Mpls Ldp-Igp Synchronization Compatibility With Igp Nonstop Forwarding; Label Distribution Protocol Igp Auto-Configuration; Mpls Te Forwarding Adjacency; Mpls Te Interarea Tunnels - Cisco ASR 9000 Series Routing Configuration Manual

Label Distribution Protocol IGP Auto-configuration

• The LDP session on the protected interface fails to recover before the LDP graceful restart recovery

MPLS LDP-IGP Synchronization Compatibility with IGP Nonstop Forwarding

IS-IS nonstop forwarding (NSF) protects traffic during IS-IS process restarts and route processor (RP) failovers.
LDP IS-IS synchronization is supported with IS-IS NSF only if LDP graceful restart is also enabled over the
interface. If IS-IS NSF is not enabled, the LDP synchronization state is not retained across restarts and failovers.
Label Distribution Protocol IGP Auto-configuration
Label Distribution Protocol (LDP) Interior Gateway Protocol (IGP) auto-configuration simplifies the procedure
to enable LDP on a set of interfaces used by an IGP instance. LDP IGP auto-configuration can be used on a
large number interfaces (for example, when LDP is used for transport in the core) and on multiple IGP instances
simultaneously.
This feature supports the IPv4 address family for the default VPN routing and forwarding (VRF) instance.
LDP IGP auto-configuration can also be explicitly disabled on individual interfaces under LDP using the igp
auto-config disable command. This allows LDP to receive all IGP interfaces except the ones explicitly
disabled.
See the MPLS configuration guide for information on configuring LDP IGP auto-configuration.

MPLS TE Forwarding Adjacency

MPLS TE forwarding adjacency allows a network administrator to handle a traffic engineering, label switch
path (LSP) tunnel as a link in an Interior Gateway Protocol (IGP) network, based on the Shortest Path First
(SPF) algorithm. A forwarding adjacency can be created between routers in the same IS-IS level. The routers
can be located multiple hops from each other. As a result, a TE tunnel is advertised as a link in an IGP network,
with the cost of the link associated with it. Routers outside of the TE domain see the TE tunnel and use it to
compute the shortest path for routing traffic throughout the network.
MPLS TE forwarding adjacency is considered in IS-IS SPF only if a two-way connectivity check is achieved.
This is possible if the forwarding adjacency is bidirectional or the head end and tail end routers of the MPLS
TE tunnel are adjacent.
The MPLS TE forwarding adjacency feature is supported by IS-IS. For details on configuring MPLS TE
forwarding adjacency, see the MPLS Configuration Guide.

MPLS TE Interarea Tunnels

MPLS TE interarea tunnels allow you to establish MPLS TE tunnels that span multiple IGP areas (Open
Shorted Path First [OSPF]) and levels (IS-IS), removing the restriction that required that both the tunnel
headend and tailend routers be in the same area. The IGP can be either IS-IS or OSPF. See the
MPLS Traffic Engineering for IS-IS, on page 374
For details on configuring MPLS TE interarea tunnels, see the MPLS Configuration Guide.
Cisco ASR 9000 Series Aggregation Services Router Routing Configuration Guide, Release 5.3.x
352
timer expires.
for information on configuring MPLS TE for IS-IS.
Implementing IS-IS
Configuring