Knowledge Based

The 802.11 wireless standards, also known as Wi-Fi standards, are a family of specifications developed by the Institute of Electrical and Electronics Engineers (IEEE) that define how devices communicate wirelessly on a WLAN (Wireless Local Area Network). These standards specify how data is transmitted and received over radio waves, ensuring compatibility between devices from various manufacturers. Here’s a breakdown of some common variations of the 802.11 standards:

• 802.11a: Launched in 1999, this standard operates in the 5 GHz band. It offered faster speeds compared to earlier standards but with a shorter range.

• 802.11b: Released in 1999, this standard operates in the 2.4 GHz band. It provided a balance between range and speed but was susceptible to interference from common devices like cordless phones and microwave ovens that also use the same frequency band.

• 802.11g: Introduced in 2003, this standard also operates in the 2.4 GHz band but offers faster data rates than 802.11b while maintaining backward compatibility.

• 802.11n: Released in 2009, this standard introduced MIMO (Multiple-Input Multiple-Output) technology, which significantly improved data rates and range over previous standards. It operates in both 2.4 GHz and 5 GHz bands.

• 802.11ac: Released in 2013, this standard offered significant speed improvements over 802.11n. It operates in both 2.4 GHz and 5 GHz bands and utilizes wider channels and higher modulation techniques to achieve faster data transfer rates.

• 802.11ax (Wi-Fi 6): Released in 2021, this is the latest standard known for even higher data rates, improved capacity to handle more devices on a network, and better performance in congested environments. It operates in the 2.4 GHz, 5 GHz, and even the 6 GHz band (where available).

It’s important to note that these are just some of the most common variations of the 802.11 standards. The IEEE 802.11 working group continues to develop new amendments and standards to address the ever-growing demands for faster speeds, wider coverage, better network congestion handling, and increased energy efficiency. pen_spark

A serial-to-Ethernet converter acts as a bridge between serial devices and Ethernet networks. Serial communication involves sending data one bit at a time over a wired connection, while Ethernet transmits data in packets over a network. The converter translates between these two different communication protocols.

Here’s a breakdown of how a serial-to-Ethernet converter works:

1. Connection: You’ll connect your serial device (usually through a serial port like RS-232) to the converter. The converter itself will then be connected to your Ethernet network using an Ethernet cable.

2. Data Transmission: When the serial device transmits data, the converter receives it as a serial data stream.

3. Encapsulation: The converter encapsulates the serial data within an Ethernet packet. This packet includes the serial data itself, along with addressing information and other control signals necessary for proper network transmission.

4. Transmission over Ethernet: The converter then transmits the Ethernet packet over the network to the designated recipient. This recipient could be another computer on the network running software that can understand the serial data, or another serial-to-Ethernet converter connected to a different serial device.

5. Decapsulation and Delivery: When the Ethernet packet reaches its destination, the receiving converter (or software) decapsulates the packet, extracts the original serial data, and delivers it to the connected serial device.

6. Bi-directional Communication: Serial-to-Ethernet converters typically operate bidirectionally. This means they can both transmit and receive data, allowing for two-way communication between the serial device and the network.

Here are some additional points to consider:

• Configuration: Serial-to-Ethernet converters might require some configuration to specify communication settings like baud rate, parity, and data bits. These settings need to match the settings of the serial device for proper communication.

• Virtual COM Ports: Some converter solutions create virtual COM ports on the connected computer. This allows software designed for traditional serial communication to interact with the serial device over the network as if it were directly connected.

• Applications: Serial-to-Ethernet converters are used in various industrial and commercial applications where legacy serial devices need to be integrated into modern Ethernet networks. This allows for remote access, monitoring, and control of these devices from a central location.

Overall, serial-to-Ethernet converters play a crucial role in bridging the gap between legacy serial devices and modern Ethernet networks, facilitating communication and data exchange in various industrial settings.

