Network Hardware Lecture 5

Future Issues

• Mobility
• mobility within an office complex is possible now
• wireless LANs at 10 Mbps
• low power radio connecting to wired communication
• problem with computing outside the office
• several factors force mobile computing outside office
• cellular phone popularity
• centrality of computing
• reliance on networking and communication
• problems are
• creating enough bandwidth
• possibly need multiple channels
• not enough spectrum
• current transmission / broadcast activities may swap

Network Protocols

• A protocol is a set of conventions for communicating
• Concerned with issues such as
• addressing and routing
• error detection and correction
• flow control and congestion control
• higher level coordination depending on the purpose of the communication
• International Standards Organization Open Systems Interconnection model (ISO OSI)
• 7 layers of protocols
• defined interfaces between each layer
• lower layers typically implemented in hardware, upper in software

Network Protocols (continued)

Network Protocols (continued)

• ISO layers
• application - detailed information about data being exchanged
• presentation - conventions for representing data
• session - management of connections between programs
• transport - delivery (reliable or otherwise) of sequences of packets
• network - format of individual data packets
• link - access to and control of transmission medium
• physical - medium of transmission
• Internet protocols (IP) are a competing set for lower layers
• network and transport
• defacto standard