The Diameter Enabler base utilizes
connections as links between a Diameter Enabler base and
a peer, as routes to determine the connection on which a Diameter packet should
be sent, as channels to convert byte streams to and from Diameter packets,
and as call flows to transmit and receive these packets.
A connection is the link between a Diameter Enabler base and
a peer. The peer may be a Diameter server or a Diameter agent that is a hop
in the path to the Diameter server. For each configured connection, there
is exactly one TCP connection between the Diameter Enabler base and
the peer that it communicates with.
Connections remain as long as both
the Diameter Enabler base and
the peer are operating. If neither party sends a packet over the connection
for a specified period of time, a watchdog message is sent to ensure that
both sides are still operating.
The Diameter layer uses routes to determine
which connection it should send a packet on. To send Diameter application
packets to a specific realm, you must configure at least one connection and
one route that uses that connection.
Note: If the specified connection's destination
is a Diameter agent, rather than a Diameter server, the Diameter packet passes
through this connection as a single hop on its way to the Diameter server.
Each
connection represents a chain of channels. These channel chains operate within
the Channel Framework Architecture (CFA) and are comprised of Diameter Channels,
SSL/TLS channels (optional), and TCP channels.
At the top of the channel
chains, there are three applications:
Rf accounting Web service,
Ro online charging Web service,
and
Sh subscriber profile Web service.
All three of these applications export APIs to external applications through
Web services interfaces.
- The Diameter Enabler base manages
connections, routes, and state machines to insure compliance with the Diameter
protocol.
- Diameter Web services use
the Diameter Enabler base to
handle packets as they pass through the CFA.
- The Diameter channel is a serialization and de-serialization layer that
converts inbound byte streams into Diameter packets and outbound Diameter
packets into byte streams. No state is kept within the Diameter channel.
Diameter applications use call flows to transmit and receive packets
for accounting,
online charging, subscriber profile retrieval
and updates, or subscribe and notify messages for subscriber profiles.
- For accounting messages, the Diameter Enabler base passes
information through the Rf accounting Web service when
sending messages to the CCF. The CCF receives the messages and sends its response
back to the Rf accounting Web service,
which responds to the client that initiated the Web service request.
- For online service requests, the Ro online charging Web service interface
receives the Web service request from the client. The request is then processed
and forwarded through the Diameter Enabler base to
the appropriate OCS. The OCS receives the message and sends its response to
the Ro online charging Web service,
which responds to the client that initiated the Web service request.
- For subscribe/notify messages:
- The Sh subscriber profile Web service interface
receives subscription requests from the IMS™ Application Server.
The requests are then forwarded as subscriptions to the HSS using the Diameter
protocol. When an update occurs at the HSS, the HSS sends a notification to
the Diameter Enabler informing
it of the update. The Sh subscriber profile Web service then
forwards the update to all IMS Application Servers
that have subscribed to the update.
- The Ro online charging Web service interface
provides subscription and notification messages to the IMS Application Server.
Notifications are sent when the CTF must reauthenticate with the OCS or when
a reauthorization subscription expires.