Flex Lsp Overview; Signaling Methods And Object Association For Flex Lsps - Cisco ASR 900 Series Manual

Flex LSP Overview

Flex LSP also known as Associated Bidirectional LSPs is the combination of static bidirectional MPLS-TP
and dynamic MPLS-TE. Flex LSP provides bidirectional label switched paths (LSPs) set up dynamically
through Resource Reservation Protocol–Traffic Engineering (RSVP-TE). It does not support non-co routed
LSPs.
Flex Label Switched Paths are LSP instances where the forward and the reverse direction paths are setup,
monitored and protected independently and associated together during signaling. You use a RSVP Association
object to bind the two forward and reverse LSPs together to form either a co-routed or non co-routed associated
bidirectional TE tunnel.
You can associate a protecting MPLS-TE tunnel with either a working MPLS-TE LSP, protecting MPLS-TE
LSP, or both. The working LSP is the primary LSP backed up by the protecting LSP. When a working LSP
goes down, the protecting LSP is automatically activated. You can configure a MPLS-TE tunnel to operate
without protection as well.
Effective Cisco IOS XE Release 3.18.1SP, Flex LSP supports inter-area tunnels with non co-routed mode.
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Signaling Methods and Object Association for Flex LSPs

This section provides an overview of the association signaling methods for the bidirectional LSPs. Two
unidirectional LSPs can be bound to form an associated bidirectional LSP in the following scenarios:
• No unidirectional LSP exists, and both must be established.
• Both unidirectional LSPs exist, but the association must be established.
• One unidirectional LSP exists, but the reverse associated LSP must be established.
Signaling Methods and Object Association for Flex LSPs, page 139
Associated Bidirectional Non Co-routed and Co-routed LSPs, page 140
Restrictions for Flex LSP, page 141
How to Configure Co-routed Flex LSPs, page 142
How to Configure Non Co-routed Inter-area Flex LSP Tunnels, page 147
Flex LSP Phase 2, page 150
MPLS Basic Configuration Guide, Cisco IOS XE Everest 16.5.1 (Cisco ASR 900 Series)
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