H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 252)

25-18
An NSSA external LSA originates from the ASBR in a NSSA and is flooded in the NSSA area only. It has
the same format as the AS external LSA.
Figure 25-20 NSSA external LSA format
Network mask
Forwarding address
LS age
Linke state ID
Advertising Router
Options 7
LS sequence number
LS checksum Length
Metric
External route tag
...
E TOS
0 7 15 31
Supported OSPF Features
Multi-process
With multi-process support, multiple OSPF processes can run on a router 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 supports authentication on packets. Only packets that pass the authentication are received. If
hello packets cannot pass authentication, no neighbor relationship can 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 attached to a network segment must be identical.
OSPF Graceful Restart
For GR information, refer to IP Routing-GR Overview.
After an OSPF GR Restarter restarts OSPF, it needs to perform the following two tasks in order to
re-synchronize its LSDB with its neighbors.
z
To obtain once again effective OSPF neighbor information, supposing the adjacencies are not
changed.
z
To obtain once again LSDB contents.
Before the restart, the GR Restarter originates Grace-LSAs to negotiate the GR capability. During the
restart, the GR Helpers continue to advertise their adjacencies with the GR Restarter.