目录
第一章 OSPF协议特性与配置
实验 1-3 OSPF的邻接关系和LSA
学习目的
·了解四个OSPF邻居路由器在以太网上邻居关系建立的过程
·掌握对OSPF的DR的选举进行干预的方法
·观察5种类型的LSA的内容，以及它们的作用
·了解OSPF的LSR、LSU、LSAck数据包的相互发送情况
拓扑图
图1-3 OSPF的邻接关系和LSA
场景
你是公司的网络管理员。现在公司的网络中有五台AR G3路由器，其中R1、R2、R3和R4在公司总部，通过以太网互联。R5在公司分部，R3通过专线与公司总部的R3相连。由于网络规模较大，为了控制LSA的洪泛，你设计了多区域的OSPF互联方式。
其中R1的Loopback0接口属于区域2。R2、R3、R4的Loopback0接口与10.1.234.0/24网段属于区域0。R3与R5之间互联的网段属于区域1。R5的Loopback0接口属于OSPF外部网络。
同时为了明确设备的Router ID，你配置设备使用固定的地址作为Router ID。
在R1、R2、R3与R4之间互联的网络上，需要干预DR与BDR的选举。实际使用中将R3定义为DR、R2定义为BDR。R4设备定义为DROther。
学习任务
步骤一.基础配置与IP编址
给所有路由器配置IP地址和掩码。配置时注意所有的Loopback接口配置掩码均为24位，模拟成一个单独的网段。
<R1>system-view
Enter system view, return user view with Ctrl+Z.
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]ip address 10.1.234.1 24
[R1-GigabitEthernet0/0/0]quit
[R1]interface LoopBack 0
[R1-LoopBack0]ip address 10.0.1.1 24
[R1-LoopBack0]quit
<R2>system-view
Enter system view, return user view with Ctrl+Z.
[R2]interface GigabitEthernet 0/0/0
[R2-GigabitEthernet0/0/0]ip address 10.1.234.2 24
[R2-GigabitEthernet0/0/0]quit
[R2]interface LoopBack 0
[R2-LoopBack0]ip address 10.0.2.2 24
[R2-LoopBack0]quit
<R3>system-view
Enter system view, return user view with Ctrl+Z.
[R3]interface GigabitEthernet 0/0/0
[R3-GigabitEthernet0/0/0]ip address 10.1.234.3 24
[R3-GigabitEthernet0/0/0]quit
[R3]interface Serial 3/0/0
[R3-Serial3/0/0]ip address 10.0.35.3 24
[R3-Serial3/0/0]quit
[R3]interface LoopBack 0
[R3-LoopBack0]ip address 10.0.3.3 24
[R3-LoopBack0]quit
<R4>system-view
Enter system view, return user view with Ctrl+Z.
[R4]interface GigabitEthernet 0/0/0
[R4-GigabitEthernet0/0/0]ip address 10.1.234.4 24
[R4-GigabitEthernet0/0/0]quit
[R4]interface LoopBack 0
[R4-LoopBack0]ip address 10.0.4.4 24
[R4-LoopBack0]quit
<R5>system-view
Enter system view, return user view with Ctrl+Z.
[R5]interface Serial 1/0/0
[R5-Serial1/0/0]ip address 10.0.35.5 24
[R5-Serial1/0/0]quit
[R5]interface LoopBack 0
[R5-LoopBack0]ip address 10.0.5.5 24
[R5-LoopBack0]quit
配置完成后，测试直连链路的连通性。
[R1]ping -c 1 10.1.234.2
PING 10.1.234.2: 56 data bytes, press CTRL_C to break
Reply from 10.1.234.2: bytes=56 Sequence=1 ttl=255 time=13 ms
--- 10.1.234.2 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 13/13/13 ms
[R1]ping -c 1 10.1.234.4
PING 10.1.234.4: 56 data bytes, press CTRL_C to break
Reply from 10.1.234.4: bytes=56 Sequence=1 ttl=255 time=6 ms
--- 10.1.234.4 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 6/6/6 ms
[R3]ping -c 1 10.1.234.1
PING 10.1.234.1: 56 data bytes, press CTRL_C to break
Reply from 10.1.234.1: bytes=56 Sequence=1 ttl=255 time=13 ms
--- 10.1.234.1 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 13/13/13 ms
[R3]ping -c 1 10.0.35.5
PING 10.0.35.5: 56 data bytes, press CTRL_C to break
Reply from 10.0.35.5: bytes=56 Sequence=1 ttl=255 time=32 ms
--- 10.0.35.5 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 32/32/32 ms
步骤二.配置多区域OSPF
在R1上配置GigabitEthernet 0/0/0属于区域0，Loopback 0属于区域2。对所有OSPF区域的Loopback接口，修改其OSPF网络类型为Broadcast类型，以便于OSPF发布Loopback口的真实掩码信息。
[R1]ospf 1 router-id 10.0.1.1
[R1-ospf-1]area 0
[R1-ospf-1-area-0.0.0.0]network 10.1.234.1 0.0.0.0
[R1-ospf-1-area-0.0.0.0]quit
[R1-ospf-1]area 2
[R1-ospf-1-area-0.0.0.2]network 10.0.1.1 0.0.0.0
[R1-ospf-1-area-0.0.0.2]quit
[R1-ospf-1]quit
[R1]interface LoopBack 0
[R1-LoopBack0]ospf network-type broadcast
[R1-LoopBack0]quit
R2、R4的所有接口均位于区域0中。
[R2]ospf 1 router-id 10.0.2.2
[R2-ospf-1]area 0
[R2-ospf-1-area-0.0.0.0]network 10.1.234.2 0.0.0.0
[R2-ospf-1-area-0.0.0.0]network 10.0.2.2 0.0.0.0
[R2-ospf-1-area-0.0.0.0]quit
[R2-ospf-1]quit
[R2-]interface LoopBack 0
[R2-LoopBack0]ospf network-type broadcast
[R2-LoopBack0]quit
[R4]ospf 1 router-id 10.0.4.4
[R4-ospf-1]area 0
[R4-ospf-1-area-0.0.0.0]network 10.1.234.4 0.0.0.0
[R4-ospf-1-area-0.0.0.0]network 10.0.4.4 0.0.0.0
[R4-ospf-1-area-0.0.0.0]quit
[R4-ospf-1]quit
[R4-]interface LoopBack 0
[R4-LoopBack0]ospf network-type broadcast
[R4-LoopBack0]quit
在R3上配置Loopback 0和GigabitEthernet 0/0/0属于区域0，Serial 3/0/0属于区域2。
[R3]ospf 1 router-id 10.0.3.3
[R3-ospf-1]area 0
[R3-ospf-1-area-0.0.0.0]network 10.1.234.3 0.0.0.0
[R3-ospf-1-area-0.0.0.0]network 10.0.3.3 0.0.0.0
[R3-ospf-1-area-0.0.0.0]quit
[R3-ospf-1]area 1
[R3-ospf-1-area-0.0.0.1]network 10.0.35.3 0.0.0.0
