配置熱備份路由協議（HSRP）

案例：HSRP配置
1.1 問題

在企業網絡到外部的鏈接方案中，要求不高的條件下能夠是單出口。一旦該出口線路出現問題，整個企業網絡就不能鏈接到外網了。爲了使得企業網絡到外網鏈接的高可用性，能夠設置兩個以上的出口，然而多個出口對於內網主機意味着我個網關。主機不能同時使用多個網關，當主機所使用的網關出現故障時，它不能實現網關的自動切換。

配置熱備份路由協議

1.2 方案

在出口設備上配置熱備份路由協議（HSRP），組成一個HSRP組，組內兩個出口設備共享一個虛擬IP地址，該IP地址做爲內網主機的網關。

HSRP組成員有主備之分，虛擬IP地址被附加到主設備上。若是主設備線路出故障，備份設備會成爲主設備，虛擬IP地址也會遷移過來。這樣，無論哪個出口設備出現問題，無論哪一個出口設備在提供外網接入，內網主機的網關都不須要改變。

網絡拓撲圖如圖－1所示：

圖－1
1.3 步驟

實現此案例須要按照以下步驟進行。

步驟一：分別在三臺路由器上配置端口IP地址

tarena-R1(config)# interface f0/0
tarena-R1(config-if)#ip address 192.168.1.252 255.255.255.0
tarena-R1(config-if)#no shutdown
tarena-R1(config-if)#interface f0/1
tarena-R1(config-if)#ip address 192.168.2.1 255.255.255.0
tarena-R1(config-if)#no shutdown
tarena-R2(config)#interface f0/0
tarena-R2(config-if)#ip address 192.168.1.253 255.255.255.0
tarena-R2(config-if)#no shutdown
tarena-R2(config-if)#interface f0/1
tarena-R2(config-if)#ip address 192.168.3.1 255.255.255.0
tarena-R2(config-if)#no shutdown
tarena-R3(config)#interface f0/0
tarena-R3(config-if)#ip address 192.168.2.2 255.255.255.0
tarena-R3(config-if)#no shutdown
tarena-R3(config-if)#interface f0/1
tarena-R3(config-if)#ip address 192.168.3.2 255.255.255.0
tarena-R3(config-if)#no shutdown
tarena-R3(config-if)#interface f1/0
tarena-R3(config-if)#ip address 192.168.4.254 255.255.255.0
tarena-R3(config-if)#no shutdown

步驟二：在R1和R2上配置到外網的默認路由

tarena-R1(config)#ip route 0.0.0.0 0.0.0.0 192.168.2.2
tarena-R1(config)#end
tarena-R1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
       i - IS-IS, 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 192.168.1.2 to network 0.0.0.0
C    192.168.1.0/24 is directly connected, FastEthernet0/0
C    192.168.2.0/24 is directly connected, FastEthernet0/1
S*   0.0.0.0/0 [1/0] via 192.168.2.2
tarena-R1#
tarena-R2(config)#ip route 0.0.0.0 0.0.0.0 192.168.3.2
tarena-R2(config)#exit
tarena-R2#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
       i - IS-IS, 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 192.168.2.2 to network 0.0.0.0
C    192.168.1.0/24 is directly connected, FastEthernet0/0
C    192.168.3.0/24 is directly connected, FastEthernet0/1
S*   0.0.0.0/0 [1/0] via 192.168.3.2

步驟三：在R3上配置到企業內網的靜態路由

tarena-R3(config)#ip route 192.168.1.0 255.255.255.0 192.168.2.1
tarena-R3(config)#ip route 192.168.1.0 255.255.255.0 192.168.3.1
tarena-R3(config)#end
tarena-R3#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
       i - IS-IS, 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
S    192.168.1.0/24 [1/0] via 192.168.2.1
                      [1/0] via 192.168.3.1
C    192.168.2.0/24 is directly connected, FastEthernet0/0
C    192.168.3.0/24 is directly connected, FastEthernet0/1
C    192.168.4.0/24 is directly connected, FastEthernet1/0
tarena-R3#

步驟四：在R1上配置HSRP，指定其優先級爲200

HSRP的默認優先級爲100，路由器啓動後，根據優先級決定誰能夠成爲活躍路由器，優先級高的將勝出。若是路由器優先級相同，再比較端口IP地址，IP地址大的成爲活路躍路由器。

