The (7-layer) OSI network model
Lawrence Berkeley National Laboratory
IEA Workshop on Digital Networks for The Future
July 6, 2007
OSI = “Open Systems Interconnection
Basic Reference Model”
• Idea for how to design network
systems that are flexible, economic,
interoperable, scalable, etc.
• Layers of standards / functions /
implementation are narrow in scope
– Each layer interacts only with adjacent layers
• Provides for diverse applications and
• Provides for easy evolution over time
• A key principle underlying developing
Internet and related technologies
# Name Function
7 Application layer “I want a web page”
6 Presentation layer .
5 Session layer .
4 Transport layer .
3 Network layer .
2 Data link layer .
1 Physical layer “Bits on a wire” (or non-wire)
(8th layer — User Interface)
Driving from IEA to Mont
• Who is driving
• What car
• Which route
• How to drive on specific
• How to follow road
Mail from IEA to LBNL
• Content: Workshop invite,
cooking recipe, jokes, etc.
• Paper/ink type
• Envelope type
• Box type
• Financial payer
• Shipping company
• Vehicle type(s)
Alternative to Layered Network
A single, separate, unique infrastructure for any purpose
• “Hot line” between Kremlin and White House
• Highly optimized
• Inflexible, not sharable, not interoperable,
Key points for building networks
Layered Network Model
• Facilitates multiple physical layer technologies
• Facilitates evolution over time
• Open standards drive low prices, interoperability
• Technology, media can be shared
Energy Efficiency Strategy
• Where to focus attention
• How to organize efforts
• Key to quantify consumption, savings