User's Manual 248 Document #: LTRT-68822
Mediant 2000
The device also supports the IP-to-IP call routing Survivability mode feature (see the figure
below) for User-type IP Groups. The device stores in its database REGISTER messages
sent by the clients of the User-type IP Group. If communication with the Serving IP Group
(e.g., IP-PBX) fails, the User-type IP Group enters into Survivability mode in which the
device uses its database for routing calls between the clients of the User-type IP Group.
The RTP packets between the clients traverse through the device. When the Serving IP
Group is available again, the device returns to normal mode, sending INVITE and
REGISTER messages to the Serving IP Group.
Figure 20-3: IP-to-IP Routing for IP-PBX Remote Users in Survivability Mode (Example)
20.1.3 Inbound and Outbound IP Routing Rules
The device's IP-to-IP call routing is performed using the following two routing rule stages:
1. Inbound IP Routing Mapping Rule: Identifies the received call as an IP-to-IP call
based on various characteristics such as the call's source IP address, and assigns it to
an IP Group.
2. Outbound IP Routing Mapping Rule: Determines the destination (i.e., IP address) to
where the incoming call associated with a specific source IP Group is finally routed.
The destination address is typically denoted by another IP Group (destination IP
Group) and therefore, the call is sent to the IP address that is defined by the Proxy Set
associated with this IP Group. If the destination is a User-type IP Group, the device
searches for a match between the request-URI of the received INVITE to an AOR
registration record in the device's database. If a match is found, the INVITE is sent to
the IP address of the registered contact.