Configuring Label Distribution Protocol Discovery Parameters; Label Distribution Protocol Discovery For Targeted Hellos - Cisco NCS 5500 Series Configuration Manual

Implementing MPLS Label Distribution Protocol

Configuring Label Distribution Protocol Discovery Parameters

LSRs that are running LDP sends hello messages on all the LDP enabled interfaces to discover each other.
So, the LSR that receives the LDP hello message on an interface is aware of the presence of the LDP router
on that interface. If LDP hello messages are sent and received on an interface, there is an LDP adjacency
across the link between the two LSRs that are running LDP. By default, hello messages are sent every 5
seconds with a hold time of 15 seconds. If the LSR does not receive a discovery hello from peer before the
hold time expires, the LSR removes the peer LSR from the list of discovered LDP neighbors . The LDP
discovery parameters can be configured to change the default parameters.
LDP session between LSRs that are not directly connected is known as targeted LDP session. For targeted
LDP sessions, LDP uses targeted hello messages to discover the extended neighbors. By default, targeted
hello messages are sent every 10 seconds with a hold time of 90 seconds.
Configuration Example
This example shows how to configure the following LDP discovery parameters:
• hello hold time
• hello interval
• targeted hello hold time
• targeted hello interval
RP/0/RP0/CPU0:Router(config)# mpls ldp
RP/0/RP0/CPU0:Router(config-ldp)# router-id 192.168.70.1
RP/0/RP0/CPU0:Router(config-ldp)# discovery hello holdtime 30
RP/0/RP0/CPU0:Router(config-ldp)# discovery hello interval 10
RP/0/RP0/CPU0:Router(config-ldp)# discovery targeted-hello holdtime 120
RP/0/RP0/CPU0:Router(config-ldp)# discovery targeted-hello interval 15
RP/0/RP0/CPU0:Router(config-ldp)# commit
Verification
This section verifies the MPLS LDP discovery parameters configuration.
RP/0/RP0/CPU0:Router# show mpls ldp parameters
LDP Parameters:
Role: Active
Protocol Version: 1
Router ID: 192.168.70.1
Discovery:
Link Hellos:
Targeted Hellos: Holdtime:120 sec, Interval:15 sec
Quick-start: Enabled (by default)
Transport address:

Label Distribution Protocol Discovery for Targeted Hellos

LDP session between LSRs that are not directly connected is known as targeted LDP session. For LDP
neighbors which are not directly connected, you should manually configure the LDP neighborship on both
the routers.
Holdtime:30 sec, Interval:10 sec
IPv4: 192.168.70.1
MPLS Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.2.x
Configuring Label Distribution Protocol Discovery Parameters
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