上一章我们介绍了OSPF路由过滤的过程和原理及相关配置命令,这一章我们来详细介绍OSPF路由过滤的实验案例及注意事项。
一、过滤写入路由表的路由信息
拓扑
1、基础配置
AR1
system
sysname AR1
int g 0/0/0
ip add 10.0.12.1 24
int g 0/0/1
ip add 10.0.13.1 24
int loopback 1
ip add 1.1.1.1 32
AR2
system
sysname AR2
int g 0/0/0
ip add 10.0.12.2 24
int g 0/0/1
ip add 10.0.23.2 24
AR3
system
sysname AR3
int g 0/0/1
ip add 10.0.23.3 24
int g 0/0/0
ip add 10.0.13.3 24
int g 0/0/2
ip add 10.0.34.3 24
AR4
system
sysname AR4
int g 0/0/0
ip add 10.0.34.4 24
int loopback 1
ip add 4.4.4.4 322、路由配置
AR1
ospf 1 router-id 1.1.1.1
area 0
netw 10.0.12.1 0.0.0.0
netw 10.0.13.1 0.0.0.0
netw 1.1.1.1 0.0.0.0
AR2
ospf 1 router-id 2.2.2.2
area 0
netw 10.0.12.2 0.0.0.0
netw 10.0.23.2 0.0.0.0
AR3
ospf 1 router-id 3.3.3.3
area 0
netw 10.0.23.3 0.0.0.0
netw 10.0.13.3 0.0.0.0
area 1
netw 10.0.34.3 0.0.0.0
AR4
ospf 1 router-id 4.4.4.4
area 1
netw 10.0.34.4 0.0.0.0
netw 4.4.4.4 0.0.0.0查看OSPF邻居状态
[AR1]display ospf peer brief
OSPF Process 1 with Router ID 1.1.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/0 2.2.2.2 Full
0.0.0.0 GigabitEthernet0/0/1 3.3.3.3 Full
----------------------------------------------------------------------------
[AR2]display ospf peer brief
OSPF Process 1 with Router ID 2.2.2.2
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/0 1.1.1.1 Full
0.0.0.0 GigabitEthernet0/0/1 3.3.3.3 Full
----------------------------------------------------------------------------[AR3]display ospf peer brief
OSPF Process 1 with Router ID 3.3.3.3
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/1 2.2.2.2 Full
0.0.0.0 GigabitEthernet0/0/0 1.1.1.1 Full
0.0.0.1 GigabitEthernet0/0/2 4.4.4.4 Full
----------------------------------------------------------------------------
[AR4]display ospf peer brief
OSPF Process 1 with Router ID 4.4.4.4
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.1 GigabitEthernet0/0/0 3.3.3.3 Full
----------------------------------------------------------------------------3、过滤AR2
配置AR2过滤掉4.4.4.4的路由信息
先查看AR2此时的路由信息
[AR2]display ospf lsdb
OSPF Process 1 with Router ID 2.2.2.2
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 3534 48 80000006 1
Router 2.2.2.2 2.2.2.2 1798 48 80000009 1
Router 1.1.1.1 1.1.1.1 5 60 8000000A 1
Router 3.3.3.3 3.3.3.3 813 48 8000000C 1
Network 10.0.23.3 3.3.3.3 1799 32 80000003 0
Network 10.0.13.3 3.3.3.3 5 32 80000004 0
Network 10.0.12.2 2.2.2.2 2 32 80000004 0
Network 10.0.34.4 4.4.4.4 3534 32 80000002 0
Sum-Net 10.0.34.0 3.3.3.3 805 28 80000002 1
