1. 1. OSPF Stub区域与NSSA区域
      1. 实验介绍
         1. 学习目标
2. 实现OSPF Stub区域的配置
3. 实现OSPF NSSA区域的配置
4. 描述Type-7 LSA的内容
5. 描述Type-7 LSA与Type-5 LSA之间的转换过程
   1. 1. 1. 实验组网介绍

1. 1. 1. 1. 1. 1. 1. 1. OSPF Stub区域与NSSA区域

设备互联方式及IP地址规划如图所示，OSPF区域规划如下：

1. R1与R3的互联接口、R1的Loopback0接口属于OSPF区域2。
2. R3与R4的互联接口以及它们的Loopback0接口属于OSPF区域0。
3. R4与R5的互联接口属于OSPF区域1，R5的Loopback0接口不属于任何区域。
4. R2与R3的互联接口属于OSPF区域3，R2的Loopback0接口不属于任何区域。
   1. 1. 1. 实验背景

你是公司的网络管理员。现在公司的网络中有五台AR路由器，其中R2、R3和R4在公司总部。R5在公司分部，R1在公司的另外一个分部。

为了减轻分部设备的压力，你设置区域1为NSSA区域、区域2为Stub区域。

同时为了明确设备的Router ID，你配置设备使用固定的地址作为Router ID。

1. 1. 1. 实验任务
         1. 任务思路
2. 设备IP地址配置。
3. 按照规划配置OSPF区域。
4. 检查OSPF配置结果，检查OSPF邻居关系状态，检查OSFP路由表。
5. 在R2、R5上将外部路由引入到OSPF中。
6. 配置区域2为Stub区域，观察区域2内OSPF路由表、LSDB的变化。
7. 配置区域1为NSSA区域，观察区域1内OSPF路由表、LSDB的变化。
8. 查看R4的OSPF路由器身份，在R4上观察Type-7 LSA向Type-5 LSA的转换。
   1. 1. 1. 任务步骤
            • • 1 互联接口、环回口IP地址配置

