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EI CCNP培训企业基础架构课程-EIGRP拓扑变更时查询机制详解

发布日期:2023-10-27 浏览次数:1446 来源:WOLFLAB杨广成

EI CCNP培训企业基础架构课程-EIGRP拓扑变更时查询机制详解

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图片1(6).png

实验拓扑如上图所示,配置接口ip地址,R1 R2 R3上运行EIGRP 90:

R1

interface Loopback0

ip address 1.1.1.1 255.255.255.0

interface Serial1/0

no shutdown

 ip address 172.16.12.1 255.255.255.0

 

router eigrp 90

 network 1.1.1.1 0.0.0.0

 network 172.16.12.1 0.0.0.0

 no auto-summary

R2

interface Loopback0

ip address 2.2.2.2 255.255.255.0

interface Serial1/0

no shutdown

 ip address 172.16.12.2 255.255.255.0

interface Serial1/1

no shutdown

 ip address 192.168.23.2 255.255.255.0

router eigrp 90

 network 2.2.2.2 0.0.0.0

 network 172.16.12.2 0.0.0.0

 network 192.168.23.2 0.0.0.0

 no auto-summary

R3

interface Loopback0

 ip address 3.3.3.3 255.255.255.0

interface Serial1/1

 no shutdown

 ip address 192.168.23.3 255.255.255.0

router eigrp 90

 network 3.3.3.3 0.0.0.0

 network 192.168.23.3 0.0.0.0

 no auto-summary

1、在R1 R2 R3上开启debug eigrp packets query reply ack。将R1的loopback接口shutdown,观察各路由器的query、reply包的传递情况,理解EIGRP DUAL扩散查询的方式。

R1R2R3

debug eigrp packets query reply ack

R1

interface Loopback0

 shutdown

R1

*Oct  1 18:24:27.391: EIGRP: Enqueueing QUERY on Serial1/0 nbr 172.16.12.2 iidbQ un/rely 0/0 peerQ un/rely 0/0 serno 91-91

*Oct  1 18:24:27.395: EIGRP: Sending QUERY on Serial1/0 nbr 172.16.12.2     //R2发出Query  ---  1

*Oct  1 18:24:27.395:   AS 90, Flags 0x0, Seq 94/90 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 91-91

*Oct  1 18:24:27.455: EIGRP: Received ACK on Serial1/0 nbr 172.16.12.2       //收到R2回复的Ack  ---  4

*Oct  1 18:24:27.459:   AS 90, Flags 0x0, Seq 0/94 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

*Oct  1 18:28:11.467:   AS 90, Flags 0x0, Seq 0/101 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

*Oct  1 18:28:11.483: EIGRP: Received REPLY on Serial1/0 nbr 172.16.12.2    //收到R2回复的Reply  ---  14

*Oct  1 18:28:11.487:   AS 90, Flags 0x0, Seq 105/101 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0

*Oct  1 18:28:11.491: EIGRP: Sending ACK on Serial1/0 nbr 172.16.12.2      //R2回复Ack  ---  15

*Oct  1 18:28:11.491:   AS 90, Flags 0x0, Seq 0/105 idbQ 0/0

R2

*Oct  1 18:28:11.355: EIGRP: Received QUERY on Serial1/0 nbr 172.16.12.1     //收到R1Query  ---  2

*Oct  1 18:28:11.359:   AS 90, Flags 0x0, Seq 100/100 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0

*Oct  1 18:28:11.359: EIGRP: Enqueueing ACK on Serial1/0 nbr 172.16.12.1

*Oct  1 18:28:11.367: EIGRP: Sending ACK on Serial1/0 nbr 172.16.12.1        //R1回复Ack  --- 3

*Oct  1 18:28:11.367:   AS 90, Flags 0x0, Seq 0/100 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 1/0

*Oct  1 18:28:11.391: EIGRP: Sending QUERY on Serial1/1 nbr 192.168.23.3     //R3发出Query  ---  5

*Oct  1 18:28:11.395:   AS 90, Flags 0x0, Seq 103/99 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 131-131

*Oct  1 18:28:11.427: EIGRP: Received ACK on Serial1/1 nbr 192.168.23.3     //收到R3回复的Ack  ---  8

*Oct  1 18:28:11.427:   AS 90, Flags 0x0, Seq 0/103 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

