Wireless bridge
Encyclopedia
A wireless bridge is a hardware component used to connect two or more network segment
s (LANs or parts of a LAN) which are physically and logically (by protocol) separated. It does not necessarily always need to be a hardware device, as some operating systems (such as Windows, Linux, Mac OS X and FreeBSD) provide software to bridge different protocols. This is seen commonly in protocols over wireless to cable. So in a sense the computer acts as a bridge by using bridging OS software.
Many wireless routers and wireless access points offer either a "bridge" mode or a "repeater
" mode, both of which perform a similar common function, the difference being the bridge mode connects two different protocol types and the repeater mode relays the same protocol type. Wireless routers, access point
s, and bridges are available that are compliant with the IEEE802.11a, b, g and n standards. The frequency bands for these wireless standards can be used license-free in most countries.
Wireless bridge devices work in pairs (point-to-point), one on each side of the "bridge". However, there can be many simultaneous "bridges" using one central device (point to multipoint).
Bridging can be via WDS (Wireless Distribution System
) which creates a transparent Level 2 wireless bridge between two or more points. Alternately the bridge can be set up as an access 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.
An 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.
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 solution works reasonably well but 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.
Network segment
A network segment is a portion of a computer network. The nature and extent of a segment depends on the nature of the network and the device or devices used to interconnect end stations.-Ethernet:...
s (LANs or parts of a LAN) which are physically and logically (by protocol) separated. It does not necessarily always need to be a hardware device, as some operating systems (such as Windows, Linux, Mac OS X and FreeBSD) provide software to bridge different protocols. This is seen commonly in protocols over wireless to cable. So in a sense the computer acts as a bridge by using bridging OS software.
Many wireless routers and wireless access points offer either a "bridge" mode or a "repeater
Wireless Repeater
When two or more hosts ought to be connected with one another over the IEEE 802.11 protocol and the distance is too long for a direct connection to be established, a wireless repeater is used to bridge the gap. It can be a specialized stand alone computer networking device. Also, some WNICs...
" mode, both of which perform a similar common function, the difference being the bridge mode connects two different protocol types and the repeater mode relays the same protocol type. Wireless routers, access point
Wireless access point
In computer networking, a wireless access point is a device that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards...
s, and bridges are available that are compliant with the IEEE802.11a, b, g and n standards. The frequency bands for these wireless standards can be used license-free in most countries.
Wireless bridge devices work in pairs (point-to-point), one on each side of the "bridge". However, there can be many simultaneous "bridges" using one central device (point to multipoint).
Bridging can be via WDS (Wireless Distribution System
Wireless Distribution System
A wireless distribution system is a system enabling the wireless interconnection of access points in an IEEE 802.11 network. It allows a wireless network to be expanded using multiple access points without the traditional requirement for a wired backbone to link them...
) which creates a transparent Level 2 wireless bridge between two or more points. Alternately the bridge can be set up as an access point – client relationship which requires the wireless devices used for the bridge to be set to the same service set identifier
Service set identifier
A service set is all the devices associated with a local or enterprise IEEE 802.11 wireless local area network .-Service set identifier :...
(SSID) and radio channel.
An example of a point-to-point bridge application would be connecting two commercial buildings.
An example of a combination point to point bridge and point to multipoint application would be connecting multiple farm buildings.
Bridging
Bridging (networking)
Bridging is a forwarding technique used in packet-switched computer networks. Unlike routing, bridging makes no assumptions about where in a network a particular address is located. Instead, it depends on flooding and examination of source addresses in received packet headers to locate unknown...
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
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
, 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.
Netbooting wirelessly
Unless a user has a wireless card with a PXE-ROM chip built into it, it is not easy to directly netbootNetwork booting
Network booting is the process of booting a computer from a network rather than a local drive. This method of booting can be used by routers, diskless workstations and centrally managed computers such as public computers at libraries and schools...
over a wireless connection. BIOS
BIOS
In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....
-based PXE
Preboot Execution Environment
The Preboot eXecution Environment is an environment to boot computers using a network interface independently of data storage devices or installed operating systems.PXE was introduced as part of the Wired for Management framework by Intel and is described in the specification The Preboot...
algorithms usually only search for a wired NIC to be used in a PXE netboot
NetBoot
NetBoot is a technology from Apple which enables Macs with capable firmware to boot from a network, rather than a local hard disk or optical disc drive. NetBoot is a derived work from the Bootstrap Protocol , and is similar in concept to the Preboot Execution Environment...
.
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 solution works reasonably well but 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.