[R3-ospf-1-area-0.0.0.1]quit
[R3-ospf-1]quit
[R3]interface LoopBack 0
[R3-LoopBack0]ospf network-type broadcast
[R3-LoopBack0]quit
在R5上配置Serial 1/0/0属于区域1，Loopback 0不属于任何区域。
[R5]osp 1 router-id 10.0.5.5
[R5-ospf-1]area 1
[R5-ospf-1-area-0.0.0.1]network 10.0.35.5 0.0.0.0
[R5-ospf-1-area-0.0.0.1]quit
[R5-ospf-1]quit
配置完成后，在R1查看设备的路由表。
[R1]display ip routing-table
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Routing Tables: Public
Destinations : 14 Routes : 14
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.1.0/24 Direct 0 0 D 10.0.1.1 LoopBack0
10.0.1.1/32 Direct 0 0 D 127.0.0.1 LoopBack0
10.0.1.255/32 Direct 0 0 D 127.0.0.1 LoopBack0
10.0.2.0/24 OSPF 10 1 D 10.1.234.2 GigabitEthernet0/0/0
10.0.3.0/24 OSPF 10 1 D 10.1.234.3 GigabitEthernet0/0/0
10.0.4.0/24 OSPF 10 1 D 10.1.234.4 GigabitEthernet0/0/0
10.0.35.0/24 OSPF 10 1563 D 10.1.234.3 GigabitEthernet0/0/0
10.1.234.0/24 Direct 0 0 D 10.1.234.1 GigabitEthernet0/0/0
10.1.234.1/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/0
10.1.234.255/32 Direct 0 0 D 127.0.0.1 GigabitEthernet0/0/0
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
127.255.255.255/32Direct 0 0 D 127.0.0.1 InLoopBack0
255.255.255.255/32Direct 0 0 D 127.0.0.1 InLoopBack0
除了没有发布进OSPF的网络10.0.5.5/24，在R1上已拥有全网的路由表。
测试网络的连通性。
[R1]ping -c 1 10.0.2.2
PING 10.0.2.2: 56 data bytes, press CTRL_C to break
Reply from 10.0.2.2: bytes=56 Sequence=1 ttl=255 time=2 ms
--- 10.0.2.2 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 2/2/2 ms
[R1]ping -c 1 10.0.4.4
PING 10.0.4.4: 56 data bytes, press CTRL_C to break
Reply from 10.0.4.4: bytes=56 Sequence=1 ttl=255 time=3 ms
--- 10.0.4.4 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 3/3/3 ms
[R3]ping -c 1 10.0.1.1
PING 10.0.1.1: 56 data bytes, press CTRL_C to break
Reply from 10.0.1.1: bytes=56 Sequence=1 ttl=255 time=3 ms
--- 10.0.1.1 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 3/3/3 ms
在R1使用display ospf brief命令查看路由器运行的基本OSPF信息。我们可以看到，由于R1的Loopback 0接口位于区域2中，所以R1成为了一台ABR。R1的GigabitEthernet 0/0/0接口所连接的网络为广播型网络，且R1为这个网段的DR。
[R1]display ospf brief
OSPF Process 1 with Router ID 10.0.1.1
OSPF Protocol Information
RouterID: 10.0.1.1 Border Router: AREA
Multi-VPN-Instance is not enabled
Global DS-TE Mode: Non-Standard IETF Mode
Graceful-restart capability: disabled
Helper support capability : not configured
Applications Supported: MPLS Traffic-Engineering
Spf-schedule-interval: max 10000ms, start 500ms, hold 1000ms
Default ASE parameters: Metric: 1 Tag: 1 Type: 2
Route Preference: 10
ASE Route Preference: 150
SPF Computation Count: 22
RFC 1583 Compatible
Retransmission limitation is disabled
Area Count: 2 Nssa Area Count: 0
ExChange/Loading Neighbors: 0
Process total up interface count: 2
Process valid up interface count: 1
Area: 0.0.0.0 (MPLS TE not enabled)
Authtype: None Area flag: Normal
SPF scheduled Count: 22
ExChange/Loading Neighbors: 0
Router ID conflict state: Normal
Area interface up count: 1
Interface: 10.1.234.1 (GigabitEthernet0/0/0)
Cost: 1 State: DR Type: Broadcast MTU: 1500
Priority: 1
Designated Router: 10.1.234.1
Backup Designated Router: 10.1.234.2
Timers: Hello 10 , Dead 40 , Poll 120 , Retransmit 5 , Transmit Delay 1
Area: 0.0.0.2 (MPLS TE not enabled)
Authtype: None Area flag: Normal
SPF scheduled Count: 20
ExChange/Loading Neighbors: 0
Router ID conflict state: Normal
Area interface up count: 1
Interface: 10.0.1.1 (LoopBack0)
Cost: 0 State: DR Type: Broadcast MTU: 1500
Priority: 1
Designated Router: 10.0.1.1
Backup Designated Router: 0.0.0.0
Timers: Hello 10 , Dead 40 , Poll 120 , Retransmit 5 , Transmit Delay 1
使用display ospf peer brief命令查看路由器的OSPF邻居关系建立情况。由于R1是DR，所以它与该网段的所有路由器形成邻接关系。在R3上查看邻居就可以发现R3和R4之间仅存在邻居关系，而没有邻接关系。
[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
----------------------------------------------------------------------------
[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
0.0.0.1 Serial3/0/0 10.0.5.5 Full
----------------------------------------------------------------------------
在R5上使用display ospf lsdb命令查看路由器的OSPF数据库信息。
[R5]display ospf lsdb
OSPF Process 1 with Router ID 10.0.5.5
Link State Database
Area: 0.0.0.1
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 10.0.5.5 10.0.5.5 1182 48 80000002 1562
