Configuring ISG Policies for Session Maintenance

First Published: March 20, 2006
Last Updated: November 5, 2009

Intelligent Services Gateway (ISG) is a Cisco IOS and Cisco IOS XE software feature set that provides a structured framework in which edge devices can deliver flexible and scalable services to subscribers. ISG provides two commands, timeout absolute and timeout idle, that each allow control over a session and a traffic class configured on the session as defined by a service policy map. Additionally, the Internet Engineering Task Force (IETF) RADIUS attributes Session-Timeout (attribute 27) and Idle-Timeout (attribute 28) can be used in non-traffic-class-based service profiles on an authentication, authorization, and accounting (AAA) server to configure the same session maintenance control.

IP subscriber session keepalive support is configured for monitoring session data traffic in the upstream direction for idleness. Address Resolution Protocol (ARP) is used for Layer 2 connected subscribers. For routed host (Layer 3 connected) subscribers, the protocol defaults to Internet Control Message Protocol (ICMP). ICMP is also used in configurations where the access interface does not support ARP.

Finding Feature Information

For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Configuring ISG Policies for Session Maintenance" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Prerequisites for Configuring Policies for Session Maintenance

•Restrictions for Configuring Policies for Session Maintenance

•Information About Configuring Policies for Session Maintenance

•How to Configure Policies for Session Maintenance Timers

•Configuration Examples for Session Maintenance Timers

•Additional References

•Feature Information for Configuring ISG Policies for Session Maintenance

Prerequisites for Configuring Policies for Session Maintenance

A traffic class is required only if an idle timer or session timer is being installed on a service that has a traffic class definition in it. If the timer is installed on a session or service that has no traffic class, a traffic class is not required. See the "Configuring ISG Subscriber Services" module for information about how to configure a traffic class.

Restrictions for Configuring Policies for Session Maintenance

For an idle timeout that is applied on an IP session (rather than on a PPP session), there is currently no way to specify the direction. By default, the direction in which the idle timer is applied is always outbound.

ISG supports both per-session and per-flow accounting. Per-session accounting is the aggregate of all the flow traffic for a session. Per-session accounting can be enabled in a user profile or in a service profile or service policy map.

Information About Configuring Policies for Session Maintenance

Before you configure the ISG session maintenance timers, you should understand the following concepts:

•Session Maintenance Timers

•Benefits of Session Maintenance Timers

•Monitoring Sessions

•Using ARP for Keepalive Messages

•Using ICMP for Keepalive Messages

Session Maintenance Timers

ISG provides two commands (each of which can be set independently) to maintain control over a session and its connection. The timeout absolute command controls how long a session can be connected before it is terminated. The timeout idle command controls how long a connection can be idle before it is terminated. Both commands detect both PPP and IP sessions and can be applied in a non-traffic-class-based service, on a per-session basis, or in a flow (traffic-class-based service). All subscriber traffic will reset the timers; however, non-network traffic such as PPP control packets will not reset the timers.

The scope of the session timers and connection timers is determined by the type of service within which the timer is specified. If specified in a service profile for which no traffic class is defined, the timer action will be to terminate the session or connection. If a traffic class specifier resides in the service profile, the timer action will be to deactivate the service.

Benefits of Session Maintenance Timers

The PPP idle timeout functionality has been replaced by the ISG idle timeout feature. The idle timer is a generic feature that can be set to detect idle traffic in both PPP and IP sessions.

You set the idle timer in a service profile that is installed on a session to control how long that service stays installed before it is removed from the session because no traffic is flowing through that service. If the service has traffic class parameters associated with it, that traffic class is terminated when this timer expires, or when the session itself is terminated.

The same is true for the session timer, except that this timer determines how long the session or service stays up, regardless of traffic flowing through it.

Monitoring Sessions

The IP subscriber session's data traffic in the upstream direction can be monitored for idleness using a keepalive feature configured for the subscriber. If a session is idle for a configured period of time, keepalive requests are sent to the subscriber. This action verifies that the connection is still active. The protocol to use for the keepalive request and response can be configured based on the IP subscriber session type. If it is a directly connected host (Layer #2 connection), ARP is used. For routed host (Layer 3 connected) subscribers, ICMP is used. If the access interface does not support ARP, the keepalive protocol defaults to ICMP.

