Is a computer positioned between a local network and the Internet that monitors the packets flowing in and out?

Network Communications Standards

Today’s networks connect terminals, devices, and computers from many different manufacturers across many types of networks, such as wide area, local area, and wireless. For the different devices on various types of networks to be able to communicate, the network must use similar techniques of moving data through the network from one application to another.

To alleviate the problems of incompatibility and ensure that hardware and software components can be integrated into any network, various organizations such as ANSI and IEEE (pronounced I triple E) propose, develop, and approve network standards. A network standard defines guidelines that specify the way computers access the medium to which they are attached, the type(s) of medium used, the speeds used on different types of networks, and the type(s) of physical cable and/or the wireless tech- nology used. A standard that outlines characteristics of how two network devices communicate is called a protocol. Hardware and software manufacturers design their products to meet the guidelines specified in a particular standard, so that their devices can communicate with the network.

The following sections discuss some of the more widely used network communications standards for both wired and wireless networks including Ethernet, token ring, TCP/IP, 802.11 (Wi-Fi), Bluetooth, UWB, IrDA, RFID, WiMAX, and WAP.

ETHERNET Ethernet is a network standard that specifies no central computer or device on the network (nodes) should control when data can be transmitted; that is, each node attempts to trans- mit data when it determines the network is able to receive communications. If two computers on an Ethernet network attempt to send data at the same time, a collision occurs, and the computers must attempt to send their messages again.

Ethernet is based on a bus topology, but Ethernet networks can be wired in a star pattern. The Ethernet standard defines guidelines for the physical configuration of the network, e.g., cabling, network cards, and nodes. Today, Ethernet is the most popular LAN standard because it is relatively inexpensive and easy to install and maintain. Ethernet networks often use cables to transmit data.

TOKEN RING The token ring standard specifies that computers and devices on the network share or pass a special signal, called a token, in a unidirectional manner and in a preset order. A token is a special series of bits that function like a ticket. The device with the token can transmit data over the network. Only one token exists per network. This ensures that only one computer transmits data at a time. Token ring is based on a ring topology (although it can use a star topology). The token ring standard defines guidelines for the physical configuration of a network. Some token ring networks connect up to 72 devices. Others use a special type of wiring that allows up to 260 connections.

TCP/IP Short for Transmission Control Protocol/Internet Protocol, TCP/IP is a network standard, specifically a protocol, that defines how messages (data) are routed from one end of a network to the other. TCP/IP describes rules for dividing messages into small pieces, called packets; providing addresses for each packet; checking for and detecting errors; sequencing packets; and regulating the flow of messages along the network.

TCP/IP has been adopted as a network standard for Internet communications. Thus, all hosts on the Internet follow the rules defined in this standard. Internet communications also use other standards, such as the Ethernet standard, as data is routed to its destination.

When a computer sends data over the Internet, the data is divided into packets. Each packet contains the data, as well as the recipient (destination), the origin (sender), and the sequence information used to reassemble the data at the destination. Each packet travels along the fastest individual available path to the recipient’s computer via communications devices called routers.

802.11 (WI-FI) Developed by IEEE, 802.11 also known as Wi-Fi (wireless fidelity) and wireless Ethernet, is a series of network standards that specifies how two wireless devices communicate over the air with each other. Using Wi-Fi, computers or devices that have the appropriate wireless capa- bility communicate via radio waves with other computers or devices. The Wi-Fi standard uses tech- niques similar to the Ethernet standard to specify how physically to configure a wireless network. Most of today’s computers and many personal mobile devices, such as smart phones and handheld game consoles, are Wi-Fi enabled. 

One popular use of the Wi-Fi standard is in hot spots that offer mobile users the ability to connect to the Internet with their Wi-Fi enabled wireless computers and devices. Many homes and small businesses also use Wi-Fi to network computers and devices together wirelessly.

BLUETOOTH Bluetooth is a standard, specifically a protocol, that defines how two Bluetooth devices use short-range radio waves to transmit data. To communicate with each other, Bluetooth devices often must be within about 10 meters (about 33 feet) but can be extended to 100 meters with additional equip- ment. Examples of Bluetooth devices can include desktop computers, notebook computers, handheld computers, smart phones, PDAs, headsets, microphones, digital cameras, and printers.

UWB UWB, which stands for ultra-wideband, is a network standard that specifies how two UWB devices use short-range radio waves to communicate at high speeds with each other. For optimal com- munications, the devices should be within 2 to 10 meters (about 6.5 to 33 feet) of each other. Examples of UWB uses include wirelessly transferring video from a digital video camera, printing pictures from a digital camera, downloading media to a portable media player, or displaying a slide show on a projector.

IRDA Some computers and devices use the IrDA specification to transmit data wirelessly to each other via infrared (IR) light waves. Infrared requires a line-of-sight transmission; that is, the sending device and the receiving device must be in line with each other so that nothing obstructs the path of the infrared light wave.

