Cabletron Systems 3Com manual Wireless LAN Service Area, 802.1d Spanning Tree Support

16CHAPTER 1: OVERVIEW OF DIGITAL WIRELESS NETWORKING

APs with the same WLAN service area define a coverage area. The wireless client searches for APs with a matching wireless LAN service area and synchronizes with an AP to establish communications. This allows wireless clients within the coverage area to roam between AP cells. As you roam from cell to cell, your wireless client switches APs. The switch occurs when the wireless client analyzes the reception quality at a particular location and selects an AP to communicate with, based on such factors as signal strength and wireless client load.

When the wireless client begins to lose the signal as it moves away from an associated AP, it performs a scan to find another AP. As wireless clients switch APs, the AP updates the association table. Roaming is invisible to the user.

Wireless LAN Service Area

The network administrator assigns the wireless LAN service area for the APs in a WSA. A valid wireless LAN service area is an alphanumeric, case-sensitive identifier of up to 32 characters. All nodes within one LAN use the same wireless LAN service area to communicate on the LAN. Multiple wireless LANs can coexist in

a single environment by assigning different wireless LAN service areas for the corresponding APs.

802.1d Spanning Tree Support

This protocol creates a loop-freetopography with exactly one path between every LAN. This is the shortest path from the Root AP to each AP and LAN. If an AP or LAN fails, a new route is calculated and added to the tree. All packet forwarding follows the spanning tree. APs have to choose one AP as the Root AP. The same holds true for WLANs associating with the root AP or another AP connected to the Ethernet LAN to prevent forming loops.