User's Manual

Configuring Network Address Translation
308625-14.00 Rev 00
2-63
Customizing Keepalive Parameters
NAT synchronization uses keepalive messages to recognize and close terminated
connections between synchronized peers. If a peer fails or disconnects without
notification, the keepalive mechanism lets the router detect the termination and
close the connection at its end. You can customize the NAT synchronization
keepalive mechanism by changing the default values for the following:
• Keepalive interval. The keepalive interval is the idle session timeout period
between peers. If an active TCP connection between two peers remains idle
for the duration of the keepalive interval, the router sends a keepalive message
to the peer. By default, the keepalive interval is set to 120 seconds. You can
specify a value from 0 through 2,147,483,647 (2
31
) seconds. Setting this value
to 0 turns off the keepalive mechanism.
• Keepalive timer. The keepalive timer specifies the number of seconds between
transmission of keepalive messages. By default, the keepalive timer is set to 3
seconds. You can specify a value from 0 through 2,147,483,647 (2
31
) seconds.
If you set the keepalive timer to 0, the router does not send keepalive
messages, and the TCP connection times out when the keepalive interval
expires. If the keepalive interval is set to 0, the keepalive timer is ignored.
• Keepalive retry count. The keepalive retry count specifies the number of times
that the router retransmits keepalive messages. By default, the keepalive retry
count is set to 5. You can specify a value from 0 through 2,147,483,647 (2
31
).
If you set the keepalive retry count to 0, the router transmits only one
keepalive message.
Using the BCC
To reset the keepalive interval, navigate to the global NAT prompt (for example,
box; ip; nat
) and enter:
synch-idle-timer
<seconds>
seconds
is any integer. To turn off the keepalive interval, enter 0.
To reset the keepalive timer value, navigate to the global NAT prompt and enter:
synch-retransmit-timer
<seconds>
seconds
is any integer. To turn off keepalive message transmission, enter 0.