DynagenでCCIEを目指す

20100416 EIGRP query reply

最終更新：2010年04月18日 13:47

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目的
問題文1
解答1
問題文2
解答2
構成
検証1 問題文1の解答確認
検証2 問題文2の解答確認

目的

下記問題の解答を確かめます。
queryパケットを観察します。

問題文1

Network topology exhibit:

You work as a network administrator at Hoge.com. Study the exhibit carefully. In this network, allrouters are configured to run EIGRP on all links. If the link between R1 and T2 fails, what is the maximum number of queries R3 will recieve for 192.168.1.0/24. assuming that all the packets transmitted during convergence are transmitted once ( assume there are no dropped ro retransmitted packets)?

A. R3 will not receive any queries from R2, because there are no alternate paths for 192.168.1.0/24
B. R3 will receive up to four queries for 192.168.1.0/24, one each from R2, R4, R5, and R6.
C. R3 will recieve one query for 192.168.1.0/24, since remote routers, R4, R5, and R6, are natural stubs in EIGRP.
D. R3 will receive up eight queries for 192.168.1.0/24 one from R2, two from R4, three from R5, and four form R6.
E. None of the other alternatives apply.

解答1

解答：B（検証結果もB)

問題文2

Network topology exhibit:(問題文1と全く同じ構成図です)

You work as a network administrator at Hoge.com. Study the exhibit carefully. In this network, allrouters are configured to run EIGRP on all links. R2 configured to only send a summary route to R4, R5, and R6.
f the link between R1 and T2 fails, what is the maximum number of queries R3 will recieve for 192.168.1.0/24. assuming that all the packets transmitted during convergence are transmitted once ( assume there are no dropped ro retransmitted packets)?Will R4, R5, and R6 recieve queries?

A. R3, R4, R5, and R6 won't receive any queries for 192.168.1.0/24, since there's no alternate path to this destination within the network.
B. R3 will receive one query for 192.168.1.0/24. R4, R5, and R6 will not receive any queries for this destination because R2 isn't advertising this network towards them.
C. R3 will receive one query for 192.168.1.0/24 from R2. R4, R5, and R6 will each receive and reply to one query each.
D. R3 will receive 4 queries for 192.168.1.0/24, one each form R2, R4, R5, and R6. R4, R5, and R6 will each receive and reply to one query each.
E. None of the other one query.

解答2

解答：C
検証結果は正答不明です。

構成

設定概要
- EIGRPによってルーティングします。
- R1 loopback 0にsecondary addressを設定します。
構成図
- 検証環境の都合上、R5, R6を省略します。

netファイル

ghostios = True
sparsemem = True
model = 3620
[localhost]
	
	[[3620]]
		image = C:\Program Files\Dynamips\images\c3620-j1s3-mz.123-18.bin
		ram = 256
	
	[[ROUTER R1]]
		f1/0 = R2 f1/0
		
	[[ROUTER R2]]
		e0/0 = R3 e0/0
		e0/1 = R4 e0/1

	[[ROUTER R3]]
		e0/2 = R4 e0/2

	[[ROUTER R4]]

初期設定 R1

!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R1
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
ip subnet-zero
!
!
!
ip cef
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 192.168.0.1 255.255.255.0 secondary
 ip address 192.168.1.1 255.255.255.0 secondary
 ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet1/0
 ip address 192.168.12.1 255.255.255.0
 duplex auto
 speed auto
!
router eigrp 1
 network 192.168.0.0
 network 192.168.1.0
 network 192.168.12.0
 no auto-summary
!
ip http server
ip classless
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

初期設定 R2

!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R2
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
ip subnet-zero
!
!
!
ip cef
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 2.2.2.2 255.255.255.255
!
interface Ethernet0/0
 ip address 192.168.23.2 255.255.255.0
 full-duplex
!
interface Ethernet0/1
 ip address 192.168.24.2 255.255.255.0
 full-duplex
!
interface Ethernet0/2
 no ip address
 shutdown
 half-duplex
!
interface Ethernet0/3
 no ip address
 shutdown
 half-duplex
!
interface FastEthernet1/0
 ip address 192.168.12.2 255.255.255.0
 duplex auto
 speed auto
!
router eigrp 1
 network 192.168.12.0
 network 192.168.23.0
 network 192.168.24.0
 no auto-summary
!
ip http server
ip classless
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

