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IS-IS 用户指南
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示例:配置多层 IS-IS 拓扑来控制区域间泛洪

date_range 16-Jun-23

此示例说明如何配置多级 IS-IS 拓扑。

要求

配置此示例之前,不需要除设备初始化之外的特殊配置。

概述

与 OSPF 类似,IS-IS 协议支持将路由域划分为具有控制区域间泛洪的级别多个区域。使用多个级别可改进协议可扩展性,因为级别 2(骨干)链路状态 PDU 通常不会泛洪到 1 级区域。

IS-IS 级别 2 区域与 OSPF 主干区域 (0) 类似,而 1 级区域的操作类似于 OSPF 完全剩余区域,因为默认路由通常用于访问级别间和 AS 外部路由。

与 OSPF 不同,IS-IS 区域边界发生在路由器之间,因此给定的路由设备始终完全包含在特定区域内。第 1 级邻接可在共享公共区域编号的路由器之间形成,而第 2 级邻接可在可能共享区域编号或不共享区域编号的路由器之间形成。

图 1 显示了此示例中使用的拓扑。

图 1:IS-IS 多层拓扑 IS-IS Multi-Level Topology

CLI 快速配置 显示了 图 1 中所有设备的配置。 第 #configuration69__isis 多级别逐步 说明部分介绍了设备 R5 上的步骤。

此示例具有以下特征:

  • 设备 R5 充当 1 级/级别 2 路由器,用于将包含设备 R6 和设备 R7 的第 2 级骨干区域 49.0001 和级别 1 区域 49.0002 互连。

  • 系统 ID 基于设备的 IPv4 lo0 地址。

  • 丢失任何单个接口不会完全中断 IS-IS 操作。

  • 所有路由器的 IPv4 lo0 地址均可通过 IS-IS 访问。

  • 设备 R3 和设备 S1 之间的链路在第 49.0001 区域显示为区域内路由。此接口上无法建立 IS-IS 邻接。这可以通过在设备 R3 的接口上配置 passive 到设备 S1 的语句来实现。

  • 级别 2 设备的环路地址不会显示在级别 1 区域中。

  • 每个设备配对只有一个邻接。

拓扑

配置

程序

CLI 快速配置

要快速配置此示例,请复制以下命令,将其粘贴到文本文件中,删除所有换行符,更改详细信息,以便与网络配置匹配,然后将命令复制并粘贴到层级的 [edit] CLI 中。

设备 R3

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 0 description to-R4
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.17/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 description to-R5
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.21/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces fe-1/2/2 unit 0 family inet address 10.0.0.41/30
set interfaces fe-1/2/2 unit 0 description to-S1  
set interfaces lo0 unit 0 family inet address 192.168.0.3/32
set interfaces lo0 unit 0 family iso address 49.0001.0192.0168.0003.00
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface lo0.0 level 1 disable
set protocols isis interface fe-1/2/2.0 passive 

设备 R4

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 0 description to-R3
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.18/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 description to-R5
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.25/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 192.168.0.4/32
set interfaces lo0 unit 0 family iso address 49.0001.0192.0168.0004.00
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface lo0.0 level 1 disable

设备 R5

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 0 description to-R3
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.22/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 description to-R4
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.26/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces fe-1/2/2 unit 0 description to-R6
set interfaces fe-1/2/2 unit 0 family inet address 10.0.0.29/30
set interfaces fe-1/2/2 unit 0 family iso
set interfaces fe-1/2/3 unit 0 description to-R7
set interfaces fe-1/2/3 unit 0 family inet address 10.0.0.38/30
set interfaces fe-1/2/3 unit 0 family iso
set interfaces lo0 unit 0 family inet address 192.168.0.5/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0005.00
set protocols isis interface fe-1/2/0.0 level 1 disable
set protocols isis interface fe-1/2/1.0 level 1 disable
set protocols isis interface fe-1/2/2.0 level 2 disable
set protocols isis interface fe-1/2/3.0 level 2 disable
set protocols isis interface lo0.0 level 1 disable

设备 R6

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set interfaces fe-1/2/0 unit 0 description to-R5
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.30/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 description to-R7
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.33/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 192.168.0.6/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0006.00
set protocols isis interface fe-1/2/0.0 level 2 disable
set protocols isis interface fe-1/2/1.0 level 2 disable
set protocols isis interface lo0.0 level 2 disable