#设备命名

略

#关闭本实验中未使用的接口

略

华为数通HCIA+HCIP高级网络工程师（理论+实验+题库）_腾讯课堂

#配置R1的GE0/0/1、Loopback0接口IP地址

[R1]interface LoopBack0

[R1-LoopBack0] ip address 10.0.1.1 255.255.255.0

[R1-LoopBack0] quit

[R1]interface GigabitEthernet0/0/1

[R1-GigabitEthernet0/0/1] ip address 10.0.13.1 255.255.255.0

[R1-GigabitEthernet0/0/1] quit

#配置R2的GE0/0/2、Loopback0接口IP地址

[R2]interface GigabitEthernet0/0/2

[R2-GigabitEthernet0/0/2] ip address 10.0.23.2 255.255.255.0

[R2-GigabitEthernet0/0/2] quit                         

[R2]interface LoopBack0

[R2-LoopBack0] ip address 10.0.2.2 255.255.255.0

[R2-LoopBack0] quit

#配置R3的GE0/0/1、GE0/0/2、GE0/0/3、Loopback0接口IP地址

[R3]interface LoopBack0

[R3-LoopBack0] ip address 10.0.3.3 255.255.255.0

[R3-LoopBack0] quit

[R3]interface GigabitEthernet0/0/1

[R3-GigabitEthernet0/0/1] ip address 10.0.13.3 255.255.255.0

[R3-GigabitEthernet0/0/1] quit

[R3]interface GigabitEthernet0/0/2

[R3-GigabitEthernet0/0/2] ip address 10.0.34.3 255.255.255.0

[R3-GigabitEthernet0/0/2] quit

[R3]interface GigabitEthernet0/0/3

[R3-GigabitEthernet0/0/3] ip address 10.0.23.3 255.255.255.0

[R3-GigabitEthernet0/0/3] quit

#配置R4的GE0/0/2、GE0/0/3、Loopback0接口IP地址

[R4]interface LoopBack0

[R4-LoopBack0] ip address 10.0.4.4 255.255.255.0

[R4-LoopBack0] quit

[R4]interface GigabitEthernet0/0/2

[R4-GigabitEthernet0/0/2] ip address 10.0.45.4 255.255.255.0

[R4-GigabitEthernet0/0/2] quit

[R4]interface GigabitEthernet0/0/3

[R4-GigabitEthernet0/0/3] ip address 10.0.34.4 255.255.255.0

[R4-GigabitEthernet0/0/3] quit

#配置R5的GE0/0/3、Loopback0接口IP地址

[R5]interface LoopBack0

[R5-LoopBack0] ip address 10.0.5.5 255.255.255.0

[R5-LoopBack0] quit

[R5]interface GigabitEthernet0/0/3

[R5-GigabitEthernet0/0/3] ip address 10.0.45.5 255.255.255.0

[R5-GigabitEthernet0/0/3] quit

#在R3、R5上检查互联地址连通性

<R3>ping -c 1 10.0.13.1

  PING 10.0.13.1: 56  data bytes, press CTRL_C to break

    Reply from 10.0.13.1: bytes=56 Sequence=1 ttl=255 time=40 ms

  --- 10.0.13.1 ping statistics ---

    1 packet(s) transmitted

    1 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 40/40/40 ms

<R3>ping -c 1 10.0.23.2

  PING 10.0.23.2: 56  data bytes, press CTRL_C to break

    Reply from 10.0.23.2: bytes=56 Sequence=1 ttl=255 time=60 ms

  --- 10.0.23.2 ping statistics ---

    1 packet(s) transmitted

    1 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 60/60/60 ms

<R3>ping -c 1 10.0.34.4

  PING 10.0.34.4: 56  data bytes, press CTRL_C to break

    Reply from 10.0.34.4: bytes=56 Sequence=1 ttl=255 time=60 ms

  --- 10.0.34.4 ping statistics ---

    1 packet(s) transmitted

    1 packet(s) received

    0.00% packet loss

round-trip min/avg/max = 60/60/60 ms

<R5>ping -c 1 10.0.45.4

  PING 10.0.45.4: 56  data bytes, press CTRL_C to break

    Reply from 10.0.45.4: bytes=56 Sequence=1 ttl=255 time=70 ms

  --- 10.0.45.4 ping statistics ---

    1 packet(s) transmitted

    1 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 70/70/70 ms

• • • • • • 2 配置多区域OSPF

按照规划配置OSPF，手动指定Loopback0接口地址为OSPF Router ID，修改Loopback0接口的网络类型为Broadcast。

#配置R1

[R1] ospf 1 router-id 10.0.1.1

[R1-ospf-1] area 0.0.0.2

[R1-ospf-1-area-0.0.0.2] network 10.0.1.1 0.0.0.0

[R1-ospf-1-area-0.0.0.2] network 10.0.13.1 0.0.0.0

[R1-ospf-1-area-0.0.0.2] quit

[R1-ospf-1] quit

[R1] interface LoopBack0

[R1-LoopBack0] ospf network-type broadcast

#配置R2

[R2] ospf 1 router-id 10.0.2.2

[R2-ospf-1] area 0.0.0.3

