OSPF非末节区域类型7到类型5的连接状态通告转换

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已更新: 2005 年 8 月 10 日
文档 ID:47867

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简介

本文显示开放式最短路径优先(OSPF)如何转换非末节区域类型7链路状态广播(LSA)到类型5 LSA。

先决条件

要求

本文档没有任何特定的要求。

使用的组件

本文档不限于特定的软件和硬件版本。

规则

有关文档规则的详细信息，请参阅 Cisco 技术提示规则。

配置

本部分提供有关如何配置本文档所述功能的信息。

注：要查找有关本文档中使用的命令的其他信息，请使用命令查找工具(仅注册客户)。

网络图

本文档使用此图所示的网络设置。

ospfdb8a.gif

配置

本文档使用此处所示的配置。

路由器 1.1.1.1 
Current configuration:

hostname r1.1.1.1

interface Loopback0
 ip address 1.1.1.1 255.0.0.0

interface Serial2/1/0
 ip address 5.0.0.1 255.0.0.0
  
interface Ethernet2/0/0
 ip address 4.0.0.1 255.0.0.0
 
router ospf 4
 redistribute static metric 5 metric-type 1
 network 5.0.0.0 0.255.255.255 area 1
 network 4.0.0.0 0.255.255.255 area 1
 area 1 nssa
 
ip route 9.0.0.0 255.0.0.0 4.0.0.2

end

路由器 2.2.2.2 
Current configuration:

hostname r2.2.2.2

interface Loopback0
 ip address 2.2.2.2 255.0.0.0
 
interface Serial0/1/0
 ip address 5.0.0.2 255.0.0.0

interface ATM1/0.20
 ip address 6.0.0.2 255.0.0.0
 
router ospf 2
 network 5.0.0.0 0.255.255.255 area 1
 network 6.0.0.0 0.255.255.255 area 0
 area 1 nssa

end

路由器 3.3.3.3 
Current configuration:

hostname r3.3.3.3

interface Loopback0
 ip address 3.3.3.3 255.0.0.0

interface ATM2/0.20 point-to-point
 ip address 6.0.0.3 255.0.0.0
 
router ospf 2
 network 6.0.0.0 0.255.255.255 area 0

end

验证

本部分所提供的信息可用于确认您的配置是否正常工作。

命令输出解释程序工具（仅限注册用户）支持某些 show 命令，使用此工具可以查看对 show 命令输出的分析。

  • show ip ospf database — 显示LSA的列表并将其键入链路状态数据库。此列表仅显示 LSA 报头中的信息。

  • show ip ospf database nssa-external — 仅显示有关NSSA外部LSA的信息。

  • show ip ospf database external - 仅显示有关外部 LSA 的信息。

  • show ip ospf database [router] [link-state-id] -显示在数据库中的一台路由器所有的LSA列表。LSA是由每个路由器生产的，并且这些基本LSA列出所有路由器链路或者接口。以及状态和链路流出开销。他们应只在产生的区内被泛洪。

  • show ip ospf database summary <link state id> -显示区域边界路由器(ABR)汇总链路。

  • show ip route - 显示路由表的当前状态。

检查 OSPF 数据库

要查看OSPF数据库在此网络环境中是什么样子的，使用show ip ospf database命令。 

r2.2.2.2#show ip ospf database 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Router Link States (Area 0) 

Link ID   ADV Router    Age    Seq#           Checksum     Link count 
2.2.2.2    2.2.2.2      1235   0x8000001D     0xD9FF           2 
3.3.3.3    3.3.3.3      1100   0x8000000B     0x9455           2 

                Summary Net Link States (Area 0) 

Link ID   ADV Router   Age    Seq#          Checksum 
4.0.0.0    2.2.2.2     1979   0x80000002    0xFDE7 
5.0.0.0    2.2.2.2     1483   0x80000004    0x8864 

                Router Link States (Area 1) 

Link ID   ADV Router   Age    Seq#          Checksum     Link count 
1.1.1.1    1.1.1.1     319    0x8000000C    0xAFA8           3 
2.2.2.2    2.2.2.2     220    0x8000002F    0xD478           2 

                Summary Net Link States (Area 1) 

Link ID   ADV Router   Age    Seq#           Checksum 
6.0.0.0    2.2.2.2     1483   0x8000001C     0x7894 

                Type-7 AS External Link States (Area 1) 

Link ID   ADV Router   Age    Seq#          Checksum     Tag 
9.0.0.0    1.1.1.1     334    0x80000005    0xD738        0 

                Type-5 AS External Link States 

Link ID   ADV Router   Age    Seq#          Checksum     Tag 
9.0.0.0    2.2.2.2     1725   0x80000004    0x50C6        0

要向NSSA通告外部路由，自治系统边界路由器(ASBR)会创建nssa外部LSA（第7类）。 

r2.2.2.2#show ip ospf database nssa-external 9.0.0.0 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Type-7 AS External Link States (Area 1) 

  Routing Bit Set on this LSA 
  LS age: 381 
  Options: (No TOS-capability, Type 7/5 translation, DC)

!--- This can be translated into a type 5 LSA by !--- an ABR. 