设备 R7

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 0 description to-R6
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.34/30
set interfaces fe-1/2/0 unit 0 family iso
set interfaces fe-1/2/1 unit 0 description to-R5
set interfaces fe-1/2/1 unit 0 family inet address 10.0.0.37/30
set interfaces fe-1/2/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 192.168.0.7/32
set interfaces lo0 unit 0 family iso address 49.0002.0192.0168.0007.00
set protocols isis interface fe-1/2/0.0 level 2 disable
set protocols isis interface fe-1/2/1.0 level 2 disable
set protocols isis interface lo0.0 level 2 disable

设备 S1

content_copy zoom_out_map
set interfaces fe-1/2/0 unit 0 family inet address 10.0.0.42/30
set interfaces fe-1/2/0 unit 0 description to-R3

逐步过程

以下示例要求您在配置层次结构中的各个级别上导航。有关导航 CLI 的信息,请参阅 CLI 用户指南中的在配置模式下使用 CLI 编辑器。

要配置多级别 IS-IS:

  1. 配置网络接口。

    通过在每个接口上包括 ISO 地址家族,在接口上启用 IS-IS。

    content_copy zoom_out_map
    [edit interfaces]
    user@R5# set fe-1/2/0 unit 0 description to-R3
    user@R5# set fe-1/2/0 unit 0 family inet address 10.0.0.22/30
    user@R5# set fe-1/2/0 unit 0 family iso
    user@R5# set fe-1/2/1 unit 0 description to-R4
    user@R5# set fe-1/2/1 unit 0 family inet address 10.0.0.26/30
    user@R5# set fe-1/2/1 unit 0 family iso
    user@R5# set fe-1/2/2 unit 0 description to-R6
    user@R5# set fe-1/2/2 unit 0 family inet address 10.0.0.29/30
    user@R5# set fe-1/2/2 unit 0 family iso
    user@R5# set fe-1/2/3 unit 0 description to-R7
    user@R5# set fe-1/2/3 unit 0 family inet address 10.0.0.38/30
    user@R5# set fe-1/2/3 unit 0 family iso
    
  2. 配置两个环路接口地址。

    一个地址用于 IPv4。

    另一个用于 IS-IS 区域 49.0002,以便设备 R5 可以与区域 49.0002 中的其他 1 级设备形成邻接。即使设备 R5 的 NET 将其标识为属于级别 1 区域 49.0002,其环路接口未配置为 1 级接口。这样做会使到设备 R5 的环路路由注入到级别 1 区域。

    content_copy zoom_out_map
    [edit interfaces lo0 unit 0]
    user@R5# set family inet address 192.168.0.5/32
    user@R5# set family iso address 49.0002.0192.0168.0005.00
    
  3. 按接口指定 IS-IS 级别。

    设备 R5 会与每个链路上同一级别上其他路由设备相邻。

    默认情况下,对于启用 ISO 协议家族的所有接口上的 IS-IS 区域(在 [edit interfaces interface-name unit logical-unit-number] 层次结构级别),都启用了 IS-IS。要禁用接口上任何特定级别的 IS-IS,请包括语句 disable

    设备 R5 的环路接口配置为仅运行级别 2。如果在 lo0.0 上启用了级别 1 操作,设备 R5 会将其环路地址包含在其 1 级链路状态 PDU 中,这一点不正确,在此示例中,级别 2 设备的环路地址不得出现在 1 级区域。

    与 OSPF 不同,您必须在 [edit protocols isis] 层次结构级别显式列出路由器的 lo0 接口,因为此接口是路由器 NET 的来源,因此必须配置为 IS-IS 接口。在 IS-IS 中,lo0 接口默认在无源模式下运行,这很理想,因为虚拟接口永远无法形成邻接。

    content_copy zoom_out_map
    [edit protocols isis]
    user@R5# set interface fe-1/2/0.0 level 1 disable
    user@R5# set interface fe-1/2/1.0 level 1 disable
    user@R5# set interface fe-1/2/2.0 level 2 disable
    user@R5# set interface fe-1/2/3.0 level 2 disable
    user@R5# set interface lo0.0 level 1 disable
    

