Vyatta Network OS Documentation

Learn how to install, configure and operate the Vyatta NOS, which helps drive our virtual networking & physical platforms portfolio.

MPLS LDP-IGP synchronization

MPLS LDP-IGP synchronization provides a means to synchronize LDP and IGPs to minimize MPLS packet loss.

MPLS LDP-IGP synchronization also provides the following benefits:

  • Provides a means to disable LDP-IGP synchronization on interfaces that you do not want enabled
  • Allows you to globally enable LDP-IGP synchronization on each interface associated with an IGP Open Shortest Path First (OSPF)

MPLS LDP-IGP synchronization may be enabled on an interface. LDP determines convergence (receipt of all labels) for a link through one of two methods:

  • Receive Label silence mechanism
  • End Of Lib mechanism (RFC 5919)

The following figure provides an example of LDP-IGP synchronization.

Figure 1. Example with LDP-IGP synchronization

When the LDP peer is not reachable, the IGP establishes the adjacency to enable the LDP session to be established. When an IGP adjacency is established on a link but LDP-IGP Synchronization is not yet achieved or is lost, the IGP advertises the maximum metric (max-metric) on the link.

Configuration considerations

  • Affects IPv4 metrics only

Configuring MPLS LDP-IGP synchronization

Configuring MPLS LDP-IGP includes the following tasks:

∙ Configuring MPLS LDP-IGP synchronization with OSPF interfaces (required)

∙ Selectively disabling MPLS LDP-IGP synchronization from some OSPF interfaces (optional)

∙ Verifying MPLS LDP-IGP synchronization with OSPF (optional)