Enabling IS-IS Auto FRR
Context
At present, the VoIP and on-line video services require high-quality real-time transmission. Nevertheless, if an IS-IS fault occurs, multiple processes, including fault detection, LSP update, LSP flooding, route calculation, and FIB entry delivery, must be performed to switch the traffic to a new link. As a result, it takes much more than 50 ms to recover the link from the fault, which cannot meet the requirement for real-time services on the network.
After the BFD session status is bound to IS-IS Auto FRR, traffic can be fast switched from the faulty link to the backup link. This ensures that the traffic interruption time is within 50 ms, which protects traffic and improves IS-IS network reliability.
Procedure
- Run system-view
The system view is displayed.
- Run isis [ process-id ]
The IS-IS process is enabled and the IS-IS view is displayed.
- Run frr
The IS-IS FRR view is displayed.
- (Optional) Run frr-policy route route-policy route-policy-name
Backup routes are filtered using a filtering policy. Only backup routes that have passed the filtering policy are added to the routing table.
- Run loop-free-alternate [ level-1 | level-2 | level-1-2 ]
IS-IS Auto FRR is enabled and the loop-free backup route is created.
By default, IS-IS Auto FRR is disabled from calculating loop-free backup routes using the loop-free alternate (LFA) algorithm.
If the IS-IS level is not specified, IS-IS Auto FRR is enabled on Level-1 and Level-2 to create the backup route.
- (Optional) Run the following command in the interface view: isis lfa-backup [ level-1 | level-2 | level-1-2 ] disable
The interface is disabled from participating in LFA calculation.
By default, an IS-IS interface can participate in LFA calculation.
During network deployment, to facilitate traffic management and fast determine the traffic forwarding path when the primary link fails, disable some interfaces from participating in LFA calculation.
- Run commit
The configuration is committed.
Verifying the Configuration
- Run the display isis route [ process-id | vpn-instance vpn-instance-name ] [ ipv4 ] [ verbose | [ level-1 | level-2 ] | ip-address [ mask | mask-length ] ] * command to check information about the primary link and backup link generated by IS-IS Auto FRR.
- Run the display isis spf-tree verbose command to check the traffic protection type of IS-IS Auto FRR.