Setting Up Ldp Forwarding - Cisco ASR 9000 Series Configuration Manual

Implementing MPLS Label Distribution Protocol
Command or Action
Step 8
backoff initial maximum
Example:
RP/0/RSP0/CPU0:router(config-ldp)# backoff
10 20
Step 9 Use the commit or end command.
Step 10
show mpls ldp neighbor
Example:
RP/0/RSP0/CPU0:router# show mpls ldp
neighbor
Related Topics
Configuring LDP Neighbors: Example, on page 54

Setting Up LDP Forwarding

Perform this task to set up LDP forwarding.
By default, the LDP control plane implements the penultimate hop popping (PHOP) mechanism. The PHOP
mechanism requires that label switched routers use the implicit-null label as a local label for the given
Forwarding Equivalence Class (FEC) for which LSR is the penultimate hop. Although PHOP has certain
advantages, it may be required to extend LSP up to the ultimate hop under certain circumstances (for example,
to propagate MPL QoS). This is done using a special local label (explicit-null) advertised to the peers after
which the peers use this label when forwarding traffic toward the ultimate hop (egress LSR).
Before You Begin
Stable router ID is required at either end of the link to ensure the link discovery (and session setup) is successful.
If you do not assign a router ID to the routers, the system will default to the global router ID. Default router
IDs are subject to change and may cause an unstable discovery.
OL-28381-02
Purpose
Configures the parameters for the LDP backoff mechanism. The LDP
backoff mechanism prevents two incompatibly configured LSRs from
engaging in an unthrottled sequence of session setup failures. If a
session setup attempt fails due to such incompatibility, each LSR
delays its next attempt (backs off), increasing the delay exponentially
with each successive failure until the maximum backoff delay is
reached.
commit—Saves the configuration changes and remains within the
configuration session.
end—Prompts user to take one of these actions:
• Yes— Saves configuration changes and exits the configuration
session.
• No—Exits the configuration session without committing the
configuration changes.
• Cancel—Remains in the configuration mode, without
committing the configuration changes.
(Optional)
Displays the status of the LDP session with its neighbors. This
command can be run with various filters as well as with the brief
option.
Cisco ASR 9000 Series Aggregation Services Router MPLS Configuration Guide, Release 4.3.x
Setting Up LDP Forwarding
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