Experiment goal

Master the single-arm router configuration method;
A single-arm router can communicate with each other between different VLANs;

Experimental background

An enterprise has two main departments, the technical department and the sales department, which are located in different offices. For security and ease of management, the hosts of the two departments are divided into VLANs. The technical department and the sales department are in different VLANs. Now due to business needs, the hosts of the sales department and the technical department need to be able to access each other and obtain the corresponding resources. The switches of the two departments are connected through a router.

Technical Principle

One-arm routing: It is a three-layer network device router for inter-VLAN communication. It only needs an Ethernet. By creating sub-interfaces, it can assume the gateway of all VLANs and forward data between different VLANs.

1. Cisco Simulator Packet Tracer configuration scheme
2. Huawei eNSP configuration scheme

First, the Cisco simulator configuration plan
Topology

Experimental equipment: one Router-PT (generic), one Switch-PT (generic), two pcs
Note: Routers and switches of different models have different implementations of some commands. If you need to follow the blogger’s configuration plan exactly, please select the same model of equipment.

Configure PC1, IP: 192.168.1.100，Submask: 255.255.255.0 ，Gateway:192.168.1.1
Configure PC2, IP: 192.168.2.100， Submask: 255.255.255.0 ，Gateway:192.168.2.1 

The configuration commands of the switch are as follows:

Switch>enable 
Switch#configure terminal 
Switch(config)#vlan 2        //Create vlan2
Switch(config-vlan)#vlan 3   //Create vlan3
Switch(config-vlan)#ex
Switch(config)#
Switch(config)#interface fastEthernet 1/1   //Enter Fast Ethernet interface1/1
Switch(config-if)#switchport mode access    //Configuration mode is access
Switch(config-if)#switchport access vlan 2  //Give the interface to vlan2

Switch(config)#interface fastEthernet 2/1
Switch(config-if)#switchport mode access 
Switch(config-if)#switchport access vlan 3

Switch(config)#interface fastEthernet 0/1
Switch(config-if)#switchport mode trunk   //Configure trunk port

The router configuration commands are as follows:

Router#configure terminal

Router(config)#int fa0/0.1 //Enter the sub-interface
Router(config-subif)#ip address 192.168.1.1 255.255.255.0 //Configure the gateway of vlan2
Router(config-subif)#encapsulation dot1Q 2

Router(config)#int fa0/0.2
Router(config-subif)#ip address 192.168.2.1 255.255.255.0
Router(config-subif)#encapsulation dot1Q 3  //Give vlan 3Encapsulate the transmitted data

Router(config)#int fa0/0
Router(config-if)#no shutdown //Activate interface

After configuring the above command, you can view it by entering show ip route in the router privilege mode. The routing entry in the second red box in the figure below needs to appear. If it does not appear, you need to reconfigure the router.

Test single-arm routing, PC1 and PC2 perform ping test. Just receive the Reply.

Second, Huawei eNSP configuration plan
The topology is as follows

Experimental equipment: one AR2240, one S3700, and two PCs.

Configure PC1, IP: 192.168.1.100，Submask: 255.255.255.0 ，Gateway:192.168.1.1
Configure PC2, IP: 192.168.2.100， Submask: 255.255.255.0 ，Gateway:192.168.2.1 

Reminder: When you configure the switch or router on the Huawei simulator, a lot of English prompts will often pop up. These are usually not needed by us and will affect our configuration progress, so you can use the following command to close English tips.

[Huawei]undo info enable  //Enter in system view mode

The configuration of the switch is as follows:

<S1>system-view 
[S1]vlan batch 2 3    //Create vlan2 at the same time And vlan3
Info: This operation may take a few seconds. Please wait for a moment...done.
[S1] i]interface Ethernet 0/0/1
[S1-Ethernet0/0/1]port link-type  access 
[S1-Ethernet0/0/1]port default vlan 2
 
[S1-Ethernet0/0/1] interface Ethernet 0/0/2
[S1-Ethernet0/0/2]port link-type access 
[S1-Ethernet0/0/2]port default vlan 3

[S1] interface Ethernet 0/0/3
[S1-Ethernet0/0/3]port link-type trunk 
[S1-Ethernet0/0/3]port trunk allow-pass vlan 2 3  //Allow vlan on the trunk 2 3by

The router configuration is as follows:

[SR1]interface GigabitEthernet0/0/0.1
[SR1-GigabitEthernet0/0/0.1]dot1q termination vid 2 //Encapsulate vlan 2
[SR1-GigabitEthernet0/0/0.1]ip address 192.168.1.1 24 //Configure the gateway
[SR1-GigabitEthernet0/0/0.1]arp broadcast enable  //Enable ARP broadcast
 
[SR1]interface GigabitEthernet0/0/0.2
[SR1-GigabitEthernet0/0/0.2]dot1q termination vid 3
[SR1-GigabitEthernet0/0/0.2]ip address 192.168.2.1 24 
[SR1-GigabitEthernet0/0/0.2]arp broadcast  enable

Note: Here you need to enable ARP address broadcast on the router's sub-interface. Otherwise, it will report a request timeout error if it fails to ping.

To test the single-arm routing, PC1 and PC2 perform a ping test. Just receive the Reply.