OSPF - detailed explanation of stub area and full stub area

Catalog

One 、STUB Area

（1）——STUB Regional profile ：

（2）——stub Regional characteristics ：

（3）—— To configure ：

（4）——STUB The illustration ：

Two 、 Completely STUB Area ：

（1）—— Completely stub Regional characteristics ：

（2）—— To configure ：

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One 、STUB Area

（1）——STUB Regional profile ：

• OSPF STUB A region is a terminal region , When one OSPF The area is in the whole Autonomous systems Boundary time , And nothing else Routing protocol , You can configure OSPF Stub Area .
• When configuring OSPF Stub After area ,Stub In the area Router Will add one to ABR Of Default route entry , When in ABR After the complete peripheral area is configured on , The routing entries of other routers in the terminal area are in addition to the directly connected routing entries , There is only one way to ABR The default route is , Will not learn routing entries from other regions , Packets to other areas pass through ABR forward . This reduces the number of routing entries and routing delivery of other routers in the terminal area , Improve router performance .

（2）——stub Regional characteristics ：

• Refuse : LSA-4  LAS-5, That is to say, in this stub The external routes that are fully sent are not allowed to enter the general router in the area , But this stub Regional ABR Router Will automatically give stub The normal router in the area advertises a OSPF Default default route

• allow : LAS-3,LSA-1,LSA-2

（3）—— To configure ：

 Every router in this area needs to be configured :
 Put the area 2 configure stub Area 
R1 (config) #router ospf 100
R1(config-router)#area 2 stub
R1(config-router) #exit 

（4）——STUB The illustration ：

Two 、 Completely STUB Area ：

（1）—— Completely stub Regional characteristics ：

• from stub Upgrade , Only need stub Regional ABR Add : no-summary
• Refuse : LSA-4,LSA-5,LSA-3, That is to say, not only the external route is rejected , meanwhile OSPF Of Inter regional routing Also refused together
• allow : LSA-1  LSA-2 And the only one LSA-3 Default route

（2）—— To configure ：

r3(config) #router os 100
r3(config-router) #area 2 stub no-summary
r3(config-router)#exit