  LS Type: AS External Link 
  Link State ID: 9.0.0.0 (External Network Number ) 

!--- The ASBR (Router 1.1.1.1) advertises !--- 9.0.0.0/8. 

  Advertising Router: 1.1.1.1

!--- Router ID of the ASBR.
 
  LS Seq Number: 80000005 
  Checksum: 0xD738 
  Length: 36 
  Network Mask: /8 
        Metric Type: 1 (Comparable directly to link state metric) 
        TOS: 0 
        Metric: 5 
        Forward Address: 4.0.0.1

!--- Forwarding address is incorrectly specified !--- as an interface on the ASBR.

ABR将第7类LSA转换为第5类LSA，并将第5类LSA传播到正常区域。

r2.2.2.2#show ip ospf database external 9.0.0.0 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Type-5 AS External Link States 

  LS age: 1782 
  Options: (No TOS-capability, DC) 
  LS Type: AS External Link 
  Link State ID: 9.0.0.0 (External Network Number )

!--- Router 2.2.2.2 advertises 9.0.0.0/8.
 
  Advertising Router: 2.2.2.2 

!--- When the conversion is complete, the advertising !--- router ID becomes the ABR router ID !--- because the ABR originates this type 5 LSA. 

  LS Seq Number: 80000004 
  Checksum: 0x50C6 
  Length: 36 
  Network Mask: /8 
        Metric Type: 1 (Comparable directly to link state metric) 
        TOS: 0 
        Metric: 5 
        Forward Address: 4.0.0.1 
        External Route Tag: 0 
  

r2.2.2.2#show ip ospf database router 1.1.1.1 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Router Link States (Area 1) 

  Routing Bit Set on this LSA 
  LS age: 426 
  Options: (No TOS-capability, DC) 
  LS Type: Router Links 
  Link State ID: 1.1.1.1

!--- For router links, Link State ID is always the same !--- as the advertising router (next line). 

  Advertising Router: 1.1.1.1
  LS Seq Number: 8000000C 
  Checksum: 0xAFA8 
  Length: 60 
  AS Boundary Router

!--- Bit E in the router LSA indicates that this router !--- originates from external LSAs.
 
   Number of Links: 3

!--- There are three links in area 1. 


    Link connected to: a Stub Network

!--- This represents the Ethernet segment 4.0.0.0/8.
 
     (Link ID) Network/subnet number: 4.0.0.0 
     (Link Data) Network Mask: 255.0.0.0 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 10

!--- The OSPF cost of the Ethernet segment.
 

    Link connected to: another Router (point-to-point) 

!--- Shows that Router 1.1.1.1 is a neighbor with !--- Router 2.2.2.2. 

     (Link ID) Neighboring Router ID: 2.2.2.2 
     (Link Data) Router Interface address: 5.0.0.1

!--- The interface address that connects to Router !--- 2.2.2.2 is 5.0.0.1.
 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 64

!--- The OSPF cost of the link that connects !--- the two routers.

    Link connected to: a Stub Network 

!--- This represents the serial link 5.0.0.0/8.
 
     (Link ID) Network/subnet number: 5.0.0.0 
     (Link Data) Network Mask: 255.0.0.0 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 64

!--- The OSPF cost of the serial link.

从此处的粗体输出可以看到，尽管路由器2.2.2.2的配置中没有任何redistribute语句，但它仍是ASBR，因为它将第7类LSA转换为第5类LSA。 

r2.2.2.2#show ip ospf database router 2.2.2.2 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Router Link States (Area 0) 

  LS age: 1361 
  Options: (No TOS-capability, DC) 
  LS Type: Router Links 
  Link State ID: 2.2.2.2 
  Advertising Router: 2.2.2.2 
  LS Seq Number: 8000001D 
  Checksum: 0xD9FF 
  Length: 48 
  Area Border Router 
  
!--- Bit B is set in the router LSA to indicate !--- that this router is an ABR.
 
  AS Boundary Router
  
!--- Bit E in the router LSA indicates that this router !--- originates from external LSAs.

   Number of Links: 2 
  
!--- There are two links in area 0. 


