Implementing Fast Reroute Loop-Free Alternate; Prerequisites For Fast Reroute With Loop-Free Alternate; Restrictions For Fast Reroute With Loop-Free Alternate - Cisco NCS 5500 Series Configuration Manuals

Implementing Fast Reroute Loop-Free Alternate

Fast Reroute Loop-Free Alternate feature enables you to tunnel a packet around a failed link to a remote
loop-free alternate that is more than one hop away.
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Prerequisites for Fast Reroute with Loop-Free Alternate

• Fast Reroute with Loop-Free Alternate functionality can protect paths that are reachable through an
• When a LAN interface is physically connected to a single neighbor, you should configure the LAN
• For a proper deployment for Fast Reroute with Remote Loop-Free Alternate feature, the protected link

Restrictions for Fast Reroute with Loop-Free Alternate

• Load balance support is available for FRR-protected prefixes, but the 50 ms cutover time is not guaranteed.
• A maximum of eight FRR-protected interfaces can simultaneously undergo a cutover.
• LFA calculations are restricted to interfaces or links belonging to the same level or area. Hence, excluding
• Only physical and physical port-channel interfaces and subinterfaces are protected. Tunnels and virtual
Prerequisites for Fast Reroute with Loop-Free Alternate, on page 249
Restrictions for Fast Reroute with Loop-Free Alternate, on page 249
IS-IS and FRR, on page 250
Repair Paths, on page 250
LFA Overview, on page 250
LFA Calculation, on page 251
Interaction Between RIB and Routing Protocols, on page 251
Fast Reroute with Remote Loop-Free Alternate, on page 252
Configuration , on page 253
interface only if the interface is a point-to-point interface.
interface as a point-to-point interface so that it can be protected through Loop-Free Alternate (LFA) FRR.
should also be configured with BFD
all neighbors on the same LAN when computing the backup LFA can result in repairs being unavailable
in a subset of topologies.
interfaces are not protected.
Routing Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.3.x
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