Configurable TCP Timers

You can configure your Oracle® Enterprise 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:

In Superuser mode, type configure terminal and press Enter.
```
ORACLE# configure terminal
```

Type system and press Enter.

ORACLE(configure)# system
ORACLE(system)#

Type network-parameters and press Enter.

ORACLE(system)# network-parameters
ORACLE(network-parameters)#

options—Set the options parameter by typing options, a Space, the option name atcp-syn-rxmt-interval=x (where x is a value in seconds between 2 and 10) with a plus sign in front of it. Then press Enter. This value will be used as the interval between TCP SYN messages when the Oracle® Enterprise Session Border Controller is trying to establish a connection with a remote peer.
Now enter a second option to set the maximum time for trying to establish a TCP connection. Set the options parameter by typing options, a Space, the option name atcp-syn-rxmt-maxtime=x (where x is a value in seconds between 5 and 75) with a plus sign in front of it. Then press Enter.
```
ORACLE(network-parameters)# options +atcp-syn-rxmt-interval=5
ORACLE(network-parameters)# options +atcp-syn-rxmt-maxtime=30
```
If you type the option without the plus sign, you will overwrite any previously configured options. In order to append the new options to the configuration’s options list, you must prepend the new option with a plus sign as shown in the previous example.

Note:
atcp-syn-rxmt-maxtime=x option is equivalent to the tcp-keepinit-timer parameter, but only affects ATCP.
Save and activate your configuration.

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® Enterprise 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:

In Superuser mode, type configure terminal and press Enter.
```
ORACLE# configure terminal
```

Type system and press Enter.

ORACLE(configure)# system
ORACLE(system)#

Type network-parameters and press Enter.

ORACLE(system)# network-parameters
ORACLE(network-parameters)#

options—Set the options parameter by typing options, a Space, the option name atcp-rxmt-interval=x (where x is a value in seconds between 2 and 60) with a plus sign in front of it. Then press Enter. This value will be used as the interval between retransmission of TCP data segments that have not been acknowledged.
Now enter a second option to set the number of times the Oracle® Enterprise Session Border Controller will retransmit a data segment before it declares the connection failed. Set the options parameter by typing options, a Space, the option name atcp-rxmt-count=x (where x is a value between 4 and 12 representing how many retransmissions you want to enable) with a plus sign in front of it. Then press Enter.
```
ORACLE(network-parameters)# options +atcp-rxmt-interval=30
ORACLE(network-parameters)# options +atcp-rxmt-count=6
```
If you type the option without the plus sign, you will overwrite any previously configured options. In order to append the new options to the configuration’s options list, you must prepend the new option with a plus sign as shown in the previous example.
Save and activate your configuration.

Timer for Idle Connections

When enabled to do so, the Oracle® Enterprise 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® Enterprise Session Border Controller consider the connection inactive. Once the timer expires and the connection is deemed inactive, the Oracle® Enterprise Session Border Controller sends a TCP RST message to the remote peer.

To configure the timer for TCP idle connections:

In Superuser mode, type configure terminal and press Enter.
```
ORACLE# configure terminal
```

Type system and press Enter.

ORACLE(configure)# system
ORACLE(system)#

Type network-parameters and press Enter.

ORACLE(system)# network-parameters
ORACLE(network-parameters)#

options—Set the options parameter by typing options, a Space, the option name atcp-idle-timer=x (where x is a value in seconds between 120 and 7200) with a plus sign in front of it. Then press Enter. This value will be used to measure the activity of TCP connections; when the inactivity on a TCP connection reaches this value in seconds, the Oracle® Enterprise Session Border Controllerdeclares it inactive and drops the session.
```
ORACLE(network-parameters)# options +atcp-idle-timer=900
```
If you type the option without the plus sign, you will overwrite any previously configured options. In order to append the new options to the configuration’s options list, you must prepend the new option with a plus sign as shown in the previous example.
Save and activate your configuration.