Goals:

• Identify, study common architectural components, protocol mechanisms, approaches we find in network architectures

Design Principles:

• Separation of data and control
• Hard State vs Soft State
• Randomisation
• Indirection
• Network Virtualisation
• Resource Sharing
• Design for scale

Signalling

State

Internet Design Philosophy:

Survivability:

• Continue to operate even under network failures
  • As long as the network is not partitioned, two endpoints should be able to communicate
• Maintain end-to-end transport state only at endpoints
• Eliminates the problem of handling state inconsistency and performing state restoration
• Stateless network architecture

Types of Services:

• datagram abstraction
• Lowest common denominator on which services can be built - IP
• Service differentiation was considered

Variety of networks:

• Internet was very successful to provide this feature
• It requires minimal service from the underlying network. It requires the underlying network to deliver the packets with a “reasonable” probability of success
• No requirement for Reliability and In-order delivery

Distributed Management

• Administrative Autonomy

Cost Effectiveness

• Sources of Inefficiency
  • Headers
  • Retransmission
  • Routing
• optimal performance was never a priority for design

Low cost of attaching a new host:

• Not the best
• Things are improving - DHCP auto configuration

Accountability:

• Anyone can share the packets in the internet
• NO ACCOUNTABILITY