结果

在配置模式下,输入和 show protocols 命令以确认show interfaces您的配置。如果输出未显示预期的配置,请重复此示例中的说明,以更正配置。

content_copy zoom_out_map
user@R5# show interfaces
fe-1/2/0 {
    unit 0{
        description to-R3;
        family inet {
            address 10.0.0.22/30;
        }
        family iso;
    }
}
fe-1/2/1 {
    unit 0 {
        description to-R4;
        family inet {
            address 10.0.0.26/30;
        }
        family iso;
    }
}
fe-1/2/2 {
    unit 0 {
        description to-R6;
        family inet {
            address 10.0.0.29/30;
        }
        family iso;
    }
}
fe-1/2/3 {
    unit 0 {
        description to-R7;
        family inet {
            address 10.0.0.38/30;
        }
        family iso;
    }
}
lo0 {
    unit 0 {
        family inet {
            address 192.168.0.5/32;
        }
        family iso {
            address 49.0002.0192.0168.0005.00;
        }
    }
}
content_copy zoom_out_map
user@R5# show protocols
isis {
    interface fe-1/2/0.0 {
        level 1 disable;
    }
    interface fe-1/2/1.0 {
        level 1 disable;
    }
    interface fe-1/2/2.0 {
        level 2 disable;
    }
    interface fe-1/2/3.0 {
        level 2 disable;
    }
    interface lo0.0 {
        level 1 disable;
    }
}

完成设备配置后,请从配置模式进入 commit

验证

确认配置工作正常。

检查接口到区域的关联

目的

请确保按预期配置接口到区域关联。

行动

在操作模式下,输入 show isis interface 命令。

content_copy zoom_out_map
user@R5> show isis interface
IS-IS interface database:
Interface             L CirID Level 1 DR       Level 2 DR       L1/L2 Metric
lo0.0                 3   0x1 Disabled          Passive             0/0
fe-1/2/0.0           2   0x3 Disabled          R5.03              10/10
fe-1/2/1.0           2   0x2 Disabled          R5.02              10/10
fe-1/2/2.0           1   0x1 R6.02         Disabled               10/10
fe-1/2/3.0           1   0x4 R5.04         Disabled               10/10

意义

输出显示,设备 R5 的接口已正确配置 ISO 系列,并且接口已放置在正确的级别。

您还可以看到,设备 R5 已在其支持广播的 IS-IS 接口上将自己选为指定的中间系统 (DIS)。

验证 IS-IS 邻接

目的

验证设备 R5 与其 IS-IS 邻接方之间是否已形成预期的邻接。

行动

在操作模式下,输入 show isis adjacency detail 命令。

content_copy zoom_out_map
user@R5> show isis adjacency detail
R3
  Interface: fe-1/2/0.0, Level: 2, State: Up, Expires in 25 secs
  Priority: 64, Up/Down transitions: 1, Last transition: 03:19:31 ago
  Circuit type: 2, Speaks: IP, IPv6, MAC address: 0:5:85:8f:c8:bc
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: R5.03, IP addresses: 10.0.0.21

R4
  Interface: fe-1/2/1.0, Level: 2, State: Up, Expires in 24 secs
  Priority: 64, Up/Down transitions: 1, Last transition: 03:19:36 ago
  Circuit type: 2, Speaks: IP, IPv6, MAC address: 0:5:85:8f:c8:bc
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: R5.02, IP addresses: 10.0.0.25

R6
  Interface: fe-1/2/2.0, Level: 1, State: Up, Expires in 6 secs
  Priority: 64, Up/Down transitions: 1, Last transition: 03:20:24 ago
  Circuit type: 1, Speaks: IP, IPv6, MAC address: 0:5:85:8f:c8:bd
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: R6.02, IP addresses: 10.0.0.30

R7
  Interface: fe-1/2/3.0, Level: 1, State: Up, Expires in 21 secs
  Priority: 64, Up/Down transitions: 1, Last transition: 03:19:29 ago
  Circuit type: 1, Speaks: IP, IPv6, MAC address: 0:5:85:8f:c8:bc
  Topologies: Unicast
  Restart capable: Yes, Adjacency advertisement: Advertise
  LAN id: R5.04, IP addresses: 10.0.0.37

意义

这些结果确认设备 R5 具有两个 2 级邻接和两个 1 级邻接。

检查 IS-IS 数据库

目的

由于设备 R5 是 1 级/级别 2 (L1/L2) 连接的路由器,因此请检查与区域 49.0002 关联的 1 级链路状态数据库,以确认来自主干路由器的环路地址未播发到级别 1 区域。

行动

在操作模式下,输入 show isis database detail 命令。

content_copy zoom_out_map
user@R5> show isis database detail
IS-IS level 1 link-state database:

