EIGRP不連続サブネット構成の検証

EIGRPで不連続サブネットで経路集約をデフォルトの有効のままにした場合、
show ip routeやshow ip eigrp toplogyでどういった出力がされるのか検証してみた。

・使用機器
Cisco1812×3台

・検証内容
①経路集約が有効の場合のshow ip routeとshow ip eigrp topologyの出力結果はどうなるか。
②10.1.1.1と10.2.2.3にpingを実行した場合の結果はどうなるか。
③10.1.1.1と10.2.2.3にtracerouteを実行した場合の結果はどうなるか。
④経路集約を無効にした場合のshow ip routeの出力結果はどうなるか。

・不連続サブネット構成図および設定コマンド
まだ経路集約はデフォルトのまま（有効）の状態。


経路集約が有効（デフォルト）のままになっていると、
R1とR3の両方がクラスフルなネットワークアドレス10.0.0.0/8で通知してしまうため、R2は正しい経路を把握できない。

例えば、10.1.1.1宛のパケットを送ろうとした場合、
R1とR3の両方から、「10.0.0.0/8の宛先なら俺に送れ」と言ってきているので
R2はどっちに送れば良いのか混乱してしまうわけです。

果たしてR2はどっちのルーターを宛先とするのか、実際に試してみた。

--------------------------------------------------------------------------------------
R2>ping 10.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!　　←成功(｀・ω・´)
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms


R2>ping 10.2.2.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.2.2.3, timeout is 2 seconds:
U.U.U　　←失敗(´・ω・｀)
Success rate is 0 percent (0/5)
--------------------------------------------------------------------------------------

うーむ、どうやらR1の方がお気に入りらしい。
見ての通りR1の10.1.1.1にはPingが通ってるけど、R3の10.2.2.3には通ってませんね。
何か優先順位でもあるんだろうか？（分かったら追記します。）

次にtracerouteをやったらどうなるかも試してみた。

--------------------------------------------------------------------------------------
R2>traceroute 10.1.1.1

Type escape sequence to abort.
Tracing the route to 10.1.1.1

  1 192.168.2.3 0 msec
    192.168.1.1 0 msec
    192.168.2.3 0 msec


R2>traceroute 10.2.2.3

Type escape sequence to abort.
Tracing the route to 10.2.2.3

  1 192.168.1.1 0 msec
    192.168.2.3 0 msec
    192.168.1.1 8 msec
--------------------------------------------------------------------------------------

10.1.1.1も10.2.2.3もダメ。
192.168.2.3と192.168.1.1を行ったり来たり。

やはり不連続サブネットだと、経路集約が有効のままでは正常なルートを把握できていませんな。

次に、経路集約を無効にしてみます。
R1とR3にno auto-summaryコマンドを投入。


pingとtracerouteの出力結果は以下の通り。
10.1.1.0/24と10.2.2.0/24で通知しているため、ルートを正しく把握できています。

--------------------------------------------------------------------------------------
・ping
R2>ping 10.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!　　←成功(｀・ω・´)
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms


R2>ping 10.2.2.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.2.2.3, timeout is 2 seconds:
!!!!!　　←成功(｀・ω・´)
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

・traceroute
R2#traceroute 10.1.1.1

Type escape sequence to abort.
Tracing the route to 10.1.1.1

  1 192.168.1.1 0 msec 0 msec *

R2>traceroute 10.2.2.3

Type escape sequence to abort.
Tracing the route to 10.2.2.3

  1 192.168.2.3 0 msec 0 msec *
--------------------------------------------------------------------------------------

【結論】
不連続サブネット構成の時は、忘れずにno auto-summaryコマンドを投入しよう！



＜おまけ＞
show ip eigrp topologyの出力結果。
経路集約有効の場合。

--------------------------------------------------------------------------------------
・R1
R1#sh ip route
Codes: C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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

     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       10.1.1.0/24 is directly connected, Loopback0
D       10.0.0.0/8 is a summary, 00:00:34, Null0
C    192.168.1.0/24 is directly connected, FastEthernet1
D    192.168.2.0/24 [90/30720] via 192.168.1.2, 02:06:57, FastEthernet1


R1#sh ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(10.1.1.1)

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

P 10.0.0.0/8, 1 successors, FD is 128256
                via Summary (128256/0), Null0
P 10.1.1.0/24, 1 successors, FD is 128256
                via Connected, Loopback0
P 192.168.1.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet1
P 192.168.2.0/24, 1 successors, FD is 30720
                via 192.168.1.2 (30720/28160), FastEthernet1

