The loop-free-alternate command enables IS-IS Auto FRR to calculate loop-free backup routes using the loop-free alternate (LFA) algorithm.
The undo loop-free-alternate command disables IS-IS Auto FRR from calculating loop-free backup routes using the LFA algorithm.
By default, IS-IS Auto FRR is disabled from calculating loop-free backup routes using the LFA algorithm.
Product |
Support |
|---|---|
S5720-EI, S5720-HI, S5730-HI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S |
Supported |
S2720-EI, S5720I-SI, S5720-LI, S5735-L, S5735S-L, S5735S-L-M, S5720S-LI, S5720S-SI, S5720-SI, S5735-S, S5735S-S, S5735-S-I, S5730S-EI, S5730-SI, S6720-LI, S6720S-LI, S6720S-SI, and S6720-SI |
Not supported |
loop-free-alternate [ level-1 | level-2 | level-1-2 ]
undo loop-free-alternate [ level-1 | level-2 | level-1-2 ]
| Parameter | Description | Value |
|---|---|---|
| level-1 | Enables Level-1 IS-IS Auto FRR to generate loop-free backup routes. If the IS level is not specified, Level-1 and Level-2 IS-IS Auto FRR is enabled to generate backup routes. | - |
| level-2 | Enables Level-2 IS-IS Auto FRR to generate loop-free backup routes. If the IS level is not specified, Level-1 and Level-2 IS-IS Auto FRR is enabled to generate backup routes. | - |
| level-1-2 | Enables Level-1 and Level-2 IS-IS Auto FRR to generate loop-free backup routes. | - |
IS-IS Auto FRR pre-computes a backup link by using the Loop-Free Alternate (LFA) algorithm, and then adds the backup link and the primary link to the forwarding table. In the case of an IS-IS network failure, IS-IS Auto FRR can fast switch traffic to the backup link before routes on the control plane converge.
PrecautionsTo make IS-IS Auto FRR to take effect, enter the IS-IS FRR view and then run the loop-free-alternate command.
IS-IS can generate loop-free backup routes only when the IS-IS Auto FRR traffic protection inequality is met.