Network interface controller

A network interface card ( NIC also for engl. Network Interface Card) is an electronic circuit for connecting a computer to a local network to exchange data.

Their primary job is to create a physical connection to the network through an appropriate access method (eg, CSMA / CD) and the implementation of the first or second OSI layer (usually Ethernet).

Term origin

The term network card based on the fact that most computers have slots for expansion modules in the electrical circuit board ( PCB ) can be used with a specific format. In addition to network cards, there are also video cards, interface cards for connection of input and output devices and many others.

Card Types

Network interface cards consist on one side of a network interface, which is adapted for the respective types of network or network architecture, and on the other side of an adapted to the particular computer architecture bus interface.

Network types

In the early 1980s there were many competing network architectures and types of cards, the more widespread had ARCNET, Ethernet, LocalTalk, and Token Ring.

  • ARCNET was operating with a token - passing method at 2.5 Mbit / s and mostly worked on coaxial cable RG -62 as a bus or star topology. It had up to 1985 significant price advantages over Ethernet, this resulted in high market shares. By the token-passing method ARCNET operates deterministically, can be used in real-time systems, which is a problem with the non- peak load -capable Ethernet ungeswitchten therefore.
  • Ethernet initially used mostly 10 Mbit / s cards, which were usually via a coaxial cable (RG -58 thin - or thick -wire ) connected as a bus. Until 1985, these cards were still very expensive, with the NE1000/NE2000-Modellen there was a decline in prices. Ethernet is the most widely used process today. Many of the initial disadvantages, in particular the problems at high load, could be largely eliminated by improved techniques and components such as switches.
  • LocalTalk was almost exclusively used by Apple computer, used a 232 kbit / s token - passing procedure over a two-wire bus cable with close reference to the RS-422 serial interfaces. This type of networking was very popular with Apple computers, because 1984-1998 was this interface with any Apple computer as standard ( no extra plug ) available. For PCs ( Novell Netware server), there were suitable LocalTalk network cards, usually in 8 -bit ISA bus version.

In 1995, the Fast Ethernet standard was approved, cleared the market and pure 10 Mbit Ethernet cards were replaced with 10 /100 Mbit cards. These are still (2006) the most common, although now Gigabit Ethernet cards (which are also 10/ 100 MBit compatible) can gain significant market share.

These cards are connected via twisted -pair cable with RJ45 connectors, to a hub or to a switch and now mostly to form a local area network (LAN).

Currently, more and more high-quality network cards are used with a transmission rate of 1000 Mbps, mostly those over twisted -pair cable with RJ45 connectors ( 1000BASE -T) or even over fiber to be connected (eg, 1000BASE- SX).

Ethernet network adapters with 10 Gbps are already available for PCI Express and PCI -X.

Network cards for wireless networking ( LAN) were initially mainly in mobile devices such as laptops or PDAs use, but are increasingly being installed in desktop PCs.

Bus systems

Bus side took turns even with network cards from different standards. Not all bus systems, there were network cards, for example, not for the Accelerated Graphics Port (AGP). There were also more exotic structures via the SCSI bus or via printer interface, the latter for a time were utilized in notebooks. In the UNIX area, workstations and server, as well as mainframes, there were numerous manufacturer-specific bus systems that have been used for network cards. Here is an overview of typical network card bus systems:

