Phase 3: Post-process the discovery information

During the postprocessing phase of discovery, the information that is collected from the various probes is consolidated to create additional logical objects in the repository. The information is also used to create connected relationships between the objects.

The postprocessing basic functions include:

• Creating LdpAdjacency connections between peering LdpProtocolEndpoints.

• Creating RsvpSession connections between peering RsvpProtocolEndpoints.

• Creating PseudoWire connections between peering ForwarderEndpoints.

• Creating BGPSession connections between peering BGPProtocolEndpoints.

• Creating TE tunnels, TE LSPs, P2MP LSPs, subLSPs, LDP LSPs, and LSPHops based on entries in the LSP table manager.

• Creating Forwarders based on ForwarderEndpoints.

• Creating VPNs based on VRFs, RouteTargets, Forwarders, ForwarderEndpoints, and PseudoWires.

• Creating VLANs and associating them with the appropriate Ethernet-VLAN VPWS or VPLS instances.

• Mapping Forwarders, ForwarderEndpoints, and PseudoWires to the appropriate LSPs and layering the Forwarders, ForwarderEndpoints, and PseudoWires over the LSPs.

• Creating relationships between the MPLS, VPN, and BGP objects and the network objects that are imported from IP Availability Manager, such as the LayeredOver relationships that (1) link LSPHops to the device interfaces that are underlying the LSPHops and (2) link VRFs to the device interfaces that are underlying the VRFs.

• Removing (pruning) stale objects and relationships from the repository.

• Setting the DisplayNames for the discovered objects.

• Printing a discovery report to the MPLS Topology Server’s log file.

  Additional topology added to the MPLS Topology Server repository identifies the additional objects that are created by the MPLS Topology Server during the postprocessing phase of discovery.

Table 1. Additional topology added to the MPLS Topology Server repository

Class name	Description
1  The MPLS signaling and control plane is entirely separate from the VPN control plane.
MPLS objects
LSP	A TE tunnel, TE LSP, P2MP LSP, subLSP, or LDP LSP. For a TE LSP, subLSP, or LDP LSP, an LSP is a concatenation of LSPHops that represents the label-switched path that is taken by labeled packets across an MPLS network.
LSPHop	A unidirectional logical link between two devices in an MPLS network across which MPLS-labeled packets are sent. No label processing occurs over the logical link.
LdpAdjacency (in the MPLS signaling and control plane) 1	A logical connection that represents an LDP session between LDP peers that are responsible for exchanging the MPLS labels for an LDP LSP. The LDP peers reside on PE or P devices that are one hop apart.
RsvpSession	A logical connection that represents an RSVP session between RSVP-TE peers that are responsible for exchanging the MPLS labels for a TE LSP or subLSP. The RSVP-TE peers reside on PE or P devices that may be multiple hops apart.
L2VPN objects
Forwarder	A logical entity within a PE device that makes switching and forwarding decisions for L2VPNs.
PseudoWire	A bidirectional virtual connection that, in the MPLS environment, is carried over a pair of LSPs and is terminated by a pair of ForwarderEndpoints and bound to a pair of Forwarders.
VPN	A collection of Forwarder, ForwarderEndpoint, and PseudoWire instances (and, for BGP-signaled L2VPNs, VRF instances), configured on PE devices in the MPLS network, that are members of the same virtual private network.
VLAN	A virtual LAN that is associated with an Ethernet-VLAN VPWS or a VPLS.
L2VPN LDP-specific objects
LdpAdjacency (in the VPN control plane) 1	A logical connection that represents a targeted LDP session between LDP peers that are responsible for exchanging the VC IDs for an LDP-signaled L2VPN. The LDP peers reside on PE devices that may be multiple hops apart.
L3VPN objects
VPN	A collection of VRF instances, configured on PE devices in the MPLS network, that are members of the same unicast VPN.
MulticastVPN	A collection of VRF instances, configured on PE devices in the MPLS network, that are members of the same multicast VPN.
MulticastGroup	A collection of multicast senders and receivers in a multicast VPN that provides an IP multigroup address (in the range 224.0.0.0 to 239.255.255.255 inclusive) for sending information to multiple recipients.
BGP objects
BGPSession	A logical connection between two BGP protocol endpoints.

For any device that is placed on the Pending Elements list during the discovery, the MPLS Topology Server will attempt to discover that device during the next pending discovery. Pending discovery is described in Chapter 10, “Using Full or Pending Discovery.”