An industrial Ethernet network is a system that connects devices on a Local Area Network (LAN) using Ethernet technology. Here’s a breakdown of what an Ethernet network is and how it works:

Components:

• Devices: These can be computers, printers, servers, gaming consoles, or any device with an Ethernet port.

• Cables: Ethernet networks traditionally use twisted-pair copper cables to connect devices. In some cases, fiber optic cables are used for longer distances or higher bandwidth needs.

• Network Devices (optional): Switches and routers are networking devices that can be used to manage data flow within the network and connect multiple Ethernet segments. For small home networks, a simple router with built-in switch functionality might be sufficient.

How it Works:

1. Data Transmission: When a device on the network wants to send data to another device, it packages the data into packets. These packets contain the destination address, source address, and the actual data itself.

2. Communication: The device transmits the data packet over the Ethernet cable to the connected network switch (or router).

3. Routing (if using a switch): The switch reads the destination address in the packet and intelligently routes it towards the intended recipient device on the network.

4. Delivery: The recipient device receives the data packet, verifies the destination address, and extracts the actual data.

Benefits of Ethernet Networks:

• Reliability: Wired connections offer a stable and dependable connection compared to Wi-Fi, which can be affected by interference and signal fluctuations.

• Speed: Ethernet provides high data transfer rates, enabling fast communication and data exchange between devices. Speeds can range from 10 Mbps (megabits per second) to 10 Gbps (gigabits per second) depending on the Ethernet standard used.

• Security: Wired connections are generally considered more secure than wireless connections, as they are less susceptible to eavesdropping.

• Scalability: Ethernet networks can be easily scaled to accommodate more devices by adding switches and extending cables.

Applications:

Ethernet networks are the foundation of wired networking in various settings, including:

• Homes: Connecting computers, printers, and other devices for sharing resources and internet access.

• Businesses: Creating a secure and reliable network for communication, data transfer, and resource sharing within an organization.

• Schools: Enabling network access for computers, labs, and other devices used for educational purposes.

Overall, Ethernet networks offer a reliable and efficient way to connect devices and share data on a Local Area Network. They provide the backbone for wired communication in homes, businesses, and many other organizations.

ACE is an acronym for Access Control Entry. It describes access permission associated with a particular ACE ID. There are three ACE frame types (Ethernet Type, ARP, and IPv4) and two ACE actions (permit and deny). The ACE also contains many detailed, different parameter options that are available for individual application.

ACL is an acronym for Access Control List. It is the list table of ACEs, containing access control entries that specify individual users or groups permitted or denied to specific traffic objects, such as a process or a program. Each accessible traffic object contains an identifier to its ACL. The privileges determine whether there are specific traffic object access rights. ACL implementations can be quite complex, for example, when the ACEs are prioritized for the various situation. In networking, the ACL refers to a list of service ports or network services that are available on a host or server, each with a list of hosts or servers permitted or denied to use the service. ACL can generally be configured to control inbound traffic, and in this context, they are similar to firewalls.

AES is an acronym for Advanced Encryption Standard. The encryption key protocol is applied in 802.1i standard to improve WLAN security. It is an encryption standard by the U.S. government, which will replace DES and 3DES. AES has a fixed block size of 128 bits and a key size of 128, 192, or 256 bits.

APS is an acronym for Automatic Protection Switching. This protocol is used to secure that switching is done bidirectional in the two ends of a protection group, as defined in G.8031.

ARP is an acronym for Address Resolution Protocol. It is a protocol that used to convert an IP address into a physical address, such as an Ethernet address. ARP allows a host to communicate with other hosts when only the Internet address of its neighbors is known. Before using IP, the host sends a broadcast ARP request containing the Internet address of the desired destination system.

ARP Inspection is a secure feature. Several types of attacks can be launched against a host or devices connected to Layer 2 networks by “poisoning” the ARP caches. This feature is used to block such attacks. Only valid ARP requests and responses can go through the switch device.

DES is an acronym for Data Encryption Standard. It provides a complete description of a mathematical algorithm for encrypting (enciphering) and decrypting (deciphering) binary coded information.

