Hello everyone!
Today, I will start to explain VLANs in the access network. In previous articles, I explained the basics of VLANs. VLANs are very important in access networks, today, I will explain standard and smart VLANs.
Types of VLAN
Standard
Smart
Mux
Super
VLAN attribute
Common
Stacking
QinQ
There are special VLAN
(OLT supports VLAN range from 2 to 4093.)
VLAN 1 is the default smart VLAN.
VLAN 4094 and VLAN 4095 are for the system.
VLAN 4079 is the default VLAN for the system. In addition to this VLAN, the next 14 VLANs are reserved for the system, from VLAN 4080 to VLAN 4093.
Now, I can start to explain the types of VLAN.
Standard VLAN
The ports in this type of VLAN are standard ethernet ports. In a standard VLAN, interfaces (ethernet ports) in the same VLAN can communicate with each other at the L2 level. The different ethernet ports can not communicate with each other.
Default VLAN is VLAN ID: 1, this is a smart VLAN. We can modify this VLAN, but we can not delete it. 15 VLANs, from 4079 to 4093 are default reserved VLANs. We can modify these VLANs.
In a GPON system, this type of VLAN can contain only ethernet ports. The standard VLAN is used for device cascading and network management.
Figure 1. Standard VLAN
Smart VLAN
This is a special type of VLAN, which is widely used on OLT in the GPON system. Smart VLAN has two types of ports: multiple service ports (downstream or users ports) and multiple upstream ports.
Service ports in the same VLAN cannot communicate with each other at the L2 level. Upstream ports can communicate with each other at the L2 level. And, service ports and upstream ports can communicate with each other.
We can use this type of VLAN for creating user groups. Different user groups belong to different VLANs. Then, we can use smart VLAN for L2 isolation in the same VLAN and when there is a limit on the number of VLANs.
Figure 2. Smart VLAN
On OLT, ports are classified into one or more upstream ports and downstream ports. Each downstream port should communicate with the upstream port. But downstream ports do not need to communicate with each other at the L2 level.
Continued in the next article >> VLANs in the access network (2)
Thank you!
