配置实例:如何过滤ospf中的lsa3

ospf中的新特性，对ios的版本要求较高：

The OSPF ABR Type 3 LSA Filtering feature is supported for the following platforms in Cisco IOS
Release 12.2(4)T:
· Cisco 1400 series
· Cisco 1600 series
· Cisco 1600R series
· Cisco 1720
· Cisco 1721 (Supported in Cisco IOS Release 12.2(8)T and above.)
· Cisco 1750
· Cisco 1751
· Cisco 2500 series
· Cisco 2600 series
· Cisco 3620
· Cisco 3631 (Supported in Cisco IOS Release 12.2(8)T and above.)
· Cisco 3640
· Cisco 3745 (Supported in Cisco IOS Release 12.2(8)T and above.)
· Cisco 3660
· Cisco MC3810
· Cisco 7100 series
· Cisco 7200 series
· Cisco 7500 series (Supported in Cisco IOS Release 12.2(4)T3 and above.)
· Cisco uBR7200 series
· Universal Router Module (Supported in Cisco IOS Release 12.2(8)T.)

以下配置在abr上完成

配置步骤：

1，过滤进入某AREA的LSA3

Command Purpose
Router(config)# router ospf process-id
Configures the router to run an OSPF process.
Router(config-router)# area area-id filter-list prefixprefix-list-name in
Configures the router to filter interarea routes into the specified area.
Router(config-router)# ip prefix-list list-name [seq seq-value] deny | permit network/len [ge ge-value] [le le-value]
Creates a prefix list with the name specified for thelist-name argument.

2，过滤从某AREA出去的LSA3

Router(config)# router ospf process-id
Configures the router to run an OSPF process.
Router(config-router)# area area-id filter-list prefix prefix-list-name out
Configures the router to filter interarea routes out of the specified area.
Router(config-router)# ip prefix-list list-name [seq seq-value] deny | permit network/len [ge ge-value] [lele-value]
Creates a prefix list with the name specified for the list-name argument.

3检查配置

router# show ip ospf 1
Routing Process "ospf 1" with ID 172.16.0.1
Supports only single TOS(TOS0) routes
Supports opaque LSA
It is an area border router
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
Number of external LSA 0. Checksum Sum 0x0
Number of opaque AS LSA 0. Checksum Sum 0x0
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
External flood list length 0
Area BACKBONE(0)
Number of interfaces in this area is 2
Area has no authentication
SPF algorithm executed 6 times
Area ranges are
10.0.0.0/8 Passive Advertise
Area-filter AREA_0_IN in
Area-filter AREA_0_OUT out
Number of LSA 5. Checksum Sum 0x29450

4，配置举例

Router(config)# router ospf 1
log-adjacency-changes
area 1 filter-list prefix AREA_1_OUT out
area 3 filter-list prefix AREA_3_IN in
network 10.0.0.0 0.255.255.255 area 3
network 172.16.1.0 0.0.0.255 area 0
network 192.168.0.0 0.255.255.255 area 1
!
ip prefix-list AREA_1_OUT seq 10 permit 10.25.0.0/8 ge 16
ip prefix-list AREA_1_OUT seq 20 permit 172.20.20.0/24
!
ip prefix-list AREA_3_IN seq 10 permit 172.31.0.0/16