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Autonegotiation
Autonegotiation is a signaling mechanism and procedure used by Ethernet over twisted pair by which two connected devices choose common transmission parameters, such as speed, duplex mode, and flow control. In this process, the connected devices first share their capabilities regarding these parameters and then choose the highest performance transmission mode they both support. Autonegotiation is defined in clause 28 of IEEE 802.3. and was originally an optional component in the Fast Ethernet standard. It is backwards compatible with the normal link pulses (NLP) used by 10BASE-T. The protocol was significantly extended in the Gigabit Ethernet standard, and is mandatory for 1000BASE-T gigabit Ethernet over twisted pair. In the OSI model, autonegotiation resides in the physical layer. Standardization and interoperability In 1995, the Fast Ethernet standard was released. Because this introduced a new speed option for the same wires, it included a means for connected network adapter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duplex Mismatch
On an Ethernet connection, a duplex mismatch is a condition where two connected devices operate in different duplex modes, that is, one operates in half duplex while the other one operates in full duplex. The effect of a duplex mismatch is a link that operates inefficiently. Duplex mismatch may be caused by manually setting two connected network interfaces at different duplex modes or by connecting a device that performs autonegotiation to one that is manually set to a full duplex mode. Duplex mismatch due to autonegotiation When a device set to autonegotiation is connected to a device that is not using autonegotiation, the autonegotiation process fails. The autonegotiating end of the connection is still able to correctly detect the speed of the other end, but cannot correctly detect the duplex mode. For backward compatibility with Ethernet hubs, the standard requires the autonegotiating device to use half duplex in these conditions. Therefore, the autonegotiating end of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
10GBASE-T
10 Gigabit Ethernet (10GE, 10GbE, or 10 GigE) is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. It was first defined by the IEEE 802.3ae-2002 standard. Unlike previous Ethernet standards, 10 Gigabit Ethernet defines only full-duplex point-to-point links which are generally connected by network switches; shared-medium CSMA/CD operation has not been carried over from the previous generations Ethernet standards so half-duplex operation and repeater hubs do not exist in 10GbE. The 10 Gigabit Ethernet standard encompasses a number of different physical layer (PHY) standards. A networking device, such as a switch or a network interface controller may have different PHY types through pluggable PHY modules, such as those based on SFP+. Like previous versions of Ethernet, 10GbE can use either copper or fiber cabling. Maximum distance over copper cable is 100 meters but because of its bandwidth requirements, hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fast Ethernet
In computer networking, Fast Ethernet physical layers carry traffic at the nominal rate of 100 Mbit/s. The prior Ethernet speed was 10 Mbit/s. Of the Fast Ethernet physical layers, 100BASE-TX is by far the most common. Fast Ethernet was introduced in 1995 as the IEEE 802.3u standard and remained the fastest version of Ethernet for three years before the introduction of Gigabit Ethernet. The acronym ''GE/FE'' is sometimes used for devices supporting both standards. Nomenclature The "100" in the media type designation refers to the transmission speed of 100 Mbit/s, while the "BASE" refers to baseband signaling. The letter following the dash ("T" or "F") refers to the physical medium that carries the signal (twisted pair or fiber, respectively), while the last character ("X", "4", etc.) refers to the line code method used. Fast Ethernet is sometimes referred to as 100BASE-X, where "X" is a placeholder for the FX and TX variants. General design Fast Ethernet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auto MDI-X
A medium dependent interface (MDI) describes the interface (both physical and electrical/optical) in a computer network from a physical layer implementation to the physical medium used to carry the transmission. Ethernet over twisted pair also defines a medium dependent interface crossover (MDI-X) interface. Auto MDI-X ports on newer network interfaces detect if the connection would require a crossover, and automatically chooses the MDI or MDI-X configuration to properly match the other end of the link. Ethernet The popular Ethernet family defines common medium-dependent interfaces. For 10BASE5, connection to the coaxial cable was made with either a vampire tap or a pair of N connectors. For 10BASE2, the connection to the coaxial cable was typically made with a single BNC connector to which a T-piece was attached. For twisted-pair cabling 8P8C, modular connectors are used (often incorrectly called "RJ45" in this context). For fiber, a variety of connectors are used depending ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physical Layer
