All about wireless networking and NMS/EMS

RSSI: RSSI is the receiver signal strength indicator, RSSI is usually a negative value; the closer to 0, the better. unit dBm. SNR Signal to Noise ratio: SNR is signal strength, relative to noise level. The higher the SNR, the better. Unit dB. Fade margin: It’s calculated from Received rssi level vs threshold rssi level. Unit dB (+ve value). Higher the value meant by good signal strength.

Logical network. A single layer 2 network portioned to create multiple broadcast domains. Which are mutually isolated, 4095 vlans (0 to 4095 are reserved). 32 bit will added to the Ethernet frame b/w source mac and etherType. It reduce the broadcasting by increasing the broadcasting domain. 16 bits 3 bits 1 bit 12 bits TPID TCI PCP DEI VID ·          Tag protocol identifier (TPID) : a 16-bit field set to a value of 0x8100 in order to identify the frame as an IEEE 802.1Q-tagged frame. This field is located at the same position as the EtherType/length field in untagged frames, and is thus used to distinguish the frame from untagged frames. ·          Tag control information (TCI) ·          Priority code point (PCP) : a 3-bit field which refers to the   IEEE 802.1p   class of service   and maps to the frame priority level. Values in order of priority are: 1 (background), 0 (best effort), 2 (excellen

SSID( service set identifier) ASSCI string : A series of 0 to 32 octets, Network name, Unique identifier for a wireless LAN. BSS(Basis service set): a single AP together with all associated clients(STAs) is called a BSS. Each BSS is uniquely identified by a   basic service set identification   (BSSID) BSSID(Basis service set identifier): the BSSID is the MAC address   of the   AP generated by combining the 24 bit Organization Unique Identifier (the manufacturer's identity) and the manufacturer's assigned 24-bit identifier. ESS(Extended Service set): each BSS still has its BSSID, however, the entire ESS uses only one SSID ( to facilitate roaming), BSSID is a locally administered MAC address generated from a 48-bit random number. Hiding SSID: AP will not broadcast the SSID, this feature is to prevent unauthorized users from being able to detect the wireless network from their wireless clients. APs send beacon frames to advertise capability information

To establish a distributed WLAN, two or more access points are configured with the same service set identifier ( SSID ). Access points configured with the same SSID make up a single  logical network  within a single  Layer 2 broadcast domain, which means that they must all be able to communicate. The most common use of a wireless distribution system is to bridge a WLAN spanning two buildings. The simplest WDS consists of two access points configured to forward messages to each other. WDS may provide two modes of access point-to-access point (AP-to-AP) connectivity: ·          Wireless bridging , in which WDS APs (AP-to-AP) communicate only with each other and don't allow wireless stations (STA) (also known as wireless clients) to access them ·          Wireless repeating , in which APs communicate with each other and with wireless STAs

WPS: Wi-Fi Protected Setup (WPS) is the industry standard method to simplify the security setup of Wi-Fi networks. You now can easily setup and connect to a WPA-enabled 802.11 network with WPS-certificated devices using either Personal Information Number (PIN) or Push Button Configuration (PBC) or NFC. Push button method : in which the user has to push a button, on both the access point and the new wireless client device. Support of this mode is mandatory for access points and optional for connecting devices. PIN entry : in all Wi-Fi Protected Setup networks, a unique PIN (Personal Identification Number) will be required for each device to join the network.  A fixed PIN label or sticker may be placed on a device, or a dynamic PIN can be generated and shown on the device's display (e.g., a TV screen or monitor).  PIN is used to make sure the intended device is added to the network being set up and will help to avoid accidental or malicious attempts to add unintended devices

IEEE802.11a, IEEE802.11b/g, IEEE802.11n and IEEE802.11ac are the widely used wifi protocols now. For Modulation and supported rate please refer the below links. 1) https://en.wikipedia.org/wiki/IEEE_802.11 2) http://mcsindex.com/

Wi-Fi stands for  wi reless  Fi delity. WiFi is based on the IEEE 802.11 family of standards. Wi-Fi uses (RF)electromagnetic signal to transmit and receive data. Frequency band 2.4,  3.6 , 5, and  60 GHz Why Wi-Fi is half Duplex? All Wi-Fi networks are contention-based TDD systems, where the access point and the mobile stations use the same channel. Because of the shared media operation, all Wi-Fi networks are half duplex. How does wifi client connects to Wifi access point:  it is important to understand how an Access Point and wireless client start their initial communication. Once the wireless network is up and running, WLAN clients connect to an Access Point that provides it the best connection and data rate possible. Before a client connects to an AP, the client must first figure out to which AP it should connect. 802.11 WLANs consist of multiple elements and behaviors which make up the foundation of the 802.11 protocol. A key part of the protocol discovers the