• DHCP – is an acronym for Dynamic Host Configuration Protocol. It is a protocol used for assigning dynamic IP addresses to devices on a network.

  DHCP Relay – is used to forward and to transfer DHCP messages between the clients and the server when they are not on the same subnet domain.

  DHCP Snooping – is used to block intruder on the untrusted ports of the switch device when it tries to intervene by injecting a bogus DHCP reply packet to a legitimate conversation between the DHCP client and server.

IP is an acronym for Internet Protocol. It is a protocol used for communicating data across an internet network. IP is a “best effort” system, which means that no packet of information sent over is assured to reach its destination in the same condition it was sent. Each device connected to a Local Area Network (LAN) or Wide Area Network (WAN) is given an Internet Protocol address, and this IP address is used to identify the device uniquely among all other devices connected to the extended network. The current version of the Internet protocol is IPv4, which has 32-bits Internet Protocol addresses allowing for in excess of four billion unique addresses. This number is reduced drastically by the practice of webmasters taking addresses in large blocks, the bulk of which remain unused. There is a rather substantial movement to adopt a new version of the Internet Protocol, IPv6, which would have 128-bits Internet Protocol addresses. This number can be represented roughly by a three with thirty-nine zeroes after it. However, IPv4 is still the protocol of choice for most of the Internet.

IPMC is an acronym for IP Multicast. IPMC supports IPv4 and IPv6 multicasting. IPMCv4 denotes multicast for IPv4. IPMCv6 denotes multicast for IPv6.

IPMC Profile is an acronym for IP Multicast Profile. IPMC Profile is used to deploy the access control on IP multicast streams.

IP Source Guard is a secure feature used to restrict IP traffic on DHCP snooping untrusted ports by filtering traffic based on the DHCP Snooping Table or manually configured IP Source Bindings. It helps prevent IP spoofing attacks when a host tries to spoof and use the IP address of another host.

LACP is an IEEE 802.3ad standard protocol. The Link Aggregation Control Protocol, allows bundling several physical ports together to form a single logical port.

The IEEE 802.2 Logical Link Control (LLC) protocol provides a link mechanism for upper layer protocols. It is the upper sub-layer of the Data Link Layer and provides multiplexing mechanisms that make it possible for several network protocols (IP, IPX) to coexist within a multipoint network. LLC header consists of 1 byte DSAP (Destination Service Access Point), 1 byte SSAP (Source Service Access Point), 1 or 2 bytes Control field followed by LLC information.

LLDP is an IEEE 802.1ab standard protocol. The Link Layer Discovery Protocol(LLDP) specified in this standard allows stations attached to an IEEE 802 LAN to advertise, to other stations attached to the same IEEE 802 LAN, the major capabilities provided by the system incorporating that station, the management address or addresses of the entity or entities that provide management of those capabilities, and the identification of the stations point of attachment to the IEEE 802 LAN required by those management entity or entities. The information distributed via this protocol is stored by its recipients in a standard Management Information Base (MIB), making it possible for the information to be accessed by a Network Management System (NMS) using a management protocol such as the Simple Network Management Protocol (SNMP).

LLDP-MED is an extension of IEEE 802.1ab and is defined by the telecommunication industry association (TIA-1057).

LLQI (Last Listener Query Interval) is the maximum response time used to calculate the Maximum Response Code inserted into Specific Queries. It is used to detect the departure of the last listener for a multicast address or source. In IGMP, this term is called LMQI (Last Member Query Interval).

Switching of frames is based upon the DMAC address contained in the frame. The switch builds up a table that maps MAC addresses to switch ports for knowing which ports the frames should go to (based upon the DMAC address in the frame). This table contains both static and dynamic entries. The static entries are configured by the network administrator if the administrator wants to do a fixed mapping between the DMAC address and switch ports. The frames also contain a MAC address (SMAC address), which shows the MAC address of the equipment sending the frame. The SMAC address is used by the switch to automatically update the MAC table with these dynamic MAC addresses. Dynamic entries are removed from the MAC table if no frame with the corresponding SMAC address have been seen after a configurable age time.

