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Learn about networking protocols and the OSI Seven Layer Model, a set of rules and software that facilitate inter-computer communication. Understand the different aspects of inter-networking and the representative layers in the model. Explore the physical, data-link, network, transport, session, presentation, and application layers. Gain knowledge about protocols such as TCP/IP, NetBEUI, and DNS. Discover network devices and their roles, including hubs, switches, routers, bridges, gateways, and proxy servers.
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Networking Protocols John R. Durrett ISQS 6343 #1
Introduction • Protocol • set of rules • software • facilitate inter-computer communication • OSI Seven Layer Model • model not reality • facilitate understanding • representative of different aspects of inter-networking • no direct correspondence with commercial implementations
The OSI Model • 7 - Application • 6 - Presentation • 5 - Session • 4 - Transport • 3 - Network • 2 - Data Link • 1 - Physical
Physical Layer • Bits over media • electrical signals • computers, NIC, “wire”, etc. • “black box” • interface assumptions with upper layers
Data-Link • Assumes physical layer • frames - groups of bits • ensures only delivery not accuracy • Examples: • Token Ring • Ethernet • IEEE model • LLC (logical link control) • MAC (Media Access Control)
Network • Assumes data-link layer • packets • routing of packets • therefore addresses necessary • network optimization • congestion handling • No error checking
Transport • Relies on network layer • Frequently combined with network layer in protocols • Messages • Error checking • UDP & TCP • NetBEUI, TCP/IP, IPX/SPX
Session • Assumes Transport layer • Sessions between computers • based on names of other computers • NetBIOS - Windows • Sockets - TCP/IP
Presentation • Assumes session layer • based on services provided • encryption, compression, translation
Application • Assumes session exists • RPC • procedural • distributed • locations required • relatively static • pipes • FTP protocol
Windows Networking • Transport Device Interface (TDI) • Network Device Interface Specification (NDIS) • Allows support of multiple transport protocols • interface between transport & session layers
NetBEUI • Compact • LAN based • not routable • ubiquitous • limits size • limits choice of clients/servers
TCP/IP • UBIQUITIOUS • performance & reliability based • standards arrived before implementations • IETF • RFCs • flexibility == difficult to manage • IPs
IPs • Dotted quad • 128.48.35.45 • Classes • C, B, A • subnets • Limits of current IPs • IPv6 or IPng • Domain Names • reversed version of IPs • DNS
Protocol choice • Clients • Windows NT • Windows 95… • DOS • OS/2 • Un*x • Macs • Network Structure • Similar servers • LCD
Interoperability • Hub - very simple relay • Switch - virtual circuits • Router - makes pathway choice based on IPs • Bridge - passes data unchanged • Gateway - translation • Proxy Server - security