7.1.3 链路状态数据库 <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
LSA 描述一个 OSPF 区域网络 top 的结果
Show ip ospf database 只显示 LSA 头部
Show ip ospf database database-summary 显示一个链路状态数据库当中局域区域和 LSA 类型的 LSA 通过的数量
LSA 的老化时间是 1 个小时，到了时间就删。
刷新时间是 30min ，序列号加 1 ，老化时间变成 0 ，同时如果原有的被破坏还可以替换
刷新有个机制让让他们不会一起泛洪 ~LSA 组步调
关于 LSA 类别的实验
Top 如下
Net top 配置都在附件中能找到
1、 LSA 的类型
路由器 LSA （ Router LSA ）
产生：每一台路由器（ OSPF ）都会产生路由器 LSA 通告
内容：路由器所有的链路或接口，链路和接口的状态和每条链路方向出站的代价，链路上已知的邻居
扩散范围：本区域
查看命令： show ip ospf database router
图片表述：
命令查看：
R1#sh ip ospf database router
OSPF Router with ID (1.1.1.1) (Process ID 1)
Router Link States (Area 1)
LS age: 749
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 1.1.1.1
Advertising Router: 1.1.1.1
LS Seq Number: 80000003
Checksum: 0x5205
Length: 60
Number of Links: 3
Link connected to: another Router (point-to-point)
(Link ID) Neighboring Router ID: 2.2.2.2
(Link Data) Router Interface address: 10.2.2.1
Number of TOS metrics: 0
TOS 0 Metrics: 64
Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.2.2.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 64
Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.1.1.1
(Link Data) Network Mask: 255.255.255.255
Number of TOS metrics: 0
TOS 0 Metrics: 1
Routing Bit Set on this LSA
LS age: 743
Options: (No TOS-capability, DC)
LS Type: Router Links
Link State ID: 2.2.2.2
Advertising Router: 2.2.2.2
LS Seq Number: 80000002
Checksum: 0x9ED1
Length: 48
Area Border Router
Number of Links: 2
Link connected to: another Router (point-to-point)
(Link ID) Neighboring Router ID: 1.1.1.1
(Link Data) Router Interface address: 10.2.2.2
Number of TOS metrics: 0
TOS 0 Metrics: 64
Link connected to: a Stub Network
(Link ID) Network/subnet number: 10.2.2.0
(Link Data) Network Mask: 255.255.255.0
Number of TOS metrics: 0
TOS 0 Metrics: 64
Routing Bit Set on this LSA 的意思是：到达这个目的地的路由在路由选择表中
网络LSA （Network LSA ）
产生：多路访问网络中的DR 产生网络LSA
内容：描述一个多路访问网络和与之相连的所有路由器
查看命令：show ip ospf database network
泛洪范围：本区域
图片解析：
命令查看：
R3#sh ip ospf da net
OSPF Router with ID (3.3.3.3) (Process ID 1)
Net Link States (Area 0)
Routing Bit Set on this LSA
LS age: 62
Options: (No TOS-capability, DC)
LS Type: Network Links
Link State ID: 192.168.1.2 (address of Designated Router)
Advertising Router: 3.3.3.3
LS Seq Number: 80000003
Checksum: 0x4C4B
Length: 36
Network Mask: /24
Attached Router: 3.3.3.3
Attached Router: 2.2.2.2
Attached Router: 4.4.4.4
网络汇总LSA ：（Network Summary LSA ）
产生：ABR 产生
内容：发送网络汇总LSA 到一个区域，通告区域外部的目的地址
泛洪范围：所有ospf 区域
查看命令：show ip ospf database summary
图片解析：
注意这张图片你可以清楚的看明白，这边给出的是度量！度量（只有在距离矢量的情况下才会直接给路由的）！不再是链路的状态！所以OSPF 在多区域的时候其实不是纯粹的链路状态协议
这边区域之就是距离矢量
这边有放环机制，这机制就是区域之间只能通过区域0 进行数据交换。防止了大家相互说的一个情况（这个容易形成环路）
命令查看：
R2#sh ip ospf database summary
OSPF Router with ID (2.2.2.2) (Process ID 1)
Summary Net Link States (Area 0)
LS age: 722
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 10.1.1.1 (summary Network Number)
Advertising Router: 2.2.2.2
LS Seq Number: 80000002
Checksum: 0x34B1
Length: 28
Network Mask: /32
TOS: 0 Metric: 65
LS age: 722
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 10.2.2.0 (summary Network Number)
Advertising Router: 2.2.2.2
LS Seq Number: 80000002
Checksum: 0x1DC8
Length: 28
Network Mask: /24
TOS: 0 Metric: 64
Routing Bit Set on this LSA
LS age: 613
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 172.16.1.0 (summary Network Number)
Advertising Router: 4.4.4.4
LS Seq Number: 80000002
Checksum: 0x12D
Length: 28
Network Mask: /24
TOS: 0 Metric: 64
Routing Bit Set on this LSA
LS age: 613
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 172.16.2.1 (summary Network Number)
Advertising Router: 4.4.4.4
LS Seq Number: 80000002
Checksum: 0x73F7
Length: 28
Network Mask: /32
TOS: 0 Metric: 1
Summary Net Link States (Area 1)
LS age: 471
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 172.16.1.0 (summary Network Number)
Advertising Router: 2.2.2.2
LS Seq Number: 80000002
Checksum: 0x47ED
Length: 28
Network Mask: /24
TOS: 0 Metric: 65
LS age: 471
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 172.16.2.1 (summary Network Number)
Advertising Router: 2.2.2.2
LS Seq Number: 80000002
Checksum: 0xB9B8
Length: 28
Network Mask: /32
TOS: 0 Metric: 2
LS age: 724
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 192.168.1.0 (summary Network Number)
Advertising Router: 2.2.2.2
LS Seq Number: 80000004
Checksum: 0x9432
Length: 28
Network Mask: /24
TOS: 0 Metric: 1
LS age: 725
Options: (No TOS-capability, DC, Upward)
LS Type: Summary Links(Network)
Link State ID: 192.168.2.1 (summary Network Number)
Advertising Router: 2.2.2.2
LS Seq Number: 80000002
Checksum: 0x8D38
Length: 28
Network Mask: /32
TOS: 0 Metric: 2
注意：通告的是这条LSA 的目的地所耗费的代价！而且是其中一条最低的代价，只有一个！ 路由器收到这个LSA 只是简单的加上从他到那台ABR 路由器将之间的路由的代价，并将这个代价放在LSA 通告中！这个就是距离矢量
距离矢量的算法来查找域间路由