Using ARP for Keepalive Messages

When a session is established and the keepalive feature is configured to use ARP, the keepalive feature saves the ARP entry as a valid original entry for verifying future ARP responses.

Note In cases where the access interface does not support ARP, the protocol for keepalives defaults to ICMP.

When ARP is configured, the ARP unicast request is sent to the subscriber. After a configured interval of time, the ARP response (if received) is verified. If the response is correct and matches the original entry that was saved when the subscriber was initially established, the keepalive feature continues monitoring the data plane for the configured interval of time. If the response is not correct, the keepalive feature resends the ARP request until a correct response is received or the configured maximum number of attempts is exceeded.

Using ICMP for Keepalive Messages

If ICMP is configured, the ICMP "hello" request is sent to the subscriber and checked for a response, until the configured maximum number of attempts is exceeded.

For IP subnet sessions, the peer (destination) IP address to be used for ICMP "hello" requests will be all the IP addresses within the subnet. This means "hello" requests will be sent sequentially (not simultaneously) to all the possible hosts within that subnet. If there is no response from any host in that subnet, the session will be disconnected.

Another option is to configure ICMP directed broadcast for keepalive requests. If the subscriber hosts recognize the IP subnet broadcast address, the ISG can send the ICMP "hello" request to the subnet broadcast address. The subscribers need not be on the same subnet as the ISG for this configuration to work. A directed broadcast keepalive request can work multiple hops away as long as these conditions are satisfied:

•The group of subscribers identified by the subnet must have the same subnet mask provisioned locally as the subnet provisioned on the subnet subscriber session on the ISG. Otherwise, the subscriber hosts will not recognize the subnet broadcast address.

•The router directly connected to the hosts must enable directed-broadcast forwarding, so that the IP subnet broadcast gets translated into a Layer 2 broadcast.

When these two conditions are satisfied, you can optimize the ICMP keepalive configuration to minimize the number of ICMP packets.

Note Because enabling directed broadcasts increases the risk of denial of service attacks, the use of subnet directed broadcasts is not turned on by default.

How to Configure Policies for Session Maintenance Timers

Configuring the session maintenance timers requires two separate tasks, one to set the idle timer and one to set the session timer. Either one or both of these tasks can be performed in order to set session maintenance control. The following tasks show how to set these timers in a service policy map and in a RADIUS AAA server profile:

•Configuring the Session Timer in a Service Policy Map

•Configuring the Session Timer on a AAA Server

•Configuring the Connection Timer in a Service Policy Map

•Configuring the Connection Timer on a AAA Server

•Verifying the Session and Connection Timer Settings

•Troubleshooting the Session and Connection Timer Settings

•Configuring a Session Keepalive on the Router

•Configuring a Session Keepalive on a RADIUS Server

•Configuring the ISG to Interact with the RADIUS Server

Configuring the Session Timer in a Service Policy Map

Perform this task to set the session timer in a service policy map.

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map type service policy-map-name

4. [priority] class type traffic class-map-name

5. timeout absolute duration-in-seconds

6. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

policy-map type service policy-map-name

Example:

Router(config)# policy-map type service policy1

Enters policy map configuration mode so you can begin configuring the service policy.

Step 4 

[priority] class type traffic class-map-name

Example:

Router(config-control-policymap)# class type traffic class1

Associates a previously configured traffic class with the policy map.

Step 5 

timeout absolute duration-in-seconds

Example:

Router(config-control-policymap-class-control)# timeout absolute 30

Specifies the session lifetime, in a range from 0 to 4294967 seconds.

Step 6 

end

Example:

Router(conf-subscriber-profile)# end

(Optional) Returns to privileged EXEC mode.

What to Do Next

You may want to configure a method of activating the service policy map or service profile; for example, control policies can be used to activate services. For more information about methods of service activation, see the module "Configuring ISG Subscriber Services."

Configuring the Session Timer on a AAA Server

Perform this task to set the session timer on a AAA server profile.

SUMMARY STEPS

1. Add the RADIUS Session-Timeout attribute to a user or service profile.

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

Session-Timeout=duration-in-seconds

Sets the IETF RADIUS session timer (attribute 27) in a user or service profile, in a range from 0 to 4294967 seconds.

