网络拓扑
实验任务
- 按照要求完成IP地址配置；
- 按照要求完成OSPF多区域配置；
- 检查OSPF配置结果，检查OSPF邻居关系状态，检查OSPF路由表，检查OSPF LSDB.
- 手动修改接口的DR优先级，人工干预OSPF DR、BDR的选举结果。
- 在R5上将直连路由引入到OSPF中，在R1上察Type-5LSA。
- 单独观察 Type-1 LSA、Type-2 LSA、Type-3 LSA、Type-4 LSA
- R1上通过debug观察OSPF LSU、LSAck、LSR报文。
实验步骤
配置互联IP地址和L0 IP地址
以R1路由器配置为例，其他配置方法相同：
java
interface GigabitEthernet0/0/0
ip address 10.0.123.1 255.255.255.0
#
interface LoopBack0
ip address 10.0.1.1 255.255.255.255
#
sysname R1
#
router id 10.0.1.1 配置OSPF多区域
以R1路由器配置为例，R1路由器G0/0/0接口属于Area 0，L0接口属于Area 2：
java
ospf 1 router-id 10.0.1.1
area 0.0.0.0
network 10.0.123.1 0.0.0.0
area 0.0.0.2
network 10.0.1.1 0.0.0.0 检查OSPF配置结果
以R1为例，查看OSPF邻居关系、路由表、LSDB
java
<R1>display ospf peer brief
OSPF Process 1 with Router ID 10.0.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/0 10.0.2.2 Full
0.0.0.0 GigabitEthernet0/0/0 10.0.3.3 Full
0.0.0.0 GigabitEthernet0/0/0 10.0.4.4 Full
----------------------------------------------------------------------------
<R1>display ospf interface
OSPF Process 1 with Router ID 10.0.1.1
Interfaces
Area: 0.0.0.0 (MPLS TE not enabled)
IP Address Type State Cost Pri DR BDR
10.0.123.1 Broadcast DR 1 1 10.0.123.1 10.0.123.2
Area: 0.0.0.2 (MPLS TE not enabled)
IP Address Type State Cost Pri DR BDR
10.0.1.1 P2P P-2-P 0 1 0.0.0.0 0.0.0.0 从OSPF接口状态可到在R1、R2、R3、R4广播网络中，R1的G0/0/0接口为DR（BDR为R2）。与R2、R3、R4建立邻接关系。
从R3上观察，R3与DR和BDR建立了邻接关系，与R3建立了邻居关系（2-Way）
java
<R3>display ospf peer brief
OSPF Process 1 with Router ID 10.0.3.3
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/0 10.0.1.1 Full
0.0.0.0 GigabitEthernet0/0/0 10.0.2.2 Full
0.0.0.0 GigabitEthernet0/0/0 10.0.4.4 2-Way
---------------------------------------------------------------------------- 在R4上查看LSDB
java
<R4>display ospf lsdb
OSPF Process 1 with Router ID 10.0.4.4
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 10.0.3.3 10.0.3.3 375 48 80000007 0
Router 10.0.4.4 10.0.4.4 375 48 80000005 0
Router 10.0.2.2 10.0.2.2 377 48 80000008 0
Router 10.0.1.1 10.0.1.1 377 36 8000000A 1
Network 10.0.123.1 10.0.1.1 377 40 80000006 0
Sum-Net 10.0.1.1 10.0.1.1 492 28 80000001 0
Sum-Net 10.0.45.0 10.0.4.4 370 28 80000001 1
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 10.0.5.5 10.0.5.5 308 36 80000004 1
Router 10.0.4.4 10.0.4.4 308 36 80000004 1
Network 10.0.45.2 10.0.5.5 308 32 80000002 0
Sum-Net 10.0.3.3 10.0.4.4 370 28 80000001 1
Sum-Net 10.0.2.2 10.0.4.4 370 28 80000001 1
Sum-Net 10.0.1.1 10.0.4.4 370 28 80000001 1
Sum-Net 10.0.4.4 10.0.4.4 370 28 80000001 0
Sum-Net 10.0.123.0 10.0.4.4 370 28 80000001 1 查看OSPF路由表
java
<R4>display ospf routing
OSPF Process 1 with Router ID 10.0.4.4
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
10.0.4.4/32 0 Stub 10.0.4.4 10.0.4.4 0.0.0.0
10.0.45.0/30 1 Transit 10.0.45.1 10.0.4.4 0.0.0.1
10.0.123.0/24 1 Transit 10.0.123.4 10.0.4.4 0.0.0.0
10.0.1.1/32 1 Inter-area 10.0.123.1 10.0.1.1 0.0.0.0