初期設定 R3

!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R3
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
ip subnet-zero
!
!
!
ip cef
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 3.3.3.3 255.255.255.255
!
interface Ethernet0/0
 ip address 192.168.23.3 255.255.255.0
 full-duplex
!
interface Ethernet0/1
 no ip address
 shutdown
 half-duplex
!
interface Ethernet0/2
 ip address 192.168.34.3 255.255.255.0
 full-duplex
!
interface Ethernet0/3
 no ip address
 shutdown
 half-duplex
!
router eigrp 1
 network 192.168.23.0
 network 192.168.34.0
 no auto-summary
!
ip http server
ip classless
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

初期設定 R4

!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname R4
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
ip subnet-zero
!
!
!
ip cef
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface Loopback0
 ip address 4.4.4.4 255.255.255.255
!
interface Ethernet0/0
 no ip address
 shutdown
 half-duplex
!
interface Ethernet0/1
 ip address 192.168.24.4 255.255.255.0
 full-duplex
!
interface Ethernet0/2
 ip address 192.168.34.4 255.255.255.0
 full-duplex
!
interface Ethernet0/3
 no ip address
 shutdown
 half-duplex
!
router eigrp 1
 network 192.168.24.0
 network 192.168.34.0
 no auto-summary
!
ip http server
ip classless
!
!
!
!
!
!
!
!
line con 0
line aux 0
line vty 0 4
!
!
end

検証1 問題文1の解答確認

デバッグの有効化

R3で、予め以下のデバッグを有効にしておきます。

R3#debug eigrp packets query reply
EIGRP Packets debugging is on
    (QUERY, REPLY)

R1, R2間のリンクダウン

R1 f1/0でshutdownを実行します。

R1(config)#interface FastEthernet 1/0
R1(config-if)#shutdown

デバッグメッセージの確認

R3のデバッグメッセージを確認します。R2, R4からqueryを受信し、replyで応答している事が確認できます。

TODO 従って答えはXXです。
R3#
*Mar  1 00:17:14.795: EIGRP: Received QUERY on Ethernet0/0 nbr 192.168.23.2
 ( ↑ R2からqueryを受信 )
*Mar  1 00:17:14.799:   AS 1, Flags 0x0, Seq 27/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:17:14.815: EIGRP: Enqueueing QUERY on Ethernet0/2 iidbQ un/rely 0/1 serno 24-25
*Mar  1 00:17:14.819: EIGRP: Enqueueing QUERY on Ethernet0/0 iidbQ un/rely 0/1 serno 24-25
*Mar  1 00:17:14.823: EIGRP: Sending QUERY on Ethernet0/2
*Mar  1 00:17:14.823:   AS 1, Flags 0x0, Seq 18/0 idbQ 0/0 iidbQ un/rely 0/0 serno 24-25
*Mar  1 00:17:14.935: EIGRP: Received QUERY on Ethernet0/2 nbr 192.168.34.4
 ( ↑ R4からqueryを受信 )
*Mar  1 00:17:14.939:   AS 1, Flags 0x0, Seq 19/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1
*Mar  1 00:17:14.943: EIGRP: Enqueueing REPLY on Ethernet0/2 nbr 192.168.34.4 iidbQ un/rely 0/1 peerQ un/rely 1/0 serno 26-27
*Mar  1 00:17:14.955: EIGRP: Sending REPLY on Ethernet0/2 nbr 192.168.34.4
 ( ↑ R4にreplyで応答 )
*Mar  1 00:17:14.959:   AS 1, Flags 0x0, Seq 20/19 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 26-27
*Mar  1 00:17:15.091: EIGRP: Received REPLY on Ethernet0/2 nbr 192.168.34.4
*Mar  1 00:17:15.095:   AS 1, Flags 0x0, Seq 21/20 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1
*Mar  1 00:17:15.111: EIGRP: Enqueueing REPLY on Ethernet0/0 nbr 192.168.23.2 iidbQ un/rely 0/1 peerQ un/rely 0/1 serno 28-29
*Mar  1 00:17:17.395: EIGRP: Sending REPLY on Ethernet0/0 nbr 192.168.23.2
 ( ↑ R2にreplyで応答 )
*Mar  1 00:17:17.399:   AS 1, Flags 0x0, Seq 21/27 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 28-29

R1, R2間のリンクアップ

検証2の準備として、R1 f1/0でno shutdownを実行します。

R1(config)#interface FastEthernet 1/0
R1(config-if)#no shutdown

検証2 問題文2の解答確認

集約ルートの定義

問題文で以下の記載があります。

R2 configured to only send a summary route to R4, R5, and R6.