*Oct  1 18:28:11.435: EIGRP: Received REPLY on Serial1/1 nbr 192.168.23.3   //收到R3回复的Reply  ---  10

*Oct  1 18:28:11.439:   AS 90, Flags 0x0, Seq 100/103 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0

*Oct  1 18:28:11.447: EIGRP: Sending ACK on Serial1/1 nbr 192.168.23.3      //R3发出Ack  ---  11

*Oct  1 18:28:11.447:   AS 90, Flags 0x0, Seq 0/100 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 1/0

*Oct  1 18:28:11.467: EIGRP: Enqueueing REPLY on Serial1/0 nbr 172.16.12.1 iidbQ un/rely 0/1 peerQ un/rely 0/0 serno 132-132

*Oct  1 18:28:11.475: EIGRP: Sending REPLY on Serial1/0 nbr 172.16.12.1    //R1回复Reply  ---  13

*Oct  1 18:28:11.475:   AS 90, Flags 0x0, Seq 105/101 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 132-132

*Oct  1 18:28:11.491: EIGRP: Received ACK on Serial1/0 nbr 172.16.12.1    /收到R1回复的Ack  ---  16

*Oct  1 18:28:11.491:   AS 90, Flags 0x0, Seq 0/105 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

R3

*Oct  1 18:28:11.407: EIGRP: Received QUERY on Serial1/1 nbr 192.168.23.2     //收到R2Query  ---  6

*Oct  1 18:28:11.411:   AS 90, Flags 0x0, Seq 103/99 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0

*Oct  1 18:28:11.423: EIGRP: Sending ACK on Serial1/1 nbr 192.168.23.2        //R2回复Ack  ---  7

*Oct  1 18:28:11.423:   AS 90, Flags 0x0, Seq 0/103 idbQ 1/0 iidbQ un/rely 0/0 peerQ un/rely 1/0

*Oct  1 18:28:11.443: EIGRP: Enqueueing REPLY on Serial1/1 nbr 192.168.23.2 iidbQ un/rely 0/1 peerQ un/rely 0/0 serno 151-151

*Oct  1 18:28:11.451: EIGRP: Sending REPLY on Serial1/1 nbr 192.168.23.2     //R2回复Reply  ---  9

*Oct  1 18:28:11.455:   AS 90, Flags 0x0, Seq 100/103 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 151-151

*Oct  1 18:28:11.475: EIGRP: Received ACK on Serial1/1 nbr 192.168.23.2     //收到R2Ack  ---  12

*Oct  1 18:28:11.475:   AS 90, Flags 0x0, Seq 0/100 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1

2、通过在R2上S1/1口设置ACL,阻止R3发送过来的所有EIGRP包,通过设置holddown time到最长,使R2-R3之间EIGRP邻居关系不会DOWN,然后shut down R1的loopback口,观察EIGRP的拓扑表,学习EIGRP的SIA状态, 以及cisco设计SIA-Query/SIA-Reply两种报文的意义。

R3

interface Serial1/1

ip hold-time eigrp 90 65535        //先将R3holddown timer设置为最大

R2

access-list 100 deny eigrp 192.168.23.3 0.0.0.0 any

access-list 100 permit ip any any

interface Serial1/1

 ip access-group 100 in

 

R2#show ip eigrp neighbors

IP-EIGRP neighbors for process 90

H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq

                                            (sec)         (ms)       Cnt Num

0   192.168.23.3            Se1/1            65530 02:08:06  387  2322  0  101

1   172.16.12.1             Se1/0             13 02:42:21   40   240  0  102

 

解析:即使R2S1/1接口调用了ACL,过滤R3发出的EIGRP的包,也包括Hello包,此时R2-R3之间的邻居关系暂时也不会downHold时间从65535秒开始倒计时。

 

R1

interface Loopback0

 shutdown

R1

R1#show ip eigrp topology

IP-EIGRP Topology Table for AS(90)/ID(1.1.1.1)

A 1.1.1.0/24, 1 successors, FD is Inaccessible

    1 replies, active 00:01:28, query-origin: Local origin

      Remaining replies:

         via 172.16.12.2, r, Serial1/0

 

R1#show ip eigrp topology

IP-EIGRP Topology Table for AS(90)/ID(1.1.1.1)

