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
- Many form factors, meaning the NIC comes in different shapes and sizes:
- 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
- WLAN Configuration
- 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.
- Dynamic RF
- 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.
- Management Plane
- Telecommunication networks are often defined as three logical planes of operation:
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
- Cloud-Enabled Networking (CEN)
- 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.