出題者がどのようなconfigを想定していたか分かりかねる文章ですが、とりあえず「summary-address」ではないかと推測して以下の設定をR2に投入します。

R2(config)#interface Ethernet 0/1
R2(config-if)#ip summary-address eigrp 1 192.168.0.0 255.255.254.0

デバッグの有効化

R3, R4で、予め以下のデバッグを有効にしておきます。

R4#debug eigrp packets query reply
EIGRP Packets debugging is on
    (QUERY, REPLY)
R4#

デバッグメッセージの確認

R3, R4のデバッグメッセージを確認します。どのqueryが192.168.1.0/24のものであるのかの判別ができません。

R3#
*Mar  1 00:22:03.019: EIGRP: Received QUERY on Ethernet0/0 nbr 192.168.23.2
*Mar  1 00:22:03.023:   AS 1, Flags 0x0, Seq 37/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:03.039: EIGRP: Enqueueing QUERY on Ethernet0/0 iidbQ un/rely 0/1 serno 34-35
*Mar  1 00:22:03.043: EIGRP: Enqueueing QUERY on Ethernet0/2 iidbQ un/rely 0/1 serno 34-35
*Mar  1 00:22:03.051: EIGRP: Sending QUERY on Ethernet0/2
*Mar  1 00:22:03.055:   AS 1, Flags 0x0, Seq 26/0 idbQ 0/0 iidbQ un/rely 0/0 serno 34-35
*Mar  1 00:22:04.415: EIGRP: Received REPLY on Ethernet0/2 nbr 192.168.34.4
*Mar  1 00:22:04.419:   AS 1, Flags 0x0, Seq 36/26 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:04.435: EIGRP: Enqueueing REPLY on Ethernet0/0 nbr 192.168.23.2 iidbQ un/rely 0/1 peerQ un/rely 0/1 serno 36-37
*Mar  1 00:22:05.003: EIGRP: Sending REPLY on Ethernet0/0 nbr 192.168.23.2
*Mar  1 00:22:05.007:   AS 1, Flags 0x0, Seq 27/37 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 36-37
*Mar  1 00:22:05.207: EIGRP: Received QUERY on Ethernet0/0 nbr 192.168.23.2
*Mar  1 00:22:05.207:   AS 1, Flags 0x0, Seq 40/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:05.211: EIGRP: Received QUERY on Ethernet0/2 nbr 192.168.34.4
*Mar  1 00:22:05.215:   AS 1, Flags 0x0, Seq 37/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:05.223: EIGRP: Enqueueing REPLY on Ethernet0/0 nbr 192.168.23.2 iidbQ un/rely 0/1 peerQ un/rely 0/0 serno 38-38
*Mar  1 00:22:05.231: EIGRP: Sending REPLY on Ethernet0/0 nbr 192.168.23.2
*Mar  1 00:22:05.231:   AS 1, Flags 0x0, Seq 28/40 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 38-38
*Mar  1 00:22:05.235: EIGRP: Enqueueing QUERY on Ethernet0/2 iidbQ un/rely 0/1 serno 39-39
*Mar  1 00:22:05.271: EIGRP: Enqueueing QUERY on Ethernet0/0 iidbQ un/rely 0/1 serno 39-39
*Mar  1 00:22:05.275: EIGRP: Sending QUERY on Ethernet0/0
*Mar  1 00:22:05.275:   AS 1, Flags 0x0, Seq 30/0 idbQ 0/0 iidbQ un/rely 0/0 serno 39-39
*Mar  1 00:22:05.335: EIGRP: Received REPLY on Ethernet0/0 nbr 192.168.23.2
*Mar  1 00:22:05.339:   AS 1, Flags 0x0, Seq 41/30 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:05.351: EIGRP: Enqueueing REPLY on Ethernet0/2 nbr 192.168.34.4 iidbQ un/rely 0/1 peerQ un/rely 0/1 serno 40-40
*Mar  1 00:22:06.635: EIGRP: Sending REPLY on Ethernet0/2 nbr 192.168.34.4
*Mar  1 00:22:06.639:   AS 1, Flags 0x0, Seq 31/37 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 40-40
R3#

