MPLS TE Per VRF Basics – Part 2

While going from home to office and back to home sometimes on same roads lead an excessive time. Everyone want to reach before time so that need to opt any other alternate path which may be long from the regular one. The same fundamental works in networks also. OSPF,EIGRP and BGP are used to manipulate the change the traffic from one path to another. Like in OSPF cost is used to change the path, in EIGRP metric is used and in BGP many attributes like weight,local preference and as-path are used. The problem with all the protocols is that unequal cost load balancing is not possible except EIGRP supports this feature.
In regular topology of service providers, two links are used one for primary and another is for secondary. Many cases the latter path remains empty and unnecessary increasing the capex of the company. With addition to this, to achieve the SLA parameters for esteemed clients, SP need to reroute the traffic of some VPN on the secondary path. For this PBR is used but its very difficult to add the static routes at each and every router in the hop.
For all the problems MPLS TE is the best optimum solution for reroute the traffic on VPN basics. With this case study, all the VPNs will follow the normal path but the one will follow the secondary path which is not used by anyone.

The topology is hypothetical model of service provider cloud which servers the MPLS VPN services its customers. New Delhi 2 router is acting as RR and New Delhi1, Hyderabad and Mumbai 1 are acting as PE. All the routers are part of area 0. New Delhi1 ,Hyderabad and Mumbai1 routers are serving two vpns one is TEST and another is TEST1. By default from New Delhi 1 to Mumbai 1 the traffic is routed via directly connected link between the two. But for some specific requirement of vpn TEST, its traffic will follow the new path New Delhi1 → Hyderabad → Mumbai 2 → Mumbai 1.

Basic Topology

Figure 1

To achieve the objective MPLS TE is used with static routes and RSVP is used for reserving the bandwidth of 200 Kbps on per interfaces.

How to achieve the objective

Now SP want to change the traffic of VRF TEST via Delhi1 → Hyderabad → Mumbai 2 → Mumbai 1.. To acomplish the task TE tunnel is created. With TE a bgp next-hop attribute is used with in the vrf and a static route is imposed on the headend router for this loopback. By doing this all the VRF TEST routes will come with the new loopback instead of MP-iBGP loopback as next hop. The static route will forward the traffic within the tunnel where the destination will be the new loopback.
MPLS TE tunnels are unidirectional. So new loopback is created at Mumbai1.


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