Router 10.0.3.3 10.0.3.3 1183 48 80000002 1562
Sum-Net 10.0.3.0 10.0.3.3 1429 28 80000001 0
Sum-Net 10.0.2.0 10.0.3.3 1429 28 80000001 1
Sum-Net 10.0.1.0 10.0.3.3 1429 28 80000001 1
Sum-Net 10.1.234.0 10.0.3.3 1429 28 80000001 1
Sum-Net 10.0.4.0 10.0.3.3 1430 28 80000001 1
可以看到由于在区域1中仅存在2台路由器，所以在R5的lsdb中，仅存在2条第一类LSA，剩余的5条第三类LSA是由R3向R5通告的区域间路由。
在R2上使用display ospf lsdb命令查看路由器的OSPF数据库信息。
[R2]display ospf lsdb
OSPF Process 1 with Router ID 10.0.2.2
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 4 48 80000009 1
Router 10.0.4.4 10.0.4.4 150 48 80000009 1
Router 10.0.2.2 10.0.2.2 149 48 8000000C 1
Router 10.0.1.1 10.0.1.1 149 36 8000000B 1
Network 10.1.234.1 10.0.1.1 149 40 80000007 0
Sum-Net 10.0.35.0 10.0.3.3 1790 28 80000001 1562
Sum-Net 10.0.1.0 10.0.1.1 817 28 80000002 0
在R2上除了4条第一类LSA以外，还有一条第二类LSA。R2的GigabitEthernet 0/0/0所连接的是一个广播型网络，该网络上的DR会产生一条第二类LSA来描述所有的邻居。在这里可以从AdvRouter字段得知生成这条LSA的路由器是R1，符合R1是该网段DR的结果。
在R1上使用display ospf lsdb命令查看路由器的OSPF数据库信息。
[R1]display ospf lsdb
OSPF Process 1 with Router ID 10.0.1.1
Link State Database
Area: 0.0.0.0
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 10.0.3.3 10.0.3.3 447 48 80000009 1
Router 10.0.4.4 10.0.4.4 592 48 80000009 1
Router 10.0.2.2 10.0.2.2 592 48 8000000C 1
Router 10.0.1.1 10.0.1.1 591 36 8000000B 1
Network 10.1.234.1 10.0.1.1 591 40 80000007 0
Sum-Net 10.0.35.0 10.0.3.3 434 28 80000002 1562
Sum-Net 10.0.1.0 10.0.1.1 1259 28 80000002 0
Area: 0.0.0.2
Type LinkState ID AdvRouter Age Len Sequence Metric
Router 10.0.1.1 10.0.1.1 1223 36 80000004 0
Sum-Net 10.0.35.0 10.0.1.1 433 28 80000002 1563
Sum-Net 10.0.3.0 10.0.1.1 541 28 80000002 1
Sum-Net 10.0.2.0 10.0.1.1 909 28 80000002 1
Sum-Net 10.1.234.0 10.0.1.1 1269 28 80000002 1
Sum-Net 10.0.4.0 10.0.1.1 711 28 80000002 1
由于R1的Loopback 0接口位于区域2中，所以R1上有2个区域的LSDB，分别是区域0和区域2的。
在R4上使用display ospf lsdb命令查看路由器的OSPF数据库信息。
[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 10.0.3.3 745 48 80000009 1
Router 10.0.4.4 10.0.4.4 888 48 80000009 1
Router 10.0.2.2 10.0.2.2 889 48 8000000C 1
Router 10.0.1.1 10.0.1.1 889 36 8000000B 1
Network 10.1.234.1 10.0.1.1 889 40 80000007 0
Sum-Net 10.0.35.0 10.0.3.3 732 28 80000002 1562
Sum-Net 10.0.1.0 10.0.1.1 1556 28 80000002 0
注意由于OSPF路由器的角色差异，OSPF链路状态数据库内容也会有所差异。对比分析R5、R2、R1与R4链路状态数据库的差异。
步骤三.修改路由器OSPF接口优先级，影响DR选举
配置R3的G0/0/0接口优先级为255，确保R3成为10.1.234.0/24网段的DR。修改R2的G0/0/0接口优先级为254，确保R2成为10.1.234.0/24网段的BDR。修改R4的G0/0/0接口优先级为0，确保R4不参加DR/BDR选举，而成为10.1.234.0/24网段的DROther。
[R3]interface GigabitEthernet 0/0/0
[R3-GigabitEthernet0/0/0]ospf dr-priority 255
[R3-GigabitEthernet0/0/0]quit
[R2]interface GigabitEthernet 0/0/0
[R2-GigabitEthernet0/0/0]ospf dr-priority 254
[R2-GigabitEthernet0/0/0]quit
[R4]interface GigabitEthernet 0/0/0
[R4-GigabitEthernet0/0/0]ospf dr-priority 0
[R4-GigabitEthernet0/0/0]quit
配置完成后，由于DR/BDR已经选举，并且DR/BDR角色不能抢占。所以必须关闭R1、R2、R3、R4的G0/0/0接口，并依次打开R3、R2、R1和R4的G0/0/0接口。
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]shutdown
[R2]interface GigabitEthernet 0/0/0
[R2-GigabitEthernet0/0/0]shutdown
[R3]interface GigabitEthernet 0/0/0
[R3-GigabitEthernet0/0/0]shutdown
[R4]interface GigabitEthernet 0/0/0
[R4-GigabitEthernet0/0/0]shutdown
[R1-GigabitEthernet0/0/0]undo shutdown
[R1-GigabitEthernet0/0/0]quit
[R2-GigabitEthernet0/0/0]undo shutdown
[R2-GigabitEthernet0/0/0]quit
[R3-GigabitEthernet0/0/0]undo shutdown
[R3-GigabitEthernet0/0/0]quit
[R4-GigabitEthernet0/0/0]undo shutdown
[R4-GigabitEthernet0/0/0]quit
查看网段10.1.234.0/24网段的DR/BDR选举情况。
[R3]display ospf peer
OSPF Process 1 with Router ID 10.0.3.3
Neighbors
Area 0.0.0.0 interface 10.1.234.3(GigabitEthernet0/0/0)'s neighbors
Router ID: 10.0.1.1 Address: 10.1.234.1
State: Full Mode:Nbr is Slave Priority: 1
DR: 10.1.234.3 BDR: 10.1.234.2 MTU: 0
Dead timer due in 29 sec
Retrans timer interval: 3
Neighbor is up for 00:02:17
Authentication Sequence: [ 0 ]
Router ID: 10.0.2.2 Address: 10.1.234.2
State: Full Mode:Nbr is Slave Priority: 254
DR: 10.1.234.3 BDR: 10.1.234.2 MTU: 0
Dead timer due in 35 sec
Retrans timer interval: 6
Neighbor is up for 00:01:14
Authentication Sequence: [ 0 ]
Router ID: 10.0.4.4 Address: 10.1.234.4
State: Full Mode:Nbr is Master Priority: 0
DR: 10.1.234.3 BDR: 10.1.234.2 MTU: 0
Dead timer due in 32 sec
