!Data Link Overview

• Layer 2
• Basic functions to move frames from one node to adjacent nodes over single communication link

Services:

• Framing: determining where frame begins/ends
• Flow control
• Error control: detection/correction
• Reliable delivery: for links with high error rates
• Medium Access Control (MAC): rules to transmit a frame

Implementation

• DL Layer implemented in every host and network device
• Mostly on a NIC (network interface card) on a chip
• Partially implemented in software, running on host's CPU
• Different links implement different link protocols