Thursday, June 4, 2015

1.4.1 Antenna types

There are a number of types of antenna used for wireless LANs. Generally they can be categorised as omnidirectional versus directional, indoor or outdoor. Many modern indoor APs have internal omnidirectional antennas. For point to point deployments, directional antennas are used. The provide high gain and are design for the outdoor environment. Examples of outdoor directional antennas are Yagi, patch, dish and mesh.


Omnidirectional antennas are design to transmit and receive signals in all directions equally (although less so along the axis of the antenna). The rubber-ducky antenna is a common example of an omnidirectional antenna.

Antennas are passive gain devices, in other words they concentrate a signal in certain directions but the overall power output is never more than the input power. Antenna gain is compare to a theoretical isotropic antenna which radiate signal in a perfect sphere. A dipole omnidirectional antenna will generally have a gain of about 2.15dBi.Its radiation pattern will be squashed in the vertical plane (usually desibed as doughnut shaped).

Directional Antennas

Directional antennas focus the energy and therefore have a higher gain than omnidirectional antennas. They are used for indoor areas such as hallways and in warehouses to direct the signal between racking.

Antennas are designated by their beamwidth. This describes how focused the energy is in the vertical plane and is calculated as the range between the half power points i.e. the points where the power output is half that of the maximum power.

1.3 Describe wireless regulatory bodies, standards, and certifications


The FCC is the regulatory body that exists in the United States and several other countries in the Americas. The FCC regulates RF frequencies, channels, and transmission power. The FCC has designated two frequency bands to be used for wireless networks, frequencies lie in the the 2.4Ghz and 5GHz bands.

ISM: 2.4–2.5-GHz
U-NII-1 (Band 1): 5.15 to 5.25 GHz
U-NII-2 (Band 2): 5.25 to 5.35 GHz
U-NII-2 Extended (Band 3): 5.47 to 5.725 GHz
U-NII-3 (Band 4): 5.725 to 5.825 GHz (also allocated as ISM)


The European Telecommunications Standards Institute (ETSI) is the European equivalent to the FCC.
Other countries have different regulatory bodies.

The bands allocated by ETSI are similar to the bands allocated by FCC however U-NII-3 is not available as it is a licenced spectrum.


The Institute of Electric and Electronic Engineers maintains the industry standards that are used for wireless LANs, among many others.

The most relevant IEE defined protocols in relation to wireless is 802.11 (Wireless LANs) and 802.15 (Personal area networks such as Bluetooth and Zigbee).

A thorough understanding of 802.3 (Ethernet) is also required.

WiFi Alliance

The Wi-Fi Alliance is a nonprofit industry association made up of wireless manufacturers around the world, all devoted to promoting wireless use. The WiFi Alliance provides a number of certification programs through which vendors of WiFi devices (Access Point and end user devices) can ensure their devices are compatible.

Trivial File transfer Protocol (TFTP)

Trivial File Transfer Protocol (TFTP) is a simple, lock-step, File Transfer Protocol which allows a Client (computing) to get from or put a file onto a remote Host (network). One of its primary uses is in the early stages of nodes booting from a Local Area Network. TFTP has been used for this application because it is very simple to implement. TFTP lacks security and most of the advanced features offered by more robust file transfer protocols such as File Transfer Protocol. TFTP uses UDP port 69.

The WCS includes a TFTP to store images for controller upgrades, backups of controller configuration files. An external TFTP server can also be used.

If you want to convert an AP from lightweight to standalone, you can do so via the command-
line interface (CLI) or by resetting the AP to factory defaults. If you do it from the
CLI, you use the following command:

archive download-sw /overwrite /force-reload { tftp:|ftp:}//location/

If you are resetting to factory defaults, use the mode button by holding it down until the
LED turns red. This causes the AP to reboot, ignoring its lightweight code, apply an IP address
of, and broadcast for an IOS file. This means you need a TFTP server on that
subnet and a default file on there with the naming convention cplatform_name-k9w7-

Cisco Discovery Protocol (CDP)/Link Layer Discovery Protocol (LLDP)

Cisco Discovery Protocol (CDP)/Link Layer Discovery Protocol (LLDP)

CDP is a Cisco proprietary layer 2 protocol used between directly connected devices. LLDP is a vendor neutral IEEE standard (IEEE 802.1AB) to perform similar functions.