MD5 is an acronym for Message-Digest algorithm 5. MD5 is a message digest algorithm, used cryptographic hash function with a 128-bit hash value. It was designed by Ron Rivest in 1991. MD5 is officially defined in RFC 1321 – The MD5 Message-Digest Algorithm.

For debugging network problems or monitoring network traffic, the switch system can be configured to mirror frames from multiple ports to a mirror port. (In this context, mirroring a frame is the same as copying the frame.) Both incoming (source) and outgoing (destination) frames can be mirrored to the mirror port.

MLD is an acronym for Multicast Listener Discovery for IPv6. MLD is used by IPv6 routers to discover multicast listeners on a directly attached link, much as IGMP is used in IPv4. The protocol is embedded in ICMPv6 instead of using a separate protocol.

MLD Querier A router sends MLD Query messages onto a particular link. This router is called the Querier. There will be only one MLD Querier that wins Querier election on a particular link.

In 2002, the IEEE introduced an evolution of RSTP: the Multiple Spanning Tree Protocol. The MSTP protocol provides for multiple spanning tree instances, while ensuring RSTP and STP compatibility. The standard was originally defined by IEEE 802.1s, but was later incorporated in IEEE 802.1D-2005.

Multicast VLAN Registration (MVR) is a protocol for Layer 2 (IP)-networks that enables multicast-traffic from a source VLAN to be shared with subscriber-VLANs. The main reason for using MVR is to save bandwidth by preventing duplicate multicast streams being sent in the core network, instead the stream(s) are received on the MVR-VLAN and forwarded to the VLANs where hosts have requested it/them.

NAS is an acronym for Network Access Server. The NAS is meant to act as a gateway to guard access to a protected source. A client connects to the NAS, and the NAS connects to another resource asking whether the client’s supplied credentials are valid. Based on the answer, the NAS then allows or disallows access to the protected resource. An example of a NAS implementation is IEEE 802.1X.

NetBIOS is an acronym for Network Basic Input/Output System. It is a program that allows applications on separate computers to communicate within a Local Area Network (LAN), and it is not supported on a Wide Area Network (WAN). The NetBIOS giving each computer in the network both a NetBIOS name and an IP address corresponding to a different host name, provides the session and transport services described in the Open Systems Interconnection (OSI) model.

NFS is an acronym for Network File System. It allows hosts to mount partitions on a remote system and use them as though they are local file systems.

NFS allows the system administrator to store resources in a central location on the network, providing authorized users continuous access to them, which means NFS supports sharing of files, printers, and other resources as persistent storage over a computer network.

NTP is an acronym for Network Time Protocol, a network protocol for synchronizing the clocks of computer systems. NTP uses UDP (datagrams) as transport layer.

OAM is an acronym for Operation Administration and Maintenance. It is a protocol described in ITU-T Y.1731 used to implement carrier Ethernet functionality. MEP functionality like CC and RDI is based on this.

A LLDP frame contains multiple TLVs For some TLVs it is configurable if the switch shall include the TLV in the LLDP frame. These TLVs are known as optional TLVs. If an optional TLVs is disabled the corresponding information is not included in the LLDP frame.

OUI is the organizationally unique identifier. An OUI address is a globally unique identifier assigned to a vendor by IEEE. User can determine which vendor a device belongs to according to the OUI address which forms the first 24 bits of a MAC address.

PCP is an acronym for Priority Code Point. It is a 3-bit field storing the priority level for the 802.1Q frame. It is also known as User Priority.

PoE is an acronym for Power Over Ethernet. Power over Ethernet is used to transmit electrical power, to remote devices over standard Ethernet cable. It could for example be used for powering IP telephones, wireless LAN Access Points (AP), IP cameras and other equipment, where it would be difficult or expensive to connect the equipment to main power supply.

