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Configuring Connectivity for BGP-LS Topology Acquisition

 

After you have successfully established a connection between the CSD-Topology and the network, you can configure topology acquisition using Border Gateway Protocol Link State (BGP-LS). For BGP-LS topology acquisition, you must configure both the CSD-Topology and the PCC routers.

Note

We recommend that you use BGP-LS instead of IGP adjacency for the following reasons:

  • The OSPF and IS-IS databases have a lifetime timer, and if the OSPF or IS-IS neighbor is down, the OSPF or IS-IS database is not removed immediately, and the CSD-Topology will not be able to determine whether the topology is valid or not.

  • Using BGP-LS minimizes the risk of making the JunosVM a transit router between AS areas if the GRE metric is not properly configured.

  • Typically, the CSD-Topology is located in a NOC Data Center and multihops away from the backbone routers and MPLS TE routers.

Note

If BGP-LS is used, JunosVM is configured to automatically accept any I-BGP session from, in this example, 0.0.0.0/0. However, you must verify that JunosVM is correctly configured and that it has IP reachability to the peering router.

Before you begin, complete the following tasks:

  • Verify IP connectivity between a switch (or router) and the x86 appliance on which CSD-Topology software is installed.

  • Make sure that PCEP is configured on each PE router in the network topology.

To configure BGP-LS topology acquisition, see:

Configuring BGP-LS Topology Acquisition on the CSD-Topology

To configure BGP-LS on the CSD-Topology for topology acquisition, perform the following configuration steps from the CSD-Topology JunosVM:

  1. Initiate an SSH or telnet session to the JunosVM external IP or management IP address.
  2. Specify the autonomous system (AS) number for the node (BGP peer).
  3. Specify the BGP group name and type for the node.
  4. Specify a description for the BGP group for the node.
  5. Specify the address of the local end of a BGP session.

    This is the IP address for the JunosVM external IP address which is used to accept incoming connections to the JunosVM peer and to establish connections to the remote peer.

  6. Enable the traffic engineering features for the BGP routing protocol.
  7. Specify the IP address for the neighbor router that connects with the CSD-Topology.
    Note

    You can specify the router loopback address if it is reachable by the BGP peer on the other end. But for loopback to be reachable, usually some IGP has to be enabled between the CSD-Topology JunosVM and the peer on the other end.

Configuring Topology Acquisition on the PCC Routers

To enable the CSD-Topology to discover the network, you must add the following configuration on each each router that peers with the CSD-Topology. The CSD-Topology JunosVM must peer with at least one router from each area (autonomous system).

To configure topology acquisition, initiate a telnet session to each PCC router and add the following configuration:

  1. Configure a policy.
    Note

    This configuration is appropriate for both OSPF and IS-IS.

  2. Import the routes into the traffic-engineering database.
  3. Configure a BGP group by specifying the IP address of the router that peers with the CSD-Topology as the local address (typically the loopback address) and the JunosVM external IP address as the neighbor.

See also