--------------------------------------------------------------------------------------
・R2
R2> sh ip route
Codes: C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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

D    10.0.0.0/8 [90/156160] via 192.168.2.3, 00:21:26, FastEthernet1
                          [90/156160] via 192.168.1.1, 00:21:26, FastEthernet0
C    192.168.1.0/24 is directly connected, FastEthernet0
C    192.168.2.0/24 is directly connected, FastEthernet1


R2> sh ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.2.2)

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

P 10.0.0.0/8, 2 successors, FD is 156160
                via 192.168.1.1 (156160/128256), FastEthernet0
                via 192.168.2.3 (156160/128256), FastEthernet1
P 192.168.1.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet0
P 192.168.2.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet1

--------------------------------------------------------------------------------------
・R3
R3#sh ip route
*Jan 13 04:14:43.603: %SYS-5-CONFIG_I: Configured from console by console
Codes: C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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

     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C       10.2.2.0/24 is directly connected, Loopback1
D       10.0.0.0/8 is a summary, 00:02:36, Null0
D    192.168.1.0/24 [90/30720] via 192.168.2.2, 02:09:08, FastEthernet0
C    192.168.2.0/24 is directly connected, FastEthernet0


R3#sh ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(10.2.2.3)

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

P 10.0.0.0/8, 1 successors, FD is 128256
                via Summary (128256/0), Null0
P 10.2.2.0/24, 1 successors, FD is 128256
                via Connected, Loopback1
P 192.168.1.0/24, 1 successors, FD is 30720
                via 192.168.2.2 (30720/28160), FastEthernet0
P 192.168.2.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet0
--------------------------------------------------------------------------------------

そして経路集約無効の場合。

--------------------------------------------------------------------------------------
・R1
R1>sh ip route
Codes: C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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

     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/158720] via 192.168.1.2, 00:02:24, FastEthernet1
C       10.1.1.0 is directly connected, Loopback0
C    192.168.1.0/24 is directly connected, FastEthernet1
D    192.168.2.0/24 [90/30720] via 192.168.1.2, 00:02:28, FastEthernet1


R1>sh ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(10.1.1.1)

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

P 10.2.2.0/24, 1 successors, FD is 158720
                via 192.168.1.2 (158720/156160), FastEthernet1
P 10.1.1.0/24, 1 successors, FD is 128256
                via Connected, Loopback0
P 192.168.1.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet1
P 192.168.2.0/24, 1 successors, FD is 30720
                via 192.168.1.2 (30720/28160), FastEthernet1

--------------------------------------------------------------------------------------
・R2
R2>sh ip route
Codes: C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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

     10.0.0.0/24 is subnetted, 2 subnets
D       10.2.2.0 [90/156160] via 192.168.2.3, 01:46:46, FastEthernet1
D       10.1.1.0 [90/156160] via 192.168.1.1, 01:46:53, FastEthernet0
C    192.168.1.0/24 is directly connected, FastEthernet0
C    192.168.2.0/24 is directly connected, FastEthernet1


R2>sh ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.1.2)

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

P 10.2.2.0/24, 1 successors, FD is 156160
                via 192.168.2.3 (156160/128256), FastEthernet1
P 10.1.1.0/24, 1 successors, FD is 156160
                via 192.168.1.1 (156160/128256), FastEthernet0
P 192.168.1.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet0
P 192.168.2.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet1

--------------------------------------------------------------------------------------
・R3
R3>sh ip route
Codes: C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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

     10.0.0.0/24 is subnetted, 2 subnets
C       10.2.2.0 is directly connected, Loopback1
D       10.1.1.0 [90/158720] via 192.168.2.2, 00:01:33, FastEthernet0
D    192.168.1.0/24 [90/30720] via 192.168.2.2, 00:01:33, FastEthernet0
C    192.168.2.0/24 is directly connected, FastEthernet0


R3>sh ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(10.2.2.3)

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

P 10.1.1.0/24, 1 successors, FD is 158720
                via 192.168.2.2 (158720/156160), FastEthernet0
P 10.2.2.0/24, 1 successors, FD is 128256
                via Connected, Loopback1
P 192.168.1.0/24, 1 successors, FD is 30720
                via 192.168.2.2 (30720/28160), FastEthernet0
P 192.168.2.0/24, 1 successors, FD is 28160
                via Connected, FastEthernet0
--------------------------------------------------------------------------------------

なにこの長文(^ω^#)ﾋﾞｷﾋﾞｷってなった人、ごめんなさい＾ｐ＾；