Understanding Remote Lfa Over Ldp Tunnels In Is-Is Networks - Juniper ACX1000 Configuration Manual

ACX Series Universal Access Router Configuration Guide
Action
Meaning
Related
Documentation

Understanding Remote LFA over LDP Tunnels in IS-IS Networks

564
From operational mode, enter the
user@R6>show ospf backup neighbor
Topology default backup neighbors:
Area 0.0.0.0 backup neighbors:
6.6.6.6 via: Direct
Neighbor to Self Metric: 1
Self to Neighbor Metric: 1
Direct next-hop: ge-0/0/0.0 via 60.1.1.1
8.8.8.8 via: Direct
Neighbor to Self Metric: 1
Self to Neighbor Metric: 1
Direct next-hop: ge-0/0/1.0 via 70.1.1.2
2.2.2.2 via: Direct
Neighbor to Self Metric: 1
Self to Neighbor Metric: 1
Direct next-hop: ge-0/0/2.0 via 80.1.1.1
4.4.4.4 via: LDP (LSP endpoint)
Neighbor to Self Metric: 3
Self to Neighbor Metric: 3
Direct next-hop: LDP->4.4.4.4 via ge-0/0/2.0
Direct next-hop: LDP->4.4.4.4 via ge-0/0/0.0
Neighbors Protected: 2
The output displays the backup neighbors available for area 0.0.0.0.
Remote LFA over LDP Tunnels in OSPF Networks Overview on page 547
Configuring Remote LFA Backup over LDP Tunnels in an OSPF Network on page 548
In an IS-IS network, a loop free alternate (LFA) is a directly connected neighbor that
provides precomputed backup paths to the destinations reachable through the protected
link on the point of local repair (PLR). A remote LFA is not directly connected to the PLR
and provides precomputed backup paths using dynamically created LDP tunnels to the
remote LFA node. The PLR uses this remote LFA backup path when the primary link fails.
The primary goal of the remote LFA is to increase backup coverage for the IS-IS networks
and provide protection for Layer 1 metro-rings.
LFAs do not provide full backup coverage for IS-IS networks. This is a major setback for
metro Ethernet networks that are often shaped as ring topologies. To overcome this
setback, Resource Reservation Protocol - Traffic Engineering (RSVP-TE) backup tunnels
are commonly used to extend the backup coverage. However, a majority of network
providers have already implemented LDP as the MPLS tunnel setup protocol and do not
want to implement the RSVP-TE protocol merely for backup coverage. LDP automatically
show ospf backup neighbor
Copyright © 2017, Juniper Networks, Inc.
command.