Retrans timer interval: 3
Neighbor is up for 00:01:26
Authentication Sequence: [ 0 ]
Neighbors
Area 0.0.0.1 interface 10.0.35.3(Serial3/0/0)'s neighbors
Router ID: 10.0.5.5 Address: 10.0.35.5
State: Full Mode:Nbr is Master Priority: 1
DR: None BDR: None MTU: 0
Dead timer due in 27 sec
Retrans timer interval: 4
Neighbor is up for 00:53:37
Authentication Sequence: [ 0 ]
在重启接口后R3成为了该网段的DR，R2成为了BDR。
查看R4与R1的邻居关系。
[R4]display ospf peer 10.0.1.1
OSPF Process 1 with Router ID 10.0.4.4
Neighbors
Area 0.0.0.0 interface 10.1.234.4(GigabitEthernet0/0/0)'s neighbors
Router ID: 10.0.1.1 Address: 10.1.234.1
State: 2-Way Mode:Nbr is Slave Priority: 1
DR: 10.1.234.3 BDR: 10.1.234.2 MTU: 0
Dead timer due in 30 sec
Retrans timer interval: 0
Neighbor is up for 00:00:00
Authentication Sequence: [ 0 ]
当邻居关系稳定以后，由于R1和R4均为DROther路由器，所以他们之间仅形成邻居关系，保持在2-way状态。
步骤四.配置将直连路由汇总并引入到OSPF区域
R5的Loopback0接口不属于OSPF区域。将这条直连路由引入到OSPF区域。
[R5]ospf 1
[R5-ospf-1]import-route direct
[R5-ospf-1]quit
在R1和R3上查看引入的外部路由。
[R1]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 6 Routes : 6
OSPF routing table status : <Active>
Destinations : 6 Routes : 6
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.2.0/24 OSPF 10 1 D 10.1.234.2 GigabitEthernet0/0/0
10.0.3.0/24 OSPF 10 1 D 10.1.234.3 GigabitEthernet0/0/0
10.0.4.0/24 OSPF 10 1 D 10.1.234.4 GigabitEthernet0/0/0
10.0.5.0/24 O_ASE 150 1 D 10.1.234.3 GigabitEthernet0/0/0
10.0.35.0/24 OSPF 10 1563 D 10.1.234.3 GigabitEthernet0/0/0
10.0.35.3/32 O_ASE 150 1 D 10.1.234.3 GigabitEthernet0/0/0
OSPF routing table status : <Inactive>
Destinations : 0 Routes : 0
[R3]display ip routing-table protocol ospf
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : OSPF
Destinations : 5 Routes : 5
OSPF routing table status : <Active>
Destinations : 4 Routes : 4
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.1.0/24 OSPF 10 1 D 10.1.234.1 GigabitEthernet0/0/0
10.0.2.0/24 OSPF 10 1 D 10.1.234.2 GigabitEthernet0/0/0
10.0.4.0/24 OSPF 10 1 D 10.1.234.4 GigabitEthernet0/0/0
10.0.5.0/24 O_ASE 150 1 D 10.0.35.5 Serial3/0/0
OSPF routing table status : <Inactive>
Destinations : 1 Routes : 1
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.35.3/32 O_ASE 150 1 10.0.35.5 Serial3/0/0
在R1和R3上均看到2条外部路由，分别是10.0.5.0/24和10.0.35.3/32。10.0.5.0/24为R5的Loopback接口，但为什么还有一条10.0.35.3/32呢？
查看R5的路由表，由于R3和R5之间是以PPP的形式封装的，R3的Serial 3/0/0的接口地址会以直连路由的形式出现在R5的路由表里，所以在R5上运行import-route direct以后该路由条目也被发布出去了（下面的输出略去了其他路由条目）。
[R5]display ip routing-table
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Routing Tables: Public
Destinations : 16 Routes : 16
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.35.0/24 Direct 0 0 D 10.0.35.5 Serial1/0/0
10.0.35.3/32 Direct 0 0 D 10.0.35.3 Serial1/0/0
10.0.35.5/32 Direct 0 0 D 127.0.0.1 InLoopBack0
10.0.35.255/32 Direct 0 0 D 127.0.0.1 InLoopBack0
最后测试网络连通性。
[R1]ping -c 1 10.0.5.5
PING 10.0.5.5: 56 data bytes, press CTRL_C to break
Reply from 10.0.5.5: bytes=56 Sequence=1 ttl=254 time=41 ms
--- 10.0.5.5 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 41/41/41 ms
在R1上查看OSPF外部路由在链路状态数据库中的情况。我们可以看到，R1的LSDB中一共有3条外部路由：10.0.5.0/24、10.0.35.0/24、10.0.35.3/32。
在R1的路由表中看见的外部路由只有2条，另一条不见了。
[R1]display ospf lsdb ase
OSPF Process 1 with Router ID 10.0.1.1
Link State Database
Type : External
Ls id : 10.0.5.0
Adv rtr : 10.0.5.5
Ls age : 834
Len : 36
Options : E
seq# : 80000001
chksum : 0xa904
Net mask : 255.255.255.0
TOS 0 Metric: 1
E type : 2
Forwarding Address : 0.0.0.0
Tag : 1
Priority : Low
Type : External
Ls id : 10.0.35.0
Adv rtr : 10.0.5.5
Ls age : 1342
Len : 36
Options : E
seq# : 80000001
chksum : 0x5e31
Net mask : 255.255.255.0
TOS 0 Metric: 1
E type : 2
Forwarding Address : 0.0.0.0
Tag : 1
Priority : Low
Type : External
Ls id : 10.0.35.3
Adv rtr : 10.0.5.5
Ls age : 1344
Len : 36
Options : E
seq# : 80000001
chksum : 0x404c
Net mask : 255.255.255.255
TOS 0 Metric: 1
E type : 2
Forwarding Address : 0.0.0.0
Tag : 1
Priority : Medium
经过比较后，可以发现10.0.35.0/24这条路由是以内部路由的形式出现在路由表中的。
检查R1的LSDB中得第三类LSA就可以看到这个条目：10.0.35.0/24。
[R1]display ospf lsdb summary 10.0.35.0
OSPF Process 1 with Router ID 10.0.1.1
Area: 0.0.0.0
Link State Database
Type : Sum-Net
Ls id : 10.0.35.0
Adv rtr : 10.0.3.3
Ls age : 236
Len : 28
Options : E
