Network Fundamentals



Wireless

Wireless LAN Norms

Norms

Wireless Norms
IEEE Max Data Rate Comments
802.11-1997 2 Mbps The original 802.11 standard ratified in 1997
802.11b 11 Mbps Introduced in 1999
802.11a 54 Mbps Introduced in 1999
802.11g 54 Mbps Introduced in 2003
802.11n 600 Mbps HT (high throughput), introduced in 2009
802.11ac 6.93 Gbps VHT (very high throughput), introduced in 2013
802.11ax 4x 802.11ac High Efficiency Wireless, Wi-Fi6; expected late 2019; will operate on other bands too, as they become available

Wireless Devices

Access Point

Workgroup Bridge

Suppose you have a device that supports a wired Ethernet link but is not capable of having a wireless connection. For example, some mobile medical devices might be designed with only a wired connection. While it is possible to plug the device into an Ethernet connection when needed, a wireless connection would be much more practical. You can use a workgroup bridge (WGB) to connect the device’s wired network adapter to a wireless network.



You might encounter two types of workgroup bridges:

■ Universal workgroup bridge (uWGB): A single wired device can be bridged to a wireless network.
■ Workgroup bridge (WGB): A Cisco-proprietary implementation that allows multiple wired devices to be bridged to a wireless network.

Outdoor Bridge

An AP can be configured to act as a bridge to form a single wireless link from one LAN to another over a long distance. Outdoor bridged links are commonly used for connectivity between buildings or between cities.

Point-to-Point Bridge

If the LANs at two locations need to be bridged, a point-to-point bridged link can be used. One AP configured in bridge mode is needed on each end of the wireless link. Special purpose antennas are normally used with the bridges to focus their signals in one direction— toward the antenna of the AP at the far end of the link. This maximizes the link distance

Point-to-Multipoint Bridge

Sometimes the LANs at multiple sites need to be bridged together. A point-to-multipoint bridged link allows a central site to be bridged to several other sites. The central site bridge is connected to an omnidirectional antenna, such that its signal is transmitted equally in all directions so that it can reach the other sites simultaneously. The bridges at each of the other sites can be connected to a directional antenna aimed at the central site
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