Specifications such as Zigbee, ISA100.11a, WirelessHART, MiWi, 6LoWPAN, Thread, and SNAP defines high-level communication protocols for low-rate wireless personal area networks (LR-WPANs) based on IEEE 802.15.4. Which of the following is not a class of Zigbee devices? (Wentz QOTD)
A. Router
B. Multiplexer
C. End device
D. Coordinator
Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.
My suggested answer is B. Multiplexer.
Wentz’s book, The Effective CISSP: Security and Risk Management, helps CISSP and CISM aspirants build a solid conceptual security model. It is a tutorial for information security and a supplement to the official study guides for the CISSP and CISM exams and an informative reference for security professionals.
There are three classes of Zigbee devices:
Zigbee coordinator (ZC): The most capable device, the coordinator forms the root of the network tree and may bridge to other networks. There is precisely one Zigbee coordinator in each network since it is the device that started the network originally (the Zigbee LightLink specification also allows operation without a Zigbee coordinator, making it more usable for off-the-shelf home products). It stores information about the network, including acting as the trust center and repository for security keys.
Zigbee router (ZR): As well as running an application function, a router can act as an intermediate router, passing data on from other devices.
Zigbee end device (ZED): Contains just enough functionality to talk to the parent node (either the coordinator or a router); it cannot relay data from other devices. This relationship allows the node to be asleep a significant amount of the time thereby giving long battery life. A ZED requires the least amount of memory and thus can be less expensive to manufacture than a ZR or ZC.
Source: Wikipedia
Multiplexer
In electronics, a multiplexer (or mux; spelled sometimes as multiplexor), also known as a data selector, is a device that selects between several analog or digital input signals and forwards the selected input to a single output line. The selection is directed by a separate set of digital inputs known as select lines. A multiplexer of 2n inputs has n select lines, which are used to select which input line to send to the output.
A multiplexer makes it possible for several input signals to share one device or resource, for example, one analog-to-digital converter or one communications transmission medium, instead of having one device per input signal. Multiplexers can also be used to implement Boolean functions of multiple variables.
Source: Wikipedia
Reference
Zigbee、ISA100.11a、WirelessHART、MiWi、6LoWPAN、Thread 和 SNAP 等規範定義了基於 IEEE 802.15.4 的低速率無線個人區域網絡 (LR-WPAN) 的高級通信協議。 以下哪個不是 Zigbee 設備的類別？ (Wentz QOTD)
A. Router
B. Multiplexer
C. End device
D. Coordinator