3.4. Configuring LDP with CLI

This section provides information to configure LDP using the command line interface.

3.5. LDP Configuration Overview

When the implementation of LDP is instantiated, the protocol is in the no shutdown state. In addition, targeted sessions are then enabled. The default parameters for LDP are set to the documented values for targeted sessions in draft-ietf-mpls-ldp-mib-09.txt.

3.6. Basic LDP Configuration

This chapter provides information to configure LDP and remove configuration examples of common configuration tasks.

The LDP protocol instance is created in the no shutdown (enabled) state.

3.7. Common Configuration Tasks

3.7.1. Enabling LDP

LDP must be enabled in order for the protocol to be active. MPLS must also be enabled. MPLS is enabled in the config>router>mpls context.

Use the following syntax to enable LDP on a router.

CLI Syntax:
ldp
Example:
config>router# ldp

3.7.2. Configuring Graceful-Restart Helper Parameters

Graceful-restart helper advertises to its LDP neighbors by carrying the fault tolerant (FT) session TLV in the LDP initialization message, assisting the LDP in preserving its IP forwarding state across the restart. Nokia’s recovery is self-contained and relies on information stored internally to self-heal. This feature is only used to help third-party routers without a self-healing capability to recover.

Maximum recovery time is the time (in seconds) the sender of the TLV would like the receiver to wait, after detecting the failure of LDP communication with the sender.

Neighbor liveness time is the time (in seconds) the LSR is willing to retain its MPLS forwarding state. The time should be long enough to allow the neighboring LSRs to re-sync all the LSPs in a graceful manner, without creating congestion in the LDP control plane.

Use the following syntax to configure graceful-restart parameters.

CLI Syntax:
config>router>ldp
[no] graceful-restart
[no] maximum-recovery-time interval
[no] neighbor-liveness-time interval

3.7.3. Applying Export and Import Policies

Both inbound and outbound label binding filtering are supported. Inbound filtering allows a route policy to control the label bindings an LSR accepts from its peers. An import policy can accept or reject label bindings received from LDP peers.

Label bindings can be filtered based on:

  1. Neighbor — Match on bindings received from the specified peer.
  2. Interface — Match on bindings received from a neighbor or neighbors adjacent over the specified interface.
  3. Prefix-list — Match on bindings with the specified prefix/prefixes.

Outbound filtering allows a route policy to control the set of LDP label bindings advertised by the LSR. An export policy can control the set of LDP label bindings advertised by the router. By default, label bindings for only the system address are advertised and propagate all FECs that are received.

Matches can be based on:

  1. Loopback — loopback interfaces.
  2. All — all local subnets.
  3. Match — match on bindings with the specified prefix/prefixes.

Use the following syntax to apply import and export policies.

CLI Syntax:
config>router>ldp
export policy-name [policy-name...(upto 32 max)]
import policy-name [policy-name...(upto 32 max)]

3.7.4. Targeted Session Parameters

Use the following syntax to specify targeted-session parameters.

CLI Syntax:
config>router# ldp
targeted-session
disable-targeted-session
hello timeout factor
keepalive timeout factor
peer ip-address
no bfd-enable
hello timeout factor
keepalive timeout factor
no shutdown

The following is a sample LDP configuration output.

A:ALA-1>config>router>ldp# info
----------------------------------------------
...
            targeted-session
              hello 5000 255
              keepalive 5000 255
              peer 10.10.10.104
 
                  hello 2500 104
                  keepalive 15 3
                exit
            exit
----------------------------------------------
A:ALA-1>config>router>ldp#

3.7.5. Interface Parameters

Use the following syntax to configure interface parameters.

CLI Syntax:
config>router# ldp
interface-parameters
hello timeout factor
keepalive timeout factor
transport-address {system|interface}
interface ip-int-name
hello timeout factor
keepalive timeout factor
transport-address {system|interface}
no shutdown

The following is a sample interface parameter configuration output.

A:ALU_SIM11>config>router>ldp# info
----------------------------------------------
     aggregate-prefix-match
          prefix-exclude "sample"
          exit
     graceful-restart
          exit
     session-parameters
     peer 1.1.1.1
               ttl-security 1
          exit
     exit
     interface-parameters
               interface "a"
          exit
     exit
     targeted-session
     exit
----------------------------------------------

3.7.6. Session Parameters

Use the following syntax to specify session parameters.

CLI Syntax:
config>router# ldp
session-parameters
peer ip-address
auth-keychain name
authentication-key [authentication-key|hash-key] [hash|hash2]
A:ALA-1>config>router>ldp# info
----------------------------------------------
     session-parameters
          peer 10.10.10.104
          authentication-key "3WErEDozxyQ" hash
          exit
     exit
     targeted-session
          hello 5000 255
          keepalive 5000 255
          peer 10.10.10.104
     no bfd-enable
          hello 2500 100
          keepalive 15 3
          exit
     exit
----------------------------------------------
A:ALA-1>config>router>ldp#

3.7.7. LDP Signaling and Services

When LDP is enabled, targeted sessions can be established to create remote adjacencies with nodes that are not directly connected. When service distribution paths (SDPs) are configured, extended discovery mechanisms enable LDP to send periodic targeted hello messages to the SDP’s far-end point. The exchange of LDP hellos trigger session establishment. The SDP’s signaling default enables tldp. The service SDP uses the targeted-session parameters configured in the config>router>ldp>targeted-session context.

Use the following syntax to configure enable LDP on an MPLS SDP.

CLI Syntax:
config>service>sdp#
signaling {off|tldp}

The following is a sample SDP configuration output showing the signaling default tldp enabled.

A:ALA-1>config>service>sdp# info detail
----------------------------------------------
            description "MPLS: to-99"
            far-end 10.10.10.99
            lsp A_D_1
            signaling tldp
            path-mtu 4462
            keep-alive
                hello-time 10
                hold-down-time 10
                max-drop-count 3
                timeout 5
                no message-length
                no shutdown
            exit
            no shutdown
----------------------------------------------
A:ALA-1>config>service>sdp# 

3.8. LDP Configuration Management Tasks

This section describes the LDP configuration management tasks.

3.8.1. Disabling LDP

The no ldp command disables the LDP protocol on the router. All parameters revert to the default settings. LDP must be shut down before it can be disabled.

Use the following command syntax to disable LDP.

CLI Syntax:
no ldp
shutdown

3.8.2. Modifying Targeted Session Parameters

The modification of LDP targeted session parameters does not take effect until the next time the session goes down and is re-establishes. Individual parameters cannot be deleted. The no form of a targeted-session parameter command reverts modified values back to the default.

The following shows the command usage to revert targeted session parameters back to the default values.

Example:
config>router# ldp
config>router>ldp# targeted-session
config>router>ldp>targeted# no authentication-key
config>router>ldp>targeted# no disable-targeted-session
config>router>ldp>targeted# no hello
config>router>ldp>targeted# no keepalive
config>router>ldp>targeted# no peer 10.10.10.99

The following output displays the default values.

A:ALA-1>config>router>ldp>targeted# info detail
----------------------------------------------
                no disable-targeted-session
                hello 45 3
                keepalive 40 4
----------------------------------------------
A:ALA-1>config>router>ldp>targeted#

3.8.3. Modifying Interface Parameters

The modification of LDP targeted session parameters does not take effect until the next time the session goes down and is re-establishes. Individual parameters cannot be deleted. The no form of a interface-parameter command reverts modified values back to the defaults.