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An Ethernet hub or concentrator is a device for connecting multiple twisted pair or fiber optic Ethernet devices together, making them act as a single segment. Hubs work at the physical layer (layer 1) of the OSI model, and the term layer 1 switch is often used interchangeably with hub. The device is thus a form of multiport repeater. Ethernet hubs are also responsible for forwarding a jam signal to all ports if it detects a collision. ImageMetadata File history File links 4_port_netgear_ethernet_hub. ...
ImageMetadata File history File links 4_port_netgear_ethernet_hub. ...
Twisted-pair cable used with 10BASE-T 8P8C plug used with 10BASE-T There are several standards for Ethernet over twisted pair or copper-based computer networking physical connectivity methods. ...
Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length. ...
Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ...
This article does not cite any references or sources. ...
The Open Systems Interconnection Basic Reference Model (OSI Reference Model or OSI Model for short) is a layered, abstract description for communications and computer network protocol design, developed as part of the Open Systems Interconnection (OSI) initiative. ...
Multiport repeater: In digital networking, an active device, having multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port. ...
In telecommunication, a jam signal is a signal that carries a bit pattern sent by a data station to inform the other stations that they must not transmit. ...
Hubs also often come with a BNC and/or AUI connector to allow connection to legacy 10BASE2 or 10BASE5 network segments. The availability of low-priced network switches has largely rendered hubs obsolete but they are still seen in older installations and more specialized applications. Male BNC connector Cables with BNC connectors Adapter between a female BNC connector and banana plugs Picture to show the similarity between 50 Ω and 75 Ω BNC connectors Pulse generators with BNC connectors and cables. ...
AUI Connectors. ...
10BASE2 cable showing BNC Connector end. ...
10BASE5 vampire tap Medium Attachment Unit (Transceiver) 10BASE5 (also known as thicknet) is the original full spec variant of Ethernet cable, using RG-8 (Radio Grade - 8) coaxial cable. ...
A network switch is a computer networking device that connects network segments. ...
Technical information
A hubbed Ethernet network behaves like a shared-medium, that is, only one device can successfully transmit at a time and each host remains responsible for collision detection and retransmission. With 10BASE-T and 100BASE-T links (which generally account for most or all of the ports on a hub) there are separate pairs for transmit and receive but they are used in half duplex mode in which they still effectively behave like shared medium links (See 10BASE-T for the pins specifications.) 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ...
100BASE-T is any of several Fast Ethernet 100 Mbit/s (12. ...
10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ...
An Ethernet hub, or repeater, is a fairly unsophisticated broadcast device. Hubs do not manage any of the traffic that comes through them, and any packet entering any port is broadcast out on every other port (other than the port of entry). Since every packet is being sent out through every other port, packet collisions result--which greatly impedes the smooth flow of traffic.
The need for hosts to be able to detect collisions limits the number of hubs and the total size of the network. For 10 Mbit/s networks, up to 5 segments (4 hubs) are allowed between any two end stations. For 100 Mbit/s networks, the limit is reduced to 3 segments (2 hubs) between any two end stations, and even that is only allowed if the hubs are of the low delay variety. Some hubs have special (and generally manufacturer specific) stack ports allowing them to be combined in a way that allows more hubs than simple chaining through Ethernet cables, but even so a large Fast Ethernet network is likely to require switches to avoid the chaining limits of hubs. In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. ...
Most hubs detect typical problems, such as excessive collisions on individual ports, and partition the port, disconnecting it from the shared medium. Thus, hub-based Ethernet is generally more robust than coaxial cable-based Ethernet, where a misbehaving device can disable the entire segment. Even if not partitioned automatically, a hub makes troubleshooting easier because status lights can indicate the possible problem source or, as a last resort, devices can be disconnected from a hub one at a time much more easily than a coaxial cable. They also remove the need to troubleshoot faults on a huge cable with multiple taps. Coaxial Cable For the weapon, see coaxial weapon. ...
Dual speed hubs In their early days, Fast Ethernet switches were relatively expensive . However, hubs suffered from the problem that as simple repeaters they could only support a single speed. Whilst normal PCs with expansion slots could be easily upgraded to Fast Ethernet with a new network card, computers with less common expansion mechanisms, or no expansion bus at all, and other equipment, such as printers, could be expensive or impossible to upgrade. Therefore, a compromise between a hub and a switch appeared known as a "dual speed hub". A network card, network adapter or NIC (network interface controller) is a piece of computer hardware designed to allow computers to communicate over a computer network. ...
Such a device essentially consisted of two hubs (one of each speed) and a two port bridge between them. Devices were connected to the appropriate hub automatically based on their speed and the bridge handled inter-speed traffic. Since the bridge only had two ports and only one of those needed to be 100Mbps it could be much simpler and cheaper than a full fast ethernet switch. Such devices have been rendered obsolete by the decreasing cost of fast ethernet switches.
Uses Historically, the main reason for purchasing hubs rather than switches was price. This has largely been eliminated by reductions in the price of switches, but hubs can still be useful in special circumstances: - A protocol analyzer connected to a switch does not always receive all the desired packets since the switch separates the ports into different segments. Connecting the protocol analyzer to a hub allows it to see all the traffic on the segment. (Expensive switches can be configured to allow one port to listen in on traffic on another port. This is called port mirroring. However, these cost much more than a hub.)
- Some computer clusters require each member computer to receive all of the traffic going to the cluster. A hub will do this naturally; using a switch requires implementing special tricks.
- When a switch is accessible for end users to make connections, for example, in a conference room, an inexperienced or careless user (or saboteur) can bring down the network by connecting two ports together, causing a loop. This can be prevented by using a hub, where a loop will break other users on the hub, but not the rest of the network. (It can also be prevented by buying switches that can detect and deal with loops, for example by implementing the Spanning Tree Protocol.)
- A cheap hub with a 10BASE2 port is probably the cheapest and easiest way to connect devices that only support 10BASE2 to a modern network (cheap switches don't tend to come with 10BASE2 ports). The same goes for linking in an old thicknet network segment using an AUI port on a hub (individual devices that were intended for thicknet can be linked to modern Ethernet by using an AUI-10BASE-T transceiver).
A packet sniffer (also known as a network analyzer or protocol analyzer or, for particular types of networks, an Ethernet sniffer or wireless sniffer) is computer software or computer hardware that can intercept and log traffic passing over a digital network or part of a network. ...
Port mirroring is used on a network switch to send a copy of all network packets seen on one switch port to a network monitoring connection on another switch port. ...
An example of a Computer cluster A computer cluster is a group of tightly coupled computers that work together closely so that in many respects they can be viewed as though they are a single computer. ...
For other uses, see Sabotage (disambiguation). ...
Based on an algorithm invented by Radia Perlman while working for Digital Equipment Corporation[1][2], Spanning Tree Protocol Is an OSI layer-2 protocol which ensures a loop free topology for any bridged LAN. The Spanning Tree Protocol (STP), is defined in the IEEE Standard 802. ...
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