Ps For An Mpls Te Tunnel; Protocols And Standards - HP 12500 Series Configuration Manual

As bypass LSPs are pre-established, FRR requires extra bandwidth. When network bandwidth is
insufficient, use FRR for crucial interfaces or links only.

PS for an MPLS TE tunnel

Protection switching (PS) refers to establishing one or more protection tunnels (backup tunnels) for a main
tunnel. A main tunnel and its protection tunnels form a protection group. When the main tunnel fails, data
is switched to a protection tunnel immediately, greatly improving the reliability of the network. When the
main tunnel recovers, data can be switched back to the main tunnel.
The switch supports only 1:1 protection switching, where one protection tunnel is used to service one main
tunnel. Two tunnels exist between the ingress and egress, one main and one backup. Normally, user data
travels along the main tunnel. If the ingress finds a defect of the main tunnel by using a probing
mechanism, it will switch data to the protection tunnel.
Protection switching may be command triggered or signal triggered.
Command switching refers to a PS triggered by an externally configured switching command, which can
define the following switching actions (in the descending order of priority):
clear: Clears all configured switching actions.
•
lock (lockout of protection): Always uses the main LSP to transfer data.
•
force (forced switch): Forces data to travel on the backup LSP.
•
manual (manual switch): Switches data from the main LSP to the backup LSP.
•
Signal switching (Signal Fail) refers to a PS automatically triggered by a signal fail declaration. Examples
include a PS that occurs during BFD detection for MPLS-TE tunnels.
The following shows the priority of the externally configured switching actions and the signal fail
switching, in the descending order:
Clear
•
Lockout of protection
•
• Signal fail of the backup LSP
Forced switch
•
Signal fail of the main LSP
•
Signal clear
•
Manual switch
•

Protocols and standards

RFC 2702, Requirements for Traffic Engineering Over MPLS
•
RFC 3212, Constraint-Based LSP Setup using LDP
•
• RFC 2205, Resource ReSerVation Protocol
RFC 3209, RSVP-TE: Extensions to RSVP for LSP Tunnels
•
RFC 2961, RSVP Refresh Overhead Reduction Extensions
•
• RFC 3564, Requirements for Support of Differentiated Service-aware MPLS Traffic Engineering
ITU-T Recommendation Y.1720, Protection switching for MPLS networks
•
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