My Notes from chapter 10 of the CWNA study guide

Wireless LAN client devices

• 802.11 Radio form factors
  • 802.11 radios are used in both client NICs and access points.
  • External Radios
    • Many form factors, meaning the NIC comes in different shapes and sizes:
      • PCMCIA adapter/PC card
      • Express Card
      • USB
  • Internal Radios
    • Installed inside the device
    • Mini PCI
    • Mini PCI Express
  • Mobile Devices
    • Smartphones
    • Tablets
    • Bar code scanners
    • VoWiFi phones
  • Wearables
    • Google Glass
    • Fitbit
    • Etc.
  • Internet of Things (IoT)
• 802.11 Radio chipsets
  • A group of integrated circuits designed to work together is often marketed as a chipset.
  • Some chipsets may only support the ability to transmit on the 2.4 GHz ISM band; other chipsets can transmit on either the 2.4 GHz or 5 GHz unlicensed frequencies
  • Many proprietary technologies turn up in the individual chipsets, and some of these technologies will become part of the standard in future 802.11 amendments.
• Client utilities
  • End user must have the ability to configure a wireless client NIC
  • Software interface is needed in the form of client utilities
  • Three major types, or categories, of client utilities exist:
    • Integrated operating system client utilities
    • Vendor-specific client utilities
    • Third-party client utilities
• Management, control and data planes
  • Telecommunication networks are often defined as three logical planes of operation:
    • Management Plane
      • WLAN Configuration
        • configurations of SSIDS, security, WMM, channel, and power settings.
      • WLAN Monitoring and Reporting
        • Monitoring of layer 2 statistics like ACKs, client associations, resassociations, and data rates occurs in the management plane
      • WLAN Firmware Management
        • The ability to upgrade access points and other WLAN devices with the latest vendor operational code is included here
    • Control Plane
      • Dynamic RF
        • Coordinated channel and power settings for multiple access points
        • Dynamic RF is also referred to by the more technical term radio resource management (RRM).
      • Roaming Mechanisms
        • Support for roaming handoffs between access points
        • L3 roaming, maintaining stateful firewall sessions of clients, and forwarding of buffered packets
      • Client Load Balancing
        • Collecting and sharing client load and performance metrics between access points to improve overall WLAN operations
      • Mesh Protocols
        • Routing user data between multiple access points requires some sort of mesh routing protocol.
    • Data Plane
      • Where user data is forwarded
      • A standalone AP handles all data forwarding operations locally
      • In a WLAN controller solution, data is normally forwarded from the centralized controller, but data can also be forwarded at the edge of the network by an AP.

WLAN architecture

• Autonomous WLAN architecture
  • The conventional access point was a standalone WLAN portal device where all three planes of operation existed and operated on the edge of the network architecture
  • All configuration settings exist in the autonomous access point itself
  • All encryption and decryption mechanisms and MAC layer mechanisms also operate within the autonomous AP.
  • An autonomous access point contains at least two physical interfaces: usually a radio frequency (RF) radio card and a 10/100/1000 Ethernet port.
  • Autonomous APs are deployed at the access layer and typically are powered by a PoE capable access layer switch.
• Centralized network management systems
  • A WNMS moves the management plane out of the autonomous access points.
  • Provides a central point of management to configure and maintain thousands of autonomous access points.
  • Network management server (NMS) is now used more often
• Cloud networking
  • Applications and network management, monitoring, functionality, and control are provided as a software service
  • The two most common cloud networking models are as follows:
    • Cloud-Enabled Networking (CEN)
      • The management plane resides in the cloud, but data plane mechanisms such as switching and routing remain on the local network
    • Cloud-Based Networking (CBN)
      • The data plane is also moved to the cloud with the intent of eliminating hardware other than that used to access the Internet at the local network
• Centralized WLAN architecture
  • Central WLAN controller that resides in the core of the network.
  • Autonomous APs have been replaced with controller-based access points, also known as lightweight APs or thin APs
  • All planes were moved out of access points and into a WLAN controller
  • Encryption and decryption capabilities might reside in the centralized WLAN controller or may still be handled by the controller-based APs, depending on the vendor
  • Some time-sensitive operations are still handled by the AP
  • WLAN Controller:
    • WLAN controllers are often referred to as wireless switches
    • Some vendors use proprietary protocols for communications between the WLAN controller and their controller-based
    • APs.
    • Many WLAN vendors use the Control and Provisioning of Wireless Access Points (CAPWAP) protocol for managing and monitoring access points
    • Can support multiple BSSIDs and VLANs
• Distributed WLAN architecture
  • Cooperative access points are used, and control plane mechanisms are enabled in the system with inter-AP communication via cooperative protocols.
  • A distributed WLAN architecture combines multiple access points with a suite of cooperative protocols, without requiring a WLAN controller
  • The control plane information is shared between the APs using proprietary protocols
• Unified WLAN architecture
  • Fully integrating WLAN controller capabilities into wired network infrastructure devices
• Hybrid architecture
  • Hybrid of any of the above

Specialty WLAN infrastructure

• Wireless workgroup bridge
  • Is a wireless device that provides wireless connectivity for wired infrastructure devices that do not have radio cards.
  • WGB is an associated client of the access point, the WGB does not provide connectivity for other wireless clients

• Wireless LAN bridges
  • The purpose of bridging is to provide wireless connectivity between two or more wired networks.
  • Wireless bridges support two major confi guration settings: root and nonroot.
  • A bridge link that connects only two wired networks is known as a point-to-point (PtP) bridge

• A point-to-multipoint (PtMP) bridge link connects multiple wired networks

• A common problem with point-to-multipoint bridging is mounting the high-gain omnidirectional antenna of the root bridge too high. The result is that the vertical line of sight with the directional antennas of the nonroot bridges is not adequate.

• Enterprise WLAN router
  • A distributed solution using enterprise-grade WLAN routers at each branch office is a common choice.
  • WLAN routers are very different from access points. Unlike access points, which use a bridged virtual interface, wireless routers have separate routed interfaces
• Wireless LAN mesh access points
  • Wireless mesh APs communicate with each other by using proprietary layer 2 routing protocols and create a self-forming and self-healing wireless infrastructure (a mesh) over which edge devices can communicate

• WLAN array
  • Xirrus offers a proprietary solution that combines a WLAN controller and multiple access points in a single hardware device known as a Wi-Fi array
  • Access-point radios using sector antennas and an embedded WLAN controller all reside in one device
  • WLAN arrays are also useful in high user density environments and can also be used to reduce cable runs
• Virtual AP system
  • A virtual access point solution uses multiple access points that all share a single basic service set identifier (BSSID).
  • Clients stations believe they are connected to only a single access point, although they may be roaming across multiple physical APs
• Real-time location systems
  • Network management servers (NMSs), WLAN controllers and WIDS solutions have some integrated capabilities to track 802.11 clients by using the access points as sensors
• VoWiFi
  • VoIP over WiFi.