Sum-Net 4.4.4.4 3.3.3.3 35 28 80000001 1
[AR2]display ospf routing
OSPF Process 1 with Router ID 2.2.2.2
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
10.0.12.0/24 1 Transit 10.0.12.2 2.2.2.2 0.0.0.0
10.0.23.0/24 1 Transit 10.0.23.2 2.2.2.2 0.0.0.0
1.1.1.1/32 1 Stub 10.0.12.1 1.1.1.1 0.0.0.0
4.4.4.4/32 2 Inter-area 10.0.23.3 3.3.3.3 0.0.0.0
10.0.13.0/24 2 Transit 10.0.12.1 3.3.3.3 0.0.0.0
10.0.13.0/24 2 Transit 10.0.23.3 3.3.3.3 0.0.0.0
10.0.34.0/24 2 Inter-area 10.0.23.3 3.3.3.3 0.0.0.0
Total Nets: 7
Intra Area: 5 Inter Area: 2 ASE: 0 NSSA: 0
[AR2]display ip routing-tabl 4.4.4.4
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
4.4.4.4/32 OSPF 10 2 D 10.0.23.3 GigabitEthernet
0/0/1过滤配置
AR2
ip ip-prefix 4 deny 4.4.4.4 32
ospf 1
filter-policy ip-prefix 4 import
查看AR2的路由信息
[AR2]display ospf lsdb
OSPF Process 1 with Router ID 2.2.2.2
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 3534 48 80000006 1
Router 2.2.2.2 2.2.2.2 1798 48 80000009 1
Router 1.1.1.1 1.1.1.1 5 60 8000000A 1
Router 3.3.3.3 3.3.3.3 813 48 8000000C 1
Network 10.0.23.3 3.3.3.3 1799 32 80000003 0
Network 10.0.13.3 3.3.3.3 5 32 80000004 0
Network 10.0.12.2 2.2.2.2 2 32 80000004 0
Network 10.0.34.4 4.4.4.4 3534 32 80000002 0
Sum-Net 10.0.34.0 3.3.3.3 805 28 80000002 1
Sum-Net 4.4.4.4 3.3.3.3 35 28 80000001 1
[AR2]display ospf routing
OSPF Process 1 with Router ID 2.2.2.2
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
10.0.12.0/24 1 Transit 10.0.12.2 2.2.2.2 0.0.0.0
10.0.23.0/24 1 Transit 10.0.23.2 2.2.2.2 0.0.0.0
1.1.1.1/32 1 Stub 10.0.12.1 1.1.1.1 0.0.0.0
4.4.4.4/32 2 Inter-area 10.0.23.3 3.3.3.3 0.0.0.0
10.0.13.0/24 2 Transit 10.0.12.1 3.3.3.3 0.0.0.0
10.0.13.0/24 2 Transit 10.0.23.3 3.3.3.3 0.0.0.0
10.0.34.0/24 2 Inter-area 10.0.23.3 3.3.3.3 0.0.0.0
Total Nets: 7
Intra Area: 5 Inter Area: 2 ASE: 0 NSSA: 0
[AR2]display ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 10 Routes : 10
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.12.0/24 Direct 0 0 D 10.0.12.2 GigabitEthernet
0/0/0
10.0.12.2/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/0
10.0.12.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/0
10.0.23.0/24 Direct 0 0 D 10.0.23.2 GigabitEthernet
0/0/1
10.0.23.2/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/1
10.0.23.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/1
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0可以看到我们在配置完过滤策略后,不仅4.4.4.4/32的路由被过滤掉了并且所有通过OSPF路由协议学习到的路由都被过滤掉了,这是为什么?