[R2-ospf-1-area-0.0.0.3] network 10.0.23.2 0.0.0.0

[R2-ospf-1-area-0.0.0.3] quit

[R2-ospf-1] quit

[R2] interface LoopBack0

[R2-LoopBack0] ospf network-type broadcast

#配置R3

[R3] ospf 1 router-id 10.0.3.3

[R3-ospf-1] area 0.0.0.0

[R3-ospf-1-area-0.0.0.0] network 10.0.3.3 0.0.0.0

[R3-ospf-1-area-0.0.0.0] network 10.0.34.3 0.0.0.0

[R3-ospf-1-area-0.0.0.0] area 0.0.0.2

[R3-ospf-1-area-0.0.0.2] network 10.0.13.3 0.0.0.0

[R3-ospf-1-area-0.0.0.2] area 0.0.0.3

[R3-ospf-1-area-0.0.0.3] network 10.0.23.3 0.0.0.0 

[R3-ospf-1-area-0.0.0.3] quit

[R3-ospf-1] quit

[R3] interface LoopBack0

[R3-LoopBack0] ospf network-type broadcast

#配置R4

[R4] ospf 1 router-id 10.0.4.4

[R4-ospf-1] area 0.0.0.0

[R4-ospf-1-area-0.0.0.0] network 10.0.4.4 0.0.0.0

[R4-ospf-1-area-0.0.0.0] network 10.0.34.4 0.0.0.0

[R4-ospf-1-area-0.0.0.0] area 0.0.0.1

[R4-ospf-1-area-0.0.0.1] network 10.0.45.4 0.0.0.0

[R4-ospf-1-area-0.0.0.1] quit

[R4-ospf-1] quit

[R4] interface LoopBack0

[R4-LoopBack0] ospf network-type broadcast

#配置R5

[R5] ospf 1 router-id 10.0.5.5

[R5-ospf-1] area 1

[R5-ospf-1-area-0.0.0.1] network 10.0.45.5 0.0.0.0

[R5-ospf-1-area-0.0.0.1] quit

[R5-ospf-1] quit

[R5] interface LoopBack0

[R5-LoopBack0] ospf network-type broadcast

• • • • • • 3 检查OSPF多区域配置

#在R3上检查OSPF邻居的概要信息

<R3>display ospf peer brief

      OSPF Process 1 with Router ID 10.0.3.3

                 Peer Statistic Information

 ----------------------------------------------------------------------------

 Area Id          Interface                      Neighbor id      State   

 0.0.0.0          GigabitEthernet0/0/2             10.0.4.4         Full       

 0.0.0.2          GigabitEthernet0/0/1             10.0.1.1         Full       

 0.0.0.3          GigabitEthernet0/0/3             10.0.2.2         Full       

 ----------------------------------------------------------------------------

#在R5上检查OSPF邻居的概要信息

<R5>display ospf peer brief

      OSPF Process 1 with Router ID 10.0.5.5

                 Peer Statistic Information

 ----------------------------------------------------------------------------

 Area Id          Interface                      Neighbor id      State   

 0.0.0.1          GigabitEthernet0/0/3             10.0.4.4         Full       

 ----------------------------------------------------------------------------

从输出信息可以判断出所有设备之间的OSPF邻居关系状态正常。

#在R3上查看OSPF路由表

<R3>display ospf routing

      OSPF Process 1 with Router ID 10.0.3.3

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop      AdvRouter       Area

 10.0.3.0/24        0     Stub       10.0.3.3        10.0.3.3        0.0.0.0

 10.0.13.0/24       1     Transit     10.0.13.3       10.0.3.3        0.0.0.2

 10.0.23.0/24       1     Transit     10.0.23.3       10.0.3.3        0.0.0.3

 10.0.34.0/24       1     Transit     10.0.34.3       10.0.3.3        0.0.0.0

 10.0.1.0/24        1     Stub       10.0.13.1       10.0.1.1        0.0.0.2

 10.0.4.0/24        1     Stub       10.0.34.4       10.0.4.4        0.0.0.0

 10.0.45.0/24       2     Inter-area   10.0.34.4       10.0.4.4        0.0.0.0

 Total Nets: 7 

 Intra Area: 6  Inter Area: 1  ASE: 0  NSSA: 0

除了未激活OSPF的R2 Loopback0接口、R5 Loopback0接口，R3已经学习到其余接口路由。

• • • • • • 4 配置将外部路由引入到OSPF中

#将R5的Loopback0接口路由引入到OSPF中

[R5] ospf 1

[R5-ospf-1] import-route direct

#在R2上配置缺省路由，且指定出接口为 Loopback0接口，并将该缺省路由引入到OSPF中，外部路由类型设置为1，Cost值设置为20，不携带always参数

