拓扑图：
基本配置省略，关键配置写一遍：
R1：
router ospf 110
router-id 91.1.1.1
network 12.1.1.1 0.0.0.0 area 1
network 1.1.1.1 0.0.0.0 area 1
R2:
router ospf 110
router-id 92.2.2.2
network 12.1.1.2 0.0.0.0 area 1
network 23.1.1.2 0.0.0.0 area 0
network 2.2.2.2 0.0.0.0 area 0
R3:
router ospf 110
router-id 93.3.3.3
network 23.1.1.3 0.0.0.0 area 0
network 34.1.1.3 0.0.0.0 area 2
network 3.3.3.3 0.0.0.0 area 2
R4:
router ospf 110
router-id 94.4.4.4
network 34.1.1.4 0.0.0.0 area 2
network 4.4.4.4 0.0.0.0 area 2
router rip
version 2
no auto-summary
network 45.0.0.0
R5:
router rip
version 2
no auto-summary
network 45.0.0.0
network 5.0.0.0
现在我们来对第一类LSA router LSA进行深入一点了解：
1、只能在自己的区域内部泛洪，不能出ABR
show ip ospf database
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
91.1.1.1 91.1.1.1 271 0x80000002 0x005AF7 3
92.2.2.2 92.2.2.2 272 0x80000001 0x004F13 2
我们看到属于area 1的两个路由器R1、R2,他们通告了什么拓扑信息？
具体看下，show ip ospf database router
这个范围有点大，我们只看R1的：show ip ospf database router adv-router 91.1.1.1
OSPF Router with ID (91.1.1.1) (Process ID 110)
Router Link States (Area 1)
LS age: 1261
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 91.1.1.1
Advertising Router: 91.1.1.1
LS Seq Number: 80000002
Checksum: 0x5AF7
Length: 60
Number of Links: 3
Link connected to: a Stub Network
(Link ID) Network/subnet number: 1.1.1.1
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1
Link connected to: another Router (point-to-point)
(Link ID) Neighboring Router ID: 92.2.2.2
(Link Data) Router Interface address: 12.1.1.1
Number of TOS metrics: 0
TOS 0 Metrics: 64
Link connected to: a Stub Network
(Link ID) Network/subnet number: 12.1.1.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 64
这里串口链接和环回口都被当做a Stub Network
该类LSA，只宣告路由器的直连网段的拓扑信息，包括前缀、掩码、度量值、链路类型
哦，忘了一点。刚才我在邻接关系创立之后，想修改RID，必须先clear ip ospf process，清除
OSPF进程数据，才可以生效。
接着，我们来研究下第二类LSA，也就是Network LSA，该LSA不出现在point-to-point链路类型中
呵呵，不好意思哦，该拓扑中没有以太网类型的链路，所以看不到了哦
还是看第三类LSA summary network LSA
传输范围：除了产生该LSA的区域外，都会泛洪
OSPF Router with ID (92.2.2.2) (Process ID 110)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
92.2.2.2 92.2.2.2 58 0x80000003 0x00F137 3
93.3.3.3 93.3.3.3 1986 0x80000001 0x007EC0 2
Summary Net Link States (Area 0)在区域0内的3类LSA
Link ID ADV Router Age Seq# Checksum
1.1.1.1 92.2.2.2 58 0x80000002 0x007C18
3.3.3.3 93.3.3.3 1981 0x80000001 0x008148
4.4.4.4 93.3.3.3 1981 0x80000001 0x00D5AF
12.1.1.0 92.2.2.2 58 0x80000002 0x00EC9E
34.1.1.0 93.3.3.3 1981 0x80000001 0x00B1C0
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
91.1.1.1 91.1.1.1 130 0x80000003 0x0058F8 3
92.2.2.2 92.2.2.2 58 0x80000002 0x004D14 2
Summary Net Link States (Area 1)这是区域1内3类LSA
Link ID ADV Router Age Seq# Checksum
2.2.2.2 92.2.2.2 58 0x80000002 0x00CB05
3.3.3.3 92.2.2.2 124 0x80000004 0x001C6E
4.4.4.4 92.2.2.2 124 0x80000004 0x0070D5
