H3C Technologies H3C S10500 Series Switches - Manual (Page 98)

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Configuring route summarization on an ABR
If contiguous network segments are available in the area, you can summarize them into a single network
segment. An ABR generates Type-3 LSAs on a per network segment basis for an attached non-backbone
area.
The ABR in the area distributes only the summary LSA to reduce the scale of LSDBs on routers in other
areas and the influence of topology changes.
Follow these steps to configure route summarization on an ABR:
To do… Use the command… Remarks
Enter system view system-view —
Enter OSPF view
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ] *
—
Enter OSPF area view area area-id —
Configure ABR route
summarization
abr-summary ip-address { mask |
mask-length } [ advertise |
not-advertise ] [ cost cost ]
Required
Not configured by default.
The command is available on an
ABR only.
Configuring route summarization when redistributing routes into OSPF on an ASBR
Without route summarization, an ASBR advertises each redistributed route in a separate ASE LSA. After
a summary route is configured, the ASBR advertises only the summary route in an ASE LSA instead of
more specific routes, which reduces the number of LSAs in the LSDB.
The ASBR summarizes redistributed Type-5 LSAs that fall into the specified address range. If the ASBR is
in an NSSA area, it also summarizes Type-7 LSAs that fall into the specified address range. If the ASBR
is also the ABR, it summarizes Type-5 LSAs translated from Type-7 LSAs.
Follow these steps to configure route summarization when redistributing routes into OSPF on an ASBR:
To do… Use the command… Remarks
Enter system view system-view —
Enter OSPF view
ospf [ process-id | router-id router-id
| vpn-instance vpn-instance-name ]*
—
Configure ASBR route
summarization
asbr-summary ip-address { mask |
mask-length } [ tag tag | not-advertise
| cost cost ] *
Required
The command is available on an
ASBR only.
Not configured by default.
Configuring OSPF inbound route filtering
NOTE:
For more information about IP prefix list and routing policy, see the chapter “Routing policy
configuration.”
OSPF calculates routes by using LSAs. The calculated routes can be filtered and only permitted routes are
installed into the OSPF routing table.