防止重複的EIGRP路由器ID

簡介

重複增強型內部網關路由協定(EIGRP)路由器ID可能會導致EIGRP外部路由的重新分配出現問題。本檔案將說明問題，並提供適當的設定以避免問題。

EIGRP路由器ID的選擇方式通常與開放最短路徑優先(OSPF)相同。 分配給環回介面的最大IP地址被選為路由器ID。如果沒有配置任何環回地址，則會選擇分配給任何其他介面的最高IP地址作為路由器ID。

必要條件

需求

本文件沒有特定需求。

採用元件

此配置是使用Cisco IOS^®軟體版本12.2(10b)開發和測試的。

本文中的資訊是根據特定實驗室環境內的裝置所建立。文中使用到的所有裝置皆從已清除（預設）的組態來啟動。如果您在即時網路中工作，請確保在使用任何命令之前瞭解其潛在影響。

慣例

如需文件慣例的詳細資訊，請參閱思科技術提示慣例。

問題

通過此網路設定可以瞭解由於存在具有重複EIGRP路由器ID的路由器而導致重分發路由的問題。

網路圖表

組態

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

顯示命令

如前所示，Router 3將路由資訊協定(RIP)路由重分發到EIGRP。這是3個路由表和EIGRP拓撲表。

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#

從上面的輸出中，您可以看到Router3已經通過RIP獲知了網路10.0.0.0。通過重分發，該路由已作為外部路由輸入到EIGRP拓撲表中。路由器3還顯示它是外部路由的始發路由器；其EIGRP路由器ID為2.2.2.2。

由於Router3似乎要重新分發外部路由，因此預計它會在Router 1的路由表中看到它。這是路由器1的路由表和EIGRP拓撲表的顯示。

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#

從先前的輸出中，您可以看到10.0.0.0/8的預期路由不在路由器1的路由表或EIGRP拓撲表中。這可能是因為路由器1和3具有相同的EIGRP路由器ID。在Cisco IOS軟體版本12.0(2)及更高版本中，Cisco在EIGRP事件日誌中記錄重複的路由器ID，您可以使用show ip eigrp events命令檢視該日誌。以下是Router 1的輸出：

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.

從先前的輸出中，您可以看到重複的路由器ID是路由器1不接受來自路由器3的路由的原因。

解決方案

解決方案是通過更改環回介面上的最高IP地址來更改其中一個路由器上的路由器ID。如果使用Cisco IOS軟體版本12.1(6)或更高版本，您還可以使用eigrp router-id <router-id> router子命令更改路由器ID。在本例中，我們更改了Router 1中的路由器ID。

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

註：在更改Eigrp路由器ID後，發出clear ip eigrp <Autonomous System命令。

外部路由現在會出現在路由表中，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# 

相關資訊

• IP路由通訊協定支援
• IP路由技術支援
• EIGRP技術支援
• RIP技術支援
• 路由器產品支援
• 技術支援與文件 - Cisco Systems