一、相关知识
- 单臂路由的原理：将路由器的一个物理接口当成多个逻辑接口来使用时，需要启用该接口上的子接口，通过一个个逻辑子接口实现物理端口以一当多的功能。
- 优点：1、节省开支；2、配置简单；维护方便
- 缺点：1、路由器CPU与内存的资源消耗大；2、网络数据包的传输效率受影响，特别是大流量；3、对于连接线路要求比较高；4、VLAN间安全性降低。
- 常见问题：1、不要对物理接口进行任何配置，只需对其子接口进行划分和设置；2、不要忘记将物理接口开启，用no shutdown，这样所有子接口会同时开启；3、如果有防病毒ACL等列表的话不要忘记在最后添加到物理以太口上；4、由于数据实际上通过物理接口传输，所以对路由器设备要求较高；5、在设置TRUNK类型时要根据实际情况选择是ISL（思科的协议）还是802.1q协议。
二、简单例子
1、拓扑结构
2、相关代码
S1：
Switch>en
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#host S1
VLAN 的划分
S1(config)#vlan 10
S1(config-vlan)#e
S1(config-vlan)#exit
S1(config)#vlan 20
S1(config-vlan)#e
S1(config-vlan)#exit
将接口划分到相应的VLAN
S1(config)#int f
S1(config)#int fastEthernet 0/1
S1(config-if)#sw
S1(config-if)#switchport mo
S1(config-if)#switchport mode acc
S1(config-if)#switchport mode access
S1(config-if)#sw
S1(config-if)#switchport ac
S1(config-if)#switchport access vlan 10
S1(config-if)#e
S1(config-if)#exit
S1(config)#int fastEthernet 0/2
S1(config-if)#switchport mode access
S1(config-if)#switchport access vlan 10
S1(config-if)#e
S1(config-if)#exit
配置trunk模式
S1(config)#int fastEthernet 0/3
S1(config-if)#switchport mode t
S1(config-if)#switchport mode trunk
S1(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up
S1(config-if)#
%LINK-5-CHANGED: Interface FastEthernet0/4, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up
S1(config-if)#exit
S1(config)#
%LINK-5-CHANGED: Interface FastEthernet0/4, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up
跟路由器相连的链路也要配置trunk 模式
S1(config)#interface fastEthernet 0/4
S1(config-if)#sw
S1(config-if)#switchport mod
S1(config-if)#switchport mode tru
S1(config-if)#switchport mode trunk
S1(config-if)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/4, changed state to up
S1(config-if)#e
S1(config-if)#exit
S2:
Switch>en
Switch#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)#host S2
VLAN 的划分
S2(config)#vlan 10
S2(config-vlan)#e
S2(config-vlan)#exit
S2(config)#vlan 20
S2(config-vlan)#e
S2(config-vlan)#exit
将接口划分到相应的VLAN
S2(config)#int f
S2(config)#int fastEthernet 0/1
S2(config-if)#sw
S2(config-if)#switchport mod
S2(config-if)#switchport mode ac
S2(config-if)#switchport mode access
S2(config-if)#sw
S2(config-if)#switchport ac
S2(config-if)#switchport access vlan 10
S2(config-if)#e
S2(config-if)#exit
S2(config)#int fastEthernet 0/2
S2(config-if)#switchport mode access
S2(config-if)#switchport access vlan 20
S2(config-if)#e
S2(config-if)#exit
交换机1 F0/3口配置了trunk模式，交换机2与它同一条链路上的接口也自动设置成trunk模式
S2(config)#%SPANTREE-2-RECV_PVID_ERR: Received 802.1Q BPDU on non trunk FastEthernet0/3 VLAN1.
%SPANTREE-2-BLOCK_PVID_LOCAL: Blocking FastEthernet0/3 on VLAN0001. Inconsistent port type.
S2(config)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up
R1：
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#host R1
R1(config)#int
R1(config)#interface g
开启物理接口
R1(config)#interface gigabitEthernet 0/0
R1(config-if)#no sh
R1(config-if)#no shutdown
设置物理接口下的逻辑接口
R1(config-if)#
%LINK-5-CHANGED: Interface GigabitEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0, changed state to up
R1(config-if)#e
R1(config-if)#exit
R1(config)#interface gigabitEthernet 0/0.10
R1(config-subif)#
（提示信息）%LINK-5-CHANGED: Interface GigabitEthernet0/0.10, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0.10, changed state to up
R1(config-subif)#en
R1(config-subif)#encapsulation ?
dot1Q IEEE 802.1Q Virtual LAN
R1(config-subif)#encapsulation d
R1(config-subif)#encapsulation dot1Q 10
R1(config-subif)#ip address 192.168.10.254 255.255.255.0
R1(config-subif)#ex
R1(config-subif)#exit
R1(config)#interface gigabitEthernet 0/0.20
R1(config-subif)#
%LINK-5-CHANGED: Interface GigabitEthernet0/0.20, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/0.20, changed state to up
R1(config-subif)#en
R1(config-subif)#encapsulation d
R1(config-subif)#encapsulation dot1Q 20
R1(config-subif)#ip add
R1(config-subif)#ip address 192.168.20.254 255.255.255.0
R1(config-subif)#ex
R1(config-subif)#exit
R1(config)#do show ip route （配置后的路由表）
Codes: L - local, 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, 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
192.168.10.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.10.0/24 is directly connected, GigabitEthernet0/0.10
L 192.168.10.254/32 is directly connected, GigabitEthernet0/0.10
192.168.20.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.20.0/24 is directly connected, GigabitEthernet0/0.20
L 192.168.20.254/32 is directly connected, GigabitEthernet0/0.20
R1(config)#
结果：各个网段之间能互相ping 通
这篇文章就写到这里啦，有哪些不好的欢迎指出！