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Session Timers

When packets stop arriving on the flows of a session, the SSR will clear the session after a period of time. The amount of time depends on the type of traffic.

Session Type Timeout​

The time the router will wait before removing the session is governed by the timeout value in the session-type matched by the traffic.

For example, the following configuration examples show the session-types for DNS and SSH. Their timeouts are 5000 milliseconds and 1900000 milliseconds respectively:

session-type                   DNS
    name            DNS
    service-class   NetworkControl
    timeout         5000
    nat-keep-alive  false

    transport       udp
        protocol    udp

        port-range  53
            start-port  53
        exit
    exit

    transport       tcp
        protocol    tcp

        port-range  53
            start-port  53
        exit
    exit
exit
session-type                   SSH
    name            SSH
    service-class   OAM
    timeout         1900000
    nat-keep-alive  false

    transport       udp
        protocol    udp

        port-range  22
            start-port  22
        exit
    exit

    transport       tcp
        protocol    tcp

        port-range  22
            start-port  22
        exit
    exit
exit

Default Timeout​

For traffic which does not match any session type, the following default timeout values are used:

  • TCP - 1900000 ms
  • UDP - 180000 ms
  • ICMP - 10000 ms

TCP Timeout​

For a session using TCP, the SSR examines the state of the flows. When first TCP packets arrive, the flows for the session are given a timeout of 10s. Once the connection reaches an established state, the timeout for the flows are updated to the default or configured session-type timeout value.