seq# : 80000007
chksum : 0x14e5
Net mask : 255.255.255.0
Tos 0 metric: 1562
Priority : Low
Area: 0.0.0.2
Link State Database
Type : Sum-Net
Ls id : 10.0.35.0
Adv rtr : 10.0.1.1
Ls age : 1637
Len : 28
Options : E
seq# : 80000002
chksum : 0x42bf
Net mask : 255.255.255.0
Tos 0 metric: 1563
Priority : Low
可以看出，当第三类和第五类LSA通告路由的网络位和掩码相同的情况下，OSPF优选第三类LSA通告的路由加到路由表里。
步骤五.查看各种类型的LSA
在R1上查看一类LSA 10.0.1.0在Area0和Area2的详细内容。
[R1]display ospf lsdb router 10.0.1.1
OSPF Process 1 with Router ID 10.0.1.1
Area: 0.0.0.0
Link State Database
Type : Router
Ls id : 10.0.1.1
Adv rtr : 10.0.1.1
Ls age : 591
Len : 36
Options : ABR E
seq# : 8000001e
chksum : 0xbc70
Link count: 1
* Link ID: 10.1.234.3
Data : 10.1.234.1
Link Type: TransNet
Metric : 1
Area: 0.0.0.2
Link State Database
Type : Router
Ls id : 10.0.1.1
Adv rtr : 10.0.1.1
Ls age : 627
Len : 36
Options : ABR E
seq# : 80000008
chksum : 0x1018
Link count: 1
* Link ID: 10.0.1.0
Date : 255.255.255.0
Link Type: StubNet
Metric : 0
Priority: Low
对于一类LSA来说，Ls id字段表示生成这条LSA的路由器的Router ID。
R1共生成了两条第一类LSA，一条在区域0中泛洪。R1在区域0中与一个Transit网段相连，所以Link Type字段为TransNet。对于TransNet，Link ID字段为该网段上DR的接口IP地址，Data字段为本地接口的IP地址。
第二条一类LSA是R1向区域2中泛洪的，R1与区域2通过Loopback接口相连。对于Loopback接口，Link Type为StubNet，此时Link ID表示该Stub网段的IP网络地址，Data表示该Stub网段的网络掩码。
在R2、R3和R4上分别查看二类LSA 10.1.234.0在Area0的详细内容。
[R2]display ospf lsdb network 10.1.234.3
OSPF Process 1 with Router ID 10.0.2.2
Area: 0.0.0.0
Link State Database
Type : Network
Ls id : 10.1.234.3
Adv rtr : 10.0.3.3
Ls age : 115
Len : 40
Options : E
seq# : 8000000f
chksum : 0x807e
Net mask : 255.255.255.0
Priority : Low
Attached Router 10.0.3.3
Attached Router 10.0.1.1
Attached Router 10.0.2.2
Attached Router 10.0.4.4
发现在R2、R3和R4上看到的这条LSA是一样的。
同样，可以通过Adv rtr字段得知这条LSA是由R3生成的。第二类LSA 的Ls id描述的是该网段上DR的接口IP地址，Attached Router为该网段上所有路由器的Router ID。
在R1和R3上查看三类LSA 10.0.35.0/24在Area0的详细内容。
[R3]display ospf lsdb summary 10.0.35.0
OSPF Process 1 with Router ID 10.0.3.3
Area: 0.0.0.0
Link State Database
Type : Sum-Net
Ls id : 10.0.35.0
Adv rtr : 10.0.3.3
Ls age : 591
Len : 28
Options : E
seq# : 8000000a
chksum : 0xee8
Net mask : 255.255.255.0
Tos 0 metric: 1562
Priority : Low
从输出中可以看到该路由是由R3向区域0中通告的。Ls id就是通告的目的网段的网络地址，Net mask描述了目的网段的掩码信息。
[R1]display ospf lsdb summary 10.0.35.0
OSPF Process 1 with Router ID 10.0.1.1
Area: 0.0.0.0
Link State Database
Type : Sum-Net
Ls id : 10.0.35.0
Adv rtr : 10.0.3.3
Ls age : 136
Len : 28
Options : E
seq# : 80000004
chksum : 0x1ae2
Net mask : 255.255.255.0
Tos 0 metric: 1562
Priority : Low
Area: 0.0.0.2
Link State Database
Type : Sum-Net
Ls id : 10.0.35.0
Adv rtr : 10.0.1.1
Ls age : 382
Len : 28
Options : E
seq# : 80000002
chksum : 0x42bf
Net mask : 255.255.255.0
Tos 0 metric: 1563
Priority : Low
在R1上共有2条描述10.0.35.0/24的第三类LSA。其中，从Adv rtr字段我们可以得知区域0中这条LSA是R3产生的。由于R1本身也是一台ABR，所以R1收到这条LSA以后又产生了一条LSA，向区域2中通告。
在R1上查看四类LSA 10.0.5.0在Area2的详细内容。第四类LSA用于描述如何到达ASBR。
[R1]display ospf lsdb asbr 10.0.5.5
OSPF Process 1 with Router ID 10.0.1.1
Area: 0.0.0.0
Link State Database
Type : Sum-Asbr
Ls id : 10.0.5.5
Adv rtr : 10.0.3.3
Ls age : 1119
Len : 28
Options : E
seq# : 80000008
chksum : 0x1df3
Tos 0 metric: 1562
Area: 0.0.0.2
Link State Database
Type : Sum-Asbr
Ls id : 10.0.5.5
Adv rtr : 10.0.1.1
Ls age : 1118
Len : 28
Options : E
seq# : 80000008
chksum : 0x41d2
Tos 0 metric: 1563
从输出中可以看到，R1从R3收到了一条第四类LSA。Ls id用于描述ASBR的Router ID。由于这类LSA不能跨区域泛洪，所以R1又生成了一条第四类LSA向区域2中泛洪。
在R2、R4以及R3的区域0的LSDB中均存在这条LSA，因为这些路由器和ASBR（R5）不在同一个区域，他们需要通过第四类LSA来得知ASBR的位置。
[R2]display ospf lsdb asbr
OSPF Process 1 with Router ID 10.0.2.2
Area: 0.0.0.0
Link State Database
Type : Sum-Asbr
Ls id : 10.0.5.5
Adv rtr : 10.0.3.3
Ls age : 1676
Len : 28
Options : E
seq# : 80000008
chksum : 0x1df3
Tos 0 metric: 1562
在区域1中就没有这条第四类LSA，同一个区域的路由器，不需要依赖这条LSA来得知ASBR的位置。
步骤六.观察LSR、LSU和LSAck
我们首先观察OSPF的Update数据包及ACK数据包发送的过程。在R1上打开debugging ospf packet update、debugging ospf packet ack。
<R1>terminal monitor
Info: Current terminal monitor is on
<R1>terminal debugging
Info: Current terminal debugging is on
<R1>debugging ospf packet update
<R1>debugging ospf packet ack
默认情况下，网络稳定运行，OSPF路由器每30分钟更新一次。为触发查询和更新信息，我们将R3的Loopback 0接口删除。
[R3]undo interface LoopBack 0
Info: This operation may take a few seconds. Please wait for a moment...succeeded.