10.0.2.2/32 1 Stub 10.0.123.2 10.0.2.2 0.0.0.0
10.0.3.3/32 1 Stub 10.0.123.3 10.0.3.3 0.0.0.0
Total Nets: 6
Intra Area: 5 Inter Area: 1 ASE: 0 NSSA: 0 修改DR优先级
干预广播网络中DR和BDR的选举。
- 修改R4路由器G0/0/0接口DR优先级为255、修改R3路由器G0/0/0接口DR优先级为254；
- 修改R2路由器G0/0/0接口DR优先级为0，不参与DR选举；
java
# R4
interface GigabitEthernet0/0/0
ip address 10.0.123.4 255.255.255.0
ospf dr-priority 255
# R3
interface GigabitEthernet0/0/0
ip address 10.0.123.3 255.255.255.0
ospf dr-priority 254
# R2
interface GigabitEthernet0/0/0
ip address 10.0.123.2 255.255.255.0
ospf dr-priority 0 由于OSPF DR为不可抢占（ENSP测试如果将DR的接口权限修改为0，其他路由器会重新选举DR），需要重启接口或OSPF进程重新选举。
java
reset ospf 1 process重启后查看DR和BDR,可以看到R1与R3和R4建立邻接关系，此时R4为DR、R3为BDR
java
<R1>display ospf peer b
OSPF Process 1 with Router ID 10.0.1.1
Peer Statistic Information
----------------------------------------------------------------------------
Area Id Interface Neighbor id State
0.0.0.0 GigabitEthernet0/0/0 10.0.2.2 2-Way
0.0.0.0 GigabitEthernet0/0/0 10.0.3.3 Full
0.0.0.0 GigabitEthernet0/0/0 10.0.4.4 Full
---------------------------------------------------------------------------
<R1>display ospf interface
OSPF Process 1 with Router ID 10.0.1.1
Interfaces
Area: 0.0.0.0 (MPLS TE not enabled)
IP Address Type State Cost Pri DR BDR
10.0.123.1 Broadcast DROther 1 1 10.0.123.4 10.0.123.3
Area: 0.0.0.2 (MPLS TE not enabled)
IP Address Type State Cost Pri DR BDR
10.0.1.1 P2P P-2-P 0 1 0.0.0.0 0.0.0.0 引入直连路由
在R5上将L0接口路由引入OSPF，引入时进行了路由过滤只引入L0接口路由。
java
acl number 2000
rule 5 permit source 10.0.5.5 0
ospf 1 router-id 10.0.5.5
filter-policy 2000 export
import-route direct 在R1上查看外部路由信息
java
<R1>display ospf routing
OSPF Process 1 with Router ID 10.0.1.1
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
10.0.1.1/32 0 Stub 10.0.1.1 10.0.1.1 0.0.0.2
10.0.123.0/24 1 Transit 10.0.123.1 10.0.1.1 0.0.0.0
10.0.2.2/32 1 Stub 10.0.123.2 10.0.2.2 0.0.0.0
10.0.3.3/32 1 Stub 10.0.123.3 10.0.3.3 0.0.0.0
10.0.4.4/32 1 Stub 10.0.123.4 10.0.4.4 0.0.0.0
10.0.45.0/30 2 Inter-area 10.0.123.4 10.0.4.4 0.0.0.0
Routing for ASEs
Destination Cost Type Tag NextHop AdvRouter
10.0.5.5/32 1 Type2 1 10.0.123.4 10.0.5.5
Total Nets: 7
Intra Area: 5 Inter Area: 1 ASE: 1 NSSA: 0 查看Type-5 LSA
java
<R1>display ospf lsdb ase
OSPF Process 1 with Router ID 10.0.1.1
Link State Database
Type : External
Ls id : 10.0.5.5
Adv rtr : 10.0.5.5
Ls age : 253
Len : 36
Options : E
seq# : 80000001
chksum : 0x7731
Net mask : 255.255.255.255
TOS 0 Metric: 1
E type : 2
Forwarding Address : 0.0.0.0
Tag : 1
Priority : Medium Type-5 LSA说明：
- Ls id：外部路由的目的网络
- Adv rtr：通告这条LSA的Router ID
- Net mask：网络掩码
!CAUTION
在同一区域内路由器通过Type-5LSA得知这条外部路由可以通过R5到达，通过R5路由器在自己的Router LSA也描述了自己是ASBR。
但是不同区域路由器不知道R5这台路由器如何到达（Router LSA只在本区域内泛洪），怎么计算路由？
根据5类LSA，R3判断5类LSA是由R5产生，但是在R3的SPF树干中并不存在R5。
当区域内有ASBR时ABR会产生一条Type-4 LSA，描述ABR到ASBR信息。
根据R4生成的4类LSA，R3将到达外部网络的下一跳路由器设置为R4.
