Lab3 OSPF的Stub和NSSA区域配置

爱卫生

本练习的目标是：

1）了解OSPF Stub区域配置

2）了解OSPF NSSA区域配置

3）使用show命令进行相关验证。

附件包含拓扑、步骤及指令、验证三部分。

本实验通过Juniper模拟器实现，所有接口名称均为em开头。如果是实际设备请将此接口名称进行替换。

部分内容摘要如下：

OSPF Stub/NSSA Area Configuration Overview

When some areas of your network have no external connections, you can make them into stub areas. This reduces the amount of OSPF protocol traffic that is flooded through the area, which improves performance on the router by decreasing the size of the OSPF routing database and thus decreasing the amount of CPU needed to perform the SPF calculations. Another common reason to set up a stub area is to allow legacy routers that don't have enough memory or CPU horsepower to participate in the OSPF network. A stub area receives OSPF routing-database information from all the other areas in the network. However, instead of receiving all AS external advertisements, the stub area gets only a default summary (0.0.0.0/0) from ABRs to reach external destinations and gets summaries for destinations in other OSPF areas.

A not-so-stubby area is an OSPF stub area that allows some external routes to be present in the database. This is accomplished with a new NSSA external LSA, type code 7. The Type 7 LSA carries external routing information from the ASBR within the NSSA. It has an area flooding scope, so only routers in the NSSA receive the Type 7 LSA. The external routing information within the LSA is converted by the ABR into an AS external LSA at the area boundary. The ABR floods the Type 5 LSA into the OSPF domain, and no other routers in the network are aware of the NSSA configuration.

In this part, we will setup ospf  stub area 1 in between R2 and R3, therefore R2 will automatically act as area border router. (The configuration below are only shown the part related configuration, some configuration in part two is omitted.)

________________________________________________________________________________________

lab@R1# show logical-routers R2 protocols ospf
area 0.0.0.1 {
    stub default-metric 2;  
    interface em2.23;
}
lab@R1# show logical-routers R3 protocols ospf
area 0.0.0.1 {
    stub;
    interface all;
}

_______________________________________________________________________________________