Prerequisites For Implementing Cisco Mpls Ldp; Information About Implementing Cisco Mpls Ldp; Overview Of Label Distribution Protocol; Label Switched Paths - Cisco ASR 9000 Series Configuration Manual

Prerequisites for Implementing Cisco MPLS LDP

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Prerequisites for Implementing Cisco MPLS LDP
These prerequisites are required to implement MPLS LDP:
• You must be in a user group associated with a task group that includes the proper task IDs. The command
• You must be running Cisco IOS XR software.
• You must install a composite mini-image and the MPLS package.
• You must activate IGP.
• We recommend to use a lower session holdtime bandwidth such as neighbors so that a session down

Information About Implementing Cisco MPLS LDP

To implement MPLS LDP, you should understand these concepts:

Overview of Label Distribution Protocol

LDP performs label distribution in MPLS environments. LDP uses hop-by-hop or dynamic path setup, but
does not provide end-to-end switching services. Labels are assigned to routes that are chosen by the underlying
IGP routing protocols. The Label Switched Paths (LSPs) that result from the routes, forward labeled traffic
across the MPLS backbone to adjacent nodes.

Label Switched Paths

LSPs are created in the network through MPLS. They can be created statically, by RSVP traffic engineering
(TE), or by LDP. LSPs created by LDP perform hop-by-hop path setup instead of an end-to-end path.

LDP Control Plane

The control plane enables label switched routers (LSRs) to discover their potential peer routers and to establish
LDP sessions with those peers to exchange label binding information.
Cisco ASR 9000 Series Aggregation Services Router MPLS Configuration Guide, Release 4.3.x
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Configuration Examples for Implementing MPLS LDP, page 52
Additional References, page 61
reference guides include the task IDs required for each command. If you suspect user group assignment
is preventing you from using a command, contact your AAA administrator for assistance.
occurs before an adjacency-down on a neighbor. Therefore, the following default values for the hello
times are listed:
• Holdtime is 15 seconds.
• Interval is 5 seconds.
For example, the LDP session holdtime can be configured as 30 seconds by using the holdtime command.
Implementing MPLS Label Distribution Protocol
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