CENG 490/510 Network Programming

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CENG 490/510Network Programming

• Russell DeatonRm. 324501-575-5590rdeaton_at_engr.u
  ark.eduhttp//www.csce.uark.edu/rdeaton/networkp
  rog/

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Why Network Programming?

• New Economy
• Software for Network Applications
• Client/Server Architecture
• Platforms?

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Class Introduction

• Syllabus
• Topics
• Resources
• Requirements
• Grading
• Computer Accounts
• Introduction to the online resources(
  http//engronline.ee.memphis.edu/ )

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Networks
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Common Xmit Media
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Shared Media

• Networks are a shared communication resource
• Only one user can access at a time

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Packet and Circuit Switched

• Circuit Public Telephone Network
• Packet Internet and US Mail
• Data divided into small units (packets) for
  transmission
• More efficient use of shared resource

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Time-Division Multiplexing
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Packets and Frames

• Packet A small, self-contained parcel of data
  sent across a computer network. Each packet
  contains a header that identifies the sender and
  recipient, and data to be delivered.
• Frame The form of a packet that the underlying
  hardware accepts and delivers.

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Frames

• Header and trailer indicates beginning and end of
  frame.

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Transmission Errors

• Error Detection and Error Correction
• Both require additional information beyond data,
  appended to end of frame
• Many Schemes
• Parity checking, Check Sum, CRC codes
• Error Correcting Codes Hamming, Reed-Solomon,
  etc...

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• Parity refers to the number of bits set to 1 in
  the data item
• Even parity - an even number of bits are 1
• Odd parity - an odd number of bits are 1
• A parity bit is an extra bit transmitted with a
  data item,
• chose to give the resulting bits even or odd
  parity
• Even parity - data 10010011, parity bit 1
• Odd parity - data 10010111, parity bit 0

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Point-to-Point Networks
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LANs

• Reduce complexity and cost by sharing
  communication channel
• TDM
• Synchronization
• Effective because of locality of reference
• Spatial
• Temporal

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Topologies

• Star, Ring, Bus

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Ethernet

• Widely used LAN technology
• Invented at Xerox PARC (Palo Alto Research
  Center) in 1970s
• Defined in a standard by Xerox, Intel and Digital
  - DIX standard
• Standard now managed by IEEE - defines formats,
  voltages, cable lengths, ...
• Uses bus topology
• Single coax cable - the ether
• Multiple computers connect
• One Ethernet cable is sometimes called a segment
• Limited to 500 meters in length
• Minimum separation between connections is 3
  meters

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• Originally 3 Mbs
• Currently, 10 Mbs
• Fast Ethernet, 100 Mbs
• One computer transmits at a time
• Signal is a modulated carrier which propagates
  from transmitter in both directions along length
  of segment

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Hardware Adresses

• Identify destination on shared channel
• Hardware or physical address
• Included in frame

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Ethernet Frame
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WAN

• Packet Switch Moves complete packets from one
  connection to another

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Protocols and Layering

• A rule that specifies format and meaning of
  messages that computers exchange
• Protocols organized in layers, each of which
  solves specific aspect of communication problem.

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ISO 7 Layer Model
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Layer 7 Application Application-specific
protocols such as FTP and SMTP (electronic mail)
Layer 6 Presentation Common formats for
representation of data Layer 5 Session
Management of sessions such as login to a remote
computer Layer 4 Transport Reliable delivery
of data between computers Layer 3 Network
Address assignment and data delivery across a
physical network Layer 2 Data Link Format of
data in frames and delivery of frames through
network interface Layer 1 Physical Basic
network hardware - such as RS-232 or Ethernet
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Nested Headers