This chapter covers
- How to configure interfaces and verify their status
- Interface speed and duplex settings
- Using autonegotiation to automatically determine an interface’s speed and duplex
- Errors that can occur when sending and receiving messages over a network
In chapter 7, we looked at how to configure IP addresses on and enable router interfaces. In this chapter, we will dig deeper into the topic of interfaces and how they operate. Whereas the previous chapter covered how to configure IP addresses on interfaces (a Layer 3 concept), this chapter will focus primarily on Layer 1 concepts, such as how to configure the speed at which an interface can send and receive data. Specifically, we will cover the following CCNA exam topics:
- 1.3.b Connections (Ethernet shared media and point-to-point)
- 1.4 Identify interface and cable issues (collisions, errors, mismatch duplex, and/or speed)
In previous chapters, I have used the terms port and interface. The exact definitions of these terms depend on who you ask; some say a port is a Layer 2 entity that forwards frames within a LAN (switches have ports), and an interface is a Layer 3 entity that forwards packets between LANs (routers have interfaces). Another definition is that a port is the physical connector on a device that you plug a cable into, and an interface is the representation of that port within the software (hence, most Cisco IOS commands use the term interface rather than port).