asbr-summary (OSPFv3 view)

Function

The asbr-summary command configures route summarization on an AS boundary router (ASBR).

The undo asbr-summary command disables route summarization from an ASBR.

By default, route summarization is not configured on ASBRs.

Format

asbr-summary ipv6-address prefix-length [ not-advertise | [ tag tag-value ] | [ cost cost-value ] | [ distribute-delay interval ] ] ^*

undo asbr-summary ipv6-address prefix-length

Parameters

Parameter	Description	Value
ipv6-address	Specifies the IPv6 address of a summary route.	The value is a 32-digit hexadecimal number, in the format of X:X:X:X:X:X:X:X.
prefix-length	Specifies the prefix length of a summary route.	The value is an integer ranging from 1 to 128.
not-advertise	Prevents the summary route with the specified IPv6 prefix length from being advertised.	By default, the summarized route with the specified IPv6 prefix length is advertised.
tag tag-value	Specifies the tag used to control summary route advertisement.	The value is an integer ranging from 0 to 4294967295.
cost cost-value	Specifies the cost of a summary route.	The value is an integer that ranges from 1 to 16777214. By default: For Type 1 external routes, the largest cost of the summarized routes is used as the cost of the summarized route. For Type 2 external routes, the cost of the summarized route is the maximum cost of the summarized routes plus 1.
distribute-delay interval	Specifies the delay for advertising a summary route.	The value is an integer ranging from 1 to 65535, in seconds. This parameter has no default value.

Views

OSPFv3 view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
ospf	write

Usage Guidelines

Usage Scenario

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.

If route summarization is configured on an ASBR using the asbr-summary command, the ASBR summarizes routes of imported Type 5 LSAs within the summary 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.

Precautions

The asbr-summary command applies only to ASBRs. To configure route summarization on an area border router (ABR), run the abr-summary command.
In case of a large number of summary routes, you can set a delay in advertising them by specifying distribute-delay. This ensures that the summary routes advertised each time contain more valid routes and prevents incorrect routing information in case of network flapping.

Example

# Configure an ASBR to summarize two imported OSPFv3 routes into a route with cost 20 and tag 100.

<HUAWEI> system-view
[~HUAWEI] ospfv3 1
[*HUAWEI-ospfv3-1] asbr-summary 2001:db8:1::1 16 cost 20 tag 100