A network is basically a set of devices connected to one another and communicating using wired or wireless mediums. There are several standard network frameworks defined for wired and wireless communication by IEEE. This post provides information about the IEEE 802 standard and network modes.
802 Standard
The 802 standard is a family of IEEE standards dealing with local and metropolitan area networks. The protocol specified in the 802 standard covers lower two layers of the OSI model that are Physical and Data Link layers. In the 802 standard, the Data link layer (Layer 2 of the OSI model) has been divided into two parts Logical Link Control (LLC) and Media Access Control (MAC) as shown in figure below.
Figure 1. Layer architecture
The active 802 standards are listed below.
Table 1. 802 standards description
| Standard | Name | Description |
| 802.1 | Internetworking | It ensures the management of the Local Area Network (LAN) / Metropolitan Area Network (MAN) network and monitors network capabilities. MAC bridging, data encryption/encoding, and network traffic management services are also provided. |
| 802.3 | Ethernet | Ethernet based technology that is primarily used for LAN, it can also be used for MAN and Wide Area Network (WAN). |
| 802.3 defines the Physical and MAC sublayer of the Data Link layer that is used in wired networks. Uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) for collision detection. Data rates can be from 10Mbps to 10Gbps. | ||
| 802.11 | WLAN, Wi-Fi | Wireless LAN uses high radio frequencies instead of cables to connect the devices in the network. Portability and setup cost is cheaper compared to wired networks but speed and security are better in wired communication. It uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) for collision avoidance. |
| 802.15 | WPAN | This covers various protocol definitions for the personal area network like Bluetooth, ZigBee & sensors networks. |
WLAN and Wi-Fi Introduction
Wireless Local Area Network (WLAN) or Wireless LAN, is a network that links two or more devices using wireless communication to form a local area network within a limited area such as a home, campus, and office building. A WLAN can be built on various wireless technologies i.e. Wi-Fi, Infrared.
Wi-Fi is a type of WLAN that follows IEEE 802.11 standards and one of the most commonly used WLAN today. Wi-Fi as a name for the standard is a trademark of the Wi-Fi Alliance.
Wi-Fi or WLAN networks use radio waves to exchange information between devices. These radio waves are transmitted on specific frequencies - 2.4 GHz and 5 GHz, depending on the 802.11 standard (IEEE 802.11a/b/g/n/ac/ax) that the device uses.
A Wi-Fi connection is established using a wireless adapter to create hotspots – areas in the vicinity of a wireless router that is connected to the network and allow users to access internet services.
All Wi-Fi versions uses license free bands (ISM bands) across the globe.
Network Modes
Ad-Hoc Mode
In this mode wireless nodes communicate to peer nodes directly. It does not use Access Point (AP) instead it uses Mesh topology. It is also called peer to peer mode. An ad-hoc wireless network is more cost-effective than its alternative, since it does not require the installation of an AP to operate. In addition, it also needs less time to set up.
Figure 2. Ad-Hoc mode
Infrastructure Mode
In this mode, devices can communicate with each other first going through AP. In infrastructure mode, the wireless devices can communicate with each other or can communicate with a wired network as it’s communicating through AP. This mode is the most commonly used network mode.
Compared to Ad-Hoc wireless networks, infrastructure mode offers the advantages of scale, centralized security management, and improved reach.
Infrastructure mode has half throughput compared to Ad-Hoc mode.
Figure 3. Infrastructure mode
Repeater Mode
When two wireless host devices have to be connected and the distance between them is long for the direct connection or obstruction is present, at that time repeater mode is used to bridge the gap. Repeater operates at the physical layer of the OSI model.
As a Wireless Repeater, an AP node extends the range of the wireless network by repeating the wireless signal of the remote AP. The Ethernet MAC address of the remote AP is required for the AP to act as a wireless range extender.
The repeater mode has certain drawbacks. Throughput is reduced by at least 50% as wireless interference is at least doubled. The bandwidth of any device connected to it is halved. This is due to the repeater receiving the signal, processing it, and then rebroadcasting it in both directions, from the router to the device and vice versa.
The Repeater must be kept in the range of AP, but not too close to the AP. Distance between AP and repeater depends on the range of the AP and repeater should be kept in such a way that maximum possible area coverage can be achieved.
Figure 4. Repeater mode
Bridge Mode
Bridge connects two or more networks to each other. It operates on the Data link layer of the OSI Model.
Bridge mode allows the AP to communicate with another AP capable of point-to-point bridging. An example of this is connecting two buildings through a wireless connection.
Figure 5. Bridge mode
