VPN Availability Configuration Guide, Cisco IOS XE Release 3S
Reverse Route Injection
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Reverse Route Injection

Table Of Contents

Reverse Route Injection

Finding Feature Information

Contents

Prerequisites for Reverse Route Injection

Restrictions for Reverse Route Injection

Information About Reverse Route Injection

Reverse Route Injection

How to Configure Reverse Route Injection

Configuring RRI Under a Static Crypto Map

Configuring RRI Under a Dynamic Map Template

Configuration Examples for Reverse Route Injection

Configuring RRI When Crypto ACLs Exist: Example

Configuring RRI When Two Routes Are Created, One for the Remote Endpoint and One for Route Recursion: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Reverse Route Injection


Reverse Route Injection


First Published: May 5, 2008
Last Updated: April 5, 2011

Reverse route injection (RRI) is the ability for static routes to be automatically inserted into the routing process for those networks and hosts protected by a remote tunnel endpoint. These protected hosts and networks are known as remote proxy identities.

Each route is created on the basis of the remote proxy network and mask, with the next hop to this network being the remote tunnel endpoint. By using the remote Virtual Private Network (VPN) router as the next hop, the traffic is forced through the crypto process to be encrypted.

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 Reverse Route Injection" 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 Reverse Route Injection

Restrictions for Reverse Route Injection

Information About Reverse Route Injection

How to Configure Reverse Route Injection

Configuration Examples for Reverse Route Injection

Additional References

Feature Information for Reverse Route Injection, page 26

Prerequisites for Reverse Route Injection

IP routing should be enabled and static routes should be redistributed if dynamic routing protocols are to be used to propagate RRI-generated static routes.

Restrictions for Reverse Route Injection

For static crypto maps, routes are always present if RRI is configured on an applied crypto map. The default behavior—of routes always being present for a static map—will not apply unless the static keyword is added to the reverse-route command.

Information About Reverse Route Injection

Reverse Route Injection

Reverse Route Injection

RRI is the ability for static routes to be automatically inserted into the routing process for those networks and hosts that are protected by a remote tunnel endpoint. These protected hosts and networks are known as remote proxy identities.

Each route is created on the basis of the remote proxy network and mask, with the next hop to this network being the remote tunnel endpoint. By using the remote VPN router as the next hop, the traffic is forced through the crypto process to be encrypted.

After the static route is created on the VPN router, this information is propagated to upstream devices, allowing them to determine the appropriate VPN router to which to send returning traffic in order to maintain IPsec state flows. Being able to determine the appropriate VPN router is particularly useful if multiple VPN routers are used at a site to provide load balancing or failover or if the remote VPN devices are not accessible via a default route. Routes are created in either the global routing table or the appropriate virtual route forwarding (VRF) table.

RRI is applied on a per-crypto map basis, whether this is via a static crypto map or a dynamic crypto map template. The default behavior for the two map types is as follows:

In the case of a dynamic crypto map, routes are created upon the successful establishment of IPsec security associations (SAs) for those remote proxies. The next hop back to those remote proxies is via the remote VPN router whose address is learned and applied during the creation of the dynamic crypto map template. The routes are deleted after the SAs are deleted. Routes created on the basis of IPsec source proxies on static crypto maps is the default behavior on static maps and overrides the creation of routes on the basis of crypto ACLs (see the next bullet).

For static crypto maps, routes are created on the basis of the destination information defined in the crypto access list. The next hop is taken from the first set peer statement that is attached to the crypto map. If at any time, RRI, the peer, or the access list is removed from the crypto map, routes will be deleted. This behavior changes with the addition of the RRI enhancements, as explained in the sections below.

How to Configure Reverse Route Injection

Configuring RRI Under a Static Crypto Map

Configuring RRI Under a Dynamic Map Template

Configuring RRI Under a Static Crypto Map

SUMMARY STEPS

1. enable

2. configure terminal

3. crypto map {map-name} {seq-name} ipsec-isakmp

4. reverse-route [static | tag tag-id [static] | remote-peer [static] | remote-peer ip-address [static]]

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-name} ipsec-isakmp

Example:

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

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

Step 4 

reverse-route [static | tag tag-id [static] | remote-peer [static] | remote-peer ip-address [static]]

Example:

Router (config-crypto-map)# reverse-route remote peer 10.1.1.1

Creates source proxy information for a crypto map entry.

Configuring RRI Under a Dynamic Map Template

SUMMARY STEPS

1. enable

2. configure terminal

3. crypto dynamic-map dynamic-map-name dynamic-seq-name

4. reverse-route [static | tag tag-id [static] | remote-peer [static] | remote-peer ip-address [static]]

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 dynamic-map dynamic-map-name dynamic-seq-name

Example:

Router (config)# crypto dynamic-map mymap 1

Creates a dynamic crypto map entry and enters the crypto map configuration command mode.

Step 4 

reverse-route [static | tag tag-id [static] | remote-peer [static] | remote-peer ip-address [static]]

Example:

Router (config-crypto-map)# reverse-route remote peer 10.1.1.1

Creates source proxy information for a crypto map entry.

Configuration Examples for Reverse Route Injection

Configuring RRI When Crypto ACLs Exist: Example

Configuring RRI When Two Routes Are Created, One for the Remote Endpoint and One for Route Recursion: Example

Configuring RRI When Crypto ACLs Exist: Example

The following example shows that all remote VPN gateways connect to the router via 192.168.0.3. RRI is added on the static crypto map, which creates routes on the basis of the source network and source netmask that are defined in the crypto access control list (ACL):

crypto map mymap 1 ipsec-isakmp
 set peer 10.1.1.1
 reverse-route
 set transform-set esp-3des-sha
 match address 102

Interface FastEthernet 0/0/1
 ip address 192.168.0.2 255.255.255.0
 standby name group1
 standby ip 192.168.0.3
 crypto map mymap redundancy group1

access-list 102 permit ip 192.168.1.0 0.0.0.255 10.0.0.0 0.0.255.255

Configuring RRI When Two Routes Are Created, One for the Remote Endpoint and One for Route Recursion: Example

In the following example, two routes are created, one for the remote endpoint and one for route recursion to the remote endpoint via the interface on which the crypto map is configured:

reverse-route remote-peer

Additional References

The following sections provide references related to Reverse Route Injection enhancements.

Related Documents

Related Topic
Document Title

Cisco IOS Security commands

Cisco IOS Security Command Reference

Other Cisco IOS commands

Cisco IOS Master Command List


Standards

Standards
Title

None


MIBs

MIBs
MIBs Link

None

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

RFCs
Title

None


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 Reverse Route Injection

Table 1 lists the features in this module and provides links to specific configuration information.

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 Reverse Route Injection 

Feature Name
Releases
Feature Information

Reverse Route Injection

Cisco IOS XE Release 2.1

Reverse route injection (RRI) is the ability for static routes to be automatically inserted into the routing process for those networks and hosts protected by a remote tunnel endpoint. These protected hosts and networks are known as remote proxy identities.

Each route is created on the basis of the remote proxy network and mask, with the next hop to this network being the remote tunnel endpoint. By using the remote Virtual Private Network (VPN) router as the next hop, the traffic is forced through the crypto process to be encrypted.

The following sections provide information about this feature:

"Reverse Route Injection" section

The following commands were introduced or modified by this feature: reverse-route.