[R2] ip route-static 0.0.0.0 0.0.0.0 LoopBack 0

[R2] ospf 1

[R2-ospf-1] default-route-advertise type 1 cost 20

#在R3上查看引入的外部路由，并测试其连通性

<R3>display ospf routing 0.0.0.0

      OSPF Process 1 with Router ID 10.0.3.3

 Destination : 0.0.0.0/0          

 AdverRouter : 10.0.2.2                 Tag       : 1    

 Cost        : 21                       Type      : Type1     

 NextHop     : 10.0.23.2                Interface : GigabitEthernet0/0/3 

 Priority    : Low                      Age       : 00h01m15s 

<R3>display ospf routing 10.0.5.5

      OSPF Process 1 with Router ID 10.0.3.3

 Destination : 10.0.5.0/24        

 AdverRouter : 10.0.5.5                 Tag       : 1    

 Cost        : 1                        Type      : Type2     

 NextHop     : 10.0.34.4                Interface : GigabitEthernet0/0/2 

 Priority    : Low                      Age       : 00h05m20s 

<R3>ping -c 1 10.0.5.5

  PING 10.0.5.5: 56  data bytes, press CTRL_C to break

    Reply from 10.0.5.5: bytes=56 Sequence=1 ttl=254 time=50 ms

  --- 10.0.5.5 ping statistics ---

    1 packet(s) transmitted

    1 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 50/50/50 ms

<R3>ping -c 1 10.0.2.2

  PING 10.0.2.2: 56  data bytes, press CTRL_C to break

    Reply from 10.0.2.2: bytes=56 Sequence=1 ttl=255 time=50 ms

  --- 10.0.2.2 ping statistics ---

    1 packet(s) transmitted

    1 packet(s) received

    0.00% packet loss

    round-trip min/avg/max = 50/50/50 ms

• • • • • • 5 配置区域2为Stub区域

#在R1上查看OSPF路由表

<R1>display ospf routing

      OSPF Process 1 with Router ID 10.0.1.1

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop       AdvRouter       Area

 10.0.1.0/24        0     Stub       10.0.1.1        10.0.1.1        0.0.0.2

 10.0.13.0/24       1     Transit     10.0.13.1       10.0.1.1        0.0.0.2

 10.0.3.0/24        1     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.4.0/24        2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.23.0/24       2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.34.0/24       2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.45.0/24       3     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 Routing for ASEs

 Destination        Cost      Type       Tag         NextHop       AdvRouter

 0.0.0.0/0          22        Type1      1           10.0.13.3       10.0.2.2

 10.0.5.0/24        1         Type2      1           10.0.13.3       10.0.5.5

 Total Nets: 9 

 Intra Area: 2  Inter Area: 5  ASE: 2  NSSA: 0

此时默认路由为OSPF外部路由。

#在R1、R3上配置区域2为Stub区域

[R1] ospf 1

[R1-ospf-1] area 0.0.0.2

[R1-ospf-1-area-0.0.0.2] stub

[R3] ospf 1

[R3-ospf-1] area 0.0.0.2

[R3-ospf-1-area-0.0.0.2] stub

#再次在R1上查看OSPF路由表

<R1>display ospf routing

      OSPF Process 1 with Router ID 10.0.1.1

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop      AdvRouter       Area

 10.0.1.0/24        0     Stub       10.0.1.1        10.0.1.1        0.0.0.2

 10.0.13.0/24       1     Transit     10.0.13.1       10.0.1.1        0.0.0.2

 0.0.0.0/0          2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.3.0/24        1     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.4.0/24        2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.23.0/24       2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.34.0/24       2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 10.0.45.0/24       3     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 Total Nets: 8 

 Intra Area: 2  Inter Area: 6  ASE: 0  NSSA: 0

此时R1上不存在OSPF外部路由，原本的OSPF外部路由条目0.0.0.0/0、10.0.5.0/24被一条缺省的OSPF区域间路由所取代。

#查看R1的OSPF LSDB

<R1>display   ospf  lsdb  

               OSPF     Process      1       with     Router        ID     10.0.1.1

                        Link  State     Database   

                                                                                           Area: 0.0.0.2

     Type                                            LinkState   ID                             AdvRouter                                                           Age                 Len                 Sequence                  Metric

     Router                                         10.0.3.3                                                               10.0.3.3                                                                                           628        36                             80000004                                                      1

     Router                                        10.0.1.1                                                               10.0.1.1                                                                                           619        48                             80000007                                                      0

     Network                            10.0.13.1                                                   10.0.1.1                                                                                           619        32                             80000002                                                      0

     Sum-Net                   0.0.0.0                                                                          10.0.3.3                                                                                           631        28                             80000001                                                      1

     Sum-Net                   10.0.34.0                                                   10.0.3.3                                                                                           631        28                             80000001                                                      1

     Sum-Net                   10.0.3.0                                                              10.0.3.3                                                                                           631        28                             80000001                                                      0

     Sum-Net                   10.0.4.0                                                              10.0.3.3                                                                                           631        28                             80000001                                                      1

