H3C Technologies H3C SR8800 - Manual (Page 92)

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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 seem like 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
A router can back up the OSPF information of the active main board (AMB) to the standby main board
(SMB). Once the AMB fails, the SMB begins to work to ensure the normal operation of OSPF.
OSPF provides the Graceful restart (GR) backup mode, which backs up only the OSPF configuration
information to the SMB. Once the AMB 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 Restarte—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.
After an OSPF GR Restarter restarts, it needs to perform the following tasks.
• To obtain OSPF neighbor information.
• To obtain the LSDB.