H3C Technologies H3C S10500 Series Switches - Manual (Page 87)

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Figure 36 NSSA external LSA format
Supported features
Multi-process
This feature allows multiple OSPF processes to run on a router both simultaneously and independently.
Routing information interactions between different processes simulate interactions between different
routing protocols. Multiple OSPF processes can use the same RID.
An interface of a router can only belong to a single OSPF process.
Authentication
OSPF can authenticate OSPF packets. Only packets that pass the authentication are received. If an
incoming hello packet cannot pass authentication, the neighbor relationship cannot be established.
The authentication type for interfaces attached to a single area must be identical. Authentication types
include non-authentication, plaintext authentication, and MD5 ciphertext authentication. The
authentication password for interfaces that are attached to a network segment must be identical.
Active/standby failover
The router supports active/standby failover for OSPF and backs up OSPF information from the active
MPU to the standby MPU. Once the active MPU fails, the standby MPU begins to work to ensure the
normal operation of OSPF.
OSPF provides two backup modes:
• Non-stop routing (NSR), which backs up all OSPF data to the standby MPU to make sure OSPF
recovers immediately upon the active MPU failure.
• Graceful restart (GR), which backs up only the OSPF configuration information to the standby MPU.
Once the active MPU fails, OSPF will perform GR to synchronize the LSDB with neighbors.
OSPF Graceful Restart
Graceful Restart (GR) ensures the continuity of packet forwarding when a routing protocol restarts or an
active/standby switchover occurs:
• GR Restarter: Graceful restarting router. It must have GR capability.
• GR Helper: A neighbor of the GR Restarter. It helps the GR Restarter to complete the GR process.