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The IPv6 over IPv4 GRE Tunnel Protection feature allows both IPv6 unicast and multicast traffic to pass through a protected generic routing encapsulation (GRE) tunnel.
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 at the end of this module.
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.
The IPv6 over IPv4 GRE Tunnel Protection feature supports IPv6 over IPv4 point-to-point GRE tunnel protection and not IPv6 over IPv4 mGRE tunnel protection.
Generic routing encapsulation (GRE) tunnels sometimes are combined with IPSec, because IPSec does not support IPv6 multicast packets. This function prevents dynamic routing protocols from running successfully over an IPSec VPN network. Because GRE tunnels do support IPv6 multicast , a dynamic routing protocol can be run over a GRE tunnel. Once a dynamic routing protocol is configured over a GRE tunnel, you can encrypt the GRE IPv6 multicast packets using IPSec.
IPSec can encrypt GRE packets using a crypto map or tunnel protection. Both methods specify that IPSec encryption is performed after GRE encapsulation is configured. When a crypto map is used, encryption is applied to the outbound physical interfaces for the GRE tunnel packets. When tunnel protection is used, encryption is configured on the GRE tunnel interface.
The following figure shows encrypted packets that enter a router through a GRE tunnel interface using a crypto map on the physical interface. Once the packets are decrypted and decapsulated, they continue to their IP destination as clear text.
Figure 1 | Using a Crypto Map to Configure IPv6 over IPv4 GRE Tunnel Encryption |
The following figure shows encryption using tunnel protection command on the GRE tunnel interface. The encrypted packets enter the router through the tunnel interface and are decrypted and decapsulated before they continue to their destination as clear text.
Figure 2 | Using Tunnel Protection to Configure IPv6 over IPv4 GRE Tunnel Encryption |
There are two key differences in using the crypto map and tunnel protection methods:
Router> enable Router# configure terminal Router(config)# ipv6 multicast-routing Router(config)# ipv6 unicast-routing Router(config)# interface tunnel 10 Router(config-if)# ipv6 address my-prefix 0:0:0:7272::72/64 Router(config-if)# tunnel mode gre ip Router(config-if)# tunnel source ethernet0 Router(config-if)# tunnel destination 172.16.0.12 Router(config-if)# exit Router(config)# crypto isakmp policy 15 Router(config-isakmp-policy)# authentication pre-share Router(config-isakmp-policy)# hash md5 Router(config-isakmp-policy)# group 2 Router(config-isakmp-policy)# encryption 3des Router(config-isakmp-policy)# exit Router(config)# crypto isakmp key cisco-10 address 172.16.0.12 255.240.0.0 Router(config)# crypto ipsec transform-set myset0 ah-sha-hmac esp-3des Router(config)# access-list 110 permit gre host 192.168.0.16 host 172.16.0.12 Router(config)# crypto map mymap 10 ipsec-isakmp Router(config-crypto-map)# set peer 10.0.0.1 Router(config-crypto-map)# set transform-set myset0 Router(config-crypto-map)# match address 102 Router(config-crypto-map)# exit Router(config)# interface ethernet1 Router(config-if)# crypto map mymap Router(config-if)# end
Router> enable Router# configure terminal Router(config)# ipv6 multicast-routing Router(config)# ipv6 unicast-routing Router(config)# crypto isakmp policy 15 Router(config-isakmp-policy)# authentication pre-share Router(config-isakmp-policy)# hash md5 Router(config-isakmp-policy)# group 2 Router(config-isakmp-policy)# encryption 3des Router(config-isakmp-policy)# exit Router(config)# crypto isakmp key cisco-10 address 172.16.0.12 255.240.0.0 Router(config)# crypto ipsec transform-set myset0 ah-sha-hmac esp-3des Router(config)# crypto ipsec profile ipsecprof Router(ipsec-profile)# set transform-set myset0 Router(ipsec-profile)# exit Router(config)# interface tunnel 1 Router(config-if)# ipv6 address 3ffe:b00:c18:1::3/127 Router(config-if)# tunnel mode gre ip Router(config-if)# tunnel source 10.0.0.1 Router(config-if)# tunnel destination 172.16.0.12 Router(config-if)# tunnel protection ipsec profile ipsecprof Router(config-if)# end
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Cisco IOS commands |
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Security commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples |
Description |
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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.
Table 1 | Feature Information for IPv6 over IPv4 GRE Tunnel Protection |
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