R5.00-00 Sequence: 0x19, Checksum: 0x7488, Lifetime: 727 secs
   IS neighbor: R5.04                     Metric:       10
   IS neighbor: R6.02                     Metric:       10
   IP prefix: 10.0.0.28/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.36/30                    Metric:       10 Internal Up

R5.04-00 Sequence: 0x14, Checksum: 0x2668, Lifetime: 821 secs
   IS neighbor: R5.00                     Metric:        0
   IS neighbor: R7.00                     Metric:        0

R6.00-00 Sequence: 0x17, Checksum: 0xa65, Lifetime: 774 secs
   IS neighbor: R6.02                     Metric:       10
   IS neighbor: R7.02                     Metric:       10
   IP prefix: 10.0.0.28/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.32/30                    Metric:       10 Internal Up
   IP prefix: 192.168.0.6/32                  Metric:        0 Internal Up

R6.02-00 Sequence: 0x13, Checksum: 0xd1c0, Lifetime: 908 secs
   IS neighbor: R5.00                     Metric:        0
   IS neighbor: R6.00                     Metric:        0

R7.00-00 Sequence: 0x17, Checksum: 0xe39, Lifetime: 775 secs
   IS neighbor: R5.04                     Metric:       10
   IS neighbor: R7.02                     Metric:       10
   IP prefix: 10.0.0.32/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.36/30                    Metric:       10 Internal Up
   IP prefix: 192.168.0.7/32                  Metric:        0 Internal Up

R7.02-00 Sequence: 0x13, Checksum: 0x404d, Lifetime: 966 secs
   IS neighbor: R6.00                     Metric:        0
   IS neighbor: R7.00                     Metric:        0

IS-IS level 2 link-state database:

R3.00-00 Sequence: 0x17, Checksum: 0x5f84, Lifetime: 1085 secs
   IS neighbor: R4.02                     Metric:       10
   IS neighbor: R5.03                     Metric:       10
   IP prefix: 10.0.0.16/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.20/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.40/30                    Metric:       10 Internal Up
   IP prefix: 192.168.0.3/32                  Metric:        0 Internal Up

R4.00-00 Sequence: 0x17, Checksum: 0xab3a, Lifetime: 949 secs
   IS neighbor: R4.02                     Metric:       10
   IS neighbor: R5.02                     Metric:       10
   IP prefix: 10.0.0.16/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.24/30                    Metric:       10 Internal Up
   IP prefix: 192.168.0.4/32                  Metric:        0 Internal Up

R4.02-00 Sequence: 0x14, Checksum: 0xf2a8, Lifetime: 1022 secs
   IS neighbor: R3.00                     Metric:        0
   IS neighbor: R4.00                     Metric:        0

R5.00-00 Sequence: 0x1f, Checksum: 0x20d7, Lifetime: 821 secs
   IS neighbor: R5.02                     Metric:       10
   IS neighbor: R5.03                     Metric:       10
   IP prefix: 10.0.0.20/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.24/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.28/30                    Metric:       10 Internal Up
   IP prefix: 10.0.0.32/30                    Metric:       20 Internal Up
   IP prefix: 10.0.0.36/30                    Metric:       10 Internal Up
   IP prefix: 192.168.0.5/32                  Metric:        0 Internal Up
   IP prefix: 192.168.0.6/32                  Metric:       10 Internal Up
   IP prefix: 192.168.0.7/32                  Metric:       10 Internal Up

R5.02-00 Sequence: 0x14, Checksum: 0x6135, Lifetime: 977 secs
   IS neighbor: R4.00                     Metric:        0
   IS neighbor: R5.00                     Metric:        0

R5.03-00 Sequence: 0x14, Checksum: 0x1483, Lifetime: 1091 secs
   IS neighbor: R3.00                     Metric:        0
   IS neighbor: R5.00                     Metric:        0

意义

此显示屏表示设备 R5 的环路接口配置正确,仅运行级别 2。如果已在 lo0.0 上启用级别 1 操作,设备 R5 将在其 1 级链路状态 PDU 中包含其环路地址。

您还可以看到,设备 R5 具有从相邻邻接方接收的 2 级链路状态 PDU。

就像 OSPF 完全剩余区域一样,默认情况下,不会将主干(级别 2) 或外部前缀泄露到级别 1 区域。但是,第 1 级前缀会泄露到 IS-IS 主干网中,如设备 R5 的级别 2 链路状态 PDU 中所示。

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