Collision domain
Encyclopedia
A collision domain is a section of a network where data packets can collide with one another when being sent on a shared medium
or through repeater
s, in particular, when using early versions of Ethernet
. A network collision occurs when more than one device attempts to send a packet on a network segment at the same time. Collisions are resolved using carrier sense multiple access
or a variant thereof in which the competing packets are discarded and re-sent one at a time. This becomes a source of inefficiency in the network.
Only one device in the collision domain may transmit at any one time, and the other devices in the domain listen to the network in order to avoid data collisions. Because only one device may be transmitting at any one time, total network bandwidth is shared among all devices. Collisions also decrease network efficiency on a collision domain; if two devices transmit simultaneously, a collision occurs, and both devices must retransmit at a later time.
Collision domains are found in a hub environment where each host segment connects to a hub that represents only one collision domain and only one broadcast domain
. Collision domains are also found in wireless network
s such as Wi-Fi
.
Modern wired networks use a network switch
to eliminate collisions. By connecting each device directly to a port on the switch, either each port on a switch becomes its own collision domain (in the case of half duplex links) or the possibility of collisions is eliminated entirely in the case of full duplex links.
Shared medium
In telecommunication, a shared medium is a medium or channel of information transfer that serves more than one user at the same time.Most channels only function correctly when one user is transmitting, so a channel access method is always in effect....
or through repeater
Repeater
A repeater is an electronic device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances.-Description:...
s, in particular, when using early versions of Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
. A network collision occurs when more than one device attempts to send a packet on a network segment at the same time. Collisions are resolved using carrier sense multiple access
Carrier Sense Multiple Access
Carrier Sense Multiple Access is a probabilistic Media Access Control protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus, or a band of the electromagnetic spectrum."Carrier Sense" describes the fact that a...
or a variant thereof in which the competing packets are discarded and re-sent one at a time. This becomes a source of inefficiency in the network.
Only one device in the collision domain may transmit at any one time, and the other devices in the domain listen to the network in order to avoid data collisions. Because only one device may be transmitting at any one time, total network bandwidth is shared among all devices. Collisions also decrease network efficiency on a collision domain; if two devices transmit simultaneously, a collision occurs, and both devices must retransmit at a later time.
Collision domains are found in a hub environment where each host segment connects to a hub that represents only one collision domain and only one broadcast domain
Broadcast domain
A broadcast domain is a logical division of a computer network, in which all nodes can reach each other by broadcast at the data link layer. A broadcast domain can be within the same LAN segment or it can be bridged to other LAN segments....
. Collision domains are also found in wireless network
Wireless network
Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...
s such as Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
.
Modern wired networks use a network switch
Network switch
A network switch or switching hub is a computer networking device that connects network segments.The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer of the OSI model...
to eliminate collisions. By connecting each device directly to a port on the switch, either each port on a switch becomes its own collision domain (in the case of half duplex links) or the possibility of collisions is eliminated entirely in the case of full duplex links.