Chapter 25. Detailed Description of the Link Layer

The Previous Chapter

The previous chapter introduced the problem for which Static Rate Control is the solution, and then provided a detailed description of how Static Rate Control works. It concluded the part of the book that focuses on the transport service types (i.e., Part 4).

This Chapter

This chapter provides a detailed description of the Link Layer. This includes:

• Link Layer functional overview.

• Link state machine.

• Detailed description of LRH.

• QoS within the subnet: SL and VLs.

• Detailed description of VL arbitration.

• Link-Level Flow Control.

• Packet CRCs.

• Intro to the packet delimiters.

• Packet receive state machine.

• Data packet check.

• Link packet (Flow Control packet) check.

• Switch performs packet forwarding.

• Overview of router port's link layer.

The Next Chapter

The next chapter provides a detailed description of the Physical Layer and includes:

• Module basics.

• Port types.

• Signal naming conventions.

• Electrical signaling and copper cable.

• Link Layer to Physical Layer interface.

• Transmit logic functions.

• Receiver logic functions.

• Link training.

• Physical Layer error handling.

• Repeaters.

• Performance counters.