VRFtoTE Tunnel Routing

What if you have an MPLS VPN network with TE enabled between the PE routers, and you want to steer VPN traffic onto TE tunnels, but different TE tunnels for different VRFs? This is possible, but consider the point of scaling: Creating one pair of TE tunnels between two PE routers for every VRF is not very scalable. However, you might want to do this in rare cases for tactical reasons. Look at Figure 8-28, which shows an example of two VRFs on the two PE routers. You can steer the VRF cust-one traffic onto TE tunnel 1 and the VRF cust-two traffic onto TE tunnel 2. A reason for this might be that you want to minimize the total delay for the traffic of VRF cust-one and therefore take a route where the links have a smaller delay. Delay is not an issue for the VRF cust-two traffic.

Figure 8-28 VRF-to-TE Tunnel Routing

^ Loopback

10 200 25

10.200.254.2/32

^ Loopback

10 200 25

10.200.254.2/32

10.200.210.2 paris brussels

TE Tunnel 2

VRF cust-one

Loopback 0 Loopback 0 "

Loopback 0 Loopback 0 "

rome I sydney

TE Tunnel 2

TE Tunnel 1

To do this, you must specify a different BGP next hop for both VRFs on the egress PE. You also must specify a static route on the ingress PE for each of those BGP next-hop addresses and point them to the respective TE tunnels. Example 8-32 shows the needed configuration.

Example 8-32 VRF-to-TE Tunnel Routing hostname paris ip route 10.200.254.8 ip route 10.200.254.9

hostname sydney

255.255.255.255 Tunnell 255.255.255.255 Tunnel2

interface Loopback0 ip address 10.200.254.7 255.255.255.255

interface Loopbackl ip address 10.200.254.8 255.255.255.255

interface Loopback2 ip address 10.200.254.9 255.255.255.255

ip vrf cust-one rd 1:1

route-target export 1:1 route-target import 1:1 bgp next-hop Loopback1

ip vrf cust-two rd 1:2

route-target export 1:2 route-target import 1:2 bgp next-hop Loopback2

NOTE For this case, in older releases of Cisco IOS, LDP does have to be enabled on the TE tunnels, even though the TE tunnels are between the PE routers.

This chapter explained the basics of MPLS TE. For more advanced topics on MPLS TE, refer to www.ciscopress.com/1587051974. DiffServ-aware TE tunnels, auto tunnels, path protection, and interarea TE tunnels are explained there.

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