Configuring the Connection Timer in a Service Policy Map

Perform this task to set the connection timer in a service policy map.

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map type service policy-map-name

4. [priority] class type traffic class-map-name

5. timeout idle duration-in-seconds

6. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

policy-map type service policy-map-name

Example:

Router(config)# policy-map type service policy1

Enters policy map configuration mode so you can begin configuring the service policy.

Step 4 

[priority] class type traffic class-map-name

Example:

Router(config-control-policymap)# class type traffic class1

Associates a previously configured traffic class to the policy map.

Step 5 

timeout idle duration-in-seconds

Example:

Router(config-control-policymap-class-control)# timeout idle 3000

Specifies how long a connection can be idle before it is terminated, in a range from 1 to 4294967 seconds.

Step 6 

end

Example:

Router(conf-subscriber-profile)# end

(Optional) Returns to privileged EXEC mode.

What to Do Next

You may want to configure a method of activating the service policy map or service profile; for example, control policies can be used to activate services. For more information about methods of service activation, see the module "Configuring ISG Subscriber Services."

Configuring the Connection Timer on a AAA Server

Perform this task to set the connection timer on a AAA server profile.

SUMMARY STEPS

1. Add the RADIUS Idle-Timeout attribute to a user profile or service profile.

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

Idle-Timeout=duration-in-seconds

Sets IETF RADIUS (attribute 28) in a user or service profile, in a range from 1 to 4294967 seconds.

Verifying the Session and Connection Timer Settings

Perform this task to verify that the timers have been installed correctly.

SUMMARY STEPS

1. enable

2. show subscriber session all

3. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

show subscriber session all

Example:

Router# show subscriber session all

Displays current subscriber information, including reports about the timers that are enabled.

Step 3 

end

Example:

Router# end

Exits privileged EXEC mode.

Troubleshooting the Session and Connection Timer Settings

The following sections list the debug commands that can be used to troubleshoot the session maintenance timers and describe the tasks you perform to enable them:

•Prerequisites for Troubleshooting the Session Maintenance Timers

•Restrictions for Troubleshooting the Session Maintenance Timers

•Debug Commands Available for the Session Maintenance Timers

•Enabling the Session Maintenance Timer Debug Commands

Prerequisites for Troubleshooting the Session Maintenance Timers

Before performing the task in this section, it is recommended that you be familiar with the use of Cisco IOS debug commands described in the introductory chapters of the Cisco IOS Debug Command Reference. Also see the module "Troubleshooting ISG with Session Monitoring and Distributed Conditional Debugging."

Restrictions for Troubleshooting the Session Maintenance Timers

Caution Because debugging output is assigned high priority in the CPU process, it can render the system unusable. For this reason, use the Cisco IOS debug commands only to troubleshoot specific problems or during troubleshooting sessions with Cisco technical support staff. Moreover, it is best to use debug commands during periods of lower network traffic and fewer users, or on a debug chassis with a single active session. Debugging during these periods decreases the likelihood that increased debug command processing overhead will affect system use.

Debug Commands Available for the Session Maintenance Timers

Table 1 lists the debug commands that can be used to diagnose problems with the session maintenance timers.

Table 1 Debug Commands for Troubleshooting Session Maintenance Timers

Command
Purpose

debug subscriber feature error

Displays general Feature Manager errors.

debug subscriber feature event

Displays general Feature Manager events.

debug subscriber feature name idle-timer error

Displays idle timer errors.

debug subscriber feature name idle-timer event

Displays idle timer events.

debug subscriber feature name session-timer error

Displays session timer errors.

debug subscriber feature name session-timer event

Displays session timer events.


Enabling the Session Maintenance Timer Debug Commands

Perform this task to enable the session maintenance timer debug commands.

SUMMARY STEPS

1. enable

2. debug command

3. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables higher privilege levels, such as privileged EXEC mode.

•Enter your password if prompted.

Step 2 

debug command

Example:

Router# debug subscriber feature name session-timer error

Enter one or more of the debug commands listed in Table 1.

•Enter the specific no debug command when you are finished.

Step 3 

end

Example:

Router# end

Exits privileged EXEC mode.

