Networking%20concepts%20and%20hardware

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Networking concepts and hardware
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Basic Communications ModelStandards are needed
at all Layers
User Layer
Application Layer
Computer (Transport) Layer
Transmission Layer
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Subnet Layer
Station B
Station A
2
2
1
1
4
3
Transmission of Messages 1. Within a Single
Subnet, or 2. in Point-to-Point Links Between
Subnets
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Internet Layer
Station B
Station A
2
1
4
3
Routing of Messages Across multiple subnets in an
internet
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Internetting
Station B
Station A
2
1
4
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internet collection of subnets such that any
station on any subnet can communicate with any
other station on any other subnet simply by
giving the internet address of the other station.
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Layering in Major Architectures
Basic Model
TCP/IP
IPX/SPX
OSI
Application
Application (7)
Application
Application
Presentation (6)
Computer (Transport)
Session (5)
Transport TCP, etc.
Complex SPX, etc.
Transport (4)
Internet
Internet
Internet
Network (3) Internet Subnet
Subnet (OSI)
Subnet (OSI)
Subnet (OSI)
Data Link (2)
Physical (1)
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LANs, MANs, WANs

• LAN
• Local area network
• Single office, building, campus
• 10 Mbps to 100 Mbps to the desktop common
• 1 Gbps coming
• Will carry most traffic, because most traffic is
  local

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PC Networking on a small LAN
Each client and server needs a NIC rather than a
modem
Network Interface Card (NIC)
In each PC
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LANs, MANs, WANs

• WAN
• Wide area network
• Intercity, international
• 9,600 bps to 1 Mbps common to the desktop
• Links with higher speed are usually shared
  (multiplexed) by several desktops
• Emerged before LANs, due to high cost of
  long-distance telephone charges

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Microsoft Layered Network Architecture
7. Application
User Mode
6. Presentation
Kernel Mode
5. Session
4. Transport
3. Network
2. Data Link
LLC
MAC
1. Physical
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Some basic concepts

• NDIS Interface Network Driver Specification
  Interface, wraps NIC drivers and allow
  communication with multiple protocols, binds a
  NIC to a protocol.
• Streams multiple channels allowing broader
  bandwidth for data transfer, envelop the
  protocols.
• Transport Driver Interface allows software
  drivers (server, redirector, etc) to communicate
  with protocols.
• Redirectors software in WS that redirect network
  drives, printers requests to network I/O
  requests.
• Servers software that allows a device to accept
  requests from other devices.

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Standard protocols

• NetBEUI - NetBIOS Extended User Interface,
  native Windows protocol, not routable.
• TCP/IP - implemented through WinSock, routable,
  supports SNMP, DHCP, WINS.
• NWLink (IPX/SPX) - used to connect to Novell
  NetWare, just a protocol, not access.
• DLC - Data Link Control, used to connect to IBM
  mainframes and HP printers directly connected to
  a network (server).

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Data Link Layer
Logical Link Control Layer
OSI Data Link Layer (Layer 2)
Media Access Control (MAC) Layer
OSI Physical Layer (Layer 1)
802.3 10Base-T
802.3 10Base-5
802.3 Other Physical Layer
802.5 Physical Layer 4 Mbps
802.5 Physical Layer 16 Mbps
Other Physical Layer
OSI Data Link Layer is subdivided into two
layers Media access control Logical
link control
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LAN Using Ethernet 10Base-T
RJ-45 jacks
10Base-T Hub (Multiport Repeater)
10Base-T UTP Wiring Bundles 4 Pairs EIA Category
3, 4, or 5
Unshielded Twisted Pair (UTP) Wiring (4-Pair
Bundle)
PC
Network Interface Card
RJ-45 Jack
NIC
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NICs

• Network Interface Cards
• Implement Physical Layer
• Plug and Electrical Signaling
• Implements the Data Link Layer (data packaging,
  access control, etc.)
• LLC (802.2)
• MAC (802.3 MAC)

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Wiring

• Unshielded Twisted Pair (UTP)
• Twisted several times per foot to reduce
  interference, T in 10Base- and Unshielded
• No protection except for plastic coating
• Distance limitation 100 meters (attenuation,
  distortion, noise and interference, crosstalk) --
  propagation
• Categories of UTP Wiring
• Category 5 The best. Good for 100 Mbps
• Category 3 and 4 lower. May be OK for 100 Mbps
• Wiring Plugs RJ-45 Standard
• Similar to home (RJ-11) jacks, but wider

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CSMA/CD Media Access Control

• CD Collision Detection
• If two stations transmit at once .
• Their signals collide, scrambling one another
• Because each sender listens (senses the carrier),
  both know that there has been a collision
• Both stop and wait a random amount of time.