RFID RFID (radio frequency identification) is a standard, specifically a protocol, that defines how a network uses radio signals to communicate with a tag placed in or attached to an object, an animal, or a person. The tag consists of an antenna and a memory chip that contains the information to be transmitted via radio waves. Through an antenna, an RFID reader reads the radio signals and trans- fers the information to a computer or computing device. Readers can be handheld or embedded in an object such as a doorway or tollbooth.

WIMAX WiMAX (Worldwide Interoperability for Microwave Access), also known as 802.16, is a newer network standard developed by IEEE that specifies how wireless devices communicate over the air in a wide area. Using the WiMAX standard, computers or devices with the appropriate WiMAX wireless capability communicate via radio waves with other computers or devices via a WiMAX tower. The WiMAX tower, which can cover up to a 30-mile radius, connects to the Internet or to another WiMAX tower. 

Two types of WiMAX specifications are fixed wireless and mobile wireless. With fixed wire- less WiMAX, a customer accesses the Internet from a desktop computer at home or other permanent location. Mobile wireless WiMAX, by contrast, enables users to access the WiMAX network with mobile computers and mobile devices such as smart phones.

The WiMAX standard provides wireless broadband Internet access at a reasonable cost over long distances to business and home users. The WiMAX standard, similar to the Wi-Fi stan- dard, connects mobile users to the Internet via hot spots. The next generation of game consoles also plans to support the WiMAX standard. 

WAP The Wireless Application Protocol (WAP) is a standard, specifically a protocol, that specifies how some mobile devices such as smart phones can display the content of Internet services such as the Web, e-mail, and chat rooms. For example, users can check weather, sports scores, and headline news from their WAP-enabled smart phone. To display a Web page on a smart phone, the phone should contain a microbrowser. WAP uses a client/server network. The wireless device contains the client software, which connects to the Internet access provider’s server. 

Modern networks are critical for any enterprise. Networks deliver business applications, multimedia messages and key data to end users around the world. A fundamental element that networks have in common is the network switch, which helps connect devices for the purpose of sharing resources within a local area network (LAN).

What is a network switch?

A network switch is a physical device that operates at the Data Link layer of the Open Systems Interconnection (OSI) model -- Layer 2. It takes in packets sent by devices that are connected to its physical ports, and forwards them to the devices the packets are intended to reach. Switches can also operate at the Network Layer (Layer 3) where routing occurs.

Switches are a common component of networks based on Ethernet, Fibre Channel, Asynchronous Transfer Mode (ATM), and InfiniBand, among others. However, most switches today use Ethernet.

How does a network switch work?

Once a device is connected to a switch, the switch notes its media access control (MAC) address, a code that’s baked into the device’s network-interface card (NIC).The NIC attaches to an Ethernet cable that connects to the switch. The switch uses the MAC address to identify which device’s outgoing packets are being sent, and where to deliver incoming packets.

The MAC address identifies the physical device and doesn’t change, while the network layer (Layer 3) IP address, can be assigned dynamically to a device and change over time. (Think of a MAC address as the VIN number on a car, and the IP address as the license plate.)

When a packet enters the switch, the switch reads its header, then matches the destination address or addresses and sends the packet out through the appropriate ports that lead to the destination devices.

To reduce the chance for collisions between network traffic going to and from a switch and a connected device at the same time, most switches offer full-duplex functionality in which packets coming from and going to a device have access to the full bandwidth of the switch connection. (Picture two people talking on smartphones as opposed to a walkie-talkie).

While it’s true that switches operate at Layer 2, they can also operate at Layer 3, which is necessary for them to support virtual LANs (VLANs), logical network segments that can span subnets. In order for traffic to get from one subnet to another it must pass between switches, and this is facilitated by routing capabilities built into the switches.

What is the difference between a switch and a hub?

A hub can also connect several devices together for the purpose of sharing resources, and the collection of devices attached to a hub is known as a LAN segment.

A hub differs from a switch in that packets sent from one of the connected devices are broadcast to all of the devices that are connected to the hub. With a switch, packets are directed only to the port that leads to the addressed device.

Switches typically connect LAN segments, so hubs attach to them. Switches filter out traffic destined for devices on the same LAN segment. Because of this capability, switches make more efficient use of their own processing resources, as well as network bandwidth.

What is the difference between a switch and a router?

Switches are sometimes confused with routers, which also offer forwarding and routing of network traffic, hence their name. But they do this with a different purpose and location.

Routers operate at Layer 3 -- the network layer -- and are used to connect networks to other networks.

An easy way to think about the difference between switches and routers is to think about LANs and WANs. Devices connect locally through switches, and networks are connected to other networks through routers. This is the path a packet might take to reach the internet: device > hub > switch > router > internet.

Of course, there are cases where switching functionality is built into a router hardware, and the router performs as the switch as well.