     Sum-Net                   10.0.45.0                                                   10.0.3.3                                                                                           631        28                             80000001                                                      2

     Sum-Net                   10.0.23.0                                                   10.0.3.3                                                                                           631        28                             80000001                                                      1

R1上此时不存在Type-4 LSA、Type-5 LSA，去往OSPF域外通过ABR生成的Type-3 LSA所携带的缺省路由实现。同时此时前往其他区域的Type-3 LSA依旧存在。

以上验证了将一个区域配置为Stub区域以后，ABR会阻断Type-4 LSA、Type-5 LSA向该区域发送，并通过Type-3 LSA向该区域内泛洪一条默认路由指向ABR自身。

#在R3上配置区域2为Totally Stub区域

[R3] ospf 1

[R3-ospf-1] area 0.0.0.2

[R3-ospf-1-area-0.0.0.2] stub no-summary

#再次在R1上查看OSPF路由表、LSDB

<R1>display ospf routing

      OSPF Process 1 with Router ID 10.0.1.1

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop      AdvRouter       Area

 10.0.1.0/24        0     Stub       10.0.1.1        10.0.1.1        0.0.0.2

 10.0.13.0/24       1     Transit     10.0.13.1       10.0.1.1        0.0.0.2

 0.0.0.0/0          2     Inter-area   10.0.13.3       10.0.3.3        0.0.0.2

 Total Nets: 3 

 Intra Area: 2  Inter Area: 1  ASE: 0  NSSA: 0

<R1>display   ospf  lsdb  

               OSPF     Process      1       with     Router        ID     10.0.1.1

                        Link  State     Database   

                                                                                           Area: 0.0.0.2

     Type                                            LinkState   ID                             AdvRouter                                                           Age            Len                           Sequence                  Metric

     Router                                        10.0.3.3                                                               10.0.3.3                                                                                           125        36                             80000005                                                      1

     Router                                        10.0.1.1                                                               10.0.1.1                                                                                           121        48                             8000000C                                                      0

     Network                            10.0.13.1                                                   10.0.1.1                                                                                           121        32                             80000002                                                      0

     Sum-Net                   0.0.0.0                                                                          10.0.3.3                                                                                           961        28                             80000001                                                      1

此时原本多条OSPF区域间路由只剩一条0.0.0.0/0缺省路由，LSDB中Type-3 LSA只剩一条0.0.0.0。

这就验证了Totally Stub区域中ABR会阻断了Type-3 LSA、Type-4 LSA、Type-5 LSA，并生成一条Type-3 LSA，通告一条指向自身的缺省路由。

• • • • • • 6 配置区域1为NSSA区域

#查看R4的OSPF路由表

<R4>display ospf routing

      OSPF Process 1 with Router ID 10.0.4.4

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop      AdvRouter       Area

 10.0.4.0/24        0     Stub       10.0.4.4        10.0.4.4        0.0.0.0

 10.0.34.0/24       1     Transit     10.0.34.4       10.0.4.4        0.0.0.0

 10.0.45.0/24       1     Transit     10.0.45.4       10.0.4.4        0.0.0.1

 10.0.1.0/24        2     Inter-area   10.0.34.3       10.0.3.3        0.0.0.0

 10.0.3.0/24        1     Stub       10.0.34.3       10.0.3.3        0.0.0.0

 10.0.13.0/24       2     Inter-area   10.0.34.3       10.0.3.3        0.0.0.0

 10.0.23.0/24       2     Inter-area   10.0.34.3       10.0.3.3        0.0.0.0

 Routing for ASEs

 Destination        Cost      Type       Tag         NextHop      AdvRouter

 0.0.0.0/0          22        Type1      1           10.0.34.3       10.0.2.2

 10.0.5.0/24        1         Type2      1           10.0.45.5       10.0.5.5

 Total Nets: 9 

 Intra Area: 4  Inter Area: 3  ASE: 2  NSSA: 0 

此时R5存在一条由Type-5 LSA描述的外部路由10.0.5.0/24。

#查看R5的OSPF路由表

<R5>display ospf routing

      OSPF Process 1 with Router ID 10.0.5.5

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop      AdvRouter       Area