Configuring a Session Keepalive on the Router

This task describes how to configure the keepalive feature on the router, using either ARP or ICMP.

Because the session keepalive feature is checking for the subscriber's health and presence, this feature is applied only to the session as a whole and not per-flow.

Restrictions

•If a service profile includes an ISG traffic class configuration, the keepalive feature will be ignored.

•If this feature is applied to a non-IP session, for example, a PPP over Ethernet (PPPoE) or PPP over ATM (PPPoA) session, this feature application will fail and the following applies:

–If the feature is applied at a session-start event, both the feature application and the session will fail.

–If this feature is pushed onto a session after the session-start event, the push will fail.

SUMMARY STEPS

1. enable

2. configure terminal

3. policy-map type service policy-map-name

4. keepalive [idle period1] [attempts max-retries] [interval period2] [protocol ICMP [broadcast] | ARP]

5. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

policy-map type service policy-map-name

Example:

Router(config)# policy-map type service policymap1

Enters service policy map configuration mode.

Note The keepalive feature can be configured only in this mode.

Step 4 

keepalive [idle period1] [attempts max-retries] [interval period2] [protocol ICMP [broadcast] | ARP]

Example:

Router(config-service-policymap)# keepalive idle 7 attempts 3 interval 1 protocol arp

Configures the maximum idle period, number of requests, interval between requests, and protocol for keepalive messages.

The ranges and defaults are:

•Idle period: range 5 to 2147483647 seconds; default is 10 seconds

•Attempts: range 3 to10; default is 5

•Interval: default is 1 to 60 seconds

•Protocol: for Layer 2 connections, the default is ARP; for routed connections, the default is ICMP

•Broadcast option: by default this option is disabled

Note If this command is applied to a non-IP session, the command will fail. If the command is applied to a non-IP session at the session-start event, the session will also fail.

Step 5 

exit

Example:

Router(config-service-policymap)# exit

Returns to global configuration mode.

Examples

The following example configures the keepalive feature on a router using ARP: 

policy-map type service accting_service

 class type traffic ALL

 !

  keepalive interval 3 protocol ARP

!

Configuring a Session Keepalive on a RADIUS Server

This task describes how to configure the session keepalive parameters on a RADIUS server.

SUMMARY STEPS

1. Service-Name password = "cisco"

2. Cisco-Avpair = "subscriber:keepalive = [idle period1] [attempts Max-retries] [interval period2] [protocol ICMP [broadcast] | ARP}"

DETAILED STEPS

Step 1 Service-Name password = "cisco"

Step 2 Cisco-Avpair = "subscriber:keepalive = [idle period1] [attempts Max-retries] [interval period2] [protocol ICMP [broadcast] | ARP}"

Configures the allowable idle period, maximum number of attempts to connect, the interval between attempts, and the communication protocol to be used.

The ranges and defaults are as follows:

•Idle period: range is 5 to 2147483647 seconds; default is 10 seconds.

•Attempts: range is 3 to 10; default is 5.

•Interval: default is 1 to 60 seconds.

•Protocol: for Layer 2 connections, the default is ARP; for routed connections, the default is ICMP.

•Broadcast option: by default this option is disabled.

Note If a service profile includes an ISG traffic class configuration, the keepalive feature will be ignored.

Configuring the ISG to Interact with the RADIUS Server

The ISG device interacts with the RADIUS server to listen for the Packet of Disconnect (POD) message from the RADIUS server. On receipt, the POD and associated attributes are handed to the appropriate client to disconnect the session. Perform this task to configure the ISG to interact with the RADIUS server to listen for the POD message.

SUMMARY STEPS

1. enable

2. configure terminal

3. aaa new-model

4. aaa server radius-dynamic author

5. client ip-address

6. port port-number

7. server-key word

8. exit

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

aaa new-model

Example:

Router(config)# aaa new-model

Enables the authentication, authorization, and accounting (AAA) access control model.

Step 4 

aaa server radius dynamic-author

Example:

Router(config)# aaa server radius dynamic-author

Configures a device as a AAA server to facilitate interaction with an external policy server and enters dynamic authorization local server configuration mode.

