VLAN

This help contains the following topics:

·     Introduction

¡     Port-based VLANs

¡     VLAN interfaces

·     Restrictions and guidelines

Introduction

The Virtual Local Area Network (VLAN) technology divides a physical LAN into multiple logical LANs. It has the following benefits:

·     Security—Hosts in the same VLAN can communicate with one another at Layer 2, but they are isolated from hosts in other VLANs at Layer 2.

·     Broadcast traffic isolation—Each VLAN is a broadcast domain that limits the transmission of broadcast packets.

·     Flexibility—A VLAN can be logically divided on a workgroup basis. Hosts in the same workgroup can be assigned to the same VLAN, regardless of their physical locations.

Port-based VLANs

Port-based VLANs group VLAN members by port. A port forwards packets from a VLAN only after it is assigned to the VLAN.

In a VLAN, a port can be added to an untagged port list to be an untagged port or be added to a tagged port list to be a tagged port. The untagged port in the VLAN sends packets untagged and the tagged port in the VLAN sends packets tagged.

You can set the link type of a port to access, trunk, or hybrid. The link types use the following VLAN tag handling methods:

·     Access—An access port can forward packets only from one VLAN and send these packets untagged. An access port can be added to an untagged port list in only one VLAN.

·     Trunk—A trunk port can forward packets from multiple VLANs. Except packets from the port VLAN ID (PVID), packets sent out of a trunk port are VLAN-tagged. In the PVID of a trunk port, the port can be added to only an untagged port list. In other VLANs, the port can be added to only an tagged port list.

·     Hybrid—A hybrid port can forward packets from multiple VLANs. The tagging status of the packets forwarded by a hybrid port depends on the port configuration. In different VLANs, a hybrid port can be added to an untagged port list or a tagged port list upon configuration requirement.

VLAN interfaces

Hosts of different VLANs use VLAN interfaces to communicate at Layer 3. VLAN interfaces are virtual interfaces that do not exist as physical entities on devices. For each VLAN, you can create one VLAN interface and assign an IP address to it. The VLAN interface acts as the gateway of the VLAN to forward packets destined for another IP subnet at Layer 3.

Restrictions and guidelines

As the system default VLAN, VLAN 1 cannot be created or deleted.