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Advanced Configuration AP-4000 Series User Guide

SSID/VLAN/Security

Figure 4-38 Components of a Typical VLAN

VLAN Workgroups and Traffic Management

Access Points that are not VLAN-capable typically transmit broadcast and multicast traffic to all wireless Network Interface Cards (NICs). This process wastes wireless bandwidth and degrades throughput performance. In comparison, a VLAN-capable AP is designed to efficiently manage delivery of broadcast, multicast, and unicast traffic to wireless clients.

The AP assigns clients to a VLAN based on a Network Name (SSID). The AP can support up to 16 SSIDs per radio, with a unique VLAN configurable per SSID.

The AP matches packets transmitted or received to a network name with the associated VLAN. Traffic received by a VLAN is only sent on the wireless interface associated with that same VLAN. This eliminates unnecessary traffic on the wireless LAN, conserving bandwidth and maximizing throughput.

In addition to enhancing wireless traffic management, the VLAN-capable AP supports easy assignment of wireless users to workgroups. In a typical scenario, each user VLAN represents a workgroup; for example, one VLAN could be used for an EMPLOYEE workgroup and the other for a GUEST workgroup.

In this scenario, the AP would assign every packet it accepted to a VLAN. Each packet would then be identified as EMPLOYEE or GUEST, depending on which wireless NIC received it. The AP would insert VLAN headers or “tags” with identifiers into the packets transmitted on the wired backbone to a network switch.

Finally, the switch would be configured to route packets from the EMPLOYEE workgroup to the appropriate corporate resources such as printers and servers. Packets from the GUEST workgroup could be restricted to a gateway that allowed access to only the Internet. A member of the GUEST workgroup could send and receive e-mail and access the Internet, but would be prevented from accessing servers or hosts on the local corporate network.

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