Rf Interface Support
▀ Features and Terminology
▄ Cisco ASR 5x00 Packet Data Network Gateway Administration Guide
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Diameter Base Protocol
The Diameter Base Protocol maintains the underlying connection between the Diameter Client and the Diameter Server.
The connection between the client and server is TCP based.
In order for the application to be compliant with the specification, state machines should be implemented at some level
within the implementation.
Diameter Base supports the following Rf message commands that can be used within the application.
Table 39.
Diameter Rf Messages
Command Name
Source Destination Abbreviation
Accounting-Request CTF
CDF
ACR
Accounting-Answer CDF
CTF
ACA
There are a series of other Diameter messages exchanged to check the status of the connection and the capabilities.
Capabilities Exchange Messages: Capabilities Exchange Messages are exchanged between the diameter peers to
know the capabilities of each other and identity of each other.
Capabilities Exchange Request (CER): This message is sent from the client to the server to know the
capabilities of the server.
Capabilities Exchange Answer (CEA): This message is sent from the server to the client in response to
the CER message.
Device Watchdog Request (DWR): After the CER/CEA messages are exchanged, if there is no more traffic
between peers for a while, to monitor the health of the connection, DWR message is sent from the client. The
Device Watchdog timer (Tw) is configurable and can vary from 6 through 30 seconds. A very low value will
result in duplication of messages. The default value is 30 seconds. On two consecutive expiries of Tw without
a DWA, the peer is considered to be down.
Important:
DWR is sent only after Tw expiry after the last message that came from the
server. Say if there is continuous exchange of messages between the peers, DWR might not be sent
if (Current Time - Last message received time from server) is less than Tw.
Device Watchdog Answer (DWA): This is the response to the DWR message from the server. This is used to
monitor the connection state.
Disconnect Peer Request (DPR): This message is sent to the peer to inform to shutdown the connection. There is
no capability currently to send the message to the Diameter server.
Disconnect Peer Answer (DPA): This message is the response to the DPR request from the peer. On receiving
the DPR, the peer sends DPA and puts the connection state to “DO NOT WANT TO TALK TO YOU” state
and there is no way to get the connection back except for reconfiguring the peer again.
A timeout value for retrying the disconnected peer must be provided.