Think of your home wireless router. It routes to a broadband connection through its WAN port, but it usually also has additional Ethernet ports that you can use to connect an Ethernet cable for a computer, television, printer or even a gaming console. While other devices on the network, such as other notebooks and phones, connect through the Wi-Fi router, it still offers switching functions through the LAN. So the router, in effect, is also a switch. And you can even connect a separate switch to the router to provide both internet and LAN access for additional devices.

What are the different types of switches?

Switches vary in size, depending on how many devices you need to connect in a specific area, as well as the type of network speed/bandwidth required. In a small office or home office, a four- or eight-port switch usually suffices, but for larger deployments you generally see switches up to 128 ports. The form factor of a smaller switch is an appliance that you can fit on a desktop, but switches are also rack-mountable for placement in a wiring closet, data center or server farm. Sizes of rack-mountable switches range from 1U to 4U, but larger ones are also available.

Switches also vary in the network speed they offer, ranging from Fast Ethernet (10/100 Mbps), Gigabit Ethernet (10/100/1000 Mbps), 10 Gigabit (10/100/1000/10000 Mbps) and even 40/100 Gbps speeds. The choice of speeds depends on the throughput needed for the tasks being supported.

Switches also differ in their capabilities. Here are four types.

1.  Unmanaged

Unmanaged switches are the most basic, offering fixed configuration. They are generally plug-and-play, which means they have few if any options for the user to choose from. They may have default settings for features such as quality of service, but they cannot be changed. The upside is that unmanaged switches are relatively inexpensive, but their lack of features make them unsuitable for most enterprise uses.

2.  Managed

Managed switches offer more functionality and features for IT professionals and are the type most likely seen in business or enterprise settings. Managed switches have command-line interfaces (CLI) to configure them. They support simple network management protocol (SNMP) agents that provide information that can be used to troubleshoot network problems.

They can also support virtual LANs, quality of service settings and IP routing. The security is also better, protecting all types of traffic that they handle. Because of their advanced features, managed switches cost much more than unmanaged switches.

3.  Smart or intelligent switches

Smart or intelligent switches are managed switches that have some features beyond what an unmanaged switch offers, but fewer than a managed switch. While they are more sophisticated than unmanaged switches, they are also less expensive than a fully managed switch. They generally lack support for telnet access and have web GUIs rather than CLIs. Other options, such as VLANs, may not have as many features as those supported by fully managed switches. Because they are less expensive, they may be a good fit for smaller companies with fewer financial resources and/or those with fewer feature needs.

4.   KVM switch

A specific type of switch used in data centers or other areas with large amounts of servers, a KVM switch provides a Keyboard, Video (monitor) and Mouse connection to multiple computers, allowing users to control groups of servers from a single location or console. By adding a KVM extender, KVM switches can allow for local and remote access to the machines, letting a company centralize server maintenance and management.

What are network switch management features?

The full list of features and functionalities of a network switch will vary depending on the switch manufacturer and any additional software provided, but in general a switch will let professionals:

• Enable and disable specific ports on the switch.
• Configure settings for duplex (half or full), as well as bandwidth.
• Set quality of service (QoS) levels for a specific port.
• Enable MAC filtering and other access control features.
• Set up SNMP monitoring of devices, including the health of the link.
• Configure port mirroring, for monitoring network traffic.

What is the value of network switches?

Switches remain important in today’s modern enterprise, as their capabilities can enable further wireless connectivity, as well as support Internet of Things devices and smart buildings that help create a more sustainable operation. The growing use of Industrial Internet of Things devices that connect sensors and machinery in factories also requires switching technologies to connect back to the enterprise network.

Modern switches now likely include Power over Ethernet (PoE) technology that can deliver up to 100W of power to support network-connected devices. This lets companies deploy devices in areas where a separate power outlet is not required, such as security cameras, outdoor lighting, wireless access points, VoIP phones and a litany of sensors (temperature, humidity, moisture, etc.) that can monitor remote areas. Data collected and transmitted from IoT devices can be collected by a switch and be applied to artificial intelligence and machine learning algorithms to help optimize smarter environments.

What are other uses for network switches?

In larger networks, switches are often used to offload traffic for analytics. This can be important to security professionals, where a switch can be placed in front of a WAN router before the traffic goes to the LAN. It can facilitate intrusion detection, performance analytics, and firewalling. In many cases, port mirroring can create a mirror image of the data flowing through the switch before it is sent to an intrusion detection system or packet sniffer.

Switches continue to be used in large data centers and cloud environments, alongside new innovations such as digital twin technologies, network cable consolidation and SD-WAN environments.

At its most basic, however, network switches quickly and efficiently deliver packets from device A to device B, whether they are located across the hallway or halfway around the world. Several other devices contribute to this delivery along the way, but the switch is an essential part of the networking architecture.

Keith Shaw is a freelance digital journalist who has written about the IT world for more than 20 years.

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