拓撲圖
搭建個網路，讓AB兩個公司的網路相互冗餘，當任意一邊出現故障無法訪問網際網路時可以保持網路的連通性，來達到提高網路穩定性的需求。
基本資訊：
AR1與AR2透過Ethernet2/0/0、Ethernet2/0/1相互互聯
配置案例
AR1基本網路配置，使得PC1透過DHCP自動獲取到IP地址及DNS，並且可以正常訪問網際網路。
The device is running!
<Huawei>system-view #進入系統檢視
Enter system view, return user view with Ctrl+Z.
[Huawei]sysname AR1 #修改裝置名稱
[AR1]undo info-center enable #關閉資訊中心提示
Info: Information center is disabled.
[AR1]interface GigabitEthernet 0/0/0 #進入埠0/0/0
[AR1-GigabitEthernet0/0/0]ip address 10.11.12.10 24 #配置上聯埠的IP地址及子網掩碼
[AR1-GigabitEthernet0/0/0]ping 10.11.12.1 #檢測與上聯閘道器連通性
PING 10.11.12.1: 56 data bytes, press CTRL_C to break
Reply from 10.11.12.1: bytes=56 Sequence=1 ttl=128 time=60 ms
Reply from 10.11.12.1: bytes=56 Sequence=2 ttl=128 time=10 ms
Reply from 10.11.12.1: bytes=56 Sequence=3 ttl=128 time=10 ms
Reply from 10.11.12.1: bytes=56 Sequence=4 ttl=128 time=10 ms
Reply from 10.11.12.1: bytes=56 Sequence=5 ttl=128 time=10 ms
--- 10.11.12.1 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 10/20/60 ms
[AR1-GigabitEthernet0/0/0]quit #退出埠
[AR1]dhcp enable #開啟dhcp功能
Info: The operation may take a few seconds. Please wait for a moment.done.
[AR1]ip pool huawei #建立IP地址，並命名為huawei
Info: It's successful to create an IP address pool.
[AR1-ip-pool-huawei]network 192.168.10.0 mask 24 #配置A公司網段以及子網長度
[AR1-ip-pool-huawei]gateway-list 192.168.10.1 #配置閘道器
[AR1-ip-pool-huawei]dns-list 114.114.114.114 #配置dhcp分配的dns伺服器地址
[AR1-ip-pool-huawei]quit #退出
[AR1]dns server 114.114.114.114 #配置AR1路由器的dns伺服器地址
[AR1]dns resolve #開啟dns功能
[AR1]ip route-static 0.0.0.0 0 10.11.12.1 #配置預設路由指向上聯閘道器
[AR1]ping www.baidu.com #檢測AR1路由器能否訪問網際網路
PING www.a.shifen.com: 56 data bytes, press CTRL_C to break
Reply from 182.61.200.7: bytes=56 Sequence=1 ttl=128 time=80 ms
Reply from 182.61.200.7: bytes=56 Sequence=2 ttl=128 time=80 ms
Reply from 182.61.200.7: bytes=56 Sequence=3 ttl=128 time=70 ms
Reply from 182.61.200.7: bytes=56 Sequence=4 ttl=128 time=70 ms
Reply from 182.61.200.7: bytes=56 Sequence=5 ttl=128 time=80 ms
--- www.a.shifen.com ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 70/76/80 ms
[AR1]interface GigabitEthernet 0/0/1 #進入埠0/0/1
[AR1-GigabitEthernet0/0/1]ip address 192.168.10.1 24 #配置AR1內網閘道器及子網掩碼
[AR1-GigabitEthernet0/0/1]dhcp select global #配置dhcp分配方式為全域性（使用上面的IP地址池）
[AR1-GigabitEthernet0/0/1]quit #退出埠
[AR1]acl 2001 #建立編號2001的基本acl
[AR1-acl-basic-2001]rule permit source 192.168.10.0 255.255.255.0 #配置允許源IP地址及長度
[AR1-acl-basic-2001]quit #退出acl
[AR1]interface GigabitEthernet 0/0/0 #進入埠0/0/0
[AR1-GigabitEthernet0/0/0]nat outbound 2001 #配置nat方向匹配acl 2001
[AR1-GigabitEthernet0/0/0]quit #退出埠AR2基本網路配置，同時也要讓PC2透過DHCP自動獲取到IP地址及DNS，並且可以正常訪問網際網路。
The device is running!
