Configure OSPFv3 Route Control

Configuration Condition

Before configuring OSPFv3 route control, ensure that:

The IPv6 forwarding function is enabled.
The OSPFv3 protocol is enabled.

Configure Route Summary between OSPFv3 Areas

When an ABR in OSPFv3 advertises inter-area routes to other areas, it advertises each route separately in the form of Type-3 LSA. You can use the inter-area route summary function to summarize some continuous network segments to form a summary route. Then the ABR advertises the summary route, reducing the size of OSPFv3 databases.

Table 8-14 Configure route summary between OSPFv3 areas

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configure the route summary between OSPFv3 areas	area area-id range ipv6-prefix/prefix-length [ advertise \| not-advertise]	Mandatory By default, ABR does not perform the route summary between the areas.

The route summary function between OSPFv3 areas is valid only for ABRs.
By default, the minimum cost value among the cost values of the routes is used as the cost value of the route summary.

Configure OSPFv3 External Route Summary

When OSPF redistributes external routes, it advertises each route separately in the form of external LSA. You can use the external route summary function to summarize some continuous network segments to form a summary route. Then OSPF advertises the summary route, reducing the size of OSPF databases.

If you run the summary-address command on an ASBR, you can summarize all Type-5 LSAs and Type-7 LSAs within the address range.

Table 8-15 Configure OSPFv3 external route summary

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configure OSPFv3 to summarize external routes.	summary-prefix ipv6-prefix/prefix-length [ not-advertise \| tag tag-value ]	Mandatory. By default, an ABR does not summarize external routes.

The OSPFv3 external route summary function is valid only for ASBRs.

Configure Route Filtering between OSPFv3 Areas

When an ABR receives inter-area routes, it performs filtration in the incoming direction based on an ACL or prefix list. When the ABR advertises inter-area routes, it performs filtration in the outgoing direction based on an ACL or prefix list.

Table 8-16 Configure route filteringbetween OSPFv3 areas

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configure the route filtering between OSPFv3 areas	area area-id filter-list { access { access-list-name \| access-list-number } \| prefix prefix-list-name } { in \| out }	Mandatory By default, ABR does not perform the route filtering between areas.

The OSPFv3 inter-area route filtering function is valid only for ABRs.

Configure OSPFv3 External Route Filtration

Configuring OSPFv3 external route filtering is to apply an ACL or prefix list to allow or not allow external routes of an OSPFv3 AS to flood into the OSPF AS.

Table 8-17 Configure OSPFv3 external route filtration

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configure the OSPFv3 external route filtering	distribute-list { access { access-list-name \| access-list-number } \| prefix prefix-list-name } out [ routing-protocol [ process-id ] ]	Mandatory By default, ASBR does not perform the external route filtering.

The OSPFv3 external route filtering function is valid only for ASBRs.

Configure OSPFv3 Route Installation Filtration

After OSPFv3 calculates routes through LSA, to prevent certain routes from being added into the routing table, OSPFv3 filters the calculated OSPFv3 route information.

Table 8-18 Configure OSPFv3 route installation filtration

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configure OSPFv3 route installation filtering	distribute-list { access { access-list-name \| access-list-number } \| gateway prefix-list-name1 \| prefix prefix-list-name2 [gateway prefix-list-name3 ] \| route-map route-map-name} in [ interface-name ]	Mandatory By default, do not configure OSPFv3 route installation filtering.

Filtration based on prefix, gateway, and route-map is mutually exclusive with filtration based on ACL. For example, if you have configured filtration based on prefix, you cannot configure filtration based on ACL again.
Filtration based on route-map and prefix is mutual exclusive with filtration based on gateway.
Filtration based on prefix and filtration based on gateway overwrite each other.

Configure the Cost Value of an OSPFv3 Interface

By default, the cost of an OSPFv3 interface is calculated based on the following formula: Reference bandwidth/Interface bandwidth.

Table 8-19 Configure the cost value of an OSPFv3 interface

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the interface configuration mode.	interface interface-name	-
Configure the cost value of an OSPFv3 interface.	ipv6 ospf cost cost [ instance-id instance-id ]	Optional. By default, the cost value is calculated through the formula Reference bandwidth/Interface bandwidth.

Configure the OSPFv3 Reference Bandwidth

The reference bandwidth of an interface is used to calculate the cost value of the interface. The default value is 100Mbit/s. The formula for calculating the cost value of the OSPFv3 interface is: Reference bandwidth/Interface bandwidth. If the calculation result is larger than 1, use the integer part. If the calculation result is smaller than 1, use the value 1. Therefore, in a network whose bandwidth is larger than 100Mbit/s, the optimal route fails to be selected. In this case, you can use the auto-cost reference-bandwidth command to configure a proper reference bandwidth to solve the problem.

Table 8-20 Configure the OSPFv3 reference bandwidth

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configuring the OSPFv3 reference bandwidth.	auto-cost reference-bandwidth reference-bandwidth	Optional. By default, the reference bandwidth is 100Mbit/s

Configure the OSPFv3 Administrative Distance

An administrative distance is used to indicate the reliability of the routing protocol. If the routes to the same destination network are learnt by different routing protocols, the route with the smallest administrative distance is selected first.

Table 8-21 Configure the OSPFv3 administrative distance

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configure the OSPFv3 administrative distance.	distance [ ospf { external distance / inter-area distance / intra-area distance } \| distance ]	Optional. By default, the administrative distance of intra-area and inter-area OSPFv3 routes is 110, and the administrative distance of external routes is 150

Configure the Maximum Number of OSPFv3 Load Balancing Routes

If multiple equivalent paths are available to reach the same destination, load balancing is achieved. This improves the utility rate of links and reduces the load of the links.

Table 8-22 Configure the maximum number of OSPFv3 load balancing routes

Step	Command	Description
Enter the global configuration mode.	configure terminal	-
Enter the OSPFv3 configuration mode.	ipv6 router ospf process-id [vrf vrf-name ]	-
Configure the maximum number of OSPFv3 load balancing routes.	maximum-paths max-number	Optional. By default, the maximum number of OSPFv3 load balancing routes is 4.