TCP/IP and OSI Layers

Physical Layer

• cables, connectors, adapter cards, bits

Data Link Layer

• frames, links
• source and destination physical (MAC) addresses

Network Layer - IP

• routing, datagrams
• connectionless - IP does not guarantee reliable or in-sequence delivery

Transport Layer - TCP

• reliable data connection services
• guaranteed, error-free, in-sequence delivery
• segments (sent to IP)

Transport Layer - UDP

• connectionless - simple database lookup applications
• datagrams/messages (sent to IP)

Application Services Layer

• standard application services:
  terminal access, file transfer, mail, NFS, WWW, news, DNS, etc.