<Huawei>system-view #進入系統檢視
Enter system view, return user view with Ctrl+Z.
[Huawei]sysname AR2 #修改裝置名稱
[AR2]undo info-center enable #關閉資訊中心提示
Info: Information center is disabled.
[AR2]interface GigabitEthernet 0/0/0 #進入埠0/0/0
[AR2-GigabitEthernet0/0/0]ip address 10.11.12.20 24 #配置上聯埠的IP地址及子網掩碼
[AR2-GigabitEthernet0/0/0]ping 10.11.12.1 #檢測與上聯埠的連通性
PING 10.11.12.1: 56 data bytes, press CTRL_C to break
Reply from 10.11.12.1: bytes=56 Sequence=1 ttl=128 time=70 ms
Reply from 10.11.12.1: bytes=56 Sequence=2 ttl=128 time=10 ms
Reply from 10.11.12.1: bytes=56 Sequence=3 ttl=128 time=10 ms
Reply from 10.11.12.1: bytes=56 Sequence=4 ttl=128 time=10 ms
Reply from 10.11.12.1: bytes=56 Sequence=5 ttl=128 time=10 ms
--- 10.11.12.1 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 10/22/70 ms
[AR2-GigabitEthernet0/0/0]quit #退出埠
[AR2]dhcp enable #開啟dhcp功能
Info: The operation may take a few seconds. Please wait for a moment.done.
[AR2]ip pool huawei #建立IP地址池，並命名為huawei
Info: It's successful to create an IP address pool.
[AR2-ip-pool-huawei]network 192.168.20.0 mask 24 #配置A公司網段以及子網長度
[AR2-ip-pool-huawei]gateway-list 192.168.20.1 #配置閘道器
[AR2-ip-pool-huawei]dns-list 114.114.114.114 #配置dhcp分配的dns伺服器地址
[AR2-ip-pool-huawei]quit #退出
[AR2]dns server 114.114.114.114 #配置AR2路由器的DNS伺服器地址
[AR2]dns resolve #開啟dns功能
[AR2]ip route-static 0.0.0.0 0 10.11.12.1 #配置預設路由並執行上聯閘道器
[AR2]ping www.baidu.com #檢測AR2路由器能否訪問到網際網路
PING www.a.shifen.com: 56 data bytes, press CTRL_C to break
Reply from 182.61.200.6: bytes=56 Sequence=1 ttl=128 time=60 ms
Reply from 182.61.200.6: bytes=56 Sequence=2 ttl=128 time=60 ms
Reply from 182.61.200.6: bytes=56 Sequence=3 ttl=128 time=60 ms
Reply from 182.61.200.6: bytes=56 Sequence=4 ttl=128 time=60 ms
Reply from 182.61.200.6: bytes=56 Sequence=5 ttl=128 time=80 ms
--- www.a.shifen.com ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 60/64/80 ms
[AR2]interface GigabitEthernet 0/0/1 #進入埠0/0/1
[AR2-GigabitEthernet0/0/1]ip address 192.168.20.1 24 #配置AR1內網閘道器及子網掩碼
[AR2-GigabitEthernet0/0/1]dhcp select global #配置dhcp分配方式為全域性（使用上面的IP地址池）
[AR2-GigabitEthernet0/0/1]quit #退出埠
[AR2]acl 2001 #建立編號2001的基本acl
[AR2-acl-basic-2001]rule permit source 192.168.20.0 0.0.0.255 #配置允許源IP地址及長度
