Vlan Introduction - UTStarcom iSpirit 3026 Manual

1.4.2 VLAN

1.VLAN introduction

VLAN is used for collecting all kinds of transmission devices in one physical local network. Any
combination of ports on a switch(including all ports) can be viewed as one VLAN. VLAN
assignment is not limited by physical connection between hardware devices, users can
configure VLAN flexibly by assigning different ports to different VLANs.
VLAN can relieve you from the restriction of physical connection when creating a broadcast
domain. A VLAN is just a set of local network devices which are independent from the physical
network topology. When they communicate with each other, all devices belong to one VLAN
seem to be in the same physical local network no matter how to connect them.
The main functionality of VLAN is as follows:
(1) can be used to constrain broadcast, flow-controlling its broadcast range. Here is an
example: suppose a device in the "Research Department" VLAN broadcast a data packet,
then only devices in the "Research Department" VLAN can receive this packet, other
devices in other departments won't receive it;
(2) Provides additional safety. Communication between different VLANs can only be
achieved through layer 3 transmission, instead of direct communication;
(3) Make it easy to move and manage devices in the network.
In a word, VLAN is for the creation of layer 3 logical broadcast domains, it can be allocated
either on one switch, or through multiple switches. VLAN can be used for logical VLAN
separation of devices in one network with the same subnet address, i.e., separating them into
multiple broadcast domains, thus avoiding broadcast storm.
2.VLAN categorization
The iSpirit 3026 switch supports port-based VLAN. It allocates a set of ports on one or more
switches into one logical group, and this is the easiest and most efficient way. Network
administrators only need to assign a specific VLAN for a port, without considering the device it
connects. IEEE802.1Q is an international standard for port-based VLAN of Ethernet switches, it
allows the co-use of devices from different factories, with VLAN configurations to be understood
by each other, thus they can communicate with each other. According to IEEE802.1Q, a port can
be assigned as Tagged or Untagged, which determines whether the device that the port
connects can support frames with 802.1Q Tag header or not. The ports on the iSpirit 3026 switch