Emerging Internet Technologies

1
Emerging Internet Technologies

• Harish Sethu
• Department of Electrical and Computer Engineering
• Drexel University

2
The Origin

• Began as ARPANET in 1969 for the purpose of
  sharing computing resources
• More rapid growth than any other medium in
  history
• New applications in education, business,
  entertainment and medicine still being developed
• Uses packet switching as opposed to circuit
  switching

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Circuit Switching
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Packet Switching
Packet 1 Packet 2
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Why Packet Switching?

• Packet switching analogous to how we share road
  space an idea waiting to be discovered.
• Leonard Kleinrock (MIT), Paul Baran (RAND
  Corporation) and Donald Davies (UK National
  Physical Laboratory) together share credit for
  inventing the technology of packet switching,
  each had a slightly different set of motivations.
• Offers improved efficiency, and improved
  tolerance to partial network failures.

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Milestones in Internet History

• TCP/IP
• Ethernet
• E-mail
• World Wide Web
• Commercialization of the Internet infrastructure

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Protocol Layering

• What is a protocol?
• What is protocol layering?
• The analogy to postal service.
• Why use protocol layering?
• Simplicity in design
• Flexibility in accommodating new technologies
• Compatibility of applications to systems

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A Common Protocol Architecture
Application Layer
Application Layer
Transport Layer
Transport Layer
Network Layer
Network Layer
Access Layer
Access Layer
Physical Layer
Physical Layer
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Switches and Routers
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Virtual Circuit Switching

• Establishes a virtual circuit
• Routes using a virtual circuit identifier on each
  packet
• Packets with same identifier routed identically
  by a switch
• Facilitates easy management of flows of traffic

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Routing

• What is routing?
• What is a route table?
• Link-State Routing used within autonomous
  domains
• Distance-Vector Routing used in the Internet core

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Flow Control and Congestion Avoidance

• What is flow control?
• What is congestion avoidance?
• Open loop flow control
• No feedback
• Pre-arranged self-regulation at the source
• Closed loop flow control
• Self-regulation based on feedback

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Token bucket regulator
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TCP Flow Control

• TCP uses closed loop flow control
• slow-start phase in TCP (exponential rate
  increase)
• congestion-avoidance phase in TCP (linear rate
  increase)
• time-outs and back-off
• Threshold for switching to a linear increase in
  rate is reduced by half upon a time-out.

15
Emerging Architectures and Services

• Onslaught of multimedia traffic
• Access networks are congested
• Need for service beyond best effort
• What is Quality of Service?
• throughput guarantee
• delay bound
• delay-jitter bound

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Fairness in Traffic Management

• The most basic QoS guarantee Fairness.
• Why not just first-come-first-serve?
• Why not just packet-by-packet round-robin
  scheduling?
• Delay guarantees through fairness
• What is fair?
• No flow should get more resources than its
  demand.
• All flows with unsatisfied demands should get an
  equal share of the resource.

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The Integrated Services Framework

• A new architectural framework to facilitate QoS
  in the Internet.
• Applications describe their traffic to the
  network, and their demand for QoS
• Network decides if the demand can be satisfied
  before admitting the application traffic
• Routers reserve bandwidths and buffers necessary
  to satisfy demand

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IntServ Service Classes

• Guaranteed service
• Requires per-flow management in the routers
• Provides hard guarantees
• Suffers from scalability problems
• Controlled Load Service
• Service similar to best-effort in a lightly
  loaded network
• Meant for applications that can tolerate some
  loss or delay
• Requires application to specify traffic
  description
• Network decides whether or not to admit a new
  flow for controlled load service

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Differentiated Services Framework

• Traffic is divided into classes
• Resources allocated on a per-class basis instead
  of a per-flow basis
• Defines a set of Per-Hop Behaviors (PHBs)
• Service by the network based on the PHB carried
  in the packet
• Standard PHBs
• Expedited Forwarding
• Assured Forwarding

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Multi-Protocol Label Switching

• Uses a concept similar to that of virtual
  circuits
• Uses fixed-size labels
• Originally designed to facilitate sending IP
  packets over ATM
• Packets are routed based on the label, instead of
  destination address.
• Achieves lower header overhead
• Supported by high-end routers today

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Concluding Remarks

• Internet is still evolving rapidly, especially so
  at the higher and lower layers of the technology
  as opposed to the middle layers
• Usage-based pricing as a potential solution to
  quality of service
• Service requirements of applications may change
  new solutions such as active networking are
  emerging.
• Engineering the Internet continues to be both
  challenging and rewarding.