java
<R3>display ospf lsdb asbr
OSPF Process 1 with Router ID 10.0.3.3
Area: 0.0.0.0
Link State Database
Type : Sum-Asbr
Ls id : 10.0.5.5
Adv rtr : 10.0.4.4
Ls age : 1242
Len : 28
Options : E
seq# : 80000001
chksum : 0xec48
Tos 0 metric: 1
<R1>display ospf routing
OSPF Process 1 with Router ID 10.0.1.1
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
10.0.1.1/32 0 Stub 10.0.1.1 10.0.1.1 0.0.0.2
10.0.123.0/24 1 Transit 10.0.123.1 10.0.1.1 0.0.0.0
10.0.2.2/32 1 Stub 10.0.123.2 10.0.2.2 0.0.0.0
10.0.3.3/32 1 Stub 10.0.123.3 10.0.3.3 0.0.0.0
10.0.4.4/32 1 Stub 10.0.123.4 10.0.4.4 0.0.0.0
10.0.45.0/30 2 Inter-area 10.0.123.4 10.0.4.4 0.0.0.0
Routing for ASEs
Destination Cost Type Tag NextHop AdvRouter
10.0.5.5/32 1 Type2 1 10.0.123.4 10.0.5.5
Total Nets: 7
Intra Area: 5 Inter Area: 1 ASE: 1 NSSA: 0 观察LSR、LSU、LSAck报文
java
<R1>terminal debugging
Info: Current terminal debugging is on.
<R1>terminal monitor
Info: Current terminal monitor is on.
<R1>debugging ospf packet request
<R1>debugging ospf packet update
<R1>debugging ospf packet ack
<R1>
Jun 3 2026 09:44:44.352.1-08:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178024 Line: 2236 Level: 0x20
OSPF 1: RECV Packet. Interface: GigabitEthernet0/0/0
<R1>
Jun 3 2026 09:44:44.352.2-08:00 R1 RM/6/RMDEBUG: Source Address: 10.0.123.4
<R1>
Jun 3 2026 09:44:44.352.3-08:00 R1 RM/6/RMDEBUG: Destination Address: 224.0.0.5
<R1>
Jun 3 2026 09:44:44.352.4-08:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 4 (Link-State Update)
<R1>
Jun 3 2026 09:44:44.352.5-08:00 R1 RM/6/RMDEBUG: Length: 84, Router: 10.0.4.4
<R1>
Jun 3 2026 09:44:44.352.6-08:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: 2134
<R1>
Jun 3 2026 09:44:44.352.7-08:00 R1 RM/6/RMDEBUG: AuType: 00
<R1>
Jun 3 2026 09:44:44.352.8-08:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * * 拓展
有5类的LSA就一定会有4类LSA吗？不一定、只有一个区域的情况下没有4类LSA。
有4类的LSA就一定会有5类LSA吗？也不一定，执行了import命令即为ASBR，但是不一定会产生5类LSA。