23.1.1.0 92.2.2.2 124 0x80000002 0x005D23
34.1.1.0 92.2.2.2 124 0x80000004 0x004CE6
我们看下R1的区域1的LSDB是否一样?show下，show ip ospf database
OSPF Router with ID (91.1.1.1) (Process ID 110)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
91.1.1.1 91.1.1.1 32 0x80000003 0x0058F8 3
92.2.2.2 92.2.2.2 1914 0x80000001 0x004F13 2
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
2.2.2.2 92.2.2.2 1909 0x80000001 0x00CD04
3.3.3.3 92.2.2.2 1879 0x80000003 0x001E6D
4.4.4.4 92.2.2.2 1879 0x80000003 0x0072D4
23.1.1.0 92.2.2.2 1909 0x80000001 0x005F22
34.1.1.0 92.2.2.2 1879 0x80000003 0x004EE5
呵呵，看到了吧，是完全一样的哦！
这里LSA的通告者就是该AS内的ABR，经过一个ABR，再次发送的时候，通告者将修改为该ABR路由器
这里通告的内容是纯路由信息。让我们看一下，这里具体的通告内容：
show ip ospf database summary
OSPF Router with ID (91.1.1.1) (Process ID 110)
Summary Net Link States (Area 1)
Routing Bit Set on this LSA
LS age: 699
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 2.2.2.2 (summary Network Number)
Advertising Router: 92.2.2.2
LS Seq Number: 80000002
Checksum: 0xCB05
Length: 28
Network Mask: /32
TOS: 0 Metric: 1
Routing Bit Set on this LSA
LS age: 699
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 3.3.3.3 (summary Network Number)
Advertising Router: 92.2.2.2
LS Seq Number: 80000004
Checksum: 0x1C6E
Length: 28
Network Mask: /32
TOS: 0 Metric: 65
Routing Bit Set on this LSA
LS age: 730
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 4.4.4.4 (summary Network Number)
Advertising Router: 92.2.2.2
LS Seq Number: 80000004
Checksum: 0x70D5
Length: 28
Network Mask: /32
TOS: 0 Metric: 129
Routing Bit Set on this LSA
LS age: 732
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 23.1.1.0 (summary Network Number)
Advertising Router: 92.2.2.2
LS Seq Number: 80000002
Checksum: 0x5D23
Length: 28
Network Mask: /24
TOS: 0 Metric: 64
Routing Bit Set on this LSA
LS age: 734
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 34.1.1.0 (summary Network Number)
Advertising Router: 92.2.2.2
LS Seq Number: 80000004
Checksum: 0x4CE6
Length: 28
Network Mask: /24
TOS: 0 Metric: 128
有网络前缀，掩码，度量值
2类LSA一般在MA网络类型中出现，需要选举DR，传输范围也在一个区域内，不能跨区域ABR
R2 Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
100.1.1.3 93.3.3.3 4 0x80000001 0x00EEB2
R3 Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
100.1.1.3 93.3.3.3 55 0x80000001 0x00EEB2
呵呵，看到了吗？2类LSA的LSDB也是一样的。Link-id就是DR的物理接口IP地址。通告者的RID也是
DR的RID
宣告的也是纯拓扑信息，包含内容：show ip ospf database network
OSPF Router with ID (93.3.3.3) (Process ID 110)
Net Link States (Area 0)
Routing Bit Set on this LSA
LS age: 261
Options: (No TOS-capability, DC)
LS Type: Network Links
Link State ID: 100.1.1.3 (address of Designated Router)
Advertising Router: 93.3.3.3
LS Seq Number: 80000001
Checksum: 0xEEB2
Length: 32
Network Mask: /24
Attached Router: 93.3.3.3
Attached Router: 92.2.2.2
