AudioCodes Mediant 3000, User Manual

Page: 281 / 872

Version 6.6 281 Mediant 3000
User's Manual 20. IP-to-IP Routing Application
20.1.1 Proxy Sets
A Proxy Set is a group of Proxy servers (for Proxy load balancing and redundancy) defined
by IP address or fully qualified domain name (FQDN). The Proxy Set is assigned to Server-
type IP Groups only, representing the address of the IP Group to where the device sends
the INVITE message (i.e., the
destination of the call). Typically, for IP-to-IP call routing,
two Proxy Sets are defined for call destination – one for each leg (i.e., one for each IP
Group) of the call (i.e., both directions).
20.1.2 IP Groups
An IP Group represents a logical SIP entity in the device's network environment such as an
ITSP SIP trunk, Proxy/Registrar server, IP-PBX, or remote IP-PBX users. The address of
the IP Group is typically defined by its associated Proxy Set.
The opposite legs of the call are each presented by an IP Group; one being a Serving IP
Group the other a Served IP Group. The Serving IP Group denotes the IP Group that
provides service (e.g., ITSP) to the Served IP Group (e.g., IP-PBX). This is the IP Group to
where the device sends INVITE messages received from the Served IP Group as well as
REGISTER messages for registering on behalf of the Served IP Group.
IP Group can be a Server or User type. For Server-type IP Groups (e.g., ITSP or IP-PBX),
the destination address (defined by the Proxy Set) is known. In contrast, User-type IP
Groups represents groups of users whose location is dynamically obtained by the device
when REGISTER requests and responses traverse (or are terminated) by the device.
Generally, these are remote IP-PBX users (e.g., IP phones and soft phones).
For registrations of User-type IP Groups, the device updates its internal database with the
AOR and Contacts of the users (see the figure below) Digest authentication using SIP
401/407 responses, if needed, is done by the Serving IP Group (e.g., IP-PBX). The device
forwards these responses directly to the remote SIP users. For a call to a registered
remote user, the device searches its dynamic database using the Request URI for an entry
that matches a registered AOR or Contact. Once an entry is found, the IP destination is
obtained and a SIP request is then sent to the user.
Figure 20-2: IP-to-IP Routing/Registration/Authentication of Remote IP-PBX Users (Example)
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