VLAN access mode

VLAN Introduce

vlan: virtual local area network, Virtual LAN
vlan It's a physical LAN A technique that is logically divided into multiple broadcast domains .
Every vlan It's a broadcast domain ,vlan The communication between hosts in the network is just like that in a lan It's the same inside , and vlan But we can't communicate with each other directly . such , Broadcast messages are limited to one vlan Inside .

vlan The essence ： Broadcast area
vlan Practical use of ： The interface of the switch exists in a vlan, For data forwarding

Mark

Ethernet frame has 2 Kind of ： nothing vlan Marked standard Ethernet frames and have vlan Marked Ethernet frame

Huawei switch vlan To configure

#vlan establish 
<Huawei>sys
[Huawei]sysname SW7
[SW7]vlan batch 8
# Add ports to vlan, Set the port to access mode 
[SW7]int GigabitEthernet 0/0/1
[SW7-GigabitEthernet0/0/1]port link-type access 
[SW7-GigabitEthernet0/0/1]port default vlan 8
# Check the switch port vlan
[SW7]dis port vlan 
Port                    Link Type    PVID  Trunk VLAN List
-------------------------------------------------------------------------------
GigabitEthernet0/0/1    access       8     -                                   
GigabitEthernet0/0/2    hybrid       1     -                                   
GigabitEthernet0/0/3    hybrid       1     -                                   
GigabitEthernet0/0/4    hybrid       1     -                                   
GigabitEthernet0/0/5    hybrid       1     -                                   
GigabitEthernet0/0/6    hybrid       1     -                                   
GigabitEthernet0/0/7    hybrid       1     -                                   
GigabitEthernet0/0/8    hybrid       1     -                                   
GigabitEthernet0/0/9    hybrid       1     -                                   
GigabitEthernet0/0/10   hybrid       1     -                                   
GigabitEthernet0/0/11   hybrid       1     -                                   
GigabitEthernet0/0/12   hybrid       1     -                                   
GigabitEthernet0/0/13   hybrid       1     -                                   
GigabitEthernet0/0/14   hybrid       1     -                                   
GigabitEthernet0/0/15   hybrid       1     -                                   
GigabitEthernet0/0/16   hybrid       1     -                                   
GigabitEthernet0/0/17   hybrid       1     -                                   
GigabitEthernet0/0/18   hybrid       1     -                                   
GigabitEthernet0/0/19   hybrid       1     -                                   
GigabitEthernet0/0/20   hybrid       1     -                                   
GigabitEthernet0/0/21   hybrid       1     -                                   
GigabitEthernet0/0/22   hybrid       1     -                                   
GigabitEthernet0/0/23   hybrid       1     -                                   
GigabitEthernet0/0/24   hybrid       1     -  

How the access mode works

Application scenario of access mode ： A large number of access end users
Check the port's vlan state

[SW7]dis port vlan active 
T=TAG U=UNTAG
-------------------------------------------------------------------------------
Port                Link Type    PVID    VLAN List
-------------------------------------------------------------------------------
GE0/0/1             access       8       U: 8
GE0/0/2             hybrid       1       U: 1
GE0/0/3             hybrid       1       U: 1
GE0/0/4             hybrid       1       U: 1
GE0/0/5             hybrid       1       U: 1
GE0/0/6             hybrid       1       U: 1
GE0/0/7             hybrid       1       U: 1
GE0/0/8             hybrid       1       U: 1
GE0/0/9             hybrid       1       U: 1
GE0/0/10            hybrid       1       U: 1
GE0/0/11            hybrid       1       U: 1
GE0/0/12            hybrid       1       U: 1
GE0/0/13            hybrid       1       U: 1
GE0/0/14            hybrid       1       U: 1
GE0/0/15            hybrid       1       U: 1
GE0/0/16            hybrid       1       U: 1
GE0/0/17            hybrid       1       U: 1
GE0/0/18            hybrid       1       U: 1
GE0/0/19            hybrid       1       U: 1
GE0/0/20            hybrid       1       U: 1
GE0/0/21            hybrid       1       U: 1
GE0/0/22            hybrid       1       U: 1
GE0/0/23            hybrid       1       U: 1
GE0/0/24            hybrid       1       U: 1

PVID: port vlan id
PVID Default equal to 1
vlan list Indicate what is allowed vlan id Frames can pass through this port
For conventional terminal equipment , They don't know vlan Mark , Therefore, the frame will be marked when it goes out of the switch to the terminal device tag Remove .
Frames need to be added before entering the switch id

On the same switch , Only the access is the same vlan The terminal can communicate ！

Port type -Access

• Only unique vlan id（ frame ） Through this port , Exclusive interface
• In the direction of flow , received untagged( No VLAN label ), The switch will force the port to be added PVID( port VLAN Mark )
• When a data frame is sent from another interface , It must be forwarded from the allowed interface , Remove the frame at the same time TAG,Access The Ethernet frame sent by the port to the opposite device is always a frame without label