    Link connected to: another Router (point-to-point) 
     (Link ID) Neighboring Router ID: 3.3.3.3 
     (Link Data) Router Interface address: 6.0.0.2 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 1 

    Link connected to: a Stub Network 
     (Link ID) Network/subnet number: 6.0.0.0 
     (Link Data) Network Mask: 255.0.0.0 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 1

                Router Link States (Area 1) 

  LS age: 346 
  Options: (No TOS-capability, DC) 
  LS Type: Router Links 
  Link State ID: 2.2.2.2 
  Advertising Router: 2.2.2.2 
  LS Seq Number: 8000002F 
  Checksum: 0xD478 
  Length: 48 
  Area Border Router 
  AS Boundary Router 
   Number of Links: 2 

    Link connected to: another Router (point-to-point) 
     (Link ID) Neighboring Router ID: 1.1.1.1 
     (Link Data) Router Interface address: 5.0.0.2 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 64 

    Link connected to: a Stub Network 
     (Link ID) Network/subnet number: 5.0.0.0 
     (Link Data) Network Mask: 255.0.0.0 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 64 
  

r2.2.2.2#show ip ospf database router 3.3.3.3 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Router Link States (Area 0) 

  LS age: 1245 
  Options: (No TOS-capability, DC) 
  LS Type: Router Links 
  Link State ID: 3.3.3.3 
  Advertising Router: 3.3.3.3 
  LS Seq Number: 8000000B 
  Checksum: 0x9455 
  Length: 48 
   Number of Links: 2 

    Link connected to: another Router (point-to-point) 
     (Link ID) Neighboring Router ID: 2.2.2.2 
     (Link Data) Router Interface address: 6.0.0.3 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 1 

    Link connected to: a Stub Network 
     (Link ID) Network/subnet number: 6.0.0.0 
     (Link Data) Network Mask: 255.0.0.0 
      Number of TOS metrics: 0 
       TOS 0 Metrics: 1

要将路由从一个区域通告到另一个区域，ABR会创建汇总LSA（第3类）。 

r2.2.2.2#show ip ospf database summary 4.0.0.0 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Summary Net Link States (Area 0) 

  LS age: 172 
  Options: (No TOS-capability, DC) 
  LS Type: Summary Links(Network) 
  Link State ID: 4.0.0.0 (summary Network Number)
  
!--- The ABR (Router 2.2.2.2) advertises !--- 4.0.0.0/8 into area 0.

  Advertising Router: 2.2.2.2 
  LS Seq Number: 80000003 
  Checksum: 0xFBE8 
  Length: 28 
  Network Mask: /8 
        TOS: 0  Metric: 74 

r2.2.2.2#show ip ospf database summary 5.0.0.0 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Summary Net Link States (Area 0) 

  LS age: 1687 
  Options: (No TOS-capability, DC) 
  LS Type: Summary Links(Network) 
  Link State ID: 5.0.0.0 (summary Network Number)
  
!--- The ABR (Router 2.2.2.2) advertises !--- 5.0.0.0/8 into area 0. 

  Advertising Router: 2.2.2.2 
  LS Seq Number: 80000004 
  Checksum: 0x8864 
  Length: 28 
  Network Mask: /8 
        TOS: 0  Metric: 64 

r2.2.2.2#show ip ospf database summary 6.0.0.0 

       OSPF Router with ID (2.2.2.2) (Process ID 2) 

                Summary Net Link States (Area 1) 

  LS age: 1697 
  Options: (No TOS-capability, DC) 
  LS Type: Summary Links(Network) 
  Link State ID: 6.0.0.0 (summary Network Number)
  
!--- The ABR (Router 2.2.2.2) advertises !--- 6.0.0.0/8 into area 1.

  Advertising Router: 2.2.2.2 
  LS Seq Number: 8000001C 
  Checksum: 0x7894 
  Length: 28 
  Network Mask: /8 
        TOS: 0  Metric: 1

在本例中，不需要ASBR汇总LSA，因为ABR发起外部LSA，并且ABR可在区域0内到达。请通过查看数据库示例How OSPF Proach External Routes into Multiple Areas，将此示例与NSSA为正常区域的场景进行比较。

此路由表输出显示9.0.0.0被每个路由器所知的不同的OSPF路由类型。 

r1.1.1.1#show ip route 9.0.0.0 
Routing entry for 9.0.0.0/8 
  Known via "static", distance 1, metric 0 
  Redistributing via ospf 4 
  Advertised by ospf 4 metric 5 metric-type 1 
  Routing Descriptor Blocks: 
  * 4.0.0.2 
      Route metric is 0, traffic share count is 1

r2.2.2.2#show ip route ospf 
O    4.0.0.0/8 [110/74] via 5.0.0.1, 01:10:13, Serial0/1/0 
O N1 9.0.0.0/8 [110/79] via 5.0.0.1, 01:07:20, Serial0/1/0 

R3.3.3.3#show ip route ospf
O IA 4.0.0.0/8 [110/75] via 6.0.0.2, 02:11:14, ATM2/0.20 
O IA 5.0.0.0/8 [110/65] via 6.0.0.2, 03:10:41, ATM2/0.20 
O E1 9.0.0.0/8 [110/80] via 6.0.0.2, 02:08:11, ATM2/0.20

故障排除

目前没有针对此配置的故障排除信息。

相关信息

修订历史记录

版本 发布日期 备注
1.0
10-Aug-2005
初始版本

提供者

  • dravindr
    pthoma
  • rvigil
    sshamim

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