Version 7.2 295 Mediant 800B Gateway & E-SBC
User's Manual 15. Services
for an appropriate destination. The request is sent to the Routing server using an HTTP Get
Route message. The request contains information about the call (SIP message and for IP-to-Tel
calls, the source IP Group based on the associated Proxy Set).
The Routing server uses its own algorithms and logic in determining the best route path. The
Routing server manages the call route between devices in "hops", which may be spread over
different geographical locations. The destination to each hop (device) can be by IP address (with
port), IP Group and/or Trunk Group. If the destination is an IP address, even though the
destination type (in the IP-to-IP Routing table) is an IP Group, the device only uses the IP Group
for profiling (i.e., associated IP Profile etc.). If multiple devices exist in the call routing path, the
Routing server sends the IP address only to the last device ("node") in the path.
Once the device receives the resultant destination hop from the Routing server, it sends the call
to that destination. The Routing server can provide the device with an appropriate route or reject
the call. However, if for the initial request (first sent Get Route request for the call) the Routing
server cannot find an appropriate route for the call or it does not respond, for example, due to
connectivity loss (i.e., the Routing server sends an HTTP 404 "Not Found" message), the device
routes the call using its routing tables. If the Get Route request is not the first one sent for the call
(e.g., in call forwarding or alternative routing) and the Routing server responds with an HTTP 404
"Not Found" message, the device rejects the call.
This HTTP request-response transaction for the routing path occurs between Routing server and
each device in the route path (hops) as the call traverses the devices to its final destination. Each
device in the call path connects to the Routing server, which responds with the next hop in the
route path. Each device considers the call as an incoming call from an IP Group or Trunk Group.
The session ID (SID) is generated by the first device in the path and then passed unchanged
down the route path, enabling the Routing server to uniquely identify requests belonging to the
same call session.
Communication between the device and the Routing server is through the device's embedded
Representational State Transfer (RESTful) API. The RESTful API is used to manage the routing-
related information exchanged between the Routing server (RESTful server) and the device
(RESTful client). When you have configured the device with connection settings of the Routing
sever and the device starts-up, it connects to the Routing server and activates the RESTful API,
which triggers the routing-related API commands.
The following figure provides an example of information exchange between devices and a
Routing server for routing calls:
Figure 15-46: Example of Call Routing Information Exchange between Devices and Routing Server
To Next Page
Loading...
