Networking, related hardware

  1. The Ethernet Address

    Ethernet-address, or MAC-address (Media Access Control)is a number that is associated with a network adapter (Ethernet add-in cards that interfaces a computer to a net work). The Mac is also known as hardware address or physical address. The Mac operates mainly within a LAN.
    Mac addresses are 12-digit hexadecimal numbers ( 6 x 8 = 48 bits long). They are writte in the following formats: MM:MM:MM:SS:SS:SS
    Or
    MM-MM-MM-SS-SS-SS
    The first three MM (24 bits) represents the ID of the manufacturer, the last three SS (24 bits) stands for the serial number assigned to the adapter by the manufacturer.
    TCP/IP architecture operates in the OSI model. In this model, network functionality is subdivided into layers. MAC addresses function at the data link layer (layer 2 in the OSI model). They allow computers to uniquely identify themselves on a network at this relatively low level.
    IP Addressing works at the data link layer, IP addressing functions at the network layer (layer 3). The MAC address generally remains fixed and follows the network device, but the IP address changes.

  2. NIC

    NIC stands for Network Interface card. It translates data from parallel data bus to serial bit stream.

  3. The related wires

    The LAN networking does not use modems, It requires interface cards, that are Ethernet cards or NICs (Network Interface Card, which is the interface between the computer and the network cable).
    RJ-11 is the telephone plug. RJ-45 is wider and carries another two pairs of wires.
    RJ-45 jack can handle an RJ-11 telephone cord plugging.
    Lots of offices use "Cat-5" wiring for both their network and their internal telephone system.

  4. Cabling

    There are some sort of cables used on networks:
    Cable type
    Symbol Name Maximum length (m)
    10Base5 Thicknet coax 500
    10Base2 Thinnet coax 185
    10BaseT Cat 3, 4, 5 TP 100
    100BaseT Cat 5 TP 100
    10BaseFL Fiber Optic 2000
    Name Transmission speed (mbps)
    Thicknet
    0.50 inches, 50 ?    		 10
    Thinnet
    0.25 inches, 50 ?    		 10
    Cat 2 TP 4
    Cat 3 TP 16
    Cat 4 TP 20
    Cat 5 TP 100
    Fiber Optic 100 - 1000
    TP stands for twisted pair.
    Thicknet are used as a backbone. Fiber Optic are used in security because it's difficult to intercept.

  5. Other devises

    Hub

    used to connect hosts on the LAN (Ethernet network)
    - Passive: receive data in one port and sent it out the other port)
    - Active: Does as a passive, plus it contains a built-in repeater to boost the signal.
    - Hybrid: has different ports for different cables

    Switching hub

    It determines the MAC address connected to the related port and pass the date only for this port.
    The hub that connects workstations on a ring network is called Multistation Accesss Unit MAU

    Repeater

    To make it much faster, the repeater boosts a signal and eliminates attenuation.

    Bridge

    As a repeater, boosts a signal, plus It can also devide a network to reduce traffic problems.

    Router

    The router is more sofisticated devise. It can play the role of bridge. What's more, It can also connect different networks with different protocols. It is able to determine the most efficient path to send packets. It operates with the associated routing table. unroutable protocols could not be forwarded
    - Static: the routing table is update manualyy
    - Dynamic: the routing table is updated automatically

    Brouter

    It compines a bridge's and a router's functions and can forward an unroutable protocol s it does abridge.

    Gateway

    It is the router that connects the network to the Internet (Global Network)

  6. Modems

    Modem stands for Modulator-Demodulator. It modulates amplitudes, frequencies or phases of signals. Here are some kind of well known modems:
    - V.32 9600 bps (3 bits/baud)
    - V.32 bis 2400 baud (6 bits/baud)
    - V.34 28800 bps = 28k8
    - V.34 bis 36k6
    - V.90 56kbps
    All of the mentioned modems contain compression and error correction that are built into them.