因为前缀列表默认deny所有,也就是隐含了一条deny 0.0.0.0 0 greater-equal 0 less-equal 32
所以我们需要在加一条permit其他路由的前缀列表
AR2
ip ip-prefix 4 permit 0.0.0.0 0 greater-equal 0 less-equal 32查看AR2的路由信息
[AR2]display ip routing-table 4.4.4.4
[AR2]可以看到4.4.4.4/32的路由已经被过滤掉了,但OSPF的LSDB和RIB表中仍然有4.4.4.4的路由信息,这一情形可看上一章OSPF路由过滤中有详细介绍。
此时虽然我们过滤掉了4.4.4.4/32的路由但有一个问题,假如AR1去访问4.4.4.4/32时,发现走AR2更优则会将数据丢给AR2,因为这里的过滤不会过滤掉其他设备的路由信息只会过滤自身的路由信息。
但此时AR2上的4.4.4.4/32的路由信息已经被我们过滤掉了,这就形成了路由黑洞AR1所有访问4.4.4.4/32的路由都将丢包。
4、过滤AR3
通过前面的配置我们得知了在本区域内过滤掉本设备的路由信息并不会影响其他设备的路由信息,但也有例外,比如说在ABR上将路由过滤掉后,其他内部路由则无法学习到该路由信息,我们将此现象称之为"矢量特性"。
矢量特性:如果ABR自己路由表没有该LSA1/2/3产生的OSPF的路由,那么就不会向其他区域产生LSA3。
当然设计这个原理肯定有它的用意:因为如果我ABR上都没有该路由的信息,我还把他引入到区域内,区域内的路由设备计算出该路由后将数据丢给我,不是一样丢包吗,所以ABR不会向区域内产生LSA3。
在配置路由过滤前,我们先查看一下AR3与AR4的路由信息
[AR3]display ospf lsdb
OSPF Process 1 with Router ID 3.3.3.3
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 2.2.2.2 2.2.2.2 75 48 8000000A 1
Router 1.1.1.1 1.1.1.1 79 60 8000000A 1
Router 3.3.3.3 3.3.3.3 887 48 8000000C 1
Network 10.0.23.3 3.3.3.3 73 32 80000004 0
Network 10.0.13.3 3.3.3.3 78 32 80000004 0
Network 10.0.12.2 2.2.2.2 78 32 80000004 0
Sum-Net 10.0.34.0 3.3.3.3 879 28 80000002 1
Sum-Net 4.4.4.4 3.3.3.3 109 28 80000001 1
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 110 48 80000007 1
Router 3.3.3.3 3.3.3.3 815 36 80000005 1
Network 10.0.34.4 4.4.4.4 810 32 80000003 0
Sum-Net 10.0.13.0 3.3.3.3 879 28 80000002 1
Sum-Net 10.0.12.0 3.3.3.3 879 28 80000002 2
Sum-Net 10.0.23.0 3.3.3.3 879 28 80000002 1
[AR3]display ospf routing
OSPF Process 1 with Router ID 3.3.3.3
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
10.0.13.0/24 1 Transit 10.0.13.3 3.3.3.3 0.0.0.0
10.0.23.0/24 1 Transit 10.0.23.3 3.3.3.3 0.0.0.0
10.0.34.0/24 1 Transit 10.0.34.3 3.3.3.3 0.0.0.1
1.1.1.1/32 1 Stub 10.0.13.1 1.1.1.1 0.0.0.0
4.4.4.4/32 1 Stub 10.0.34.4 4.4.4.4 0.0.0.1
10.0.12.0/24 2 Transit 10.0.13.1 2.2.2.2 0.0.0.0
10.0.12.0/24 2 Transit 10.0.23.2 2.2.2.2 0.0.0.0
Total Nets: 7
Intra Area: 7 Inter Area: 0 ASE: 0 NSSA: 0
[AR3]display ip routing-table 1.1.1.1
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.1/32 OSPF 10 1 D 10.0.13.1 GigabitEthernet
0/0/0[AR4]display ospf lsdb
OSPF Process 1 with Router ID 4.4.4.4
Link State Database
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 281 48 80000007 1
Router 3.3.3.3 3.3.3.3 988 36 80000005 1
Network 10.0.34.4 4.4.4.4 982 32 80000003 0
Sum-Net 10.0.13.0 3.3.3.3 1052 28 80000002 1
Sum-Net 10.0.12.0 3.3.3.3 1052 28 80000002 2
Sum-Net 1.1.1.1 3.3.3.3 11 28 80000001 1
Sum-Net 10.0.23.0 3.3.3.3 1052 28 80000002 1
[AR4]display ospf routing
OSPF Process 1 with Router ID 4.4.4.4
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
4.4.4.4/32 0 Stub 4.4.4.4 4.4.4.4 0.0.0.1
10.0.34.0/24 1 Transit 10.0.34.4 4.4.4.4 0.0.0.1
