MPLS: Layer 3 VPNs Configuration Guide, Cisco IOS XE Release 3S
MPLS VPN 6VPE Support Over IP Tunnels
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MPLS VPN 6VPE Support Over IP Tunnels

MPLS VPN 6VPE Support Over IP Tunnels

This feature allows the use of IPv4 generic routing encapsulation (GRE) tunnels to provide IPv6 Virtual Private Network (VPN) over Multiprotocol Label Switching (MPLS) functionality to reach the Border Gateway Protocol (BGP) next hop.

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 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.

Information About MPLS VPN 6VPE Support Over IP Tunnels

MPLS Forwarding

When it receives IPv6 traffic from one customer site, the ingress provider edge (PE) device uses Multiprotocol Label Switching (MPLS) to tunnel IPv6 Virtual Private Network (VPN) packets over the backbone toward the egress PE device identified as the Border Gateway Protocol (BGP) next hop. The ingress PE device prepends the IPv6 packets with the outer and inner labels before putting the packet on the egress interface.

Under normal operation, a provider (P) device along the forwarding path does not look inside the frame beyond the first label. The provider (P) device either swaps the incoming label with an outgoing one or removes the incoming label if the next device is a PE device. Removing the incoming label is called penultimate hop popping. The remaining label (BGP label) is used to identify the egress PE interface toward the customer site. The label also hides the protocol version (IPv6) from the last P device, which it would otherwise need to forward an IPv6 packet.

A P device is ignorant of the IPv6 VPN routes. The IPv6 header remains hidden under one or more MPLS labels. When the P device receives an MPLS-encapsulated IPv6 packet that cannot be delivered, it has two options. If the P device is IPv6 aware, it exposes the IPv6 header, builds an Internet Control Message Protocol (ICMP) for IPv6 message, and sends the message, which is MPLS encapsulated, to the source of the original packet. If the P device is not IPv6 aware, it drops the packet.

6VPE over GRE Tunnels

In some Cisco software releases, the ingress provider edge (PE) device uses IPv4 generic routing encapsulation (GRE) tunnels combined with IPv6 over MPLS (6VPE) over Multiprotocol Label Switching (MPLS) to tunnel IPv6 Virtual Private Network (VPN) packets over the backbone toward the egress PE device identified as the Border Gateway Protocol (BGP) next hop.

Additional References

Related Documents

Related Topic

Document Title

Cisco IOS commands

Cisco Master Command List, All Releases

IPv6 addressing and connectivity

IPv6 Configuration Guide Library

IPv6 commands

Cisco IOS IPv6 Command Reference

Cisco IOS IPv6 features

IPv6 Feature Mapping

Standards and RFCs

Standard/RFC

Title

RFCs for IPv6

IPv6 RFCs

Technical Assistance

Description

Link

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http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

Feature Information for MPLS VPN 6VPE Support Over IP Tunnels

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 MPLS VPN 6VPE Support Over IP Tunnels

Feature Name

Releases

Feature Information

MPLS VPN 6VPE Support Over IP Tunnels

12.2(33)SRB1

12.2(33)SXI

Cisco IOS XE Release 3.1S

This feature allows the use of IPv4 GRE tunnels to provide IPv6 VPN over MPLS functionality to reach the BGP next hop.