In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the electrical connectors, the frequencies to broadcast on, the line code to use and similar low-level parameters, are specified by the physical layer. Role The physical layer defines the means of transmitting a stream of raw bits over a physical data link connecting network nodes. The bitstream may be grouped into code words or symbols and converted to a physical signal that is transmitted over a transmission medium. The physical layer consists of the electronic circuit transmission technologies of a network. It is a fundamental layer underlying the higher level functions in a network, and can be i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethernet Over Twisted Pair
Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. They are a subset of all Ethernet physical layers. Early Ethernet used various grades of coaxial cable, but in 1984, StarLAN showed the potential of simple unshielded twisted pair. This led to the development of 10BASE-T and its successors 100BASE-TX, 1000BASE-T and 10GBASE-T, supporting speeds of 10 and 100 megabit per second, then 1 and 10 gigabit per second respectively. Two new variants of 10 megabit per second Ethernet over a ''single'' twisted pair, known as 10BASE-T1S and 10BASE-T1L, were standardized in IEEE Std 802.3cg-2019. 10BASE-T1S has its origins in the automotive industry and may be useful in other short-distance applications where substantial electrical noise is present. 10BASE-T1L is a long-distance Ethernet, supporting connections up to 1 km in length. Both of these standards are finding applications implementing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unipolar Encoding
Unipolar encoding is a line code. A positive voltage represents a binary 1, and zero volts indicates a binary 0. It is the simplest line code, directly encoding the bitstream, and is analogous to on-off keying in modulation. Its drawbacks are that it is not self-clocking and it has a significant DC component, which can be halved by using return-to-zero, where the signal returns to zero in the middle of the bit period. With a 50% duty cycle each rectangular pulse is only at a positive voltage for half of the bit period. This is ideal if one symbol is sent much more often than the other and power considerations are necessary, and also makes the signal self-clocking. NRZ (Non-Return-to-Zero) - Traditionally, a unipolar scheme was designed as a non-return-to-zero (NRZ) scheme, in which the positive voltage defines bit 1 and the zero voltage defines bit 0. It is called NRZ because the signal does not return to zero at the middle of the bit, as instead happens in other line coding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collision (telecommunications)
A collision is the situation that occurs when two or more demands are made simultaneously on equipment that can handle only one at any given instant.Source: from Federal Standard 1037C and from MIL-STD-188 It may refer to: * Collision domain, a physical network segment where data packets can "collide" ** Carrier-sense multiple access with collision avoidance, (CSMA/CA) used for example with wireless LANs ** Carrier-sense multiple access with collision detection, (CSMA/CD) used with Ethernet * Late collision, a specific type of collision that should not occur on properly operating networks * Local collision is a collision that occurs in the network interface rather than on the network itself See also * Collision (other) * Contention (telecommunications) In statistical time division multiplexing, contention is a media access method that is used to share a broadcast medium. In contention, any computer in the network can transmit data at any time (first come-first served). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pause Frame
Ethernet flow control is a mechanism for temporarily stopping the transmission of data on Ethernet family computer networks. The goal of this mechanism is to avoid packet loss in the presence of network congestion. The first flow control mechanism, the pause frame, was defined by the IEEE 802.3x standard. The follow-on priority-based flow control, as defined in the IEEE 802.1Qbb standard, provides a link-level flow control mechanism that can be controlled independently for each class of service (CoS), as defined by IEEE P802.1p and is applicable to data center bridging (DCB) networks, and to allow for prioritization of voice over IP (VoIP), video over IP, and database synchronization traffic over default data traffic and bulk file transfers. Description A sending station (computer or network switch) may be transmitting data faster than the other end of the link can accept it. Using flow control, the receiving station can signal the sender requesting suspension of transmissions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