[R3]
Oct 25 2016 15:32:27+00:00 R3 %%01IFNET/4/LINK_STATE(l)[58]:The line protocol IP on the interface LoopBack0 has entered the DOWN state
我们可以观察到首先在R1上接收到10.1.234.3发来的Update消息，消息的目的地址为224.0.0.5（即所有OSPF路由器），描述了一个网段（# Links: 1），后面有该网段的LinkID和LinkData。
<R1>
Oct 25 2016 15:24:57.790.1+00:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178024 Line: 2271 Level: 0x20
OSPF 1: RECV Packet. Interface: GigabitEthernet0/0/0
<R1>
Oct 25 2016 15:24:57.790.2+00:00 R1 RM/6/RMDEBUG: Source Address: 10.1.234.3
Oct 25 2016 15:24:57.790.3+00:00 R1 RM/6/RMDEBUG: Destination Address: 224.0.0.5
Oct 25 2016 15:24:57.790.4+00:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 4 (Link-State Update)
Oct 25 2016 15:24:57.790.5+00:00 R1 RM/6/RMDEBUG: Length: 64, Router: 10.0.3.3
Oct 25 2016 15:24:57.790.6+00:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: d8ce
Oct 25 2016 15:24:57.790.7+00:00 R1 RM/6/RMDEBUG: AuType: 00
Oct 25 2016 15:24:57.790.8+00:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Oct 25 2016 15:24:57.790.9+00:00 R1 RM/6/RMDEBUG: # LSAS: 1
Oct 25 2016 15:24:57.790.10+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 15:24:57.790.11+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.3.3
Oct 25 2016 15:24:57.790.12+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 15:24:57.790.13+00:00 R1 RM/6/RMDEBUG: LSA Age: 1
Oct 25 2016 15:24:57.790.14+00:00 R1 RM/6/RMDEBUG: Options: ExRouting:ON
Oct 25 2016 15:24:57.790.15+00:00 R1 RM/6/RMDEBUG: Length: 36, Seq# 80000020
Oct 25 2016 15:24:57.790.16+00:00 R1 RM/6/RMDEBUG: CheckSum: 9090
Oct 25 2016 15:24:57.790.17+00:00 R1 RM/6/RMDEBUG: NtBit: 0 VBit: 0 EBit: 0 BBit: 1
Oct 25 2016 15:24:57.790.18+00:00 R1 RM/6/RMDEBUG: # Links: 1
Oct 25 2016 15:24:57.790.19+00:00 R1 RM/6/RMDEBUG: LinkID: 10.1.234.3
Oct 25 2016 15:24:57.790.20+00:00 R1 RM/6/RMDEBUG: LinkData: 10.1.234.3
Oct 25 2016 15:24:57.790.21+00:00 R1 RM/6/RMDEBUG: LinkType: 2
Oct 25 2016 15:24:57.790.22+00:00 R1 RM/6/RMDEBUG: TOS# 0 Metric 1
最后是R1自己发送的ACK报文。报文源地址为R1 GigabitEthernet 0/0/0的接口地址，目的地址为224.0.0.6。该报文是发送给DR和BDR的。该报文的序列号也是80000020。
<R1>
Oct 25 2016 15:24:58.200.1+00:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178025 Line: 4708 Level: 0x20
OSPF 1: SEND Packet. Interface: GigabitEthernet0/0/0
<R1>
Oct 25 2016 15:24:58.200.2+00:00 R1 RM/6/RMDEBUG: Source Address: 10.1.234.1
Oct 25 2016 15:24:58.200.3+00:00 R1 RM/6/RMDEBUG: Destination Address: 224.0.0.6
Oct 25 2016 15:24:58.200.4+00:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 5 (Link-State Ack)
Oct 25 2016 15:24:58.200.5+00:00 R1 RM/6/RMDEBUG: Length: 44, Router: 10.0.1.1
Oct 25 2016 15:24:58.200.6+00:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: c5ef
Oct 25 2016 15:24:58.200.7+00:00 R1 RM/6/RMDEBUG: AuType: 00
Oct 25 2016 15:24:58.200.8+00:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Oct 25 2016 15:24:58.200.9+00:00 R1 RM/6/RMDEBUG: # LSA Headers: 1
Oct 25 2016 15:24:58.200.10+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 15:24:58.200.11+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.3.3
Oct 25 2016 15:24:58.200.12+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 15:24:58.200.13+00:00 R1 RM/6/RMDEBUG: LSA Age: 2
Oct 25 2016 15:24:58.200.14+00:00 R1 RM/6/RMDEBUG: Options: ExRouting:ON
Oct 25 2016 15:24:58.200.15+00:00 R1 RM/6/RMDEBUG: Length: 36, Seq# 80000020
Oct 25 2016 15:24:58.200.16+00:00 R1 RM/6/RMDEBUG: CheckSum: 9090
接下来恢复R3上删除的Loopback0接口。
[R3]interface loopback 0
[R3-LoopBack0]ip address 10.0.3.3 24
[R3-LoopBack0]quit
和刚才一样，R1首先收到来自R3的Update报文，但这次在报文中通告了一个新的网段，所以# Links这里值为2，后面有新通告的网段的网络号和掩码。
<R1>
Oct 25 2016 15:51:26.250.1+00:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178024 Line: 2271 Level: 0x20
OSPF 1: RECV Packet. Interface: GigabitEthernet0/0/0
<R1>
Oct 25 2016 15:51:26.250.2+00:00 R1 RM/6/RMDEBUG: Source Address: 10.1.234.3
Oct 25 2016 15:51:26.250.3+00:00 R1 RM/6/RMDEBUG: Destination Address: 224.0.0.5
Oct 25 2016 15:51:26.250.4+00:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 4 (Link-State Update)
Oct 25 2016 15:51:26.250.5+00:00 R1 RM/6/RMDEBUG: Length: 76, Router: 10.0.3.3
Oct 25 2016 15:51:26.250.6+00:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: 2c6f
Oct 25 2016 15:51:26.250.7+00:00 R1 RM/6/RMDEBUG: AuType: 00
Oct 25 2016 15:51:26.250.8+00:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Oct 25 2016 15:51:26.250.9+00:00 R1 RM/6/RMDEBUG: # LSAS: 1
Oct 25 2016 15:51:26.250.10+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 15:51:26.250.11+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.3.3
Oct 25 2016 15:51:26.250.12+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 15:51:26.250.13+00:00 R1 RM/6/RMDEBUG: LSA Age: 1
Oct 25 2016 15:51:26.250.14+00:00 R1 RM/6/RMDEBUG: Options: ExRouting:ON
Oct 25 2016 15:51:26.250.15+00:00 R1 RM/6/RMDEBUG: Length: 48, Seq# 8000002a
Oct 25 2016 15:51:26.250.16+00:00 R1 RM/6/RMDEBUG: CheckSum: 2cca
Oct 25 2016 15:51:26.250.17+00:00 R1 RM/6/RMDEBUG: NtBit: 0 VBit: 0 EBit: 0 BBit: 1
Oct 25 2016 15:51:26.250.18+00:00 R1 RM/6/RMDEBUG: # Links: 2
