What Are 802.11 Topologies? We’re Going Back to Basics

For all its simplicity to end users, Wi-Fi is really an incredibly complex technology. In this series, we “get back to basics” of the technology.

In the last installment of of my “Back to the Basics” blog series I discussed 2.4 GHz Channel Planning. This week we will take a look at 802.11 topologies. 

First, what is a network topology? In communication networks, a topology is usually a schematic description of the arrangement of a network, including its nodes and connecting lines.

Before getting straight into 802.11 topologies, it is important to note that there are four major wireless topologies 

WWAN: wireless wide area network

WMAN: wireless metropolitan area network

WPAN: wireless personal area network

WLAN: wireless local area network

The 802.11 wireless medium is a perfect fit for local area networking (WLAN), which is the fourth topology listed above. This is what I will focus on for the remainder of this blog. The main component of an 802.11 wireless network is the radio. The radio can be inside a wireless access point or can be used as a client station.

Looking a little more closely, there are four 802.11 service sets that describe how these radios may be used to communicate with each other. The first is a basic service set (BSS) which is the foundation of an 802.11 network. A BSS consists of one AP radio with one or more client stations. These client stations connect to the AP and communicate through the AP. The physical area of coverage provided by an access point in a BSS is known as the basic service area (BSA).

Next is the extended service set (ESS). An extended service set is two or more basic service sets connected by a distribution system medium. The distribution system medium (DSM) is a physical medium that is used to connect access points. The most common DSM is a wired medium.

Third is the independent basic service set (IBSS). An IBSS is made up solely of client stations and no access points. The client stations transmit frames to each other directly, which is called peer to peer communication.

And lastly we have the mesh basic service set (MBSS). When access points support mesh functions, they may be deployed where wired network access is not available or possible. By using mesh functions, the access points provide wireless distribution for network traffic and form a mesh basic service set. One or more mesh APs will usually be connected to the wired infrastructure and the other mesh APs that are not connected to the wired network will form wireless backhaul connections to that specific AP. 

In summary, there are four main service sets as defined by the 802.11 standard, and each has a specific purpose. Network administrators typically work with extended service sets but each of the four sets can be used in a multitude of situations.

In my next installment, I will discuss Radio Frequency and Antenna Concepts.

All Posts In The Back To Basics Series:

How to Set Up Online Donations Using The Cloud And School Wi-Fi
Let Technology Help Fund Your School By Simplifying Recurring Online Donations

1) Do you know the RF fundamentals?

2) How are RF signals transmitted? Let’s talk equipment

3) A history of wireless standards

4) Do you know your 802.11 industry organizations?

5) Getting Familiar with Wi-Fi Channels?

6) 2.4 GHz Channel Planning

7) What Are 802.11 Topologies?

8) Radio Frequency And Antenna Concepts


Alexandra Gates is a Senior Product Marketing Manager at Aerohive Networks, where she helps define market strategy and vision for the cloud and WLAN products. She is a CWNA with a comprehensive background in wireless technology, including capacity and management planning, RF design, network implementation, and general industry knowledge.

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