R4#
*Mar  1 00:22:04.007: EIGRP: Received QUERY on Ethernet0/1 nbr 192.168.24.2
*Mar  1 00:22:04.011:   AS 1, Flags 0x0, Seq 36/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:04.019: EIGRP: Received QUERY on Ethernet0/2 nbr 192.168.34.3
*Mar  1 00:22:04.023:   AS 1, Flags 0x0, Seq 26/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:04.031: EIGRP: Enqueueing REPLY on Ethernet0/1 nbr 192.168.24.2 iidbQ un/rely 0/1 peerQ un/rely 0/0 serno 38-39
*Mar  1 00:22:04.039: EIGRP: Sending REPLY on Ethernet0/1 nbr 192.168.24.2
*Mar  1 00:22:04.043:   AS 1, Flags 0x0, Seq 33/36 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 38-39
*Mar  1 00:22:04.047: EIGRP: Enqueueing QUERY on Ethernet0/2 iidbQ un/rely 0/1 serno 40-41
*Mar  1 00:22:04.339: EIGRP: Enqueueing QUERY on Ethernet0/1 iidbQ un/rely 0/1 serno 40-41
*Mar  1 00:22:04.343: EIGRP: Sending QUERY on Ethernet0/1
*Mar  1 00:22:04.343:   AS 1, Flags 0x0, Seq 35/0 idbQ 0/0 iidbQ un/rely 0/0 serno 40-41
*Mar  1 00:22:04.491: EIGRP: Received REPLY on Ethernet0/1 nbr 192.168.24.2
*Mar  1 00:22:04.495:   AS 1, Flags 0x0, Seq 38/35 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:04.511: EIGRP: Enqueueing REPLY on Ethernet0/2 nbr 192.168.34.3 iidbQ un/rely 0/1 peerQ un/rely 0/1 serno 42-43
*Mar  1 00:22:05.327: EIGRP: Sending REPLY on Ethernet0/2 nbr 192.168.34.3
*Mar  1 00:22:05.331:   AS 1, Flags 0x0, Seq 36/26 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 42-43
*Mar  1 00:22:06.119: EIGRP: Received QUERY on Ethernet0/1 nbr 192.168.24.2
*Mar  1 00:22:06.123:   AS 1, Flags 0x0, Seq 39/0 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:06.139: EIGRP: Enqueueing QUERY on Ethernet0/2 iidbQ un/rely 0/1 serno 44-44
*Mar  1 00:22:06.143: EIGRP: Enqueueing QUERY on Ethernet0/1 iidbQ un/rely 0/1 serno 44-44
*Mar  1 00:22:06.147: EIGRP: Sending QUERY on Ethernet0/2
*Mar  1 00:22:06.147:   AS 1, Flags 0x0, Seq 37/0 idbQ 0/0 iidbQ un/rely 0/0 serno 44-44
*Mar  1 00:22:07.571: EIGRP: Received REPLY on Ethernet0/2 nbr 192.168.34.3
*Mar  1 00:22:07.575:   AS 1, Flags 0x0, Seq 31/37 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/0
*Mar  1 00:22:07.591: EIGRP: Enqueueing REPLY on Ethernet0/1 nbr 192.168.24.2 iidbQ un/rely 0/1 peerQ un/rely 0/0 serno 45-45
*Mar  1 00:22:07.599: EIGRP: Sending REPLY on Ethernet0/1 nbr 192.168.24.2
*Mar  1 00:22:07.603:   AS 1, Flags 0x0, Seq 39/39 idbQ 0/0 iidbQ un/rely 0/0 peerQ un/rely 0/1 serno 45-45
R4#

パケットキャプチャの確認

デバッグメッセージでの解答の確認が難しいので、パケットキャプチャから解答を確認します。192.168.1.0/24に関するqueryをまとめると、以下の表の通りです。

送信元	宛先
R2(192.168.23.2)	R3(224.0.0.10)
R3(192.168.23.3)	R2(224.0.0.10)
R2(192.168.24.2)	R4(224.0.0.10)
R4(192.168.24.4)	R2(224.0.0.10)
R3(192.168.34.3)	R4(224.0.0.10)
R4(192.168.34.4)	R3(224.0.0.10)

従って、検証結果の解答はいずれでもないEになってしまいました。
しかし、恐らく以下の文に関して、私の解釈と出題者の意図で差異があるため、このような検証結果になったと思います。何か情報がつかめたら、修正したいと思います。

R2 configured to only send a summary route to R4, R5, and R6.

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20100416 EIGRP query reply

目的

問題文1

解答1

問題文2

解答2

構成

検証1 問題文1の解答確認

検証2 問題文2の解答確認

メインコンテンツ

更新履歴

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