A 1.1.1.0/24, 1 successors, FD is Inaccessible

    1 replies, active 00:01:34, query-origin: Local origin, retries(1)

      Remaining replies:

         via 172.16.12.2, r, Serial1/0

 

 

R2

R2#show ip eigrp topology

IP-EIGRP Topology Table for AS(90)/ID(2.2.2.2)

A 1.1.1.0/24, 1 successors, FD is Inaccessible, Q

    1 replies, active 00:01:24, query-origin: Successor Origin

      Remaining replies:

         via 192.168.23.3, r, Serial1/1

 

R2#show ip eigrp topology

IP-EIGRP Topology Table for AS(90)/ID(2.2.2.2)

A 1.1.1.0/24, 1 successors, FD is Inaccessible, Qqr

    1 replies, active 00:01:36, query-origin: Successor Origin

      Remaining replies:

         via 192.168.23.3, r, Serial1/1

    SIA-Stuck: 1 peers

      Peers:

         via 192.168.23.3, s, Serial1/1

解析:

  由于R3回复的AckReply没有到R2上,R2就不会向R1回复Reply,所以此时在R1R2上的EIGRP拓扑表中看到1.1.1.0/24这条路由为Active状态;

  R1迟迟收不到R2回复的ReplyR1会在active状态90s的时候向R2发送SIA-QueryR2收到以后会向R1回复SIA-Reply,此时R1即可确认R1-R2之间的状态是正常的。即使到了active状态3分钟,R1-R2之间的邻居也不会down

  由于R3回复的AckReply没有到R2上,R2到了active状态3分钟的时候,清除与R3EIGRP邻居,此时R2相当于边界路由器了,向R1回复Reply

3、在R1 R2 R3上修改Active Time为1分钟。并在R1-R2之间开启EIGRP的认证,密码为cisco。

R1R2R3

router eigrp 90

 timers active-time 1     //默认是3分钟

R1R2

key chain A

 key 1

  key-string cisco

 

interface Serial1/0

ip authentication mode eigrp 90 md5

 ip authentication key-chain eigrp 90 A

4、把R3配置成为EIGRP Stub路由器,设置为Stub receive-only, R1上能否看到R3的loopback路由。

R3

router eigrp 90

eigrp stub receive-only    //此时R1上看不到3.3.3.0/24路由。R3不会向邻居通告任何路由。

5、在R3上增加一条静态路由 33.3.3.0/24 指向null0, 重分布该静态路由进EIGRP,通过配置stub redistributed /static,在R1上可以看到33.3.3.0/24路由。

R3

ip route 33.3.3.0 255.255.255.0 null 0

 

router eigrp 90

redistribute static

eigrp stub redistributed static

 

解析:stub后面配置redistributed参数可以将所有重分布的路由通告给邻居;而stub后面配置static参数只会将重分布静态的路由通告给邻居。

6、删除第5题的配置。将R2设置为stub路由器,通过配置leak-map,要求在R1上可以看到3.3.3.0/24路由。

R3

router eigrp 90

no eigrp stub

R2:

access-list 1 permit 3.3.3.0

route-map LEAK permit 10

 match ip address 1

 

router eigrp 90

 eigrp stub leak-map LEAK

 

解析:通告leak-map做路由泄露,只能针对动态学到的路由才有效。对于自己始发的路由,无效。

7、在R1上使用distance 255的方法过滤33.3.3.0/24,观察实验现象,是否生效。

R1

access-list 1 permit 33.3.3.0

router eigrp 90

distance 255 172.16.12.2 0.0.0.0 1    //没有生效,R1的路由表中可以看到33.3.3.0/24

 

解析:distance xx此方法只能修改EIGRP内部路由的管理距离,对于DEX路由是无效的。

可以通过distance eigrp xx yy来修改EIGRP管理距离,xx为内部路由管理距离,yy为外部路由管理距离。

8、在R3上使用distribute-list过滤这条33.3.3.0/24,在R1 R2上看不到此路由,不能使用基于接口的过滤。

R3

access-list 1 deny 33.3.3.0 0.0.0.0

access-list 1 permit any

 

router eigrp 90

 distribute-list 1 out static     //基于协议的过滤,只能用于出向。针对重分布静态的路由,发出时做过滤。

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