Page 134 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes point – client relationship which requires the wireless devices used for the bridge to be set to the
same service set identifier (SSID) and radio channel.
An example of a point-to-point bridge application would be connecting two commercial
buildings.

Example: Example of a combination point-to-point bridge and point to multipoint
application would be connecting multiple farm buildings.
Bridging has historically referred to propagation of data across a device without traversing
a network stack, such as TCP/IP. Wireless bridging is a colloquial term. A more accurate
description of connecting two local area networks would be a Wireless LAN to LAN bridge. The
distinction is important. While a device may not support bridging to a remote wireless access
point to connect two LANs, it may be desirable (and supported) that a wireless access point
support true bridging; where packets traverse from a wireless to wired network without passing
through an internal protocol stack, firewall or other network abstraction. Two bridged networks
could be treated as parts of a single subnet under Internet Protocol (IP). A wireless client would
be able to make a DHCP request to a wired DHCP server if the wired and wireless networks were
bridged. In the ISO OSI model, a device in which packets traverse the network layer is considered
a router, a device in which packets traverse the data link layer only is considered a bridge.
Unless a user has a wireless card with a PXE-ROM chip built into it, it is not easy to directly
netboot over a wireless connection. BIOS-based PXE algorithms usually only search for a wired
NIC to be used in a PXE netboot.
It is possible to connect a “wireless bridge” (i.e. a wireless router or access point set to the “bridge”
mode) to the wired NIC of a PC. The PC then netboots through the wired Ethernet NIC as usual,
but the data is then transmitted from the NIC to the wireless AP/router connected to it and then
wirelessly “across the bridge” to a central wireless access point/router.
This requires two wireless devices (one wireless access point and one client device), making it a
more expensive solution. It is sometimes, however, easier or less expensive than running extra
Ethernet cables between the two points.

8.2.2 Bridges versus Access Points

a network bridge can connect wired devices to a wireless network. The benefits are obvious: say
goodbye to the miles of cable you’d otherwise need to connect faraway wired devices to your
router. When you connect wired devices to a bridge, they can communicate wirelessly with your
router and all of the devices on your network.

The confusion sets in when the term “bridge” is interchanged with the phrase “access point.”
Calling a device a bridge is a shorthand way to say that it supports network bridging, but you
won’t often see a standalone bridge for sale. Instead, you’ll find wireless access points with
bridging capability built in — and switching between either mode is as easy as flicking a switch
on the rear of the access point.

Figure 8.1: AP Positioning

Source: http://resource.dlink.com/connect/the-difference-between-bridges-and-access-points/

128 LOVELY PROFESSIONAL UNIVERSITY