Cisco devices send CDP announcements to the multicast destination address 01-00-0c-cc-cc-cc every 60 seconds by default. Each Cisco device that supports CDP stores the information received from other devices in a table that can be viewed using the show cdp neighbors command. By default information is aged out of the table after 180 seconds unless refreshed.

Cisco wired IP phones perform an intelligent exchange of information between the phone and the
switchport it is plugged into using Cisco Discovery Protocol (CDP). When the switch discovers a Cisco
IP phone, it can extend QoS trust to it dynamically. CDP can be enabled on Cisco wireless phones via Communications Manager.

Cisco recommends that you disable Cisco Discovery Protocol on the controller and access point when connected to non-Cisco switches as CDP is unsupported on non-Cisco switches and network elements.

By default, CDP is disabled on radio interfaces on indoor (nonindoor mesh) access points.

LLDP information is sent by devices from each of their interfaces at a fixed interval, to a series of multicast addresses. Information is stored and can be queried via SNMP. 

If an AP is configured for DHCP, then you can use CDP/LLDP to find out what IP address it has been given by showing the CDP neighbours on the switch to which the AP is connected.

Wednesday, June 3, 2015

NTP (Network Time Protocol)

NTP is a networking protocol design to synchronise clocks from time sources over networks. The NTP protocol is designed to handle the variability of latency in local and wide area networks.

NTP uses a client-server model with time messages sent via UDP on port 123. The current protocol is version 4 (NTPv4), which is a proposed standard as documented in RFC 5905.

NTP uses a hierarchical, semi-layered system of time sources. Each level of this hierarchy is termed a "stratum" and is assigned a number starting with zero at the top.

Stratum 0 

These are high-precision timekeeping devices such as atomic (cesium, rubidium) clocks, GPS clocks or other radio clocks.

Generally it is considered best practice for a client to poll three or more servers and determine the best source of time messages based on returned timestamps.

The Wireless LAN Controller (WLC) requires setting the system time. Once the time is set it will be maintained until a system reset. Using NTP to manage the time on the WLC is preferable. For lightweight APs the time is synchronised to the WLC time. For autonomous APs the time can be set manually.

How to configure time on Autonomous APs

How to configure NTP and SNTP on the Cisco AP

CCNA Wireless Certification - syllabus

Implementing Cisco Unified Wireless Networking Essentials (640-722)

Exam Description: The “Implementing Cisco Unified Wireless Network Essential” (IUWNE) v2.0 640- 722 exam is a 90-minute test with 60–70 questions that are associated with the Cisco CCNA® Wireless certification. This exam tests a candidate's knowledge of installing, configuring, operating, and troubleshooting small to medium-size WLANs.

The following topics are general guidelines for the content that is likely to be included on the exam.
However, other related topics may also appear on any specific instance of the exam. To better reflect the contents of the exam and for clarity purposes, these guidelines may change at any time without notice.

1.       Describe WLAN Fundamentals 20%
1.1   Describe basics of spread spectrum technology
1.2.1          Bluetooth
1.2.2          WiMAX
1.2.3          ZigBee
1.2.4          Cordless phone
1.3.1          FCC
1.3.2          ETSI
1.3.3          802.11a/b/g/n
1.3.4          WiFi Alliance
1.4   Describe WLAN RF principles
1.4.1          Antenna types
1.4.2          RF gain/loss
1.4.3          EIRP
1.4.4          Refraction
1.4.5          Reflection
1.5   Describe networking technologies that are used in wireless
1.5.1          SSID to WLAN_ID to interface to VLAN
1.5.2          802.1q trunking
1.6   Describe wireless topologies
1.6.1          IBSS
1.6.2          BSS
1.6.3          ESS
1.6.4          Point-to-point
1.6.5          Point-to-multipoint
1.6.6          Mesh
1.6.7          Bridging
1.7   Describe 802.11 authentication and encryption methods
1.7.1          Open
1.7.2          Shared
1.7.3          802.1X
1.7.4          EAP
1.7.5          TKIP
1.7.6          AES
1.8   Describe frame types
1.8.1          Associated and unassociated
1.8.2          Management
1.8.3          Control
1.8.4          Data
1.9   Describe basic RF deployment considerations related to site survey design of data or VoWLAN applications
1.9.1          Common RF interference sources such as devices, building material, AP location
1.9.2          Basic RF site survey design related to channel reuse, signal strength, and cell overlap
1.9.3          DNS
1.9.4          DHCP
1.9.5          TFTP
1.9.6          NTP
1.9.7          CDP/LLDP

