CCIE R/S Written Sample Question – Part 2 を解いてみる

問題

http://blog.internetworkexpert.com/2009/08/29/ccie-rs-written-sample-question-part-2/

ルータの出力

R1#sh ip ro | b ^G

Gateway of last resort is not set

10.0.0.0/24 is subnetted, 7 subnets

D 10.37.37.0 [90/307200] via 10.30.30.3, 00:02:16, FastEthernet0/1

D 10.36.36.0 [90/307200] via 10.30.30.3, 00:34:05, FastEthernet0/1

C 10.30.30.0 is directly connected, FastEthernet0/1

D 10.25.25.0 [90/307200] via 10.20.20.2, 00:03:09, FastEthernet0/0

D 10.24.24.0 [90/307200] via 10.20.20.2, 00:34:05, FastEthernet0/0

C 10.20.20.0 is directly connected, FastEthernet0/0

C 10.10.10.0 is directly connected, Loopback0

R2#sh ip ro | b ^G

Gateway of last resort is not set

10.0.0.0/24 is subnetted, 7 subnets

D 10.37.37.0 [90/332800] via 10.20.20.1, 00:02:53, FastEthernet0/0

D 10.36.36.0 [90/332800] via 10.20.20.1, 00:34:41, FastEthernet0/0

D 10.30.30.0 [90/307200] via 10.20.20.1, 00:34:41, FastEthernet0/0

C 10.25.25.0 is directly connected, FastEthernet1/0

C 10.24.24.0 is directly connected, FastEthernet0/1

C 10.20.20.0 is directly connected, FastEthernet0/0

D 10.10.10.0 [90/409600] via 10.20.20.1, 00:32:17, FastEthernet0/0

R3#sh ip ro | b ^G

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 8 subnets, 2 masks

C 10.37.37.0/24 is directly connected, FastEthernet1/0

C 10.36.36.0/24 is directly connected, FastEthernet0/1

C 10.30.30.0/24 is directly connected, FastEthernet0/0

D 10.25.25.0/24 [90/332800] via 10.30.30.1, 00:04:08, FastEthernet0/0

D 10.24.24.0/24 [90/332800] via 10.30.30.1, 00:35:04, FastEthernet0/0

D 10.20.20.0/24 [90/307200] via 10.30.30.1, 00:35:04, FastEthernet0/0

D 10.10.10.0/24 [90/409600] via 10.30.30.1, 00:32:40, FastEthernet0/0

D 10.0.0.0/8 is a summary, 00:03:16, Null0

R4#sh ip ro | b ^G

Gateway of last resort is not set

10.0.0.0/24 is subnetted, 7 subnets

D 10.37.37.0 [90/358400] via 10.24.24.2, 00:03:31, FastEthernet0/0

D 10.36.36.0 [90/358400] via 10.24.24.2, 00:33:51, FastEthernet0/0

D 10.30.30.0 [90/332800] via 10.24.24.2, 00:33:51, FastEthernet0/0

D 10.25.25.0 [90/307200] via 10.24.24.2, 00:04:24, FastEthernet0/0

C 10.24.24.0 is directly connected, FastEthernet0/0

D 10.20.20.0 [90/307200] via 10.24.24.2, 00:33:51, FastEthernet0/0

D 10.10.10.0 [90/435200] via 10.24.24.2, 00:32:55, FastEthernet0/0

R5#sh ip ro | b ^G

Gateway of last resort is not set

10.0.0.0/24 is subnetted, 7 subnets

D 10.37.37.0 [90/358400] via 10.25.25.2, 00:03:47, FastEthernet0/0

D 10.36.36.0 [90/358400] via 10.25.25.2, 00:31:29, FastEthernet0/0

D 10.30.30.0 [90/332800] via 10.25.25.2, 00:31:29, FastEthernet0/0

C 10.25.25.0 is directly connected, FastEthernet0/0

D 10.24.24.0 [90/307200] via 10.25.25.2, 00:31:29, FastEthernet0/0

D 10.20.20.0 [90/307200] via 10.25.25.2, 00:31:29, FastEthernet0/0

D 10.10.10.0 [90/435200] via 10.25.25.2, 00:31:29, FastEthernet0/0

R6#sh ip ro | b ^G

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 10.36.36.0/24 is directly connected, FastEthernet0/0

D 10.0.0.0/8 [90/307200] via 10.36.36.3, 00:04:01, FastEthernet0/0

R7#sh ip ro | b ^G

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 10.37.37.0/24 is directly connected, FastEthernet0/0

D 10.0.0.0/8 [90/307200] via 10.37.37.3, 00:04:16, FastEthernet0/0

ポイント

• クエリの範囲を制限する方法 (複数の EIGRP AS、EIGRP Stub、prefix filtering) についての質問である。
• R2 の auto-summary は、全てのルータが同じメジャー ネットワーク (10/8) に所属しているので、意味が無い。
• R3 に手動の集約があるので、どのルータも R6 と R7 を超えて、このサブネットのクエリを受信することは無いが、R6 と R7 は、クエリを受信する。

参考

• EIGRP Query Scoping
• ip summary-address eigrp as-number ip-address mask [admin-distance] [leak-map name]
• Enhanced IGRP – テクニカルサポート – Cisco Systems