Step 5 

client ip-address

Example:

Router(config-locsvr-da-radius)# client 10.10.10.11

Specifies a RADIUS client from which a device will accept Change of Authorization (CoA) and disconnect requests.

•The example specifies 10.10.10.11 as the IP address of the RADIUS client.

Step 6 

port port-number

Example:

Router(config-locsvr-da-radius)# port 1650

Specifies the port on which a device listens for RADIUS requests from configured RADIUS clients.

•The example specifies port 1650.

Step 7 

server-key word

Example:

Router(config-locsvr-da-radius)# server-key abc

Configures the RADIUS key to be shared between a device and RADIUS clients.

•The example specifies "abc" as the encryption key shared with the RADIUS client.

Step 8 

exit

Example:

Router(config-locsvr-da-radius)# exit

Returns to global configuration mode.

Configuration Examples for Session Maintenance Timers

This section contains the following examples:

•Session Timer Configuration in a Service Policy Map: Example

•Connection Idle Timer Configuration in a Service Policy Map: Example

•Session Timer Show Command Output: Example

•Connection Idle Timer Show Command Output: Example

•Session Timer Debug Output: Example

•Connection Idle Timer Debug Output: Example

Session Timer Configuration in a Service Policy Map: Example

The following example limits session time in a service policy map to 4800 seconds (80 minutes): 

class-map type traffic match-any traffic-class

 match access-group input 101

 match access-group output 102

policy-map type service video-service

 class type traffic traffic-class

  police input 20000 30000 60000

  police output 21000 31500 63000

  timeout absolute 4800

 class type traffic default output

 drop

Connection Idle Timer Configuration in a Service Policy Map: Example

The following example limits idle connection time in a service policy map to 30 seconds: 

class-map type traffic match-any traffic-class

 match access-group input 101

 match access-group output 102

policy-map type service video-service

 class type traffic traffic-class

  police input 20000 30000 60000

  police output 21000 31500 63000

  timeout idle 30

 class type traffic default output

 drop

Session Timer Show Command Output: Example

The following example shows the settings for the session timer displayed by the show subscriber session all privileged EXEC command. 

Current Subscriber Information: Total sessions 1

--------------------------------------------------

Unique Session ID: 3

Identifier: user01

SIP subscriber access type(s): PPPoE/PPP

Current SIP options: Req Fwding/Req Fwded

Session Up-time: 00:02:50, Last Changed: 00:02:53

AAA unique ID: 4

Interface: Virtual-Access2.1


Policy information:

  Context 02DE7380: Handle 1B000009

  Authentication status: authen

  User profile, excluding services:

    Framed-Protocol      1 [PPP]

    username             "user01"

    Framed-Protocol      1 [PPP]

    username             "user01"

  Prepaid context: not present



Non-datapath features:

 Feature: Session Timeout

  Timeout value is 180000 seconds

  Time remaining is 2d01h

Configuration sources associated with this session:

Interface: Virtual-Template1, Active Time = 00:02:52

Connection Idle Timer Show Command Output: Example

The following example shows the settings for the idle timer as displayed by the show subscriber session all privileged EXEC command. 

Current Subscriber Information: Total sessions 1

--------------------------------------------------

Unique Session ID: 4

Identifier: user01

SIP subscriber access type(s): PPPoE/PPP

Current SIP options: Req Fwding/Req Fwded

Session Up-time: 00:01:44, Last Changed: 00:01:46

AAA unique ID: 5

Interface: Virtual-Access2.1


Policy information:

  Context 02DE7380: Handle AD00000C

  Authentication status: authen

  User profile, excluding services:

    Framed-Protocol      1 [PPP]

    username             "user01"

    Framed-Protocol      1 [PPP]

    username             "user01"

  Prepaid context: not present



Session outbound features:

 Feature: PPP Idle Timeout

  Timeout value is 2000		

  Idle time is 00:01:44		

Configuration sources associated with this session:

Interface: Virtual-Template1, Active Time = 00:01:47

Session Timer Debug Output: Example

The following example shows output when the session timer debug commands (debug subscriber feature error, debug subscriber feature event, debug subscriber feature name session-timer error, and debug subscriber feature name session-timer event) are enabled. 

