Network Hardware

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Network Hardware

• Network Design

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Objectives

• Identify the functions of LAN connectivity
  hardware
• Describe the factors involved in choosing network
  hardware
• Discuss the functions of repeaters, hubs,
  bridges, switches and routers

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Hosts

• Devices that connect directly to segment
• Include computers, (clients, servers), printers,
  scanners, etc
• Operate at all 7 layers of OSI model
• Perform encapsulation and decapsulation

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Network Adapters

• Layer two
• Printed circuit board
• Function - adapt host device to network medium
• Also called network interface cards, NICs, or
  network cards

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Network Adapters

• Connectivity devices that enable a workstation,
  server, printer or other node to receive and
  transmit data over network media
• Each NIC has unique code, MAC address
• MAC - used to control data communication for host
• NIC controls the host's access to medium

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Network Adapters

• Types of Network Adapters
• PCI (Peripheral Component Interconnect)
• The most popular expansion board NIC
• A newer version of the PCI standard is PCI
  Express

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Network Adapters

• Externally Attached Network Adapters
• USB (universal serial bus), PCMCIA (Personal
  Computer Memory Card International Association),
  or CompactFlash slots are used to connect network
  adapters
• One advantage to externally attached network
  adapters is their simple installation

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Network Adapters

• Wireless Network Adapters use an antenna (either
  internal or external) to exchange signals with a
  base station transceiver or another wireless NIC
• One disadvantage to using wireless network
  adapters is that currently they are somewhat more
  expensive than wire-bound network adapters

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Network Adapters

• Interpreting LED Indicators
• Most modern NICs have LEDs that indicate whether
  or not theyre communicating with the network
• The only way to know for certain what your NICs
  LEDs are trying to tell you is to read the
  documentation

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Network Adapters

• Choosing the Right Network Adapter
• Compatibility with your existing system
• Must match the networks bus type, access method,
  connector types and transmission speed
• Correct drivers available

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Repeaters

• One disadvantage of CAT5 UTP is cable length
• If need to extend network beyond that limit, must
  add a repeater
• Layer 1 device
• The simplest type of connectivity device that
  regenerates a digital signal
• Contains one input port and one output port
• Suited only to bus topology networks
• The advantage to using a repeater is that it
  allows you to extend a network inexpensively

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Hubs

• A repeater with more than one output port
• Repeating signals from each node
• May contain multiple ports for devices and one
  port that connects to a networks backbone
• On Token Ring networks, hubs are called
  Multistation Access Units (MAUs)

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Hubs

• Elements of most hubs
• Ports - receptacles where patch cables connect
  workstations or other devices to the hub
• Uplink port - receptacle used to connect one hub
  to another hub in a daisy-chain or hierarchical
  fashion
• Link LED - light on a port that indicates whether
  it is in use

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Hubs

• Collision LED - light that roughly indicates
  collisions by blinking
• Status LED - light that indicates that the hub is
  receiving power
• Power supply - device that provides power to the
  hub
• Ventilation fan - device used to cool a internal
  electronics

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Hubs

• Types of Hubs
• Standalone - hubs that serve a group of computers
  that are isolated from the rest of the network or
  that form their own small network
• Stackable - resemble standalone hubs, but are
  physically designed to be linked with other hubs
  in a single telecommunications closet

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Hubs

• Stackable hubs
• Linked together logically represent one large hub
  to the network
• A benefit to using stackable hubs is that your
  network/workgroup does not depend on a single hub
  (single point of failure)
• May support a number of different media
  connectors and transmission speeds and may come
  with or without special processing features

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Hubs

• The simplest type of hubs (passive hubs) only
  repeat signals
• Intelligent hubs (aka managed hubs) because they
  can be managed from anywhere on the network

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Bridges

• Layer 2 device designed to connect two LAN
  segments
• Purpose - filter traffic on LAN (keep local
  traffic local, yet allow connectivity to other
  segments)
• Uses MAC address table

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Bridges

• Devices that connect two network segments by
  analysing incoming frames and making decisions
  about where to direct them based on each frames
  MAC address
• Single input and a single output port
• Can move data more rapidly than traditional
  routers

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Bridges

• Take longer to transmit data than either
  repeaters or hubs, because bridges analyse each
  packet
• Inserting a bridge into a network, you can add
  length beyond the maximum limits that apply to
  segments

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Bridges

• Can help improve network performance because they
  can be programmed to filter out certain types of
  frames
• As nodes transmit data through the bridge, the
  bridge establishes a filtering database (also
  known as a forwarding table) of known MAC
  addresses and their locations on the network

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Switches

• Layer 2 device
• Aka a multi-port bridge
• Make decisions based on MAC addresses
• Make LAN more efficient
• Switch data only out appropriate port

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Switches

• Connectivity devices that subdivide a network
  into smaller logical pieces/segments
• Most have an internal processor, an operating
  system, memory and several ports that enable
  other nodes to connect to it

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Switches

• A collision domain is a logically or physically
  distinct Ethernet network segment on which all
  participating devices must detect and accommodate
  data collisions
• Switches provide at least two advantages better
  security and better performance

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Switches

• Switches differ in the method of switching they
  use
• cut-through mode
• store and forward mode

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Switches

• Cut-through mode
• Reads a frames header and decides where to
  forward the data before it receives the entire
  packet
• The most significant advantage of the cut-through
  mode is its speed

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Switches

• Store and forward mode
• Switch reads the entire data frame into its
  memory and checks it for accuracy before
  transmitting the information
• Transmits data more accurately
• More appropriate for larger LAN environments
  because they do not propagate data errors

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Switches

• Using Switches to Create VLANs
• Switches can create virtual local area networks
  (VLANs), logically separate networks within
  networks, by grouping a number of ports into a
  broadcast domain
• A broadcast domain is a combination of ports that
  make up a Layer 2 segment

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Switches

• VLANs
• Can include ports from more than one
  switch/segment
• On a wireless network,VLANs allow mobile clients
  to move from one access points range to another
  without losing network functionality or having to
  re-authenticate with the network
• Created by configuring a switchs software

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Switches

• Reasons for using VLANs include
• Separating groups of users who need special
  security or network functions
• Isolating connections with heavy or unpredictable
  traffic patterns
• Identifying groups of devices whose data should
  be given priority handling
• Containing groups of devices that rely on legacy
  protocols incompatible with the majority of the
  networks traffic

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Routers

• Layer 3 device
• Make decisions based on network addresses as
  opposed to individual MAC addresses
• Can connect different Layer 2 technologies
  (Ethernet, Token-ring and FDDI)
• Because of ability to route packets based on
  Layer 3 info, have become backbone of Internet

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Routers

• Entry/exit point to a network connects networks
• Multiport connectivity device that directs data
  between nodes on a network
• Can integrate LANs and WANs running at different
  transmission speeds and using a variety of
  protocols

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Routers

• Purpose - examine incoming packets, choose best
  path and then switch them to the proper outgoing
  port
• Most important traffic-regulating devices on
  large networks
• Enable virtually any type of computer to
  communicate with any other computer anywhere in
  the world

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Routers

• Can determine the shortest, fastest path between
  two nodes
• Typically has an internal processor, an operating
  system, memory, input and output jacks for
  different types of network connectors and usually
  a management console interface
• A router with multiple slots that can hold
  different interface cards or other devices is
  called a modular router

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Summary

• Functions of LAN connectivity hardware
• Factors involved in choosing a network adapter,
  hub, switch or router
• Functions of repeaters, hubs, bridges, switches
  and routers