Subscriber host idle timeout

An idle timeout is the maximum time that a subscriber session can be idle before the session is terminated or a connectivity check is started. Idle timeout applies to PPPoE and IPoE hosts.

The time/volume based accounting model is used to configure an idle timeout.

Create a category-map (see Category map and categories)

• Define a category with queues and policers to be monitored for activity (packets being forwarded).

• An activity threshold (in kb/s) must be configured for idle timeout to take effect. The activity threshold suppresses background traffic (for example control flows) from activity monitoring.

The following in an example of a category map configuration:

config>subscr-mgmt
        category-map "idle-timeout" create
            activity-threshold 25
            category "cat-1" create
                queue 1 ingress-egress 
            exit
        exit 

In the sla-profile, associate the category-map and optionally define

• An idle-timeout (60 to 15552000 seconds). The default is infinite (no idle-timeout).

  The idle-timeout can also be specified from RADIUS in an access-accept or CoA message with the [28] Idle-Timeout attribute. A RADIUS specified idle-timeout overrides the CLI- configured value. The values outside the limits are accepted but rounded to these boundaries.

  Table: Idle-timeout attribute

  Attribute ID	Attribute name	Type	Limits	Purpose and format
  28	Idle-Timeout	integer	60 to 15552000 seconds	0 = infinite (no idle-timeout) 60 to 15552000, in seconds For example: Idle-Timeout = 3600

• An idle-action:

  shcv-check

  Perform a subscriber host connectivity check (IPoE hosts only). Host connectivity verification should be enabled on the corresponding group-interface for the idle-timeout-action shcv-check to take effect:

  configure>service ies | vprn service-id subscriber-interface ip-int-name >group-interface ip-int-name>host-connectivity-verify

  If the SHCV check is successful, the subscriber host is not disconnected, and the idle-timeout timer is reset to zero. If the SHCV check fails, the subscriber host is disconnected (same as terminate).

  For PPP hosts, the idle-timeout-action shcv-check is ignored and has the same effect as idle-timeout-action terminate.

  IPoE:

  Terminate (default): disconnect the subscriber hosts

  • Delete the subscriber host
  • Send a DHCP release message to the DHCP server
  • Send an Accounting Stop message to the RADIUS accounting server

  PPP:

  • Delete the subscriber host
  • Send a terminate request message to the CPE
  • Send an Accounting Stop message to the RADIUS accounting server

Example

config>subscr-mgmt
        sla-profile "sla-profile-1" create
            category-map "idle-timeout"
                category "cat-1" create
                    idle-timeout 3600
                    idle-timeout-action terminate
                exit
            exit
        exit 

At host instantiation, a timer is initialized to the idle-timeout value (one timer per sla-profile instance). Each queue or policer in the category is monitored for activity over a fixed polling interval:

During the polling interval:

• If the forwarding rate falls below the configured activity threshold then the timer is deducted by the polling interval (time elapsed).
• If the forwarding rate is above the configured activity threshold then the timer is initialized to the idle-timeout value.

When the timer becomes zero, the idle-timeout-action is performed for all hosts associated with the SLA-profile-instance (all hosts from a subscriber on a single sap and that share the same sla-profile).