HSRP 実践編:(5) HSRP のアクティブ・ルーターに障害を発生させてみる(2)

アクティブ・ルーターとなっているRouter-A で別な障害を発生させてみます。

a

 インターフェイスs2/0 をshutdown します。















Router-A#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router-A(config)#interface serial2/0
Router-A(config-if)#shutdown
Router-A(config-if)#^Z
Router-A#
Feb 6 22:39:33.594: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.104 on Serial2/0 from FULL to DOWN, Neighbor Down: Interface down or detached
Feb 6 22:39:34.206: %SYS-5-CONFIG_I: Configured from console by console
Feb 6 22:39:35.586: %LINK-5-CHANGED: Interface Serial2/0, changed state to administratively down
Feb 6 22:39:36.594: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/0, changed state to down

インターフェイスs2/0 がダウンした以外、何も変化が見られません。

Router-A#show standby
Ethernet0/0 - Group 10
State is Active
1 state change, last state change 00:26:54
Virtual IP address is 192.168.1.1
Active virtual MAC address is 0000.0c07.ac0a
Local virtual MAC address is 0000.0c07.ac0a (v1 default)
Hello time 3 sec, hold time 10 sec
Next hello sent in 2.488 secs
Preemption enabled
Active router is local
Standby router is 192.168.1.103, priority 100 (expires in 7.488 sec)
Priority 105 (configured 105)
IP redundancy name is "hsrp-Et0/0-10" (default)
Router-A#

アクティブ・ルーターのままです。

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.U.U.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

PC-1 からサーバーへのPing も、一時的に不通となっただけです。

Router-A のルーティング・テーブルを見てみます。

Router-A#show 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

1.0.0.0/32 is subnetted, 4 subnets
C 1.1.1.101 is directly connected, Loopback0
O 1.1.1.103 [110/11] via 192.168.1.103, 00:02:57, Ethernet0/0
O 1.1.1.102 [110/11] via 192.168.1.102, 00:02:57, Ethernet0/0
O 1.1.1.104 [110/75] via 192.168.1.103, 00:02:57, Ethernet0/0
[110/75] via 192.168.1.102, 00:02:57, Ethernet0/0
O 192.168.4.0/24 [110/74] via 192.168.1.103, 00:02:57, Ethernet0/0
O 192.168.5.0/24 [110/84] via 192.168.1.103, 00:02:57, Ethernet0/0
[110/84] via 192.168.1.102, 00:02:57, Ethernet0/0

C 192.168.1.0/24 is directly connected, Ethernet0/0
O 192.168.3.0/24 [110/74] via 192.168.1.102, 00:02:57, Ethernet0/0
Router-A#


192.168.5.0/24 宛のネクスト・ホップが、Router-B とC のEthernet0/0 に変わっています。

Ping が一時的に不通となったのは、Router-A のルーティング・テーブルから192.168.5.0/24 へ到達するための経路が存在しなくなったからです。

ネクスト・ホップがRouter-B とC のインターフェイスe0/0 へ変わることにより、通信は復旧します。

hsrp-b5.png