Wireless Access Points

Wireless access has become the de facto standard for connecting devices to the network. This is primarily because of the need to do away with cables, and the ability to connect to the network while on the move. Wireless Infrastructures are becoming more and more common, and Wireless speeds have increased tremendously over the last couple of years.

An Access Point (AP) is the equivalent of an access switch that converts the electrical signals to the Radio Frequency (RF) signals and vice versa for communication. Each AP has an RF antenna that is used to radiate the RF signals into the air, and a physical port for connecting the user back to the network. Some APs are also deployed in a mesh mode, where the backhaul or connectivity to the network is via a series of RF hops. However, in typical campus scenarios, the AP would have a wired port to connect back to the core network over an Ethernet port. Some APs also draw power over the same Ethernet port using Power over Ethernet (PoE) technology defined in the IEEE 802.3af standard, that can provide up to 15W of power over the UTP cables of category 5e (Cat5e) or higher. This was later enhanced to PoE + (IEEE Standard 802.3at), providing 30W, and Cisco proprietary UPOE that provides 60W of power to devices. The upcoming standard 802.3bt would enhance this limit to 90W over an Ethernet cable.

Wi-Fi standards for RF transmission have also evolved from time to time, providing different access speeds over the RF interface:

We will compare the technologies used in the Wi-Fi domain in more detail in Chapter 5, Understanding and Configuring Wireless Access Technologies.