CCNP Enterprise Core (350-401)

A directional antenna has a higher gain than an omnidirectional antenna as they focus the radio frequency energy in a particular direction. A typical use for a directional antenna is down long highways or in the aisle of a warehouse. Directional antennas can be used outdoors for areas away from a building or to cover…

An omnidirectional antenna is one of two types of commonly available antennas for wireless devices. The omnidirectional antenna is normally made up of the shape of a cylinder. It usually tries to propagate a signal equally in all directions from the cylinder, resulting in a donut shape pattern that extended further in the H-plane rather…

When an alternating current is applied to an antenna, a wave is produced. The electromagnetic wave will leave the antenna in a certain orientation. A length of wire pointing upwards will produce a wave that oscillates up and down in a vertical direction as it moves through free space. Other types of antennas may move…

Beam width of an antenna gives an idea of the antennas focus. Beamwidth is listed in degrees for both planes in a polar point graph. The beam width is calculated by finding the strongest point on a plot, somewhere on the outer circle. The plot is followed in either direction until the value decreases by…

Antennas are passive devices that do not utilise any external power or circuitry to boost the signal. They amplify or gain the signal by focusing the RF energy and how it is propagated into open space The gain of the antenna is a measure of how effectively it focuses the RF energy in a certain…

Antennas come in all shapes and sizes with their own gain values and intended purposes. Antenna gain is a comparison of an antenna against a isotropic (perfect) antenna is measured in dBi. The isotropic antenna does not actually exist, as a perfect antenna can not be physically made. To visualise an isotropic antenna it can…

From the wireless LAN controller, a lightweight access point can be configured to operate in several different types of mode: Local The default mode of a lightweight access point. It offers one or more basic service sets on a specific channel. When the access point is not transmitting it scans the other channels to measure…

When an AP has completed the staging process and joined a wireless LAN controller, it needs to maintain the connection to the wireless LAN controller to remain functional. If the wireless LAN controller fails, it could mean dozens of access points may drop off the the network, likewise if a group of access points lose…

After the discovery process of a lightweight access point; it should of built a list of live wireless LAN controllers that it can communicate with. The lightweight access point begins a separate process of selecting a single wireless LAN controller and sending a CAPWAP Join Request to it. The access point will wait until the…

Once the lightweight Cisco access point starts up, it operates in a number of different states before it becomes a functional basic service set (BSS). Each of these possible states are defined as part of the Control and Provisioning of Wireless Access Points (CAPWAP) specification in a process called a state machine. Access Point Boots…