防止重复的 EIGRP 路由器 ID

简介

重复的增强型内部网关路由协议(EIGRP)路由器ID可能导致EIGRP外部路由的重分发问题。本文解释了问题，并提供了正确的配置来防止问题。

EIGRP路由器ID的选择方式通常与开放最短路径优先(OSPF)相同。 为环回接口分配的最高IP地址被选作路由器ID。如果未配置任何环回地址，则选择分配给任何其他接口的最高IP地址作为路由器ID。

先决条件

要求

本文档没有任何特定的要求。

使用的组件

此配置是使用Cisco IOS®软件版^本12.2(10b)开发和测试的。

本文档中的信息都是基于特定实验室环境中的设备创建的。本文档中使用的所有设备最初均采用原始（默认）配置。如果您是在真实网络上操作，请确保您在使用任何命令前已经了解其潜在影响。

规则

有关文档规则的详细信息，请参阅 Cisco 技术提示规则。

问题

通过此网络设置，可以了解由于存在具有重复EIGRP路由器ID的路由器而导致的重分布路由的问题。

网络图

配置

interface Loopback0

 ip address 1.1.1.1 255.255.255.255

!

interface Loopback1

 ip address 10.10.10.10 255.255.255.0

!

interface Ethernet0

 ip address 172.16.3.4 255.255.255.0

!

router rip

 version 2

 network 10.0.0.0

 network 172.16.0.0

interface Loopback0

 ip address 2.2.2.2 255.255.255.255

!

interface Ethernet0

 ip address 172.16.3.3 255.255.255.0

 ip pim sparse-dense-mode

!

interface Serial1

 ip address 172.16.13.3 255.255.255.0

 clockrate 4000000

!

router eigrp 7

 redistribute rip metric 1 1 1 1 1

 network 172.16.0.0

!

router rip

 version 2

 network 172.16.0.0

interface Loopback0

 ip address 2.2.2.2 255.255.255.0

!

interface Serial1

 ip address 172.16.13.1 255.255.255.0

 no ip mroute-cache

!

router eigrp 7

 network 172.16.0.0

 auto-summary

 no eigrp log-neighbor-changes

显示命令

如前所示，路由器3将路由信息协议(RIP)路由重分发到EIGRP。这是3个路由表和EIGRP拓扑表。

Router-3#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route

Gateway of last resort is not set

     2.0.0.0/32 is subnetted, 1 subnets
C       2.2.2.2 is directly connected, Loopback0
R    10.0.0.0/8 [120/1] via 172.16.3.4, 00:00:25, Ethernet0 
!--- Router 3 sees network 10.0.0.0. 
     172.16.0.0/24 is subnetted, 3 2 subnets
C       172.16.13.0 is directly connected, Serial1
C       172.16.3.0 is directly connected, Ethernet0
router-3#


router-3#show ip eigrp topology 10.0.0.0 255.0.0.0
IP-EIGRP (AS 7): topology entry for 10.0.0.0/8
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2560000256
  Routing Descriptor Blocks:
  0.0.0.0, from Redistributed, Send flag is 0x0
      Composite metric is (2560000256/0), Route is External
      Vector metric:
        Minimum bandwidth is 1 Kbit
        Total delay is 10 microseconds
        Reliability is 1/255
        Load is 1/255
        Minimum MTU is 1
        Hop count is 0
      External data:
        Originating router is 2.2.2.2 (this system)
!--- Shows that Router 3 is the originating router of the external route.

        AS number of route is 0
        External protocol is RIP, external metric is 1
        Administrator tag is 0 (0x00000000)
router-3#

从上一输出中，您可以看到路由器3通过RIP获知了网络10.0.0.0。通过重分发，路由已作为外部路由输入到EIGRP拓扑表中。路由器3还显示它是外部路由的始发路由器；其EIGRP路由器ID为2.2.2.2。

由于路由器3似乎会重分发外部路由，因此路由器1的路由表中应该会显示该路由。这是Router 1的路由表和EIGRP拓扑表的显示。

router-1#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set

     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
     172.16.0.0/24 is subnetted, 3 2 subnets
C       172.16.13.0 is directly connected, Serial1
D       172.16.3.0 [90/2195456] via 172.16.13.3, 00:31:59, Serial1
router-1#


router-1# show ip eigrp topology
IP-EIGRP Topology Table for AS(7)/ID(2.2.2.2)

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status

P 172.16.13.0/24, 1 successors, FD is 2169856
         via Connected, Serial1
P 172.16.3.0/24, 1 successors, FD is 2195456
         via 172.16.13.3 (2195456/281600), Serial1
router-1#

从前面的输出中，您可以看到，路由器1的路由表或EIGRP拓扑表中不包含预期的10.0.0.0/8路由。原因可能是路由器1和3具有相同的EIGRP路由器ID。在Cisco IOS软件版本12.0(2)及更高版本中，Cisco在EIGRP事件日志中记录重复的路由器ID，您可以使用show ip eigrp events命令查看该日志。以下是路由器1的输出：

router-1 #show ip eigrp events 
Event information for AS 7:
1    18:06:15.863 Change queue emptied, entries: 1
2    18:06:15.863 Ignored route, metric: 10.0.0.0 2560512256
3    18:06:15.863 Ignored route, neighbor info: 172.16.13.3 Serial2
4    18:06:15.863 Ignored route, dup router: 2.2.2.2


!--- Output suppressed.

从前面的输出中，您可以看到重复的路由器ID是路由器1不接受来自路由器3的路由的原因。

解决方案

解决方案是通过更改环回接口上的最高IP地址来更改其中一台路由器上的路由器ID。如果因Cisco IOS软件版本12.1(6)或更高版本而停用，您也可以使用eigrp router-id <router-id> router子命令来更改路由器ID。在本例中，我们更改了路由器1中的路由器ID。

router-1(config)#router eigrp 7 
router-1(config-router)#eigrp router-id 3.3.3.3

注意：更改Eigrp路由器ID后，发出clear ip eigrp <Autonomous System命令。

外部路由现在显示在路由表中，如下所示。

router-1#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, IA - IS-IS inter area
       * - candidate default, U - per-user static route, o - ODR
       P - periodic downloaded static route

Gateway of last resort is not set
     2.0.0.0/24 is subnetted, 1 subnets
C       2.2.2.0 is directly connected, Loopback0
     172.16.0.0/24 is subnetted, 2 subnets
C       172.16.13.0 is directly connected, Serial1
D       172.16.3.0 [90/2195456] via 172.16.13.3, 00:00:00, Serial1
D EX 10.0.0.0/8 [170/2560512256] via 172.16.13.3, 00:00:00, Serial1
router-1# 

相关信息

• IP路由协议支持
• IP 路由技术支持
• EIGRP技术支持
• RIP技术支持
• 路由器产品支持
• 技术支持和文档 - Cisco Systems