Configuring Is-Is Nsr; Configuring Is-Is Frr - HPE FlexNetwork HSR6800 Configuration Manual

Configuring IS-IS NSR

According to the GR feature, after an active/standby MPU switchover in standalone mode or a global
active/standby MPU switchover, the GR restarter obtains routing information from its neighbors, and
the IS-IS process must learn all routes. If the network topology has changed during the switchover
period, removed routes cannot be updated to the device, which might cause blackhole routes.
NSR solves the problem in the follow way:
•
In standalone mode, NSR backs up IS-IS link state information from the active MPU to the
standby MPU. After an active/standby MPU switchover, NSR can complete link state recovery
and route regeneration without requiring the cooperation of other devices.
•
In IRF mode, NSR backs up IS-IS link state information from the global active MPU to the global
standby MPU. After a global active/standby MPU switchover, NSR can complete link state
recovery and route regeneration without requiring the cooperation of other devices.
The IS-IS NSR and IS-IS GR features are mutually exclusive.
To configure IS-IS NSR:
Step
Enter system view
1.
Enter IS-IS view.
2.
Enable IS-IS NSR.
3.
Set the NSR
4.
interval.

Configuring IS-IS FRR

When a link fails, the packets on the path are discarded, and a routing loop might occur until IS-IS
completes the routing convergence based on the new network topology.
You can enable IS-IS fast reroute (FRR) to reduce traffic recovery time.
Figure 48 Network diagram for IS-IS FRR
In Figure 48, after you enable FRR on Router B, IS-IS automatically calculates or designates a
backup next hop when a link failure is detected. In this way, packets are directed to the backup next
hop to reduce traffic recovery time. Meanwhile, IS-IS calculates the shortest path based on the new
network topology, and forwards packets over the path after network convergence.
You can either enable IS-IS FRR to calculate a backup next hop automatically, or designate a backup
next hop with a routing policy for routes matching specific criteria.
Configuration prerequisites
Before you configure IS-IS FRR, complete the following tasks:
Command
system-view
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
non-stop-routing
non-stop-routing interval
interval-value
150
Remarks
N/A
N/A
Disabled by default.
0 seconds by default, that is, no NSR
interval is configured.