[AR2-acl-basic-2001]quit #退出埠
[AR2]interface GigabitEthernet 0/0/0 #進入埠0/0/0
[AR2-GigabitEthernet0/0/0]nat outbound 2001 #配置nat方向匹配acl 2001
[AR2-GigabitEthernet0/0/0]quit #退出埠以上基本的路由就完成了，A公司B公司內部的PC1以及PC2都可以獲取到地址並且可以訪問到網際網路
開始配置兩個網路的靜態路由互通，這樣就可以從另一臺路由器訪問到網際網路
AR1互聯配置，配置訪問AR2時資料包透過2/0/0端口出去，返回時透過2/0/1埠回來，並新增NAT的匹配地址
[AR1]interface Ethernet 2/0/0 #進入埠2/0/0
[AR1-Ethernet2/0/0]ip address 10.12.1.1 24 #配置與AR2的互聯地址及子網掩碼
[AR1-Ethernet2/0/0]quit #退出埠
[AR1]interface Ethernet 2/0/1 #進入埠2/0/1
[AR1-Ethernet2/0/1]ip address 10.12.2.2 24 #配置與AR2的互聯地址及子網掩碼
[AR1-Ethernet2/0/1]quit #退出埠
[AR1]ip route-static 192.168.20.0 255.255.255.0 10.12.2.1 #配置訪問AR2內部網路的路由
#如果不想AB兩個內網可以相互訪問，可以將上面這條路由刪除，我這裡就保留
[AR1]ip route-static 0.0.0.0 0 10.12.2.1 preference 100 #配置優先順序為100的預設路由並指向AR2
[AR1]ping 192.168.20.254 #檢測與PC2的聯通性
PING 192.168.20.254: 56 data bytes, press CTRL_C to break
Request time out
Reply from 192.168.20.254: bytes=56 Sequence=2 ttl=127 time=20 ms
Reply from 192.168.20.254: bytes=56 Sequence=3 ttl=127 time=20 ms
Reply from 192.168.20.254: bytes=56 Sequence=4 ttl=127 time=20 ms
Reply from 192.168.20.254: bytes=56 Sequence=5 ttl=127 time=20 ms
--- 192.168.20.254 ping statistics ---
5 packet(s) transmitted
4 packet(s) received
20.00% packet loss
round-trip min/avg/max = 20/20/20 ms
[AR1]acl 2001 #進入ACL 2001
[AR1-acl-basic-2001]rule permit source 192.168.20.0 0.0.0.255 #新增AR2內網的源IP地址及長度
[AR1-acl-basic-2001]quit #退出AR2互聯配置，與AR1的相反，配置訪問AR1時資料包透過2/0/1端口出去，返回時透過2/0/0埠回來，並新增NAT的匹配地址
[AR2]interface Ethernet 2/0/0 #進入埠2/0/0
[AR2-Ethernet2/0/0]ip address 10.12.2.1 24 #配置與AR1的互聯IP地址及子網掩碼
[AR2-Ethernet2/0/0]ping 10.12.2.2 #檢測網路連通性
PING 10.12.2.2: 56 data bytes, press CTRL_C to break
Reply from 10.12.2.2: bytes=56 Sequence=1 ttl=255 time=40 ms
Reply from 10.12.2.2: bytes=56 Sequence=2 ttl=255 time=10 ms
Reply from 10.12.2.2: bytes=56 Sequence=3 ttl=255 time=10 ms
Reply from 10.12.2.2: bytes=56 Sequence=4 ttl=255 time=20 ms
Reply from 10.12.2.2: bytes=56 Sequence=5 ttl=255 time=20 ms
--- 10.12.2.2 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 10/20/40 ms
[AR2-Ethernet2/0/0]quit #退出埠
[AR2]interface Ethernet 2/0/1 #進入埠2/0/1
[AR2-Ethernet2/0/1]ip address 10.12.1.2 24 #配置與AR2的互聯IP地址及子網掩碼
