Nonbroadcast Multiple Access Network
Encyclopedia
A non-broadcast multiple access network (NBMA) is a computer network
to which multiple hosts are attached, but data is transmitted only directly from one computer to another single host over a virtual circuit
or across a switched fabric
. NBMA networks do not support multicast
or broadcast traffic. Some common examples of nonbroadcast network technologies include Asynchronous Transfer Mode
(ATM), Frame Relay
, X.25
, and home power line networking.
G.hn
standard provides a specification for creating a high-speed (up to 1 Gigabit/s) local area network
using existing home power lines
, phone lines and coaxial cables
.
Because of multipath propagation, power lines use frequency-selective channels. Channel frequency response is different for each pair of transmitter and receiver, so modulation parameters are unique for each transmitter and receiver pair. Since each pair of devices uses a different modulation scheme for communication, other devices may not be able to demodulate the information sent between them.
s in order to prevent routing loops. This family of protocol relies on link layer
broadcasting for route advertisement propagation, so when this feature is absent, it has to be emulated with series of unicast transmissions, which may result in receiver node sending a route advertisement back to the node it has just received it from.
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
to which multiple hosts are attached, but data is transmitted only directly from one computer to another single host over a virtual circuit
Virtual circuit
In telecommunications and computer networks, a virtual circuit , synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication...
or across a switched fabric
Switched fabric
Switched fabric, switching fabric, or just fabric, is a network topology where network nodes connect with each other via one or more network switches . The term is popular in telecommunication, Fibre Channel storage area networks and other high-speed networks, including InfiniBand...
. NBMA networks do not support multicast
Multicast
In computer networking, multicast is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source creating copies automatically in other network elements, such as routers, only when the topology of the network requires...
or broadcast traffic. Some common examples of nonbroadcast network technologies include Asynchronous Transfer Mode
Asynchronous Transfer Mode
Asynchronous Transfer Mode is a standard switching technique designed to unify telecommunication and computer networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from approaches such as the Internet Protocol or Ethernet that...
(ATM), Frame Relay
Frame relay
Frame Relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology...
, X.25
X.25
X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
, and home power line networking.
Power line networks
The ITU-TITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
G.hn
G.hn
G.hn is the common name for a home network technology family of standards developed under the International Telecommunication Union's Standardization arm and promoted by the HomeGrid Forum...
standard provides a specification for creating a high-speed (up to 1 Gigabit/s) local area network
Local area network
A local area network is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building...
using existing home power lines
Power line communication
Power line communication or power line carrier , also known as power line digital subscriber line , mains communication, power line telecom , power line networking , or broadband over power lines are systems for carrying data on a conductor also used for electric power transmission.A wide range...
, phone lines and coaxial cables
Ethernet over coax
Ethernet over Coax is a family of technologies that supports the transmission of Ethernet frames over coaxial cable.- History :The first Ethernet standard, known as 10BASE5 in the family of IEEE 802.3, specified baseband operation over coaxial cable...
.
Because of multipath propagation, power lines use frequency-selective channels. Channel frequency response is different for each pair of transmitter and receiver, so modulation parameters are unique for each transmitter and receiver pair. Since each pair of devices uses a different modulation scheme for communication, other devices may not be able to demodulate the information sent between them.
Split horizon route advertisement
In NBMA networks a special technique called split horizon route advertisement must be employed by distance-vector routing protocolDistance-vector routing protocol
In computer communication theory relating to packet-switched networks, a distance-vector routing protocol is one of the two major classes of routing protocols, the other major class being the link-state protocol...
s in order to prevent routing loops. This family of protocol relies on link layer
Link Layer
In computer networking, the link layer is the lowest layer in the Internet Protocol Suite , the networking architecture of the Internet . It is the group of methods or protocols that only operate on a host's link...
broadcasting for route advertisement propagation, so when this feature is absent, it has to be emulated with series of unicast transmissions, which may result in receiver node sending a route advertisement back to the node it has just received it from.
See also
- Open Shortest Path FirstOpen Shortest Path FirstOpen Shortest Path First is an adaptive routing protocol for Internet Protocol networks. It uses a link state routing algorithm and falls into the group of interior routing protocols, operating within a single autonomous system . It is defined as OSPF Version 2 in RFC 2328 for IPv4...
- Routing protocolRouting protocolA routing protocol is a protocol that specifies how routers communicate with each other, disseminating information that enables them to select routes between any two nodes on a computer network, the choice of the route being done by routing algorithms. Each router has a priori knowledge only of...