2         Install a Basic Cisco Wireless LAN 17%
2.1   Identify the components of the Cisco Unified Wireless Network architecture
2.1.1          Split MAC
2.1.2          LWAPP
2.1.3          Standalone AP versus controller-based AP
2.1.4          Specific hardware examples
2.2   Install and configure autonomous access points in the small business environment
2.3   Describe the modes of controller-based AP deployment
2.3.1          Local
2.3.2          Monitor
2.3.3          HREAP
2.3.4          Sniffer
2.3.5          Rogue detector
2.3.6          Bridge
2.3.7          OEAP
2.3.8          SE-Connect
2.4   Describe controller-based AP discovery and association
2.4.1          DHCP
2.4.2          DNS
2.4.3          Master-Controller
2.4.4          Primary-Secondary-Tertiary
2.4.5          n+1 redundancy
2.5   Describe roaming
2.5.1          Layer 2 and Layer 3
2.5.2          Intracontroller and intercontroller
2.5.3          Mobility list
2.6   Configure a WLAN controller and access points
2.6.1          WLC: Ports, interfaces, WLANs, NTP, CLI and Web UI, CLI wizard, and LAG
2.6.2          AP: Channel and Power
2.7   Describe RRM fundamentals including ED-RRM
2.8   Verify basic wireless network operation

3         Install Wireless Clients 15%
3.1   Describe client WLAN configuration requirements, such as SSID, security selection, and authentication
3.2   Identify basic configuration of common wireless supplicants
3.2.1          Macintosh
3.2.2          Intel Wireless Pro
3.2.3          Windows
3.2.4          iOS
3.2.5          Android
3.3   Describe basic Cisco AnyConnect 3.0 or above wireless configuration parameters
3.4   Identify capabilities available in Cisco Unified CCX versions 1 through 5

4         Implement Basic WLAN Security 19%
4.1   Describe the general framework of wireless security and security components
4.1.1          Authentication
4.1.2          Encryption
4.1.3          MFP
4.1.4          IPS
4.2   Describe the evolution of supported authentication methods
4.2.1          PSK
4.2.2          802.1X including EAP-TLS, EAP-FAST, PEAP, LEAP, and WPA/WPA2
4.3   Configure the different sources of authentication
4.3.1          EAP local or EAP external
4.3.2          RADIUS
4.4   Configure authentication and encryption methods on a WLAN
4.4.1          WPA/WPA2 with PSK and 802.1x
4.5   Implement wireless guest networking

5         Operate Basic WCS 17%
5.1   Identify key functions of the Cisco WCS and Navigator (versions and licensing)
5.2   Navigate the WCS interface
5.3   Configure controllers and access points (APs)
5.3.1          Using the configuration tab, not templates
5.4   Use preconfigured maps in the WCS
5.4.1          Adding, relocating, removing access points
5.4.2          Turn heat maps on/off
5.4.3          View client location
5.4.4          View CleanAir zones of influence
5.5   Use the WCS Monitor tab and alarm summary to verify WLAN operations
5.6   Generate standard WCS reports
5.6.1          Inventory
5.6.2          CleanAir
5.6.3          Client-related
5.6.4          AP-related
5.6.5          Utilization

6         Conduct Basic WLAN Maintenance and Troubleshooting 12%
6.1   6.1 Identify and use basic WLAN troubleshooting tools
6.1.1          WLC show debug
6.1.2          Logging for client to AP connectivity, AP-to-controller connectivity
6.2   Use the WCS client troubleshooting tool
6.3   Transfer logs, configuration files, and operating system images to and from the WLC via the GUI
6.4   Differentiate and use WLC and AP (autonomous and LAP) management access methods
6.4.1          Console port
6.4.2          CLI
6.4.3          Telnet
6.4.4          SSH
6.4.5          HTTP
6.4.6          HTTPS
6.4.7          Wired versus wireless management