Network segment

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title: "Network segment" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["ethernet", "network-architecture"] description: "Portion of a computer network" topic_path: "technology/networking" source: "https://en.wikipedia.org/wiki/Network_segment" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Portion of a computer network ::

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

According to the defining IEEE 802.3 standards for Ethernet, a network segment is an electrical connection between networked devices using a shared medium. In the original 10BASE5 and 10BASE2 Ethernet varieties, a segment would therefore correspond to a single coax cable and all devices tapped into it. At this point in the evolution of Ethernet, multiple network segments could be connected with repeaters (in accordance with the 5-4-3 rule for 10 Mbit Ethernet) to form a larger collision domain.

With twisted-pair Ethernet, electrical segments can be joined using repeaters or repeater hubs as can other varieties of Ethernet. This corresponds to the extent of an OSI layer 1 network and is equivalent to the collision domain. The 5-4-3 rule applies to this collision domain.

Using switches or bridges, multiple layer-1 segments can be combined to a common layer-2 segment, i.e. all nodes can communicate with each other through MAC addressing or broadcasts. A layer-2 segment is equivalent to a broadcast domain. Traffic within a layer-2 segment can be separated into virtually distinct partitions by using VLANs. Each VLAN forms its own logical layer-2 segment.

IP

A layer-3 segment in an IP network is called a subnetwork, formed by all nodes sharing the same network prefix as defined by their IP addresses and the network mask. Communication between layer-3 subnets requires a router. Hosts on a subnet communicate directly using the layer-2 segment that connects them. Most often a subnetwork corresponds exactly with the underlying layer-2 segment but it is also possible to run multiple subnets on a single layer-2 segment.

References

References

1. (2 October 2005). "Network Segment Definition".
2. (26 December 2008). "802.3-2008 Part 3: Carrier sense multiple access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications". IEEE.
3. "Segment (Network)".
4. "Segment".
5. "What is a Network Segment?".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::