*Jan 12 18:38:51.947: SSF[Vi2.1/Abs Timeout]: Vaccess interface config

update; not per-user, ignore

*Jan 12 18:38:53.195: SSF[Vt1/uid:3]: Install interface configured

features

*Jan 12 18:38:53.195: SSF[Vt1/uid:3]: Associate segment element handle

0x95000002 for session 1191182344, 1 entries

*Jan 12 18:38:53.195: SSF[Vt1/uid:3/Abs Timeout]: Group feature install

*Jan 12 18:38:53.195: SSF[uid:3/Abs Timeout]: Adding feature to none segment(s)

Connection Idle Timer Debug Output: Example

The following example shows output when the idle timer debug commands (debug subscriber feature error, debug subscriber feature event, debug subscriber feature name idle-timer error, and debug subscriber feature name idle-timer event) are enabled. 

*Jan 12 18:43:15.167: SSF[Vt1/uid:4]: Install interface configured

features

*Jan 12 18:43:15.167: SSF[Vt1/uid:4]: Associate segment element handle

0xF4000003 for session 67108875, 1 entries

*Jan 12 18:43:15.167: SSF[Vt1/uid:4/Idle Timeout]: Group feature install

*Jan 12 18:43:15.167: SSF[uid:4/Idle Timeout]: Adding feature to outbound

segment(s)	

*Jan 12 18:43:15.167: Idle Timeout[uid:4]: Idle timer start, duration 2000

seconds, direction: outbound

*Jan 12 18:43:16.327: SSM FH: [SSS:PPPoE:8198:Idle Timeout:4097] created

02DFFDD8

*Jan 12 18:43:16.327: SSM FH: [SSS:PPPoE:8198:Idle Timeout:4097] added

02DFFDD8 [outbound]

*Jan 12 18:43:16.327: SSM FH: [SSS:PPPoE:8198:Idle Timeout:4097]

installed: ok

*Jan 12 18:43:16.327: SSM FH: [SSS:PPPoE:8198:Idle Timeout:4097]

installed: ok

*Jan 12 18:43:19.147: SSM FH: [SSS:PPPoE:8198:Idle Timeout:4097] bound

Additional References

The following sections provide references related to session maintenance timers.

Related Documents

Related Topic
Document Title

ISG commands

Cisco IOS Intelligent Services Gateway Command Reference

ppp timeout idle and timeout absolute PPP timer commands

Cisco IOS Dial Technologies Command Reference


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Feature Information for Configuring ISG Policies for Session Maintenance

Table 2 lists the features in this module and provides links to specific configuration information. For information on a feature in this technology that is not documented here, see the Cisco IOS XE Intelligent Services Gateway Features Roadmap.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 2 list only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.

Table 2 Feature Information for ISG Session Maintenance 

Feature Name
Releases
Feature Configuration Information

ISG: Session: Lifecycle: Idle Timeout

Cisco IOS XE Release 2.2

The ISG idle timeout controls how long a connection can be idle before it is terminated.

The following sections provide information about this feature:

•Session Maintenance Timers

•How to Configure Policies for Session Maintenance Timers

ISG: Session Protection & Resiliency: Keepalive-ARP, ICMP

Cisco IOS XE Release 2.2

IP subscriber session keepalive support is configured for monitoring session data traffic in the upstream direction for idleness. Address Resolution Protocol (ARP) is used for Layer 2 connected subscribers. For routed hosts (Layer 3 connected) subscribers, the protocol defaults to Internet Control Message Protocol (ICMP). ICMP is also used in configurations where the access interface does not support ARP.

The following sections provide information about this feature:

•Configuring a Session Keepalive on the Router

•Configuring a Session Keepalive on a RADIUS Server

The following command was introduced: keepalive [idle period1] [attempts max-retries] [interval period2] [protocol ICMP [broadcast] | ARP].

ISG: Session: Lifecycle: Packet of Disconnect (POD)

Cisco IOS XE Release 2.2

An ISG can be configured to interact with external policy servers. A policy server can use RADIUS Packet of Disconnect (POD) to manage the life cycle of any ISG session. The primary role of the POD message is to terminate an ISG session.

The following sections provide information about this feature:

•Session Maintenance Timers

•How to Configure Policies for Session Maintenance Timers


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