有网络掩码，直连的路由器ID
下面就是看看5类LSA 也就是外部LSA，需要将该拓扑中RIP路由宣告进OSPF进程中
R4：
router ospf 110
redistribute rip subnets
查看R1 show ip ospf database，看看多了什么？
OSPF Router with ID (91.1.1.1) (Process ID 110)
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
91.1.1.1 91.1.1.1 1637 0x80000003 0x0058F8 3
92.2.2.2 92.2.2.2 1568 0x80000002 0x004D14 2
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
2.2.2.2 92.2.2.2 1568 0x80000002 0x00CB05
3.3.3.3 92.2.2.2 436 0x80000005 0x00FBC3
4.4.4.4 92.2.2.2 436 0x80000005 0x00502B
23.1.1.0 92.2.2.2 1568 0x80000002 0x005D23
34.1.1.0 92.2.2.2 436 0x80000005 0x002C3C
100.1.1.0 92.2.2.2 505 0x80000001 0x005416
Summary ASB Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
94.4.4.4 92.2.2.2 3 0x80000001 0x00A97B
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
5.5.5.0 94.4.4.4 10 0x80000001 0x008D99 0
45.1.1.0 94.4.4.4 14 0x80000001 0x00DF27 0
是不是多出了两个不同类型的LSA，summary ASB就是四类LSA，用来通告谁是ASBR
而下面type-5 就是 AS External LSA就是AS域外LSA
我们看RIP进程的路由宣告进了OSPF了。它的传输范围是整个AS域内
通告者就是ASBR，在这里就是R4
通告内容为纯路由信息，看下和3类LSA的纯路由信息有什么不同
show ip ospf database external
OSPF Router with ID (91.1.1.1) (Process ID 110)
Type-5 AS External Link States
Routing Bit Set on this LSA
LS age: 336
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 5.5.5.0 (External Network Number )
Advertising Router: 94.4.4.4
LS Seq Number: 80000001
Checksum: 0x8D99
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
Routing Bit Set on this LSA
LS age: 336
Options: (No TOS-capability, DC)
LS Type: AS External Link
Link State ID: 45.1.1.0 (External Network Number )
Advertising Router: 94.4.4.4
LS Seq Number: 80000001
Checksum: 0xDF27
Length: 36
Network Mask: /24
Metric Type: 2 (Larger than any link state path)
TOS: 0
Metric: 20
Forward Address: 0.0.0.0
External Route Tag: 0
呵呵，还是大不同的啊！metric type 是2，
在路由表，我们看下该条路由是什么样子的？
O E2 5.5.5.0 [110/20] via 12.1.1.2, 00:08:42, Serial1/0
呵呵，它就是external type 2，也就是刚才metric type 2，这个2有什么意思？
看看它的度量值是20，我们在看下R2的度量值有什么不同。
O E2 5.5.5.0 [110/20] via 100.1.1.3, 00:10:34, FastEthernet0/0
看到了吧，也就是度量值在每个域内的路由器上都是20，这就是seed metric，固定值
如果需要精确度量的话，需要修改为type 1
那怎么修改呢？在哪里修改呢？
因为通告者是ASBR，也就是R4，所以seed metric值也需要在R4上修改
命令如下：
router ospf 110
redistribute rip subnets metric-type 1 metric 具体的度量值
O E1 5.5.5.0 [110/158] via 12.1.1.2, 00:00:15, Serial1/0
23.0.0.0/24 is subnetted, 1 subnets
再看R2上的
5.0.0.0/24 is subnetted, 1 subnets
O E1 5.5.5.0 [110/94] via 100.1.1.3, 00:00:56, FastEthernet0/0
呵呵，看到了吧，度量值随着路由器而改变
下面讲下四类LSA，也就是 summary asb LSA
Summary ASB Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
94.4.4.4 92.2.2.2 1183 0x80000001 0x00A97B
传输范围就是除ASBR所在区域外，通告者为每个区域的ABR，link-id就是ASBR的RID
查看R2的
Summary ASB Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
94.4.4.4 93.3.3.3 1267 0x80000001 0x002704
呵呵，通告者是变化的哦，记住了！
