egress LER where MPLS packets are decapsulated and the IP packets contained within
the MPLS packets are forwarded using information in the IP forwarding table.
Configuring MPLS on the LER is the same as configuring an LSR.
•
Uniform and pipe mode configuration providing different types of visibility in the MPLS
network. Uniform mode makes all the nodes that a label-switched path (LSP) traverses
visible to nodes outside the LSP tunnel. Uniform mode is the default. Pipe mode makes
only the LSP ingress and egress points visible to nodes outside the LSP tunnel. Pipe
mode acts like a circuit and must be enabled with the global no-propagate-ttl statement
at the [edit protocols mpls] hierarchy level on each router that is in the path of the LSP.
The no-propagate-ttl statement disables time-to-live (TTL) propagation at the router
level and affects all RSVP-signalled or LDP-signalled LSPs. Only the global configuration
of TTL propagation is supported.
•
Exception packet handling of IP packets not processed by the normal packet flow
through the Packet Forwarding Engine. The following types of exception packet handling
are supported:
•
Router alert
•
Time-to-live (TTL) expiry value
•
Virtual circuit connection verification (VCCV)
•
LSP hot standby for secondary paths configuration to maintain a path in a hot-standby
state enabling swift cut over to the secondary path when downstream routers on the
current active path indicate connectivity problems.
•
Redundancy for a label-switched path (LSP) path with the configuration of fast reroute.
•
Configuration of link protection to ensure that traffic traversing a specific interface
from one router to another can continue to reach its destination in the event that this
interface fails.
Related
Documentation
MPLS Applications Feature Guide•
• Disabling Normal TTL Decrementing
• Fast Reroute Overview
• Configuring Fast Reroute
• MPLS and Traffic Protection
• Configuring Link Protection on Interfaces Used by LSPs
• Configuring Hot Standby of Secondary Paths for LSPs
TTL Processing on Incoming MPLS Packets
The flow chart on Figure 30 on page 590 illustrates TTL processing on incoming MPLS
packets. On a transit LSR or an egress LER, MPLS pops one or more labels and can push
one or more labels. The incoming TTL of the packet is determined by the configured TTL
processing tunnel model.
Copyright © 2017, Juniper Networks, Inc.588
ACX Series Universal Access Router Configuration Guide
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