An ABR can summarize routes with the same prefix into one LSA and advertise the summarized route in other areas. An ASBR can also summarize imported routes with the same prefix into one LSA and then advertise the summarized route to other areas. This can reduce the size of the LSDB in other areas.
If multiple continuous network segments exist in this area, use the abr-summary command to summarize them into one network segment. In this way, the ABR only sends an LSA after summarization. No LSA that belongs to the summarization network segment is separately transmitted, therefore reducing the LSDB size of other areas.
When a large number of routes are imported, use the asbr-summary command to summarize the imported routes and set the delay for advertising the summarized route. In this manner, the summarized route advertised each time contains more valid routing information, and network flapping caused by incorrect routing information is avoided.
Perform the following steps on the ABR that runs OSPFv3:
Access the system view.
Access the OSPFv3 process view.
ospfv3 [ process-id ]
Access the OSPFv3 area view.
area area-id
Configure route summarization in the OSPFv3 area.
abr-summary ipv6-address prefix-length [ cost cost | not-advertise ] *
cost cost set the cost of a summarized route. By default, the cost of a summarized route is the maximum cost among those of routes that are summarized. The value ranges from 1 to 16777214.
If not-advertise is set, no routing information of the network segment is advertised.
Perform the following steps on the ASBR that runs OSPFv3:
Access the system view.
Access the OSPFv3 process view.
ospfv3 [ process-id ]
Configure route summarization on the ASBR.
asbr-summary ipv6-address summary-prefix-length [ cost summary-cost | tag summary-tag | distribute-delay dist-delay-interval | not-advertise ] *
cost cost specifies the cost of a summarized route. By default, the cost of a summarized route is the maximum cost among those of routes that are summarized. The value ranges from 1 to 16777214.
tag tag specifies the tag used to control route advertisement. The value of this parameter ranges from 1 to 4294967295.
If not-advertise is specified in the command, the summarized IPv6 route that matches a specified IPv6 prefix or prefix length is not advertised.
distribute-delay interval specifies the delay for advertising a summarized route.