Oct 25 2016 15:51:26.250.19+00:00 R1 RM/6/RMDEBUG: LinkID: 10.1.234.3
Oct 25 2016 15:51:26.250.20+00:00 R1 RM/6/RMDEBUG: LinkData: 10.1.234.3
Oct 25 2016 15:51:26.250.21+00:00 R1 RM/6/RMDEBUG: LinkType: 2
Oct 25 2016 15:51:26.250.22+00:00 R1 RM/6/RMDEBUG: TOS# 0 Metric 1
Oct 25 2016 15:51:26.250.23+00:00 R1 RM/6/RMDEBUG: LinkID: 10.0.3.3
Oct 25 2016 15:51:26.250.24+00:00 R1 RM/6/RMDEBUG: LinkData: 255.255.255.255
Oct 25 2016 15:51:26.250.25+00:00 R1 RM/6/RMDEBUG: LinkType: 3
Oct 25 2016 15:51:26.250.26+00:00 R1 RM/6/RMDEBUG: TOS# 0 Metric 0
R1首先收到BDR的ACK报文。
<R1>
Oct 25 2016 15:51:27.90.1+00:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178024 Line: 2271 Level: 0x20
OSPF 1: RECV Packet. Interface: GigabitEthernet0/0/0
<R1>
Oct 25 2016 15:51:27.90.2+00:00 R1 RM/6/RMDEBUG: Source Address: 10.1.234.2
Oct 25 2016 15:51:27.90.3+00:00 R1 RM/6/RMDEBUG: Destination Address: 224.0.0.5
Oct 25 2016 15:51:27.90.4+00:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 5 (Link-State Ack)
Oct 25 2016 15:51:27.90.5+00:00 R1 RM/6/RMDEBUG: Length: 44, Router: 10.0.2.2
Oct 25 2016 15:51:27.90.6+00:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: 289f
Oct 25 2016 15:51:27.90.7+00:00 R1 RM/6/RMDEBUG: AuType: 00
Oct 25 2016 15:51:27.90.8+00:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Oct 25 2016 15:51:27.90.9+00:00 R1 RM/6/RMDEBUG: # LSA Headers: 1
Oct 25 2016 15:51:27.90.10+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 15:51:27.90.11+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.3.3
Oct 25 2016 15:51:27.90.12+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 15:51:27.90.13+00:00 R1 RM/6/RMDEBUG: LSA Age: 2
Oct 25 2016 15:51:27.90.14+00:00 R1 RM/6/RMDEBUG: Options: ExRouting:ON
Oct 25 2016 15:51:27.90.15+00:00 R1 RM/6/RMDEBUG: Length: 48, Seq# 8000002a
Oct 25 2016 15:51:27.90.16+00:00 R1 RM/6/RMDEBUG: CheckSum: 2cca
最后是R1自己发送的ACK报文。
<R1>
Oct 25 2016 15:51:26.430.1+00:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178025 Line: 4708 Level: 0x20
OSPF 1: SEND Packet. Interface: GigabitEthernet0/0/0
<R1>
Oct 25 2016 15:51:26.430.2+00:00 R1 RM/6RMDEBUG: Source Address: 10.1.234.1
Oct 25 2016 15:51:26.430.3+00:00 R1 RM/6/RMDEBUG: Destination Address: 224.0.0.6
Oct 25 2016 15:51:26.430.4+00:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 5 (Link-State Ack)
Oct 25 2016 15:51:26.430.5+00:00 R1 RM/6/RMDEBUG: Length: 44, Router: 10.0.1.1
Oct 25 2016 15:51:26.430.6+00:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: 29a1
Oct 25 2016 15:51:26.430.7+00:00 R1 RM/6/RMDEBUG: AuType: 00
Oct 25 2016 15:51:26.430.8+00:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Oct 25 2016 15:51:26.430.9+00:00 R1 RM/6/RMDEBUG: # LSA Headers: 1
Oct 25 2016 15:51:26.430.10+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 15:51:26.430.11+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.3.3
Oct 25 2016 15:51:26.430.12+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 15:51:26.430.13+00:00 R1 RM/6/RMDEBUG: LSA Age: 1
Oct 25 2016 15:51:26.430.14+00:00 R1 RM/6/RMDEBUG: Options: ExRouting:ON
Oct 25 2016 15:51:26.430.15+00:00 R1 RM/6/RMDEBUG: Length: 48, Seq# 8000002a
Oct 25 2016 15:51:26.430.16+00:00 R1 RM/6/RMDEBUG: CheckSum: 2cca
在下面一个步骤中我们看Request报文。正常情况下，路由器不会主动发送该报文，为观察该报文的发送，我们将R1的OSPF进程重启。在路由器上观察到的是R1向R2发起了LS Request。
<R1>terminal monitor
Info: Current terminal monitor is on
<R1>terminal debugging
Info: Current terminal debugging is on
<R1>debugging ospf packet update
<R1>debugging ospf packet ack
<R1>debugging ospf packet request
<R1>reset ospf process
Warning: The OSPF process will be reset. Continue? [Y/N]:y
<R1>
Oct 25 2016 16:17:59.750.1+00:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178025 Line: 2993 Level: 0x20
OSPF 1: SEND Packet. Interface: GigabitEthernet0/0/0
<R1>
Oct 25 2016 16:17:59.750.2+00:00 R1 RM/6/RMDEBUG: Source Address: 10.1.234.1
Oct 25 2016 16:17:59.750.3+00:00 R1 RM/6/RMDEBUG: Destination Address: 10.1.234.2
Oct 25 2016 16:17:59.750.4+00:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 3 (Link-State Req)
Oct 25 2016 16:17:59.750.5+00:00 R1 RM/6/RMDEBUG: Length: 156, Router: 10.0.1.1
Oct 25 2016 16:17:59.750.6+00:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: 8b05
Oct 25 2016 16:17:59.750.7+00:00 R1 RM/6/RMDEBUG: AuType: 00
Oct 25 2016 16:17:59.750.8+00:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Oct 25 2016 16:17:59.750.9+00:00 R1 RM/6/RMDEBUG: # Requesting LSAs: 11
Oct 25 2016 16:17:59.750.10+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 16:17:59.750.11+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.2.2
Oct 25 2016 16:17:59.750.12+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.2.2
Oct 25 2016 16:17:59.750.13+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 16:17:59.750.14+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.1.1
Oct 25 2016 16:17:59.750.15+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.1.1
Oct 25 2016 16:17:59.750.16+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 16:17:59.750.17+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.4.4