1.1.1.1/32 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.12.0/24 3 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.13.0/24 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.23.0/24 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
Total Nets: 6
Intra Area: 2 Inter Area: 4 ASE: 0 NSSA: 0
[AR4]display ip routing-table 1.1.1.1
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.1/32 OSPF 10 2 D 10.0.34.3 GigabitEthernet
0/0/0路由过滤配置
AR3
ip ip-prefix 1 index 10 deny 1.1.1.1 32
ip ip-prefix 1 index 20 permit 0.0.0.0 0 less-equal 32
ospf 1
filter-policy ip-prefix 1 import
查看路由信息
[AR3]display ospf lsdb
OSPF Process 1 with Router ID 3.3.3.3
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 2.2.2.2 2.2.2.2 291 48 8000000A 1
Router 1.1.1.1 1.1.1.1 295 60 8000000A 1
Router 3.3.3.3 3.3.3.3 1103 48 8000000C 1
Network 10.0.23.3 3.3.3.3 289 32 80000004 0
Network 10.0.13.3 3.3.3.3 294 32 80000004 0
Network 10.0.12.2 2.2.2.2 294 32 80000004 0
Sum-Net 10.0.34.0 3.3.3.3 1095 28 80000002 1
Sum-Net 4.4.4.4 3.3.3.3 325 28 80000001 1
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 326 48 80000007 1
Router 3.3.3.3 3.3.3.3 1031 36 80000005 1
Network 10.0.34.4 4.4.4.4 1026 32 80000003 0
Sum-Net 10.0.13.0 3.3.3.3 1095 28 80000002 1
Sum-Net 10.0.12.0 3.3.3.3 1095 28 80000002 2
Sum-Net 1.1.1.1 3.3.3.3 54 28 80000001 1
Sum-Net 10.0.23.0 3.3.3.3 1095 28 80000002 1
[AR3]display ospf routing
OSPF Process 1 with Router ID 3.3.3.3
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
10.0.13.0/24 1 Transit 10.0.13.3 3.3.3.3 0.0.0.0
10.0.23.0/24 1 Transit 10.0.23.3 3.3.3.3 0.0.0.0
10.0.34.0/24 1 Transit 10.0.34.3 3.3.3.3 0.0.0.1
1.1.1.1/32 1 Stub 10.0.13.1 1.1.1.1 0.0.0.0
4.4.4.4/32 1 Stub 10.0.34.4 4.4.4.4 0.0.0.1
10.0.12.0/24 2 Transit 10.0.13.1 2.2.2.2 0.0.0.0
10.0.12.0/24 2 Transit 10.0.23.2 2.2.2.2 0.0.0.0
Total Nets: 7
Intra Area: 7 Inter Area: 0 ASE: 0 NSSA: 0
[AR3]display ip routing-table 1.1.1.1
[AR3]可以看到AR3与AR2上路由过滤后的路由信息一致,在OSPF RIB表中存在该路由的信息,但在IP RIB中则被过滤掉的该路由信息。
查看AR4的路由信息
[AR4]display ospf lsdb
OSPF Process 1 with Router ID 4.4.4.4
Link State Database
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 427 48 80000007 1
Router 3.3.3.3 3.3.3.3 1134 36 80000005 1
Network 10.0.34.4 4.4.4.4 1128 32 80000003 0
Sum-Net 10.0.13.0 3.3.3.3 1198 28 80000002 1
Sum-Net 10.0.12.0 3.3.3.3 1198 28 80000002 2
Sum-Net 10.0.23.0 3.3.3.3 1198 28 80000002 1
[AR4]display ospf routing
OSPF Process 1 with Router ID 4.4.4.4
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
4.4.4.4/32 0 Stub 4.4.4.4 4.4.4.4 0.0.0.1
10.0.34.0/24 1 Transit 10.0.34.4 4.4.4.4 0.0.0.1
10.0.12.0/24 3 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.13.0/24 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.23.0/24 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
Total Nets: 5