 10.0.45.0/24       1     Transit    10.0.45.5       10.0.5.5        0.0.0.1

 10.0.1.0/24        3     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.3.0/24        2     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.4.0/24        1     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.13.0/24       3     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.23.0/24       3     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.34.0/24       2     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 Routing for ASEs

 Destination        Cost      Type       Tag         NextHop        AdvRouter

 0.0.0.0/0          23        Type1      1           10.0.45.4       10.0.2.2

 Total Nets: 8 

 Intra Area: 1  Inter Area: 6  ASE: 1  NSSA: 0

在R5的OSPF路由表中出现的缺省路由是由Type-5 LSA所描述的，该LSA由R2产生。

#在R4、R5上配置区域1为NSSA区域

[R4]ospf 1

[R4-ospf-1] area 0.0.0.1

[R4-ospf-1-area-0.0.0.1] nssa

[R5]ospf 1

[R5-ospf-1] area 0.0.0.1

[R5-ospf-1-area-0.0.0.1] nssa

#再次查看R5的OSPF路由表

<R5>display ospf routing

      OSPF Process 1 with Router ID 10.0.5.5

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop     AdvRouter       Area

 10.0.45.0/24       1     Transit    10.0.45.5       10.0.5.5        0.0.0.1

 10.0.1.0/24        3     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.3.0/24        2     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.4.0/24        1     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.13.0/24       3     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.23.0/24       3     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 10.0.34.0/24       2     Inter-area  10.0.45.4       10.0.4.4        0.0.0.1

 Routing for NSSAs

 Destination        Cost      Type       Tag         NextHop       AdvRouter

 0.0.0.0/0          1         Type2      1           10.0.45.4       10.0.4.4

 Total Nets: 8 

 Intra Area: 1  Inter Area: 6  ASE: 0  NSSA: 1

此时不存在由R2发布的缺省路由，存在一条由R4发布的Type-7 LSA描述的OSPF缺省路由。

#查看R5 LSDB

<R5>display   ospf  lsdb  

               OSPF     Process      1       with     Router        ID     10.0.5.5

                        Link  State     Database   

                                                                                           Area: 0.0.0.1

     Type                                            LinkState   ID                             AdvRouter                                                                             Age        Len                 Sequence                  Metric

     Router                                                  10.0.5.5                                                                10.0.5.5                                                                                           100        36                             80000005                                                      1

     Router                                                  10.0.4.4                                                                10.0.4.4                                                                                           105        36                             80000005                                                      1

     Network                                     10.0.45.5                                                   10.0.5.5                                                                                           100        32                             80000002                                                      0

     Sum-Net                            10.0.34.0                                                   10.0.4.4                                                                                           151        28                             80000001                                                      1

     Sum-Net                            10.0.13.0                                                   10.0.4.4                                                                                           151        28                             80000001                                                      2

     Sum-Net                            10.0.3.0                                                              10.0.4.4                                                                                           151        28                             80000001                                                      1

     Sum-Net                            10.0.1.0                                                              10.0.4.4                                                                                           151        28                             80000001                                                      2

     Sum-Net                            10.0.4.0                                                              10.0.4.4                                                                                           151        28                             80000001                                                      0

     Sum-Net                            10.0.23.0                                                   10.0.4.4                                                                                           151        28                             80000001                                                      2

     NSSA                                                   10.0.5.0                                                                10.0.5.5                                                                                           143        36                             80000001                                                      1

     NSSA                                                   10.0.45.0                                                    10.0.5.5                                                                                           143        36                             80000002                                                      1

     NSSA                                                   0.0.0.0                                                                           10.0.4.4                                                                                       151             36                              80000001                                                  1