Oct 25 2016 16:17:59.750.18+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.4.4
Oct 25 2016 16:17:59.750.19+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 16:17:59.750.20+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.3.3
Oct 25 2016 16:17:59.750.21+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 16:17:59.750.22+00:00 R1 RM/6/RMDEBUG: LSA Type 2
Oct 25 2016 16:17:59.750.23+00:00 R1 RM/6/RMDEBUG: LS ID: 10.1.234.3
Oct 25 2016 16:17:59.750.24+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 16:17:59.750.25+00:00 R1 RM/6/RMDEBUG: LSA Type 3
Oct 25 2016 16:17:59.750.26+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.1.0
Oct 25 2016 16:17:59.750.27+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.1.1
Oct 25 2016 16:17:59.750.28+00:00 R1 RM/6/RMDEBUG: LSA Type 3
Oct 25 2016 16:17:59.750.29+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.35.0
Oct 25 2016 16:17:59.750.30+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 16:17:59.750.31+00:00 R1 RM/6/RMDEBUG: LSA Type 4
Oct 25 2016 16:17:59.750.32+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.5.5
Oct 25 2016 16:17:59.750.33+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.3.3
Oct 25 2016 16:17:59.750.34+00:00 R1 RM/6/RMDEBUG: LSA Type 5
Oct 25 2016 16:17:59.750.35+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.5.0
Oct 25 2016 16:17:59.750.36+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.5.5
Oct 25 2016 16:17:59.750.37+00:00 R1 RM/6/RMDEBUG: LSA Type 5
Oct 25 2016 16:17:59.750.38+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.35.0
Oct 25 2016 16:17:59.750.39+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.5.5
Oct 25 2016 16:17:59.750.40+00:00 R1 RM/6/RMDEBUG: LSA Type 5
Oct 25 2016 16:17:59.750.41+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.35.3
Oct 25 2016 16:17:59.750.42+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.5.5
随后R1收到了来自R3的LS Request。
<R1>
Oct 25 2016 16:30:10.80.1+00:00 R1 RM/6/RMDEBUG:
FileID: 0xd0178024 Line: 2271 Level: 0x20
OSPF 1: RECV Packet. Interface: GigabitEthernet0/0/0
<R1>
Oct 25 2016 16:30:10.80.2+00:00 R1 RM/6/RMDEBUG: Source Address: 10.1.234.3
Oct 25 2016 16:30:10.80.3+00:00 R1 RM/6/RMDEBUG: Destination Address: 10.1.234.1
Oct 25 2016 16:30:10.80.4+00:00 R1 RM/6/RMDEBUG: Ver# 2, Type: 3 (Link-State Req)
Oct 25 2016 16:30:10.80.5+00:00 R1 RM/6/RMDEBUG: Length: 48, Router: 10.0.3.3
Oct 25 2016 16:30:10.80.6+00:00 R1 RM/6/RMDEBUG: Area: 0.0.0.0, Chksum: c4c2
Oct 25 2016 16:30:10.80.7+00:00 R1 RM/6/RMDEBUG: AuType: 00
Oct 25 2016 16:30:10.80.8+00:00 R1 RM/6/RMDEBUG: Key(ascii): * * * * * * * *
Oct 25 2016 16:30:10.80.9+00:00 R1 RM/6/RMDEBUG: # Requesting LSAs: 2
Oct 25 2016 16:30:10.80.10+00:00 R1 RM/6/RMDEBUG: LSA Type 1
Oct 25 2016 16:30:10.80.11+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.1.1
Oct 25 2016 16:30:10.80.12+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.1.1
Oct 25 2016 16:30:10.80.13+00:00 R1 RM/6/RMDEBUG: LSA Type 3
Oct 25 2016 16:30:10.80.14+00:00 R1 RM/6/RMDEBUG: LS ID: 10.0.1.0
Oct 25 2016 16:30:10.80.15+00:00 R1 RM/6/RMDEBUG: Adv Rtr: 10.0.1.1
附加实验: 思考并验证
假设区域2存在一台路由器R6。它计算到达10.0.5.0/24网段的路由信息与R2、R3计算该信息的步骤有什么差异？
类型4的LSA什么时候会出现？
实验中如果将R1和R4都配置成DROther，会有什么隐患？
最终设备配置
<R1>display current-configuration
[V200R007C00SPC600]
#
sysname R1
#
interface GigabitEthernet0/0/0
ip address 10.1.234.1 255.255.255.0
#
interface LoopBack0
ip address 10.0.1.1 255.255.255.0
ospf network-type broadcast
#
ospf 1 router-id 10.0.1.1
area 0.0.0.0
network 10.1.234.1 0.0.0.0
area 0.0.0.2
network 10.0.1.1 0.0.0.0
#
return
<R2>display current-configuration
[V200R007C00SPC600]
#
sysname R2
#
interface GigabitEthernet0/0/0
ip address 10.1.234.2 255.255.255.0
ospf dr-priority 254
#
interface LoopBack0
ip address 10.0.2.2 255.255.255.0
ospf network-type broadcast
#
ospf 1 router-id 10.0.2.2
area 0.0.0.0
network 10.1.234.2 0.0.0.0
network 10.0.2.2 0.0.0.0
#
return
<R3>display current-configuration
[V200R007C00SPC600]
#
sysname R3
#
interface Serial3/0/0
link-protocol ppp
ip address 10.0.35.3 255.255.255.0
#
interface GigabitEthernet0/0/0
ip address 10.1.234.3 255.255.255.0
ospf dr-priority 255
#
interface LoopBack0
ip address 10.0.3.3 255.255.255.0
ospf network-type broadcast
#
ospf 1 router-id 10.0.3.3
area 0.0.0.0
network 10.1.234.3 0.0.0.0
network 10.0.3.3 0.0.0.0
area 0.0.0.1
network 10.0.35.3 0.0.0.0
#
return
<R4>display current-configuration
[V200R007C00SPC600]
#
sysname R4
#
interface GigabitEthernet0/0/0
ip address 10.1.234.4 255.255.255.0
ospf dr-priority 0
#
interface LoopBack0
ip address 10.0.4.4 255.255.255.0
ospf network-type broadcast
#
ospf 1 router-id 10.0.4.4
area 0.0.0.0
network 10.1.234.4 0.0.0.0
network 10.0.4.4 0.0.0.0
#
return
<R5>display current-configuration
[V200R007C00SPC600]
#
sysname R5
#
interface Serial1/0/0
link-protocol ppp
ip address 10.0.35.5 255.255.255.0
#
interface LoopBack0
ip address 10.0.5.5 255.255.255.0
#
ospf 1 router-id 10.0.5.5
import-route direct
area 0.0.0.1
network 10.0.35.5 0.0.0.0
#
return