Intra Area: 2 Inter Area: 3 ASE: 0 NSSA: 0
[AR4]display ip routing-table
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Tables: Public
Destinations : 11 Routes : 11
Destination/Mask Proto Pre Cost Flags NextHop Interface
4.4.4.4/32 Direct 0 0 D 127.0.0.1 LoopBack1
10.0.12.0/24 OSPF 10 3 D 10.0.34.3 GigabitEthernet
0/0/0
10.0.13.0/24 OSPF 10 2 D 10.0.34.3 GigabitEthernet
0/0/0
10.0.23.0/24 OSPF 10 2 D 10.0.34.3 GigabitEthernet
0/0/0
10.0.34.0/24 Direct 0 0 D 10.0.34.4 GigabitEthernet
0/0/0
10.0.34.4/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/0
10.0.34.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet
0/0/0
127.0.0.0/8 Direct 0 0 D 127.0.0.1 InLoopBack0
127.0.0.1/32 Direct 0 0 D 127.0.0.1 InLoopBack0
127.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
255.255.255.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0可以看到我们在AR3上配置了路由过滤后,AR4上同样也被过滤掉了该路由信息。
二、过滤三类LSA
拓扑
基础配置和路由配置与上实验一致这里不过多赘述
1、过滤掉AR4的1.1.1.1/32的路由信息
查看AR4的路由信息
[AR4]display ospf lsdb
OSPF Process 1 with Router ID 4.4.4.4
Link State Database
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 497 48 80000007 1
Router 3.3.3.3 3.3.3.3 1204 36 80000005 1
Network 10.0.34.4 4.4.4.4 1198 32 80000003 0
Sum-Net 10.0.13.0 3.3.3.3 1268 28 80000002 1
Sum-Net 10.0.12.0 3.3.3.3 1268 28 80000002 2
Sum-Net 10.0.23.0 3.3.3.3 1268 28 80000002 1
[AR4]display ospf routing
OSPF Process 1 with Router ID 4.4.4.4
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
4.4.4.4/32 0 Stub 4.4.4.4 4.4.4.4 0.0.0.1
10.0.34.0/24 1 Transit 10.0.34.4 4.4.4.4 0.0.0.1
1.1.1.1/32 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.12.0/24 3 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.13.0/24 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
10.0.23.0/24 2 Inter-area 10.0.34.3 3.3.3.3 0.0.0.1
Total Nets: 6
Intra Area: 2 Inter Area: 4 ASE: 0 NSSA: 0
[AR4]display ip routing-table 1.1.1.1
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
1.1.1.1/32 OSPF 10 2 D 10.0.34.3 GigabitEthernet
0/0/0路由过滤配置
AR3
ip ip-prefix 1 index 10 deny 1.1.1.1 32
ip ip-prefix 1 index 20 permit 0.0.0.0 0 less-equal 32
ospf 1
area 0
filter ip-prefix 1 export
查看AR4的路由信息
[AR4]dis ospf lsdb
OSPF Process 1 with Router ID 4.4.4.4
Link State Database
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 4.4.4.4 4.4.4.4 412 48 8000000E 1
Router 3.3.3.3 3.3.3.3 875 36 80000008 1
Network 10.0.34.4 4.4.4.4 875 32 80000005 0
Sum-Net 10.0.13.0 3.3.3.3 875 28 80000004 1
Sum-Net 10.0.12.0 3.3.3.3 875 28 80000004 2
Sum-Net 10.0.23.0 3.3.3.3 875 28 80000004 1
三、过滤五类LSA
拓扑
基础配置与路由配置与上实验一致,这里不过多赘述
这里我们需要将AR4的直连路由以引入的方式注入到OSPF当中
AR4
ospf 1
area 1
undo netw 4.4.4.4 0.0.0.0
q
import-route direct
查看AR1上的路由信息
[AR1]display ospf lsdb
OSPF Process 1 with Router ID 1.1.1.1
