LSA Type Explanation - lsa-1 [type 1 LSA - router LSA] detailed explanation

Catalog

One 、LSA—1：

（1）—— brief introduction ：

（2）—— Header information :

（3）—— Data section :

（4）—— The illustration ： 

（5）—— Case list （ according to LSA-1 Draw the topology ）：

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One 、LSA—1：

（1）—— brief introduction ：

• Router LSA（Router LSA）： Every router will produce a router LSA notice . This is the most basic LSA The announcement lists all links or interfaces of the router , Their states and the outbound overhead along each link direction are indicated , And all known on the chain OSPF neighbor . these LSA Announcements will only be made within the area from which they originated flooding Spread . Through the command show ip ospf database router You can view all routers listed in the database LSA notice . It mainly describes the topology .
• produce : The router in the area will generate a unique LSA-1
• Flood boundary range : Only here Inside the area flooding , Will not enter into other areas ,

（2）—— Header information :

• Ls/ age : Aging time ,1800~~3600 second , among 1800s It's cyclical LSA Refresh time ,3600s yes LSA Maximum aging room
• Options : optional
• LS Type: router
• Link State ID : This LSA Who made it , Just take this router RID Written here
• Advertising Router : This LSA Who made it , Just take this router RID Written here
• LS Seq Number : LSA The serial number of , Use this serial number to determine LSA Is the latest ,LSA Every update , Serial number +1
• Checksum ; Parity sum , Used to verify the integrity of teaching data transmission
• Length ： It contains the total length of header information and data part
• Number of Links :

（3）—— Data section :

• V : Set as 1 Represents the virtual link configuration node （0——1)
• E : Set as 1 Representative Representative ASBR Router （0——1）
• B : Set as 1 Delegate delegate is a ABR Router interface （0——1）

Interface link type	link ID Express ：	Link data representation ：	Interface cost value
Point to point	Neighbor's RID	Interface to connect neighbors IP	cost value
radio broadcast	DR The interface of IP Address	Connect DR Interface IP Address	cost value
stub( Peripheral )	Loopback interface 32 position IP Address	Loopback interface 32 Mask	cost value
Virtual link	Like point-to-point	Like point-to-point	cost value

• Interface cost value =10 Of 8 Power / Interface bandwidth （100M）=1
• The link type is point-to-point : By default, only the interface is serial port or E1 Interface 、T1 Interface 、POS In the case of WAN interface, this interface OSFF The link type is point-to-point link
• The type is broadcast : By default, only the interface is Ethernet interface （FO/0, GO/0,T0/O), This interface OSPF The link type is broadcast
   
• Link type stub : Loopback interface ,OSPF The default loopback interface in the network is stub type , Even if the loopback interface is configured according to 24 Bit mask configured , however OSPF It will still loop back to the interface according to 32 Bit host routes for notification updates , Unless the link type of the loopback interface is changed to point-to-point :

  R1(config)#int loopback l
  R1(config-if)#ip ospf network point-to-point
  R1(config-if) #exit

（4）—— The illustration ： 

（5）—— Case list （ according to LSA-1 Draw the topology ）：

show ip ospf database router—— see

   The above is only a personal point of view , If there are any mistakes, please point out ！ Feel free to leave a comment ！