PD is an acronym for Powered Device. In a PoE system the power is delivered from a PSE ( power sourcing equipment ) to a remote device. The remote device is called a PD.

PHY is an abbreviation for Physical Interface Transceiver and is the device that implements the Ethernet physical layer (IEEE-802.3).

Ping (Packet InterNet Grouper) is a program that sends a series of packets over a network or the Internet to a specific computer in order to generate a response from that computer. The other computer responds with an acknowledgment that it received the packets. Ping was created to verify whether a specific computer on a network or the Internet exists and is connected. Ping uses Internet Control Message Protocol (ICMP) packets. The PING Request is the packet from the origin computer, and the PING Reply is the packet response from the target.

A policer can limit the bandwidth of received frames. It is located in front of the ingress queue.

POP3 is an acronym for Post Office Protocol version 3. It is a protocol for email clients to retrieve email messages from a mail server.

POP3 is designed to delete mail on the server as soon as the user has downloaded it. However, some implementations allow users or an administrator to specify that mail be saved for some period of time. POP can be thought of as a “store-and-forward” service.

An alternative protocol is Internet Message Access Protocol (IMAP). IMAP provides the user with more capabilities for retaining e-mail on the server and for organizing it in folders on the server. IMAP can be thought of as a remote file server.

POP and IMAP deal with the receiving of e-mail and are not to be confused with the Simple Mail Transfer Protocol (SMTP). You send e-mail with SMTP, and a mail handler receives it on your recipient’s behalf. Then the mail is read using POP or IMAP. IMAP4 and POP3 are the two most prevalent Internet standard protocols for e-mail retrieval. Virtually all modern e-mail clients and servers support both.

PPPoE is an acronym for Point-to-Point Protocol over Ethernet. It is a network protocol for encapsulating Point-toPoint Protocol (PPP) frames inside Ethernet frames. It is used mainly with ADSL services where individual users connect to the ADSL transceiver (modem) over Ethernet and in plain Metro Ethernet networks.

In a private VLAN, PVLANs provide layer 2 isolation between ports within the same broadcast domain. Isolated ports configured as part of PVLAN cannot communicate with each other. Member ports of a PVLAN can communicate with each other.

PTP is an acronym for Precision Time Protocol, a network protocol for synchronizing the clocks of computer systems. It is follow IEEE1588v1/2 standard.

QCE is an acronym for QoS Control Entry. It describes QoS class associated with a particular QCE ID. There are six QCE frame types: Ethernet Type, VLAN, UDP/TCP Port, DSCP, TOS, and Tag Priority. Frames can be classified by one of 4 different QoS classes: “Low”, “Normal”, “Medium”, and “High” for individual application.

QCI is an acronym for QoS Class Identifier. This is a special identifier defining the quality of packet communication provided by LTE (Long Term Evolution, marketed as 4G LTE).

QCL is an acronym for QoS Control List. It is the list table of QCEs, containing QoS control entries that classify to a specific QoS class on specific traffic objects. Each accessible traffic object contains an identifier to its QCL. The privileges determine specific traffic object to specific QoS class.

QL In SyncE this is the Quality Level of a given clock source. This is received on a port in a SSM indicating the quality of the clock received in the port.

QoS is an acronym for Quality of Service. It is a method to guarantee a bandwidth relationship between individual applications or protocols.

A communications network transports a multitude of applications and data, including high-quality video and delay sensitive data such as real-time voice. Networks must provide secure, predictable, measurable, and sometimes guaranteed services.

Achieving the required QoS becomes the secret to a successful end-to-end business solution. Therefore, QoS is the set of techniques to manage network resources.

QoS class

Every incoming frame is classified to a QoS class, which is used throughout the device for providing queuing, scheduling and congestion control guarantees to the frame according to what was configured for that specific QoS class. There is a one to one mapping between QoS class, queue and priority. A QoS class of 0 (zero) has the lowest priority.