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 2.2.2.2 2.2.2.2 1265 48 8000000A 1
Router 1.1.1.1 1.1.1.1 1270 60 8000000A 1
Router 3.3.3.3 3.3.3.3 278 48 8000000D 1
Network 10.0.23.3 3.3.3.3 1266 32 80000004 0
Network 10.0.13.3 3.3.3.3 1271 32 80000004 0
Network 10.0.12.2 2.2.2.2 1269 32 80000004 0
Sum-Net 10.0.34.0 3.3.3.3 526 28 80000001 1
Sum-Net 4.4.4.4 3.3.3.3 482 28 80000001 1
Sum-Asbr 4.4.4.4 3.3.3.3 20 28 80000001 1
AS External Database
Type LinkState ID AdvRouter Age Len Sequence Metric
External 10.0.34.0 4.4.4.4 21 36 80000001 1
External 4.4.4.4 4.4.4.4 21 36 80000001 1
[AR1]display ospf routing
OSPF Process 1 with Router ID 1.1.1.1
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
1.1.1.1/32 0 Stub 1.1.1.1 1.1.1.1 0.0.0.0
10.0.12.0/24 1 Transit 10.0.12.1 1.1.1.1 0.0.0.0
10.0.13.0/24 1 Transit 10.0.13.1 1.1.1.1 0.0.0.0
4.4.4.4/32 2 Inter-area 10.0.13.3 3.3.3.3 0.0.0.0
10.0.23.0/24 2 Transit 10.0.12.2 3.3.3.3 0.0.0.0
10.0.23.0/24 2 Transit 10.0.13.3 3.3.3.3 0.0.0.0
10.0.34.0/24 2 Inter-area 10.0.13.3 3.3.3.3 0.0.0.0
Total Nets: 7
Intra Area: 5 Inter Area: 2 ASE: 0 NSSA: 0
[AR1]display ip routing-table 4.4.4.4
Route Flags: R - relay, D - download to fib
------------------------------------------------------------------------------
Routing Table : Public
Summary Count : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
4.4.4.4/32 OSPF 10 2 D 10.0.13.3 GigabitEthernet
0/0/1在AR4上过滤掉4.4.4.4/32的五类LSA
为什么要在AR4上去过滤呢?
因为我们前面说了过滤LSA时,都是在产生者设备上进行过滤
AR4
ip ip-prefix 4 index 10 deny 4.4.4.4 32
ip ip-prefix 4 index 20 permit 0.0.0.0 0 less-equal 32
ospf 1
filter-policy ip-prefix 4 export
查看AR1的路由信息
[AR1]display ospf lsdb
OSPF Process 1 with Router ID 1.1.1.1
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 2.2.2.2 2.2.2.2 1763 48 8000000A 1
Router 1.1.1.1 1.1.1.1 1768 60 8000000A 1
Router 3.3.3.3 3.3.3.3 776 48 8000000D 1
Network 10.0.23.3 3.3.3.3 1764 32 80000004 0
Network 10.0.13.3 3.3.3.3 1769 32 80000004 0
Network 10.0.12.2 2.2.2.2 1767 32 80000004 0
Sum-Net 10.0.34.0 3.3.3.3 1024 28 80000001 1
Sum-Net 4.4.4.4 3.3.3.3 43 28 80000001 1
Sum-Asbr 4.4.4.4 3.3.3.3 518 28 80000001 1
AS External Database
Type LinkState ID AdvRouter Age Len Sequence Metric
External 10.0.34.0 4.4.4.4 519 36 80000001 1
[AR1]display ospf routing
OSPF Process 1 with Router ID 1.1.1.1
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
1.1.1.1/32 0 Stub 1.1.1.1 1.1.1.1 0.0.0.0
10.0.12.0/24 1 Transit 10.0.12.1 1.1.1.1 0.0.0.0
10.0.13.0/24 1 Transit 10.0.13.1 1.1.1.1 0.0.0.0
10.0.23.0/24 2 Transit 10.0.12.2 3.3.3.3 0.0.0.0
10.0.23.0/24 2 Transit 10.0.13.3 3.3.3.3 0.0.0.0
10.0.34.0/24 2 Inter-area 10.0.13.3 3.3.3.3 0.0.0.0
Total Nets: 6
Intra Area: 5 Inter Area: 1 ASE: 0 NSSA: 0
[AR1]display ip routing-table 4.4.4.4
[AR1]
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