- Overview of ISG
- Configuring ISG Control Policies
- Configuring ISG Access for PPP Sessions
- Configuring ISG Access for IP Subscriber Sessions
- Configuring ISG IPv6 Support
- Configuring MQC Support for IP Sessions
- Configuring ISG Port-Bundle Host Key
- Configuring ISG as a RADIUS Proxy
- ISG RADIUS Proxy Support for Mobile Users: Hotspot Roaming and Accounting Start Filtering
- Walk-By User Support for PWLANs in ISG
- Configuring RADIUS-Based Policing
- Configuring Ambiguous VLAN support for IP sessions over ISG
- Configuring ISG Policies for Automatic Subscriber Logon
- Configuring DHCP Option 60 and Option 82 with VPN-ID Support for Transparent Automatic Logon
- Enabling ISG to Interact with External Policy Servers
- Configuring ISG Subscriber Services
- Configuring ISG Network Forwarding Policies
- Configuring ISG Accounting
- Configuring ISG Support for Prepaid Billing
- Configuring ISG Policies for Session Maintenance
- Redirecting Subscriber Traffic Using ISG Layer 4 Redirect
- Configuring Layer 4 Redirect Logging
- Configuring ISG Policies for Regulating Network Access
- Configuring ISG Integration with SCE
- Service Gateway Interface
- ISG MIB
- ISG SSO and ISSU Support
- Troubleshooting ISG with Session Monitoring and Distributed Conditional Debugging
- Configuring ISG Troubleshooting Enhancements
- Finding Feature Information
- Prerequisites for ISG Policies for Session Maintenance
- Information About ISG Policies for Session Maintenance
- How to Configure ISG Policies for Session Maintenance
- 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
- Configuration Examples for ISG Policies for Session Maintenance
- Example: 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
- Additional References
- Feature Information for ISG Policies for Session Maintenance
Configuring ISG Policies for Session Maintenance
Intelligent Services Gateway (ISG) is a software feature set that provides a structured framework in which edge devices can deliver flexible and scalable services to subscribers. This module describes how to configure a session timer and connection timer through 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 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
- Prerequisites for ISG Policies for Session Maintenance
- Information About ISG Policies for Session Maintenance
- How to Configure ISG Policies for Session Maintenance
- Configuration Examples for ISG Policies for Session Maintenance
- Additional References
- Feature Information for ISG Policies for Session Maintenance
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for ISG 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.
Information About ISG Policies for Session Maintenance
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.
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.
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. |
HA Support for Session Maintenance Timers
The SSO and ISSU feature provides high availability (HA) support for ISG timers including the connection timer, session timer, and the session keepalive. The timers and keepalive are restarted on the new standby Route Processor (RP) after a stateful switchover (SSO) or In Service Software Upgrade (ISSU) event.
For information about configuring HA on the ISG router, see the High Availability Configuration Guide, Cisco IOS XE Release 3S.
How to Configure ISG Policies for Session Maintenance
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
1.
enable
2.
configure
terminal
3.
policy-map
type
service
policy-map-name
4. [priority] class type trafficclass-map-name
5.
timeout
absolute
duration-in-seconds
6.
end
DETAILED STEPS
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 configure the session timer in a service profile on a AAA server.
1.
Session-Timeout=duration-in-seconds
DETAILED STEPS
Command or Action | Purpose |
---|
Configuring the Connection Timer in a Service Policy Map
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 [both |
inbound]
6.
end
DETAILED STEPS
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 (idle timeout) in a AAA service profile.
1.
idle-timeout=
duration-in-seconds
2.
idle-timeout-direction=
direction
DETAILED STEPS
Example
simulator radius subscriber 999 vsa cisco generic 1 string "subscriber:idle-timeout- direction=inbound" attribute 44 string "00000008" attribute 28 numeric 100
Verifying the Session and Connection Timer Settings
Perform this task to verify that the timers have been installed correctly.
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.
|
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
|
Returns to privileged EXEC mode. |
Troubleshooting the Session and Connection Timer Settings
The following sections describe the debug commands that can be used to troubleshoot the session maintenance timers:
- Prerequisites for Troubleshooting the Session Maintenance Timers
- Restrictions for Troubleshooting the Session Maintenance Timers
- Debug Commands Available for the Session Maintenance Timers
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, we recommend that you 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
The table below lists the debug commands that can be used to diagnose problems with the 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. |
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.
Note |
1.
enable
2.
configure
terminal
3.
policy-map
type
service
policy-map-name
4.
keepalive
[idle
idle-seconds] [attempts
max-retries] [interval
retry-seconds] [protocol {ARP |
ICMP [broadcast]}]
5.
exit
DETAILED STEPS
Example
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.
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:
|
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.
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.
|
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.
|
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.
|
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.
|
Step 8 |
exit
Example: Router(config-locsvr-da-radius)# exit |
Returns to global configuration mode. |
Configuration Examples for ISG Policies for Session Maintenance
Example: Session Timer Configuration in a Service Policy Map
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 traffic-class police input 20000 30000 60000 police output 21000 31500 63000 timeout absolute 4800 class type traffic default drop
Example: Connection Idle Timer Configuration in a Service Policy Map
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 drop
Example: Session Timer Show Command Output
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
Example: Connection Idle Timer Show Command Output
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
Example: Session Timer Debug Output
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)
Example: Connection Idle Timer Debug Output
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
Related Documents
Related Topic |
Document Title |
---|---|
Cisco IOS commands |
|
ISG commands |
|
ppp timeout idle and timeout absolute PPP timer commands |
|
HA commands |
|
HA configuration |
High Availability Configuration Guide |
Technical Assistance
Description |
Link |
---|---|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for ISG Policies for Session Maintenance
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Name |
Releases |
Feature 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. |
ISG: Session Protection and 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 command was introduced: keepalive (ISG). |
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. |
Downstream Idle Timeout Support |
Cisco IOS XE Release 3.4.1S |
The connection timer (idle timeout) can be applied to subscriber traffic in a specific direction, through an ISG service policy map or a AAA service profile. The following command was modified: timeout idle. |
Session Timeout Ext to 360 Days |
Cisco IOS XE Release 3.5S |
Maximum value of the session timer was increased to 31,104,000 seconds. Maximum value of the connection timer was increased to 15,552,000 seconds. The following commands were modified: timeout absolute, timeout idle. |
ISG: Flow Control: SSO/ISSU |
Cisco IOS XE Release 3.5S |
HA support was added for the session maintenance timers and keepalive. |