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Configuring MPLS on Your Network


For MPLS to run on the routers in your network, you must enable MPLS and the Resource Reservation Protocol (RSVP), configure an interior gateway protocol (IGP) and Border Gateway Protocol (BGP) to run over the relevant interfaces, and configure each interface with the following:

  • Basic IP information
  • MPLS support

In addition, you must configure a label-switched path (LSP) from the ingress router to the egress router. For more information on ingress and egress routers, see the JUNOS MPLS Applications Configuration Guide.

You can configure your MPLS network with either Intermediate System-to-Intermediate System (IS-IS) or Open Shortest Path First (OSPF) as the IGP. The example network in Figure 1 is configured with IS-IS. To configure interfaces with OSPF, see the JUNOS Routing Protocols Configuration Guide.

An IGP is required for the Constrained Shortest Path First (CSPF) LSP, which is the default with the JUNOS software. The example network in Figure 1 focuses on CSPF LSPs.

Figure 1 illustrates the example MPLS network topology used in this section and throughout this book. The example network uses IS-IS Level 2 and a policy to create traffic. However, IS-IS Level 1 or an OSPF area can be used and the policy omitted if the network has existing BGP traffic.

Figure 1: MPLS Network Topology

Image g015527.gif

The MPLS network in Figure 1 illustrates a router-only network with SONET interfaces that consist of the following components:

  • A full-mesh interior BGP (IBGP) topology, using AS 65432
  • MPLS and RSVP enabled on all routers
  • A send-statics policy on routers R1 and R6 that allow a new route to be advertised into the network
  • Two unidirectional LSPs between routers R1 and R6, which allow for bidirectional traffic

The network shown in Figure 1 is a BGP full-mesh network. Since route reflectors and confederations are not used to propagate BGP learned routes, each router must have a BGP session with every other router running BGP.

See Example Configurations for an MPLS Topology for complete configurations for all routers in this example MPLS network. The following sections outline the steps for configuring MPLS on a network based on the topology shown in Figure 1.

You can enable MPLS throughout the rest of the network by repeating Step 1, Configure IP Addresses on Router Interfaces through Step 5, Enable MPLS and RSVP as appropriate on other routers until all routers and interfaces are enabled for MPLS.

To configure the MPLS network, follow these steps:

  1. Configure IP Addresses on Router Interfaces
  2. Configure IS-IS as the IGP
  3. Configure OSPF as the IGP
  4. Set Up BGP on Routers in Your Network
  5. Enable MPLS and RSVP
  6. Establish an LSP in Your Network

Published: 2010-01-25

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