  • ISA: Around 1980, initially dominated the PC network cards with the widely used ISA -bus interface, first in 8 -bit technology (eg NE1000 ) later in 16 -bit version ( eg NE2000 )
  • PCMCIA: This interface is mainly used in notebooks, roughly speaking, is a miniaturized ISA interface.
  • VESA Local Bus: more ephemeral standard in the first half of the 1990s, designed to accelerate the integration of plug-in cards.
  • NuBus: From 1980, a widespread at Apple Computer and NeXT computer interface.
  • MCA: A propagated in 1987 by IBM as a successor to the ISA bus system. A failed attempt to introduce an incompatible and not open, but improved bus.
  • EISA: One end of the 1980s propagated by all except IBM as a successor to the ISA bus bus system. A compatible ISA bus add-in for 32 bit transfer per line in prolonged contact bar. EISA came especially for workstations and servers to use.
  • PCI: Around 1990, the actual successor to the ISA bus architecture. As an open standard, he also replaced the EISA bus and was also used to replace various proprietary bus systems. For example, PCI sparked at Apple Computer from the NuBus, at Hewlett -Packard GSC / HSC and HP- PB, as well as the IBM MCA.
  • PC Card: This interface is mainly used in notebooks, roughly speaking, is a miniaturized PCI interface.
  • PCI -Express: As of 2004, an enhanced PCI bus; replaces the popular graphics cards for AGP bus.
  • ExpressCard: based on PCI - Express x1 notebook interface
  • OnBoard: Since the early 2000s almost all computer motherboards have built- LAN interfaces, dedicated plug-in are no longer necessary. Often get the same electronic modules are used, missing only the connections, often is also the controller integrated in chipset. By the driver software, the chips are treated, such as plug-in (for example, there is usually a PCI interface, which is controlled / programmed ).

Pictures

MCA network card with RG58 connector

NuBus Ethernet Network Card with RJ45 socket

Network Card with RG58 connector for printer interface

Equipment

A common network card has only one Ethernet port, special designs and multiple (up to four). The price of a cheap standard network card has dropped about 5-15 EUR of several 100 EUR 1990 to the current ( 2009). Higher network cards ( with better throughput, lower CPU load, better equipment ) cost depending on the version up to 100 EUR, very special cards (eg, with multiple independent connections ) also above. Since late 2003, with many new PCs are already 1- Gbit ports on the motherboard.

Every Ethernet network card has a globally unique MAC address that is assigned by the manufacturer. However, there are drivers that allow you to change the MAC address via software temporarily, causing safety problems in a LAN may arise.

Booting From the Network

Many network adapters have a socket for a so-called boot PROM (also called boot ROM ). This memory block is mapped into the address space of the computer and allows you to start the computer from the network without a local ( built into the computer or directly connected ) mass storage such as a hard disk. Different computer architectures (Apple, PC), operating systems and different network environments (IPX / SPX, TCP / IP) require different boot programs, so it is left to the user, the network card with a PROM ( or EPROM) with each matching to equip boot program. The classic way for PCs is a so-called Novell boot PROM for use with Novell Netware and Novell's own network protocol. More modern, based on TCP / IP concepts, for example, Intel's PXE and the open source and free solutions Etherboot and Netboot.

All approaches have one thing in common: the program in the boot PROM is started and connects to it to continue the boot process. At some point, either before or after the search for a bootable local media, the boot PROM is activated again and loads over the network operating system after the. Usually this is done in small steps, first a utility with advanced networking features, then large parts of the operating system. Finally, control is passed to the operating system, which then more network services typically takes to complete.

Some network cards have taken the base directly into the chipset of the NIC integrated, re-programmable EEPROM that can be loaded with a utility with various boot programs, thus eliminating the need to open the computer. Motherboards with integrated network adapter, as well as many UNIX workstations, use a portion of the already existing system EEPROM (BIOS) as a boot PROM, also here you can usually use a utility to any boot program be loaded or is the manufacturer determines BOOTP or PXE ago. For cost reasons, especially manufacturers of cheap products often forego on the base of the boot PROM. Outside the PC world starting from the network is often a part of the fixed launcher, such as many Sun machines and modern Macintosh systems. However, this is usually only a specific, certified by the manufacturer, supports selection of network adapters.

All modern Apple computer can boot from a computer that is running the server version of Mac OS X.

Left

  • Commons: Network adapter - collection of images, videos and audio files
  • Commons: WLAN module - collection of images, videos and audio files
  • Network device
Carrier sense multiple access with collision detection Industry Standard Architecture Ethernet hub Extended Industry Standard Architecture Hewlett-Packard Controller (computing) Preboot Execution Environment
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