Importance Of Protection - Cisco ASR 9000 Series Configuration Manual

MPLS Traffic Engineering Shared Risk Link Groups
NNHOP backup tunnels also provide protection from link failures by bypassing the failed link as well as the
node. Figure 18: NNHOP Backup Tunnel with SRLG constraint
Figure 18: NNHOP Backup Tunnel with SRLG constraint
In the topology shown in the above figure, the backup tunnel path computation can be performed in this
manner:
• Get all SRLG values from the exclude-SRLG link (SRLG values 5 and 6)
• Mark all links with the same SRLG value to be excluded from SPF
• Verify path with SRLG constraint
• Path computation as CSPF R2->R9->R10->R4
Related Topics
Configuring the SRLG Values of Each Link that has a Shared Risk with Another Link, on page 212
Creating an Explicit Path With Exclude SRLG, on page 214
Using Explicit Path With Exclude SRLG, on page 216
Creating a Link Protection on Backup Tunnel with SRLG Constraint, on page 218
Creating a Node Protection on Backup Tunnel with SRLG Constraint, on page 221
Configure the MPLS-TE Shared Risk Link Groups: Example, on page 259

Importance of Protection

This section describes the following:
• Delivery of Packets During a Failure
• Multiple Backup Tunnels Protecting the Same Interface
Cisco ASR 9000 Series Aggregation Services Router MPLS Configuration Guide, Release 4.3.x
148
Implementing MPLS Traffic Engineering
illustrates an NNHOP backup tunnel.
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