此时不存在Type-4 LSA、Type-5 LSA，外部路由以Type-7 LSA（NSSA）的形式存在。

#查看R4的OSPF路由表

[R4]display ospf routing

      OSPF Process 1 with Router ID 10.0.4.4

                 Routing Tables

 Routing for Network

 Destination        Cost  Type       NextHop       AdvRouter       Area

 10.0.4.0/24        0     Stub       10.0.4.4        10.0.4.4        0.0.0.0

 10.0.34.0/24       1     Transit     10.0.34.4       10.0.4.4        0.0.0.0

 10.0.45.0/24       1     Transit     10.0.45.4       10.0.4.4        0.0.0.1

 10.0.1.0/24        2     Inter-area   10.0.34.3       10.0.3.3        0.0.0.0

 10.0.3.0/24        1     Stub       10.0.34.3       10.0.3.3        0.0.0.0

 10.0.13.0/24       2     Inter-area   10.0.34.3       10.0.3.3        0.0.0.0

 10.0.23.0/24       2     Inter-area   10.0.34.3       10.0.3.3        0.0.0.0

 Routing for ASEs

 Destination        Cost      Type       Tag         NextHop       AdvRouter

 0.0.0.0/0          22        Type1      1           10.0.34.3       10.0.2.2

 Routing for NSSAs

 Destination        Cost      Type       Tag         NextHop       AdvRouter

 10.0.5.0/24        1         Type2      1           10.0.45.5       10.0.5.5

 Total Nets: 9 

 Intra Area: 4  Inter Area: 3  ASE: 1  NSSA: 1

R5所引入的外部路由10.0.5.0/24由Type-7 LSA所描述。

以上验证了NSSA区域阻断了外部的Type-4 LSA、Type-5 LSA进入，并且ABR会向区域内下发一条由Type-7 LSA描述的默认路由。ASBR向NSSA区域内下发Type-7 LSA描述本区域中引入的外部路由。

• • • • • • 7 观察NSSA对OSPF产生的影响

#在R4上查看OSPF概要信息

<R4>display ospf brief

      OSPF Process 1 with Router ID 10.0.4.4

                OSPF Protocol Information

 RouterID: 10.0.4.4         Border Router:  AREA  AS  NSSA

 Multi-VPN-Instance is not enabled

 Global DS-TE Mode: Non-Standard IETF Mode

 Spf-schedule-interval: max 10000ms, start 500ms, hold 1000ms

 Default ASE parameters: Metric: 1 Tag: 1 Type: 2

 Route Preference: 10

 ASE Route Preference: 150

 SPF Computation Count: 22   

 RFC 1583 Compatible

 Retransmission limitation is disabled

 Area Count: 2   Nssa Area Count: 1

 ExChange/Loading Neighbors: 0

 Area: 0.0.0.0          (MPLS TE not enabled)

 Authtype: None   Area flag: Normal

 SPF scheduled Count: 22   

 ExChange/Loading Neighbors: 0

 Router ID conflict state: Normal

 Interface: 10.0.4.4 (LoopBack0)

 Cost: 0       State: DR        Type: Broadcast    MTU: 1500 

 Priority: 1

 Designated Router: 10.0.4.4

 Backup Designated Router: 0.0.0.0

 Timers: Hello 10 , Dead 40 , Poll  120 , Retransmit 5 , Transmit Delay 1

 Interface: 10.0.34.4 (GigabitEthernet0/0/3)

 Cost: 1       State: BDR       Type: Broadcast    MTU: 1500 

 Priority: 1

 Designated Router: 10.0.34.3

 Backup Designated Router: 10.0.34.4

 Timers: Hello 10 , Dead 40 , Poll  120 , Retransmit 5 , Transmit Delay 1

 Area: 0.0.0.1          (MPLS TE not enabled)

 Authtype: None   Area flag:   NSSA

 SPF scheduled Count: 6    

 ExChange/Loading Neighbors: 0

 NSSA Translator State: Elected

 Router ID conflict state: Normal

 Interface: 10.0.45.4 (GigabitEthernet0/0/2)

