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LOCAL foilset Networking Basics-CPS606fall96

Given by Nancy J. McCracken at CPS606fall96 on Fall Semester 96. Foils prepared 11 May 1997
Abstract * Foil Index for this file

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The first section of this talk covers basic networking terminology, the OSI networking layers, the TCP/IP protocol, and routing.
Further sections will contain a brief introduction to the emerging ATM standard and other high performance physical networks.

Table of Contents for full HTML of Networking Basics-CPS606fall96

1 Networking Basics
2 Networking Basics
3 Networking Basic Definitions
4 Networking Standards: OSI Layers
5 Simplified communication protocol model
6 The TCP/IP protocol suite
7 Typical message formats
8 Communications Issues
9 RealAudio Server from Progressive Networks
10 RealAudio File Sizes
11 RealMedia Architecture
12 RTSP: Real-Time Streaming Protocol

This table of Contents Abstract

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Foil 1 Networking Basics

From Networking Basics-CPS606fall96 CPS606fall96 -- Fall Semester 96. * See also color IMAGE
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Dr. Nancy McCracken, NPAC, 3-234 CST
Syracuse University
111 College Place
Syracuse NY 13244-4100
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Foil 2 Networking Basics

From Networking Basics-CPS606fall96 CPS606fall96 -- Fall Semester 96. * See also color IMAGE
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The first section of this talk covers basic networking terminology, the OSI networking layers, the TCP/IP protocol, and routing.
Further sections will contain a brief introduction to the emerging ATM standard and other high performance physical networks.
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Foil 3 Networking Basic Definitions

From Networking Basics-CPS606fall96 CPS606fall96 -- Fall Semester 96. * See also color IMAGE
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A computer network is a communication system for connecting end-systems usually called hosts.
A local area network, LAN, connects computer systems within a few kilometers, usually within a single building. A common technology is Ethernet, which operates at 10Mbps (million bits per second). Computers or workstations connect to the LAN via an interface card.
A wide area network, WAN, connects computers in different cities or countries. A common technology is leased telephone lines operating between 9600 bps and 1.544 Mbps.
Computers in a network use a set of protocols to communicate.
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Foil 4 Networking Standards: OSI Layers

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Network communication protocols are usually described via a set of layering conventions from the International Standards Organization (ISO) known as the Open Systems Interconnection (OSI) Model.
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Foil 5 Simplified communication protocol model

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We simplify the model to the four lowest software layers - user applications use the process layer and the remaining three are usually included in the operating system, such as Unix, which has an OSI stack to process messages through the layers.
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Foil 6 The TCP/IP protocol suite

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TCP - Transmission Control Protocol. A connection-oriented protocol used by most Internet applications to provide a reliable, full-duplex, byte stream for a user process.
UDP - User Datagram Protocol. A connectionless protocol for user processes. Also not reliable.
ICMP - Internet Control Message Protocol. Handles error and control information between gateways and hosts.
IP - Internet Protocol. Provides the packet delivery service for the upper layers.
ARP - Address Resolution Protocol. Maps an Internet address into a hardware address.
RARP - Reverse Address Resolution Protocol.
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Foil 7 Typical message formats

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Each layer adds control information to the message - this process is called encapsulation.
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Foil 8 Communications Issues

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Multiplexing - Different protocols can be used to send different messages through the same network.
Fragmentation and reassembly - Most networks have a maximum packet size. In the TCP/IP protocols, the IP layer breaks up two long packets into a sequence of shorter frames, which are reassembled on the other side.
Sequencing is the property that data is received by the receiver in the same order as transmitted by the sender, which is not true in a packet-switched network.
Error control guarantees that error-free data is received by the application programs. Data can either get corrupted by the transmission medium or get lost. Checksums are added to the data and received data is acknowledged. If there is any problem, retransmission occurs.
Flow control assures that the sender doesn't overwhelm the receiver by sending data at a faster rate than it can process.
Error and flow control are handled on an end-to-end basis by TCP and on a hop-by-hop basis by IP. (A hop goes to only one intermediate machine on the network route.)
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Foil 9 RealAudio Server from Progressive Networks

From Networking Basics-CPS606fall96 CPS606fall96 -- Fall Semester 96. * See also color IMAGE
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Properties of RealAudio
  • Delivers live or on-demand audio to your Website
  • Delivery is real-time, with download delays
  • Full random access, just like a CD player
  • Full monitoring of performance and traffic
  • Improved delivery with fewer packets lost
Server stores audio clips encoded for different bandwidths
  • Broadcast quality radio AM, optimized for speach, not music, at 14.4 kbps
  • Broadcast quality radio FM, including music, at 28.8 kbps
  • Near CD-like sound for ISDN and LAN bandwidths
Servers are set up with different numbers of stream capacities:
  • 56kbps frame relay: 4 streams
  • ISDN 5-10 streams
  • T1 100 streams
  • T3 3,000-4,000 streams
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Foil 10 RealAudio File Sizes

From Networking Basics-CPS606fall96 CPS606fall96 -- Fall Semester 96. * See also color IMAGE
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source: http://www.realaudio.com/
RealAudio files are time-based audio streams; they are both file compressed and audio compressed.
Audio files can be recorded at different sampling rates:
  • For 1 minute of sound,
    • .wav file sampled at 22 KHz, 16 bit 21.6 Megabytes
    • .wav file sampled at 8 KHz, 8 bit 470 Kilobytes
Encoded to RealAudio at 14.4 channel capacity 60 Kilobytes
    • 28.8 channel capacity 113 Kilobytes
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Foil 11 RealMedia Architecture

From Networking Basics-CPS606fall96 CPS606fall96 -- Fall Semester 96. * See also color IMAGE
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Current plan is to design a uniform platform for the integration and delivery of diverse media through streaming architecture, with similar properties to RealAudio.
  • interactive stream control (start, stop, pause stream)
  • error mitigation (smooth out audio effect of lost packets)
  • bandwidth negotiation (client requests a bandwidth - performance monitoring may adjust bandwidth that server is sending if network traffic is high.
  • multicasting (one media stream can be directed to multiple clients)
  • scalability (broadcast length?)
  • live broadcasting and monitoring
Multimedia streams are time-based files with multiple tracks of media
Designed as an open framework for client/server plug-ins
Types of media: audio, video, MIDI, text, images, animations, presentations
Current separate media servers that could be served from this architecture: FutureSplash, Enliven, Crescendo, RealAudio & LiveMedia, ClearVideo, and OLiVR
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Foil 12 RTSP: Real-Time Streaming Protocol

From Networking Basics-CPS606fall96 CPS606fall96 -- Fall Semester 96. * See also color IMAGE
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New Draft Proposal sent to IETF October 9, 1996, sponsored by Progressive Networks and Netscape
Proposal for new protocol to control and deliver real-time content streams
The delivery is based on RTP (IETF RFC 1889): Real-time Transport Protocol, for lower level delivery of multimedia data.
RTSP would take advantage of UDP (User Datagram Protocol - provides multiplexing of packets to help support real-time transfer), SCP (Session Control Protocol) with TCP/IP, or IP Multicast.
Source for Draft Proposal:
http://www.realaudio.com/prognet/rt/
Northeast Parallel Architectures Center, Syracuse University, npac@npac.syr.edu

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