Network interface card: What is its role?

Network Interface Card (NIC)

A network interface card is also called a Network adapter or transceiver transmitter-receiver. It is a component that connects a computer physically to a transmission media. It converts digital signals to analog and vice versa before transmitting and after receiving them. A NIC Could be physical such that it can be slotted into ISA- industrial standard architecture in older type PCs or PCI -peripheral component interconnect or can still be slotted into AGP -Accelerated Graphics port for the more advanced technology.

NICs can also be in-built into the motherboard through serial and parallel ports or PCMCIA - personal computer memory card International Association interface. Also, NICs can be wireless and use antennae for transmission and receiving transmissions. The wide range of types and speeds is a requirement because the performance of the NIC is important for good the performance of the entire network.

Various Forms of NICs

Image of various forms of NIC
                                                                          Courtesy: Various forms of NIC

Image of parts of an NIC

                                                                         Courtesy: Parts of an NIC

Parts of an NIC

Expansion bus connection
  • This is an expansion that connects to the board system or motherboard.
Media connector
  • This a Port connector to the transmission media which is then connected to the RJ45 terminator.
  • This is the memory chip that stores data temporarily on open reception transmission.
Boot ROM (optional)
  • This is applicable for thin client technology so that computers can boot from it other than booting from a storage device.
  • This is a cheap that is next to a media connector and converts analog transmissions to digital transmissions and vice versa.


A hub acts as a point of connection between network nodes. Intelligent hubs / management hubs may have processing mechanisms that allow remote management to take place, filter data and provide network diagnostic information. Therefore in layer 1 in OSI reference model is used as access points or hotspots in wi-fi.
Image of a Hub
                                                            Courtesy: A Hub
When the distance between mess network and the server room is 200m, and if a low speed cable such as a UTP has been used will result in signals not arriving. There will be a need for a boost to the signal
Image of a connection Illustration
                                            Courtesy: Illustration of connection


Repeaters Connect similar segments of Local Area Networks. They receive transmitted data from one segment, clean it and amplify the signal which is then transmitted to the next segment by signal broadcasting. Therefore passive, in layer 1 OSI reference model. They extends network size e.g. enables coaxial cable extend from 185 m to 925m or thick coaxial from 500m to 2.5km and is usually two ported but may be multiport for multiple segments.
Image of Repeater devices
                                           Courtesy: Image of repeaters


Bridges connect 2 dissimilar network segments by way of filtering signals from one segment to another by a filtering database also called forwarding table of MAC address to let through traffic between them by MAC address. It filters traffic, intelligent and in layer 2 of OSI. Can be used to extend network size and avoid exceeding network limits for segment size, segment number of devices. Also, it can be a standalone or a PC node assigned the job utilizing two NICs, physical addressing information. The  protocol independent.
Image of a Bridge
                                     Courtesy: Bridge and its connection illustration
  • Bridges are faster than routers and are protocol independent. Slower than repeaters and hubs analyzes packets before transmission.
  • Can extend a network without extending further collision domains or can also extend segments Improves network performance: can be programmed to filter out certain frames e.g. unnecessary broadcast frames.
  • They are useful for LANs which extend over different floors in a building or LANs built on departmental levels.

Types of Bridges

Local bridges

  • They directly connect to local area networks (LANs)

Remote bridges

  • They can be used to create wide area network (WAN) link between Local Area Networks. Where there is a slower connecting link than the end link, they are replaced by routers.

Wireless bridges

  • These ones can be used to join Local Area Networks and remote stations to LANS.
Also read, Network Translators: What are Network Translators
PreviousTransmission Media: How signals are processed
NextNetwork Architecture: The forms and structures

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