in the 6400-S.
Enabling redundancy allows a DNS server to provide a list of multiple call
processing servers to the 6400-S in the answers to SRV lookups. Each server in
the list will be monitored using periodic messages by the 6400-S and the
highest priority server that is currently reachable will be used for signaling.
The 6400-S uses the reachability settings described below to determine the
status of remote servers and remove inoperable servers from the list.
Triggers can also be used by the 6400-S appliance to determine when to
forward call requests to a secondary server in the list. A trigger is set when a
configured number of resends are received by the 6400-S from a SIP user agent
attempting to place a call. When initiating a call a SIP user agent will send an
INVITE message to the 6400-S that will then be forwarded to the primary
server. In the event that the primary server fails before a reachability alarm has
been declared using the heartbeat messages the user agent will resend INVITE
messages until the trigger condition is met. At this point the 6400-S forwards
the call request on to the secondary server in the list.
Sofswitch survivability includes:
• Softswitch reachability configuration