 Cost: 1       State: BDR       Type: Broadcast    MTU: 1500 

 Priority: 1

 Designated Router: 10.0.45.5

 Backup Designated Router: 10.0.45.4

 Timers: Hello 10 , Dead 40 , Poll  120 , Retransmit 5 , Transmit Delay 1

在Border Router字段可以看到R4此时的身份为：AREA  AS  NSSA，分别代表该路由器为ABR、ASBR以及存在接口属于NSSA区域。

#在R4上观察Type-7 LSA向Type-5 LSA转换的过程，以10.0.5.0/24为例观察路由信息的传递过程

<R4>display ospf lsdb nssa 10.0.5.0

      OSPF Process 1 with Router ID 10.0.4.4

                        Area: 0.0.0.0

                Link State Database

                        Area: 0.0.0.1

                Link State Database

  Type      : NSSA

  Ls id     : 10.0.5.0

  Adv rtr   : 10.0.5.5 

  Ls age    : 587

  Len       : 36

  Options   :  NP  

  seq#      : 80000001

  chksum    : 0x3336

  Net mask  : 255.255.255.0

  TOS 0  Metric: 1

  E type    : 2

  Forwarding Address : 10.0.45.5

  Tag       : 1

  Priority  : Low

首先查看描述10.0.5.0/24的Type-7 LSA，其options字段为NP，表示该LSA可以被ABR转化成一条Type-5 LSA。

#在R4上查看生成的用于描述10.0.5.0/24的Type-5 LSA

<R4>display ospf lsdb ase 10.0.5.0

      OSPF Process 1 with Router ID 10.0.4.4

                Link State Database

  Type      : External

  Ls id     : 10.0.5.0

  Adv rtr   : 10.0.4.4 

  Ls age    : 753

  Len       : 36

  Options   :  E 

  seq#      : 80000001

  chksum    : 0xb6bc

  Net mask  : 255.255.255.0

  TOS 0  Metric: 1

  E type    : 2

  Forwarding Address : 10.0.45.5

  Tag       : 1

  Priority  : Low

可以看到与Type-7 LSA相比，其Ls id、net mask、FA地址字段内容完全相同，adv rtr字段值从10.0.5.5变为了10.0.4.4，说明该Type-5 LSA由R4产生。

1. 1. 1. 思考题

在什么场景下适合使用NSSA区域？

1. 1. 1. 配置参考

R1设备配置

#

sysname R1

#

interface GigabitEthernet0/0/1

 ip address 10.0.13.1 255.255.255.0

#

interface LoopBack0

 ip address 10.0.1.1 255.255.255.0

 ospf network-type broadcast

#

ospf 1 router-id 10.0.1.1

 area 0.0.0.2

  network 10.0.1.1 0.0.0.0

  network 10.0.13.1 0.0.0.0

  stub

#

R2设备配置

#

sysname R2

#

interface GigabitEthernet0/0/2

 ip address 10.0.23.2 255.255.255.0

#

interface LoopBack0

 ip address 10.0.2.2 255.255.255.0

 ospf network-type broadcast

#

ospf 1 router-id 10.0.2.2

 default-route-advertise cost 20 type 1

 area 0.0.0.3

  network 10.0.23.2 0.0.0.0

#

ip route-static 0.0.0.0 0.0.0.0 LoopBack0

#

R3设备配置

#

sysname R3

#

interface GigabitEthernet0/0/1

 ip address 10.0.13.3 255.255.255.0

#

interface GigabitEthernet0/0/2

 ip address 10.0.34.3 255.255.255.0

#

interface GigabitEthernet0/0/3

 ip address 10.0.23.3 255.255.255.0

#

interface LoopBack0

 ip address 10.0.3.3 255.255.255.0

 ospf network-type broadcast

#

ospf 1 router-id 10.0.3.3

 area 0.0.0.0

  network 10.0.3.3 0.0.0.0

  network 10.0.34.3 0.0.0.0

 area 0.0.0.2

  network 10.0.13.3 0.0.0.0

  stub no-summary

 area 0.0.0.3

  network 10.0.23.3 0.0.0.0

#

R4设备配置

#

sysname R4

#

interface GigabitEthernet0/0/2

 ip address 10.0.45.4 255.255.255.0

#

interface GigabitEthernet0/0/3

 ip address 10.0.34.4 255.255.255.0

#

interface LoopBack0

 ip address 10.0.4.4 255.255.255.0

 ospf network-type broadcast

#

ospf 1 router-id 10.0.4.4

 area 0.0.0.0

  network 10.0.4.4 0.0.0.0

  network 10.0.34.4 0.0.0.0

 area 0.0.0.1

  network 10.0.45.4 0.0.0.0

  nssa

#

R5设备配置

#

sysname R5

#

interface GigabitEthernet0/0/3

 ip address 10.0.45.5 255.255.255.0

#

interface LoopBack0

 ip address 10.0.5.5 255.255.255.0

 ospf network-type broadcast

#

ospf 1 router-id 10.0.5.5

 import-route direct

 area 0.0.0.1

  network 10.0.45.5 0.0.0.0

  nssa

#