OSI Levels
Physical Layer: electrical details of bits on the wire
Data Link: sending “frames” of bits and error detection
Network Layer:” routing packets to the destination
Transport Layer: reliable transmission of messages, disassembly/assembly, ordering, retransmission of lost packets
Session Layer; really part of transport, typ. Not impl.
Presentation Layer: data representation in the message
Application: high-level protocols (mail, ftp, etc.)