另外，若是優先級低的路由器先啓動了，它將成爲活躍路由器。優先級高的路由器啓動後，發現已有活躍路由器存在，它將接受現狀，直到活躍路由器出現故障它纔會在從新選舉時成爲活躍角色。

tarena-R1(config)#interface f0/0
tarena-R1(config-if)#standby 1 ip 192.168.1.254
tarena-R1(config-if)#standby 1 priority 200
%HSRP-6-STATECHANGE: FastEthernet0/0 Grp 1 state Speak -> Standby
%HSRP-6-STATECHANGE: FastEthernet0/0 Grp 1 state Standby -> Active

配置HSRP後，經過輸出日誌能夠觀察到路由器角色的改變。

步驟五：在R2上配置HSRP，指定其優先級爲195

tarena-R2(config)#interface f0/0
tarena-R2(config-if)#standby 1 ip 192.168.1.254
tarena-R2(config-if)#standby 1 priority 195
%HSRP-6-STATECHANGE: FastEthernet0/0 Grp 1 state Speak -> Standby

步驟六：分別在R1和R2上查看HSRP信息

tarena-R1#show standby brief 
                        P indicates configured to preempt.
                        |
Interface   Grp  Pri P State    Active          Standby         Virtual IP
Fa0/0        1    200   Active   local           192.168.1.253     192.168.1.254
tarena-R2#show standby brief 
                        P indicates configured to preempt.
                        |
Interface   Grp  Pri P State    Active          Standby         Virtual IP
Fa0/0        1    195   Standby  192.168.2.252     local           192.168.1.254

步驟七：在內部主機上測試到外網主機的連通性

SERVER>ipconfig
FastEthernet0 Connection:(default port)
Link-local IPv6 Address.........: FE80::207:ECFF:FE80:557D
IP Address......................: 192.168.1.1
Subnet Mask.....................: 255.255.255.0
Default Gateway.................: 192.168.1.254
PC>ping 192.168.4.1
Pinging 192.168.4.1 with 32 bytes of data:
Reply from  192.168.4.1: bytes=32 time=0ms TTL=126
Reply from  192.168.4.1: bytes=32 time=0ms TTL=126
Reply from  192.168.4.1: bytes=32 time=0ms TTL=126
Reply from  192.168.4.1: bytes=32 time=1ms TTL=126
Ping statistics for  192.168.4.1
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum = 1ms, Average = 0ms

步驟八：在R1配置端口跟蹤、R2配置佔先權

tarena-R1(config)#interface fastEthernet 0/0
tarena-R1(config-if)#standby 1 track f0/1
tarena-R2(config)#interface fastEthernet 0/0
tarena-R2(config-if)#standby 1 preempt

步驟九：關閉R1的f0/1接口，模擬設備故障，查看R2的HSRP信息

tarena-R1(config)#interface fastEthernet 0/1
tarena-R1(config-if)#shutdown
tarena-R2#show standby brief 
                        P indicates configured to preempt.
                        |
Interface   Grp  Pri P State    Active          Standby         Virtual IP
Fa0/0        1    195   Active   local           unknown         192.168.1.254

結果顯示R2已成爲活躍路由器，而備份路由器狀態未知。虛擬路由器的IP地址192.168.1.254/24也已遷移到R2上了。

步驟十：在R1配置佔先權，並激活R1的f0/1接口並查狀態

備份路由器成爲活躍路由器後，原來的活躍路由器R1即便線路修復也不會從新成爲進入活躍狀態。

爲了使路由器徹底根據優先級來決定其狀態，須要配置佔先權。佔先權保證了嚴格根據優先級來決定哪臺設備進入活躍狀態。

tarena-R1(config)#interface f0/0
tarena-R1(config-if)#standby 1 preempt
tarena-R1(config)#interface f0/1
tarena-R1(config-if)#no shutdown
tarena-R1#show standby brief 
                        P indicates configured to preempt.
                        |
Interface   Grp  Pri P State    Active          Standby         Virtual IP
Fa0/0        1    200   Active   local           192.168.1.253     192.168.1.254