DATA COMMUNICATION NETWORKSEthernet with a bus topology:
DATA COMMUNICATION NETWORKS Ring topology net:Note: No switching nodes ,media is shared in LAN For packet radio,every station can hear every other, the media is shared so this is a LAN technology
Computer Communications ArchitectureThe Three Layer ModelApplication run on computer which use networks ¢ network layer - xchange of data between computer and network ¢ transport layer - error detection and correction ¢ application layer - file xfer etc.
Transmission TerminologyANSI Defs: – simplex - one direction only – half-duplex - two-way but not at the same time. – full-duplex - simultaneous two way transmission
Transmission Terminology¢CCITT – CCITT vs ANSI – simplex = half-duplex – duplex = full-duplex¢CCITT = international telegraph and telephone consultive committee
ISO-OSI Model¢ISO= International Standards Organization¢OSI = Open Systems Interconnection¢OSI Model = a 7 layer model used to describe most networks today
1. Physical Layer¢Thisis a physicalconnection betweenmachines. BITS
2. Data Link Layer¢Provides reliabletransfer of informationacross the physicallinks. FRAMES/Packetsor DLPDU