OSPF-LSA详解—LSA TYPE 1

通用属性：
类型TYPE、Link ID、ADV Router三者标示了LSA的唯一性


Age存在时间，最大为3600s，正常情况下不会超过1800s，30min周期更新，3600s没有更新会删掉LSA
Seq number范围是80000001-7FFFFFFF
Checksum说明LSA在传输过程有没有出现错误
Age、Seq number和Checksum三者标示了LSA的新旧程度
当多份LSA来到设备时会比较Age、Seq number和Checksum三者来选取一份放入LSDB表中
——————————————————————————————————————————
环回口：a Stub Network  路由
以太网口：a Transit Network 拓扑（描述和谁相连）
串口：a Stub Network  路由 和 another Router 拓扑（描述和谁相连）


通告者：自己的router-id
传播范围：在本区域内传播
内容：拓扑（a Transit Network、another Router）和路由（a Stub Network）
——————————————————————————————————————————
 
R1#show ip ospf database 


            OSPF Router with ID (0.0.0.1) (Process ID 100)


                Router Link States (Area 0)


Link ID         ADV Router      Age         Seq#       Checksum Link count
0.0.0.1         0.0.0.1         1349        0x80000005 0x007B74 2
0.0.0.2         0.0.0.2         1355        0x80000008 0x00E42B 4
0.0.0.3         0.0.0.3         1388        0x80000001 0x0090B9 3


推导：在某个区域里看到多少条LSA，就说明在这个区域有多少台设备运行OSPF
——————————————————————————————————————————
#show ip ospf database router


OSPF Router with ID (0.0.0.1) (Process ID 100)


                Router Link States (Area 0)


  LS age: 99
  Options: (No TOS-capability, DC)
  LS Type: Router Links
  Link State ID: 0.0.0.1
  Advertising Router: 0.0.0.1
  LS Seq Number: 80000005
  Checksum: 0x7B74
  Length: 48
  Number of Links: 2


    Link connected to: a Transit Network                    以太网口
     (Link ID) Designated Router address: 12.1.1.2      DR的IP地址
     (Link Data) Router Interface address: 12.1.1.1      本设备连接DR的接口IP地址
      Number of TOS metrics: 0
       TOS 0 Metrics: 10                                            开销


    Link connected to: a Stub Network                        环回口
     (Link ID) Network/subnet number: 1.1.1.1           IP地址
     (Link Data) Network Mask: 255.255.255.255        子网掩码
      Number of TOS metrics: 0
       TOS 0 Metrics: 1                                              开销




  LS age: 109
  Options: (No TOS-capability, DC)
  LS Type: Router Links
  Link State ID: 0.0.0.2
  Advertising Router: 0.0.0.2
  LS Seq Number: 80000008
  Checksum: 0xE42B
  Length: 72
  Number of Links: 4


    Link connected to: another Router (point-to-point)
     (Link ID) Neighboring Router ID: 0.0.0.3                    描述对端设备的router-id
     (Link Data) Router Interface address: 23.1.1.2             本设备连接对端的接口IP地址
      Number of TOS metrics: 0
       TOS 0 Metrics: 64                                                   开销


    Link connected to: a Stub Network
     (Link ID) Network/subnet number: 23.1.1.0
     (Link Data) Network Mask: 255.255.255.0
      Number of TOS metrics: 0
       TOS 0 Metrics: 64


    Link connected to: a Transit Network
     (Link ID) Designated Router address: 12.1.1.2
     (Link Data) Router Interface address: 12.1.1.2
      Number of TOS metrics: 0
       TOS 0 Metrics: 10


    Link connected to: a Stub Network
     (Link ID) Network/subnet number: 2.2.2.2
     (Link Data) Network Mask: 255.255.255.255
      Number of TOS metrics: 0
       TOS 0 Metrics: 1




  LS age: 160
  Options: (No TOS-capability, DC)
  LS Type: Router Links
  Link State ID: 0.0.0.3
  Advertising Router: 0.0.0.3
  LS Seq Number: 80000001
  Checksum: 0x90B9
  Length: 60
  Number of Links: 3


    Link connected to: another Router (point-to-point)
     (Link ID) Neighboring Router ID: 0.0.0.2
     (Link Data) Router Interface address: 23.1.1.3
      Number of TOS metrics: 0
       TOS 0 Metrics: 64


    Link connected to: a Stub Network
     (Link ID) Network/subnet number: 23.1.1.0
     (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: 3.3.3.3
     (Link Data) Network Mask: 255.255.255.255
      Number of TOS metrics: 0
       TOS 0 Metrics: 1