001110
X
101010
Collision
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Ethernet 10Base-T LAN with Multiple Hubs
Hub 2
Hub 3
Hub 1
UTP Wire
UTP Wire
UTP Wire
Station C
UTP Wire
Hub 4
Daisy chain, no Loops allowed!
UTP Wire
Station A
Station B
Station D
Maximum distance between farthest Stations is 4
Hubs/5 100 meter segments
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Switches
With a switch, multiple stations may transmit
simultaneously no congestion as traffic grows.
Switch
Station C
Station A
Connection 1 A-C
Connection 1 A-C
Station D
Station B
Connection 2 B-D
Connection 2 B-D
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Wireless LAN
Broadcast Signal
Antenna
Cluster Transceiver Receiving
Transceiver Transmitting
Hub Controller
Transceiver Receiving
Wireless LAN
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Wireless LAN with Access Points
Access Point
Industry Standard Coffee Cup
Wireless Notebook NIC
Antenna (Fan)
To Ethernet Switch
PC Card Connector
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802.11 Wireless LAN Speeds

• 802.11 2 Mbps (rare) 2.4 GHz band (limited in
  bandwidth)
• 802.11b 11 Mbps, 2.4 GHz 3
  channels/access point
• 802.11a 54 Mbps, 5 GHz (gt bandwidth than 2.4
  GHz) 11 channels/access point
• 802.11g 54 Mbps, 2.4 GHz limited
  bandwidth

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Addresses

• Ethernet address (MAC address )
• 48-bit unique addresses hard wired in NICs (280
  trillion)
• 12 hex numbers, e.g. 00-A0-C9-9F-00-07
• first three identify company, Intel in the
  example
• how to see IPconfig, or System Information
• IP address (number)
• 32-bit value, not hard coded (4 billion),
  assigned manually or by DHCP
• four dotted quads, each quad a decimal from
  0-255, corresponding to eight bits, e.g. UBMAIL
  IP address is 198.202.0.25
• to convert open Calculator select View,
  Scientific, decimal and type dotted quad decimal
  value, then select binary.

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Interneting

• Station A wants to send message to station D, but
  IP number is not in the same subnet -- no can do!
• Sends the message to the default IP router --
  default gateway
• All stations belonging to the same subnet share
  the first three dotted quads.
• 204.52.128.67 and 204.52.128.147 are in the same
  subnet, while 198.202.0.25 is not.

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A,B and C-Class Networks

• A-class networks
• first 8 bits fixed, from 0-126 (only 127)
• very large companies like IBM, BBN, DEC,HP
• can assign 3 dotted quads - up to 16 million
  hosts
• B-class networks
• first 16 bits fixed, first quad 128-191 and
  second 0-255 (16,384)
• Medium-sized companies like Microsoft, Exxon
• can assign 2 dotted quads - up to 65,535 hosts
• C-class networks
• first 24 bits fixed, first quad 192-223, second
  and third 0-255 (2,097,152)
• can assign 1 dotted quad - up to 253 hosts, 0 is
  the subnet address., 1 default router address,
  255 broadcast address.

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Sockets and WinSock

• Sockets are the basic TCP requirement
• Socket address
• IP address of the receiver
• Port number of the receiving program (80,21,23)
• Type of port TCP or UDP
• WinSock is an adaptation of sockets to the PC
• it now comes as part of the PC OSs
• it is an application programming interface

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Internet Host Names

• Host names in Windows
• HOSTS - a list of IP and names (each machine)
• DNS - a server with a common table of IP names
  (use with Windows 2000, together with Active
  Directory)
• WINS - Windows Internet Name Server
• not DNS compatible (use only with NT/9x)
• can resolve IP addresses inside a Windows
  network
• good with dealing with NetBEUI names
• FQDN
• Fully Qualified Domain Name
• name of a host like machine.org.domain, e.g.
  ubmail.ubalt.edu, with a DNS assignment to an
  IP

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Setting static IP addresses

• Open Control Panel and select Network Connections
• Under LAN or High-Speed Internet select local
  area connection,
• right-click and select properties
• select Internet Protocol (TCP/IP) and click on
  properties
• fill in IP number, Subnet Mask, Default Gateway
  and DNS server
• click OK, close.
• Use ping to test your setup.