Behaviors and Limitations of TI-LFA
Feature Name |
Release Information |
Feature Description |
---|---|---|
Increased Number of Labels on Topology-Independent Loop-Free Alternate Backup Paths |
Release 7.9.1 |
This feature increases the maximum number of labels that can be pushed on the Topology-Independent Loop-Free Alternate (TI-LFA) backup path (including the label of the protected prefix) from three to eight. The increase in TI-LFA backup labels provides support for primary and backup paths that go over the same Shared Risk Link Groups (SRLG). |
BFDv6-triggered TI-LFA |
Release 7.3.2 |
Topology-Independent Loop-Free Alternate (TI-LFA) uses segment routing to provide link, node, and Shared Risk Link Groups (SRLG) protection in topologies where other fast reroute techniques cannot provide protection. BFDv6-triggered TI-LFA allows you to obtain link, node, and SRLG protection using the Bidirectional Forwarding Detection (BFD) over IPv6 protocol. |
BFDv4-triggered TI-LFA |
Release 7.3.1 |
Topology-Independent Loop-Free Alternate (TI-LFA) uses segment routing to provide link, node, and Shared Risk Link Groups (SRLG) protection in topologies where other fast reroute techniques cannot provide protection. BFD-triggered TI-LFA allows you to obtain link, node, and SRLG protection by using the Bidirectional Forwarding Detection (BFD) protocol. |
The TI-LFA behaviors and limitations are listed below:
-
IGP directly programs a TI-LFA backup path requiring eight or fewer labels, including the label of the protected destination prefix.
-
Programming of TI-LFA backup paths requiring more than eight labels is not supported.
TI-LFA Functionality | IS-IS1 | OSPFv2 |
---|---|---|
Protected Traffic Types | ||
Protection for SR labeled traffic | Supported | Supported |
Protection of IPv4 unlabeled traffic | Supported (IS-ISv4) | Supported |
Protection of IPv6 unlabeled traffic |
Supported (IS-ISv6) |
N/A |
Protection Types | ||
Link Protection | Supported | Supported |
Node Protection | Supported | Supported |
Local SRLG Protection |
Supported |
Supported |
Weighted Remote SRLG Protection |
Supported |
Supported |
Line Card Disjoint Protection |
Unsupported |
Unsupported |
Interface Types | ||
Ethernet Interfaces | Supported | Supported |
Ethernet Bundle Interfaces | Supported | Supported |
TI-LFA over GRE Tunnel as Protecting Interface | Unsupported |
Unsupported |
Additional Functionality | ||
Maximum number of labels that can be pushed on the backup path (including the label of the protected prefix) |
8 |
8 |
BFDv4-triggered |
Supported |
Supported |
BFDv6-triggered |
Supported |
N/A |
Prefer backup path with lowest total metric |
Unsupported |
Unsupported |
Prefer backup path from ECMP set |
Unsupported |
Unsupported |
Prefer backup path from non-ECMP set |
Unsupported |
Unsupported |
Load share prefixes across multiple backups paths |
Supported |
Supported |
Limit backup computation up to the prefix priority | Supported | Supported |