Configurable TCP Timers
You can configure your Oracle Communications Session Border Controller to detect failed TCP connections more quickly so that data can be transmitted via an alternate connection before timers expire. Across all protocols, you can now control the following for TCP:
- Connection establishment
- Data retransmission
- Timer for idle connections
These capabilities all involve configuring an options parameter that appears in the network parameters configuration.
Configuring TCP Connection Establishment
To establish connections, TCP uses a three-way handshake during which two peers exchange TCP SYN messages to request and confirm the active open connection. In attempting this connection, one peer retransmits the SYN messages for a defined period of time if it does not receive acknowledgement from the terminating peer. You can configure the amount of time in seconds between the retries as well as how long (in seconds) the peer will keep retransmitting the messages.
You set two new options in the network parameters configuration to specify these amounts of time: atcp-syn-rxmt-interval and atcp-syn-rxmt-maxtime.
Note that for all configured options, any values entered outside of the valid range are silently ignored during configuration and generate a log when you enter the activate command.
To configure TCP connection establishment:
Configuring TCP Data Retransmission
TCP is considered reliable in part because it requires that entities receiving data must acknowledge transmitted segments. If data segments go unacknowledged, then they are retransmitted until they are finally acknowledged or until the maximum number of retries has been reached. You can control both the number of times the Oracle Communications Session Border Controller tries to retransmit unacknowledged segments and the periodic interval (how often) at which retransmissions occur.
You set two new options in the network parameters configuration to specify how many retransmissions are allowed and for how long: atcp-rxmt-interval and atcp-rxmt-count.
To configure TCP data retransmission:
Timer for Idle Connections
When enabled to do so, the Oracle Communications Session Border Controller monitors inbound TCP connections for inactivity. These are inbound connections that the remote peer initiated, meaning that the remote peer sent the first SYN message. You can configure a timer that sets the maximum amount of idle time for a connection before the Oracle Communications Session Border Controller consider the connection inactive. Once the timer expires and the connection is deemed inactive, the Oracle Communications Session Border Controller sends a TCP RST message to the remote peer.
To configure the timer for TCP idle connections: