Who is Who in the Internet ?

1
Who is Who in the Internet ?

• Internet Engineering Task Force (IETF) The IETF
  is the protocol engineering and development arm
  of the Internet. Subdivided into many working
  groups, which specify Request For Comments or
  RFCs. (www.ietf.org)
• IRTF (Internet Research Task Force) The Internet
  Research Task Force is a composed of a number of
  focused, long-term and small Research Groups.
• E.g., Anti-spam group, delay tolerant networking
  group, Network management group, Routing research
  group, Peer-to-peer research group
  (www.irtf.org)
• Internet Architecture Board (IAB)
• The Internet Engineering Steering Group (IESG)

2
Internet Standardization Process

• All standards of the Internet are published as
  RFC (Request for Comments).
• A typical way of standardization is
• Internet Drafts
• RFC
• Proposed Standard
• Draft Standard (requires 2 working
  implementation)
• Internet Standard (declared by IAB)
• Consensus based standardization

3
At The Not So Very Beginning
4
Necessity

• Proliferation of Computers in Public and Business
  Utilities
• Availability of Data Based Services (no pun
  intended)
• End User Growth
• Communication Technology Evolved
• Research and Commercial Motives

5
Sample Applications

• Remote Access to Resources
• E.g., Telnet
• Shared access to data/files
• FTP, NFS, AFS
• Remote Computer Aided Learning
• Online audio/video lectures, web casting, demos
• Remote Data Operations and Computation
• E.g., Airline reservation systems, inventory
  control systems
• Other applications like, e-mail, ftp, http, p2p,
  instant messaging, news groups etc
• Now IP- (Telephony, TV, Radio, Movies, Music
  etc)

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Network Classification Parameters

• Latency
• Bandwidth
• Loss rate
• Number of end systems
• Service interface (how to invoke?)
• Other details
• Reliability
• Communication capability unicast, multicast,
  broadcast
• Applicability E.g., Real-time (e.g., postal
  service?)
• Switching technology message vs. packet

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Network Classification Parameters...

• Communication Medium Electrons and photons
• Links Optical fiber, copper, satellite, etc
• Switches Electronic/optical, crossbar/Banyan
• Protocols TCP/IP, ATM, MPLS, SONET, Ethernet,
  PPP, X.25, FrameRelay, AppleTalk, IPX, SNA
• Functionalities Routing, error control,
  congestion control, Quality of Service (QoS)
• Applications FTP, WEB, X windows, SSH

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Types of Computer Networks

• Geographical distance
• Local Area Networks (LAN) Ethernet, Token ring,
  FDDI
• Metropolitan Area Networks (MAN) DQDB and later,
  SMDS
• Wide Area Networks (WAN) X.25, ATM, frame relay
• Information type
• Data networks vs. telecommunication networks
• Application type
• Special purpose networks airline reservation
  network, banking network, credit card network,
  telephony
• General purpose network Internet

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Types of Computer Networks

• Right to use
• private enterprise networks
• public telephony network, Internet
• Ownership of protocols
• proprietary SNA, DNA
• open IP
• Technologies
• terrestrial vs. satellite
• wired vs. wireless
• Protocols
• IP, AppleTalk, SNA

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Definition of Computer Network

• A computer network is an interconnected
  collection of autonomous computers.
• Two computer are interconnected if they are able
  to exchange information
• Two computer are autonomous if they are capable
  of operating independently, that is, neither is
  capable of forcibly starting, stopping, or
  controlling the other
• Network users (not necessarily application users)
  are aware of the network existence
• Autonomous

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Just to be clear What are not Computer Networks

• Master/slave systems (ref. any centralized
  cluster)
• Single-host networks (E.g., UNIX)
• Multi-computers, such as the hypercube (ref.
  parallel computing)
• In terms of (operating) systems, there is some
  distinction between network systems and
  distributed systems
• Distributed system gives the view of a single
  computer to the user (user not aware of
  networking behind scenes)
• Failure of any node in the system might stop
  other nodes from operating correctly
  (non-autonomous)
• Focus is on software, distributed computation,
  that can do better resource sharing, concurrent
  processing etc
• Important problems load balancing,
  fault-tolerance, mutual exclusion

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Now That We are Clear

• How to build a computer network?
• Agree upon the communication technique (circuit
  switching or store-and-forward switching)
• Develop communication languages for hosts to
  interact (protocols)
• Implement appropriate functionality without
  affecting the computers performance (designing
  the protocol stack)
• Develop network-centric algorithms (routing,
  reliability, congestion control)

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Types of Communication Networks

• Exchange mechanism

Communication Network
SwitchedCommunication Network
BroadcastCommunication Network
Packet-SwitchedCommunication Network
Circuit-SwitchedCommunication Network
Virtual Circuit Network
Datagram Network
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Broadcast vs. Switched Communication Networks

• Broadcast communication networks
• information transmitted by any node is received
  by every other node in the network in range
• E.g., usually in LANs (Ethernet, Wireless) ,
  Radio
• Problem coordinate the access of all nodes to
  the shared communication medium (Multiple Access
  Problem)
• Switched communication networks
• information is transmitted to a sub-set of
  designated nodes
• Examples WANs (Telephony Network, Internet), ATM
• Problem how to forward information to intended
  node(s)
• This is done by special nodes (E.g., bridges,
  routers, switches) running routing protocols

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A Taxonomy of Communication Networks
Communication Network
SwitchedCommunication Network
BroadcastCommunication Network
Packet-SwitchedCommunication Network
Circuit-SwitchedCommunication Network
Virtual Circuit Network
Datagram Network
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Circuit Switching

• Three phases
• circuit establishment
• data transfer
• circuit termination
• If circuit not available Busy signal
• Examples
• Telephone networks
• ISDN (Integrated Services Digital Networks)

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Timing in Circuit Switching
Host 1
Host 2
Node 1
Node 2
DATA
processing delay at Node 1
propagation delay between Host 1 and Node 1
propagation delay between Host 2 and Node 1
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Circuit Switching

• A node (switch) in a circuit switching network

Node
incoming links
outgoing links
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Circuit Switching Multiplexing/Demultiplexing

• Time divided in frames and frames divided in
  slots
• Relative slot position inside a frame determines
  which conversation the data belongs to
• Needs synchronization between sender and receiver
• In case of non-permanent conversations
• Needs to dynamic bind a slot to a conservation
• How to do this?

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A Taxonomy of Communication Networks
Communication Network
SwitchedCommunication Network
BroadcastCommunication Network
Packet-SwitchedCommunication Network
Circuit-SwitchedCommunication Network
Virtual Circuit Network
Datagram Network
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Packet Switching

• Data are sent as formatted bit-sequences,
  so-called packets.
• Packets have the following structure
• Header and Trailer carry control information
  (e.g., destination address, check sum)
• Each packet is passed through the network from
  node to node along some path (Routing)
• At each node the entire packet is received,
  stored briefly, and then forwarded to the next
  node (Store-and-Forward Networks)
• Typically no capacity is allocated for packets

Header
Data
Trailer
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Packet Switching

• A node in a packet switching network

Node
incoming links
outgoing links
Memory
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Packet Switching Multiplexing/Demultiplexing

• Data from any conversation can be transmitted at
  any given time
• How to tell them apart?
• use meta-data (header) to describe data

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A Taxonomy of Communication Networks
Communication Network
SwitchedCommunication Network
BroadcastCommunication Network
Packet-SwitchedCommunication Network
Circuit-SwitchedCommunication Network
Virtual Circuit Network
Datagram Network
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Datagram Packet Switching

• Each packet is independently switched
• Each packet header contains destination address
• No resources are pre-allocated (reserved) in
  advance
• Example IP networks

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Timing of Datagram Packet Switching
Host 1
Host 2
Node 1
Node 2
propagation delay between Host 1 and Node 2
transmission time of Packet 1 at Host 1

processing delay of Packet 1 at Node 2
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Datagram Packet Switching
Host C
Host D
Host A
Node 1
Node 2
Node 3
Node 5
Host B
Host E
Node 7
Node 6
Node 4
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A Taxonomy of Communication Networks
Communication Network
SwitchedCommunication Network
BroadcastCommunication Network
Packet-SwitchedCommunication Network
Circuit-SwitchedCommunication Network
Virtual Circuit Network
Datagram Network
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Virtual-Circuit Packet Switching

• Hybrid of circuit switching and packet switching
• data is transmitted as packets
• all packets from one packet stream are sent along
  a pre-established path (virtual circuit)
• Guarantees in-sequence delivery of packets
• However Packets from different virtual circuits
  may be interleaved
• Example ATM networks

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Virtual-Circuit Packet Switching

• Communication with virtual circuits takes place
  in three phases
• VC establishment
• data transfer
• VC disconnect
• On demand circuit setup, several packets may
  share same virtual link

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Packet-Switching vs. Circuit-Switching

• Most important advantage of packet-switching over
  circuit switching Ability to exploit statistical
  multiplexing
• efficient bandwidth usage ratio between peek and
  average rate is 31 for audio, and 151 for data
  traffic
• However, packet-switching needs to deal with
  congestion
• more complex routers
• harder to provide good network services (e.g.,
  delay and bandwidth guarantees)
• In practice they are combined
• IP over SONET, IP over Frame Relay