Configuring OSPFv3 Route Summarization

Routes with the same IPv6 prefix can be summarized into one route. On a large-scale OSPFv3 network, route lookup may slow down because of the large size of the routing table. To reduce the routing table size and simplify management, configure route summarization. With route summarization, if a link connected to a device within an IPv6 address range that has been summarized alternates between Up and Down, the link status change is not advertised to the devices beyond the IPv6 address range. This prevents route flapping and improves network stability.

Context

OSPFv3 route summarization is classified as follows:

Route summarization on an ABR, which is configured using the abr-summary command. When an ABR transmits routing information to other areas, it generates Type 3 LSAs for each network segment. If contiguous segments exist in this area, run the abr-summary command to summarize these segments into one segment so that the ABR sends only one summarized LSA.
Route summarization on an ASBR, which is configured using the asbr-summary command. The ASBR summarizes routes of imported Type 5 LSAs within the summarized address range. If a large number of routes with the same IPv6 prefix are imported, run the asbr-summary command to summarize them into one route.

Procedure

Configure route summarization on an ABR.
1. Run system-view
  The system view is displayed.
2. Run ospfv3 [ process-id ]
  The OSPFv3 view is displayed.
3. Run area area-id
  The OSPFv3 area view is displayed.
4. Run abr-summary ipv6-address prefix-length [ not-advertise | cost cost-value| hold-max-cost interval ] ^*
  Route summarization is configured on an ABR.
  - The not-advertise parameter prevents the summarized route in the specified network segment from being advertised.
  - The cost cost parameter sets a cost for a summarized route.
5. Run commit
  The configuration is committed.
Configure route summarization on an ASBR.
1. Run system-view
  The system view is displayed.
2. Run ospfv3 [ process-id ]
  The OSPFv3 view is displayed.
3. Run asbr-summary ipv6-address prefix-length [ not-advertise | tag tag-value | cost cost-value | distribute-delay interval ] ^*
  Route summarization is configured on an ASBR.
  - The cost cost parameter sets a cost for a summarized route.
  - The tag tag parameter sets a tag to control summarized route advertisement.
  - The not-advertise parameter prevents the summarized route with the specified IPv6 prefix or prefix length from being advertised.
  - The distribute-delay interval parameter sets a delay in advertising summarized routes, which ensures that the summarized routes advertised each time contain more valid routes and prevents incorrect routing information in case of network flapping.
4. Run commit
  The configuration is committed.