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Configuring Topology Acquisition

Overview

After you have successfully established a connection between the NorthStar Controller and the network, you can configure topology acquisition using Border Gateway Protocol Link State (BGP-LS) or an IGP (OSPF or IS-IS). For BGP-LS topology acquisition, you must configure both the NorthStar Controller and the PCC routers.

We recommend that you use BGP-LS instead of IGP adjacency because:

  • The OSPF and IS-IS databases have lifetime timers. If the OSPF or IS-IS neighbor goes down, the corresponding database is not immediately removed, making it impossible for the NorthStar Controller to determine whether the topology is valid.

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

  • Typically, the NorthStar Controller is located in a network operations center (NOC) data center, multihops away from the backbone and MPLS TE routers. This is easily accommodated by BGP-LS, but more difficult for IGP protocols because they would have to employ a tunneling mechanism such as GRE to establish adjacency.

Note:

If BGP-LS is used, the Junos VM is configured to automatically accept any I-BGP session. However, you must verify that the Junos VM is correctly configured and that it has IP reachability to the peering router.

Before You Begin

Before you begin, complete the following tasks:

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

  • Configure the Network Topology Acquisition Daemon (NTAD). The NTAD forwards topology information from the network to the NorthStar application, and it must be running on the Junos VM.

    Use the following command to enable the NTAD:

    Use the following command to verify that the NTAD is running; if the topology-export statement is missing, the match produces no results:

  • Configure BGP Monitoring Protocol (BMP) if you have decided to use BMP as an alternative to NTAD. BMP must be enabled on both the NorthStar and Junos VM sides.

    1. Use a text editing tool such as vi to modify the /opt/northstar/data/northstar.cfg file, changing topology_src_protocol from 1 (which is NTAD) to 2 (which is BMP):

    2. Restart toposerver so the change takes effect:

    3. On the Junos VM, disable NTAD by deleting the protocols topology-export statement.

    4. On the Junos VM, under “firewall”, configure the firewall filter to permit BMP TCP segments from NorthStar toward the Junos VM.

      Note:

      Be sure to insert “term bmp” before “term default-discard”.

    5. On the Junos VM, under “routing options”, enable BMP:

Configuring Topology Acquisition Using BGP-LS

Configure BGP-LS Topology Acquisition on the NorthStar Controller

To configure BGP-LS topology acquisition on the NorthStar Controller, perform the following configuration steps from the NorthStar Junos VM:

  1. Initiate an SSH or a telnet session to the Junos VM 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 Junos VM external IP address that is used to accept incoming connections to the Junos VM 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 NorthStar Controller.
    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 NorthStar Junos VM and the peer on the other end.

Configure the Peering Router to Support Topology Acquisition

To enable the NorthStar Controller to discover the network, you must add the following configuration on each router that peers with the NorthStar Controller. The NorthStar Junos VM must peer with at least one router from each area (autonomous system).

To enable 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 NorthStar Controller as the local address (typically the loopback address) and the Junos VM external IP address as the neighbor.

Configuring Topology Acquisition Using OSPF

Configure OSPF on the NorthStar Controller

To configure OSPF on the NorthStar Controller:

  1. Configure the policy.
  2. Populate the traffic engineering database.
  3. Configure OSPF.

Configure OSPF over GRE on the NorthStar Controller

Once you have configured OSPF on the NorthStar Controller, you can take the following additional steps to configure OSPF over GRE:

  1. Initiate an SSH or telnet session using the NorthStar Junos VM external IP address.
  2. Configure the tunnel.
  3. Enable OSPF traffic engineering on the Junos VM and add the GRE interface to the OSPF configuration.

Configuring Topology Acquisition Using IS-IS

Configure IS-IS on the NorthStar Controller

To configure IS-IS topology acquisition and enable IS-IS routing, perform the following steps on the NorthStar Junos VM:

  1. Configure interfaces for IS-IS routing. For example:
  2. Configure the policy.
  3. Populate the traffic engineering database.
  4. Configure IS-IS.

Configure IS-IS over GRE on the NorthStar Controller

Once you have configured IS-IS on the NorthStar Controller, you can take the following additional steps to configure IS-IS over GRE:

  1. Initiate an SSH or telnet session using the IP address for the NorthStar Junos VM external IP address.
  2. Configure the tunnel.
  3. Add the GRE interface to the IS-IS configuration.

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