H3C Technologies H3C S12500-X Series Switches - Manual (Page 346)

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After the active/standby switchover, the GR restarter sends a Grace LSA to tell its neighbors that it
performs a GR. Upon receiving the Grace LSA, the neighbors with the GR helper capability enter the
helper mode (and are called "GR helpers"). Then, the GR restarter retrieves its adjacencies and LSDB
with the help of the GR helpers.
411B
Configuring GR restarter
You can configure the GR restarter capability on a GR restarter.
To configure GR restarter:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3. Enable the GR
capability.
graceful-restart enable
By default, OSPFv3 GR restarter
capability is disabled.
4. (Optional.) Configure
the GR interval.
graceful-restart interval
interval-value By default, the GR interval is 120
seconds.
412B
Configuring GR helper
You can configure the GR helper capability on a GR helper.
To configure GR helper:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter OSPFv3 view.
ospfv3 [ process-id | vpn-instance
vpn-instance-name ] *
N/A
3. Enable the GR helper
capability.
graceful-restart helper enable
By default, the GR helper capability is
enabled.
4. Enable strict LSA
checking.
graceful-restart helper
strict-lsa-checking By default, strict LSA checking is
disabled.
111B
Configuring BFD for OSPFv3
Bidirectional forwarding detection (BFD) provides a mechanism to quickly detect the connectivity of links
between OSPFv3 neighbors, improving the convergence speed of OSPFv3. For more information about
BFD, see High Availability Configuration Guide.
After discovering neighbors by sending hello packets, OSPFv3 notifies BFD of the neighbor addresses,
and BFD uses these addresses to establish sessions. Before a BFD session is established, it is in the down
state. In this state, BFD control packets are sent at an interval of no less than 1 second to reduce BFD
control packet traffic. After the BFD session is established, BFD control packets are sent at the negotiated
interval, thereby implementing fast fault detection.