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CHAPTER
27-1
Cisco 10000 Series Router Software Configuration Guide
OL-2226-23
27
IP Tunneling
This chapter describes IP tunneling features implemented on the Cisco 10000 series routers and includes
the following topics:
• GRE Tunnel IP Source and Destination VRF Membership, page 27-1
• Restrictions for GRE Tunnel IP Source and Destination VRF Membership, page 27-3
• How to Configure GRE Tunnel IP Source and Destination VRF Membership, page 27-3
• Configuration Examples, page 27-4
GRE Tunnel IP Source and Destination VRF Membership
The Generic Routing Encapsulation (GRE) Tunnel IP Source and Destination VRF Membership feature
enables both unicast and multicast traffic from subscribers to traverse a tunnel interface on the router
and terminate in a VRF. Instead of the termination point being in the global routing table, the tunnel’s
source and destination endpoints terminate within a non-global VRF.
The following software enhancements provide the functionality required to implement this feature:
• Tunnel VRF, page 27-1
• VRF-Aware VPDN Tunnels, page 27-2
For more information, see the GRE Tunnel IP Source and Destination VRF Membership,
Release
12.2(31)SB5 feature guide, located at the following URL:
http://www.cisco.com/en/US/products/ps6566/products_feature_guides_list.html
Tunnel VRF
The Tunnel VRF feature allows you to terminate GRE tunnels in a virtual private network (VPN) routing
and forwarding (VRF) instance. Using this feature, you can configure the source and destination of a
tunnel to belong to any VRF table.
A VRF table stores routing data for each VPN. The VRF table defines the VPN membership of a
customer site attached to the network access server (NAS). Each VRF table comprises an IP routing
table, a derived Cisco Express Forwarding (CEF) table, and guidelines and routing protocol parameters
that control the information that is included in the routing table.
Previously, GRE IP tunnels required the IP tunnel destination to be in the global routing table. Tunnel
VRF enables you to configure the tunnel source and destination to belong to any VRF. Like existing GRE
tunnels, the tunnel is disabled if no route to the tunnel destination is defined.