[AR2-Ethernet2/0/1]ping 10.12.1.1 #檢測網路連通性
PING 10.12.1.1: 56 data bytes, press CTRL_C to break
Reply from 10.12.1.1: bytes=56 Sequence=1 ttl=255 time=30 ms
Reply from 10.12.1.1: bytes=56 Sequence=2 ttl=255 time=30 ms
Reply from 10.12.1.1: bytes=56 Sequence=3 ttl=255 time=20 ms
Reply from 10.12.1.1: bytes=56 Sequence=4 ttl=255 time=20 ms
Reply from 10.12.1.1: bytes=56 Sequence=5 ttl=255 time=20 ms
--- 10.12.1.1 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 20/24/30 ms
[AR2-Ethernet2/0/1]quit #退出埠
[AR2]ip route-static 192.168.10.0 255.255.255.0 10.12.1.1 #配置訪問AR1內部網路的路由
#如果不想AB兩個內網可以相互訪問，可以將上面這條路由刪除，我這裡就保留
[AR2]ip route-static 0.0.0.0 0 10.12.1.1 preference 100 #配置優先順序為100的預設路由並指向AR1
[AR2]ping 192.168.10.254 #檢測與PC1的連通性
PING 192.168.10.254: 56 data bytes, press CTRL_C to break
Request time out
Reply from 192.168.10.254: bytes=56 Sequence=2 ttl=127 time=20 ms
Reply from 192.168.10.254: bytes=56 Sequence=3 ttl=127 time=20 ms
Reply from 192.168.10.254: bytes=56 Sequence=4 ttl=127 time=20 ms
Reply from 192.168.10.254: bytes=56 Sequence=5 ttl=127 time=30 ms
--- 192.168.10.254 ping statistics ---
5 packet(s) transmitted
4 packet(s) received
20.00% packet loss
round-trip min/avg/max = 20/22/30 ms
[AR2]acl 2001 #進入ACL 2001
[AR2-acl-basic-2001]rule permit source 192.168.10.0 0.0.0.255 新增AR2內網的源IP地址及長度
[AR2-acl-basic-2001]quit #退出配置完成後我們模擬一下AR1以及AR2出口線路故障後，PC1以及PC2能否正常訪問網路
檢測
關閉AR1的出口，模擬線路故障
[AR1]interface GigabitEthernet 0/0/0 #進入埠0/0/0
[AR1-GigabitEthernet0/0/0]shutdown #關閉埠
[AR1-GigabitEthernet0/0/0]quit #退出檢視AR1的路由表資訊
優先順序100指向AR2的預設路由生效
PC1訪問網路
路由追蹤時多了一跳路由
透過對去往AR2的出入埠抓包
PC1傳送的資料包
AR2 Ethernet2/0/1
百度回傳的資料包
AR1 Ethernet2/0/1
這樣當AR1無法正常連線網際網路時就可以讓流量走到AR2訪問
恢復AR1的出介面，並禁用AR2出介面模擬線路故障
[AR1]interface GigabitEthernet 0/0/0 #進入埠0/0/0
[AR1-GigabitEthernet0/0/0]undo shutdown #取消關閉埠
[AR1-GigabitEthernet0/0/0]quit #退出[AR2]interface GigabitEthernet 0/0/0 #進入埠0/0/0
[AR2-GigabitEthernet0/0/0]shutdown #關閉埠
[AR2-GigabitEthernet0/0/0]quit #退出檢視下AR2的路由表
優先順序100指向AR1的預設路由生效
PC2訪問網路
路由追蹤也是多了一跳
透過對去往AR1的出入埠抓包
PC2傳送的資料包
AR1 Ethernet2/0/0
百度回傳的資料表
AR2 Ethernet2/0/0
至此，我們的需求就配置完成了，達到了當AR1外網故障時會切換到AR2的出口進行訪問網際網路，同理AR2的外網故障時也會自動切換到AR1的出口進行訪問，雖然切換的會有短暫的丟包，但是可以馬上恢復網路訪問。
