IPsec Data Plane Configuration Guide, Cisco IOS XE Release 3S
IPsec Security Association Idle Timers
Downloads: This chapterpdf (PDF - 143.0KB) | Feedback

IPsec Security Association Idle Timers

Table Of Contents

IPsec Security Association Idle Timers

Finding Feature Information

Contents

Prerequisites for IPsec Security Association Idle Timers

Information About IPsec Security Association Idle Timers

Lifetimes for IPsec Security Associations

IPsec Security Association Idle Timers

How to Configure IPsec Security Association Idle Timers

Configuring the IPsec SA Idle Timer Globally

Configuring the IPsec SA Idle Timer per Crypto Map

Configuration Examples for IPsec Security Association Idle Timers

Configuring the IPsec SA Idle Timer Globally: Example

Configuring the IPsec SA Idle Timer per Crypto Map: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for IPsec Security Association Idle Timers


IPsec Security Association Idle Timers


First Published: March 17, 2003
Last Updated: July 31, 2009

When a router running the Cisco IOS XE software creates an IPsec security association (SA) for a peer, resources must be allocated to maintain the SA. The SA requires both memory and several managed timers. For idle peers, these resources are wasted. If enough resources are wasted by idle peers, the router could be prevented from creating new SAs with other peers. The IPsec Security Association Idle Timers feature introduces a configurable idle timer to monitor SAs for activity, allowing SAs for idle peers to be deleted. Benefits of this feature include:

Increased availability of resources

Improved scalability of Cisco IOS XE IPsec deployments. Because this feature prevents the wasting of resources by idle peers, more resources will be available to create new SAs as required.

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 IPsec Security Association Idle Timers" 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://tools.cisco.com/ITDIT/CFN/jsp/index.jsp. An account on Cisco.com is not required.

Contents

Prerequisites for IPsec Security Association Idle Timers

Information About IPsec Security Association Idle Timers

How to Configure IPsec Security Association Idle Timers

Configuration Examples for IPsec Security Association Idle Timers

Additional References

Feature Information for IPsec Security Association Idle Timers

Prerequisites for IPsec Security Association Idle Timers

You must configure Internet Key Exchange (IKE) as described in the "Configuring Internet Key Exchange Security Protocol" chapter of the Cisco IOS XE Security Configuration Guide.

Information About IPsec Security Association Idle Timers

To configure the IPsec Security Association Idle Timers feature, you must understand the following concepts:

Lifetimes for IPsec Security Associations

IPsec Security Association Idle Timers

Lifetimes for IPsec Security Associations

The Cisco IOS XE software currently allows the configuration of lifetimes for IPsec SAs. Lifetimes can be configured globally or per crypto map. There are two lifetimes: a "timed" lifetime and a "traffic-volume" lifetime. A security association expires after the first of these lifetimes is reached.

IPsec Security Association Idle Timers

The IPsec SA idle timers are different from the global lifetimes for IPsec SAs. The expiration of the global lifetime is independent of peer activity. The IPsec SA idle timer allows SAs associated with inactive peers to be deleted before the global lifetime has expired.

If the IPsec SA idle timers are not configured, only the global lifetimes for IPsec SAs are applied. SAs are maintained until the global timers expire, regardless of peer activity.


Note If the last IPsec SA to a given peer is deleted due to idle timer expiration, the Internet Key Exchange (IKE) SA to that peer will also be deleted.


How to Configure IPsec Security Association Idle Timers

This section contains the following procedures:

Configuring the IPsec SA Idle Timer Globally

Configuring the IPsec SA Idle Timer per Crypto Map

Configuring the IPsec SA Idle Timer Globally

This task configures the IPsec SA idle timer globally. The idle timer configuration will be applied to all SAs.

SUMMARY STEPS

1. enable

2. configure terminal

3. crypto ipsec security-association idle-time seconds

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 

crypto ipsec security-association idle-time seconds

Example:

Router(config)# crypto ipsec security-association idle-time 600

Configures the IPsec SA idle timer.

The seconds argument specifies the time, in seconds, that the idle timer will allow an inactive peer to maintain an SA. Valid values for the seconds argument range from 60 to 86400.

Configuring the IPsec SA Idle Timer per Crypto Map

This task configures the IPsec SA idle timer for a specified crypto map. The idle timer configuration will be applied to all SAs under the specified crypto map.

SUMMARY STEPS

1. enable

2. configure terminal

3. crypto map map-name seq-number ipsec-isakmp

4. set security-association idle-time seconds

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 

crypto map map-name seq-number ipsec-isakmp

Example:

Router(config)# crypto map test 1 ipsec-isakmp

Creates or modifies a crypto map entry and enters crypto map configuration mode.

Step 4 

set security-association idle-time seconds

Example:

Router(config-crypto-map)# set security-association idle-time 600

Specifies the maximum amount of time for which the current peer can be idle before the default peer is used.

The seconds argument is the number of seconds for which the current peer can be idle before the default peer is used. Valid values are 60 to 86400.

Configuration Examples for IPsec Security Association Idle Timers

This section provides the following configuration examples:

Configuring the IPsec SA Idle Timer Globally: Example

Configuring the IPsec SA Idle Timer per Crypto Map: Example

Configuring the IPsec SA Idle Timer Globally: Example

The following example globally configures the IPsec SA idle timer to drop SAs for inactive peers after 600 seconds:

crypto ipsec security-association idle-time 600

Configuring the IPsec SA Idle Timer per Crypto Map: Example

The following example configures the IPsec SA idle timer for the crypto map named test to drop SAs for inactive peers after 600 seconds:

crypto map test 1 ipsec-isakmp
 set security-association idle-time 600

Additional References

The following sections provide references related to the IPsec Security Association Idle Timers feature.

Related Documents

Related Topic
Document Title

Additional information about configuring IKE

Internet Key Exchange for IPsec VPNs

Additional information about configuring global lifetimes for IPsec SAs

Configuring Security for VPNs with IPsec

IPsec Preferred Peer

Additional Security commands

Cisco IOS Security Command Reference


Standards

Standards
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.


MIBs

MIB
MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS XE software releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

-—


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for IPsec Security Association Idle Timers

Table 1 lists the release history for this feature.

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://tools.cisco.com/ITDIT/CFN/jsp/index.jsp. An account on Cisco.com is not required.


Note Table 1 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.


Table 1 Feature Information for IPsec Security Association Idle Timers

Feature Name
Releases
Feature Information

IPsec Security Association Idle Timers

Cisco IOS XE Release 2.1

When a router running the Cisco IOS XE software creates an IPsec security association (SA) for a peer, resources must be allocated to maintain the SA. The SA requires both memory and several managed timers. For idle peers, these resources are wasted. If enough resources are wasted by idle peers, the router could be prevented from creating new SAs with other peers. The IPsec Security Association Idle Timers feature introduces a configurable idle timer to monitor SAs for activity, allowing SAs for idle peers to be deleted.

The following command was introduced or modified: crypto ipsec security-association idle-time.

 

Cisco IOS XE Release 2.1

The set security-association idle-time command was added, allowing for the configuration of an IPsec idle timer for a specified crypto map.

The following command was introduced or modified: set security-association idle-time.