Ethernet Switches: What is it and how it works? Our FAQ

At the end of our series of in-depth studies dedicated to network switches, we publish the answers to the questions most frequently asked by readers (FAQ, frequently asked questions).

Using a high-performance Ethernet switch, updated and, preferably, manageable through a web interface, is increasingly important, especially in professional firms and small and medium enterprises.

With the increasing traffic generated by individual workstations within the local network, data storage systems, servers, VoIP and multimedia devices, it is essential to have one or more reliable and high-performance switches.

The benefits are obvious: a latest-generation Gigabit Ethernet switch will allow you to better manage the available bandwidth also allowing the adoption of effective policies for traffic prioritization, the creation of subnets and the isolation of groups of machines and devices.

Netgear’s ProSAFE Plus switches represent an excellent combination of performance, functionality and efficiency.

What is an Ethernet Switch?

An Ethernet switch allows the Ethernet devices connected to it to communicate as if the switch itself did not exist (it is said that its behavior is “transparent”).

Unlike old hubs, a switch forwards frames (that’s the name of the Ethernet packet) coming from any of its ports only to the one to which the frame recipient node is connected.

In this way a switch can drastically reduce the traffic generated by resetting the superfluous traffic. Unlike a hub (which sends data to the entire network), the switch controls the destination of each packet and sends it to the correct device (the connection between the device from which the Ethernet packet starts and the device that is to receive it is direct).

What is the Difference Between a Router and a Switch?

Routers and switches are two network devices that perform different tasks. The first, which can also host a modem (although universally used, the term is incorrect because with modern broadband and ultra-wideband connections there is no signal to be modulated/demodulated as was the case with old 56k modems when bit sequences were properly recoded as electrical signals …), integrates the logic needed to route packets correctly on the basis of the IP address and maintains the necessary routing tables.

In the case of a local network that connects to the Internet, the router plays a fundamental role because it offers NAT functionality: the device allows individual devices connected to the LAN to exchange data, in both directions, with remote systems sharing the same public IP.

To implement NAT, the router therefore needs to perform connection tracking, i.e. to keep track of all the connections that pass through it.

While a router, with reference to the ISO/OSI stack, is a level 3 device (“Network”), the switches are generally level 2 (“Connection” or “Link”).

The task of the switches is in fact to deliver Ethernet frames directly using MAC addresses as reference and avoiding collisions of data packets.

What is the Difference Between Unmanaged and Managed Switches?

Unmanaged switches connect downstream devices to networks and are delivered in a standard configuration that cannot be changed.

Managed switches are highly configurable devices with traffic management, control and prioritization mechanisms.

Netgear offers a wide range of managed web switches that integrate all the most advanced features of managed switches and make them easily accessible and manageable from a web interface (manageable with any browser).

Netgear’s managed (Plus) web switches offer an excellent quality/price ratio: features previously integrated only in high-cost network devices now become usable with a very low economic outlay.

Even if the local network is not composed of a large number of machines, a managed web switch can be a great solution to better manage traffic.

Thanks to VLAN support (also simply port-based), you can create “virtual subnets” completely separate from the main one by setting different policies for traffic management and the distribution of available bandwidth.

However, there is nothing to prevent the use of one or more unmanaged switches alongside, for example, a main managed web switch.

In already structured networks, one can think of replacing some of the unmanaged switches with the new Netgear managed web switches.

How do I Configure a Managed Web Switch?

Just like unmanaged switches, Netgear managed switches are plug and play: they can be connected to the network and “work immediately” without further steps.

Web managed switches were born, however, with the aim of putting in the hands of the network administrator a wide range of additional features.

The suggestion is to change the default IP of the switch by assigning a static one (outside the range used by the DHCP server, generally integrated in the router). This way you can manage it from the browser installed in any workstation.

By typing this IP into the browser address bar and then entering the default username and password (to be changed immediately), you will access the configuration panel of the managed web switch.

The maximum speed at which data can be transferred depends on the specifications of the switch, the port used on the system connected via Ethernet and the cable used.

Today it is always a good idea to choose a Gigabit Ethernet switch that is capable of transferring data up to 1 Gbps. The color of the led located at each port on the switch usually indicates if the Ethernet port is connected to a system capable of transferring data up to 1 Gbps or if (it may also depend on the category of cable used: Ethernet cables: differences and characteristics) you can not go over 100 Mbps.

The most performing switches are the 10 GbE which allow to transfer up to 10 Gbps.

A Gigabit Ethernet switch is now essential to optimize the exchange of data within the local network (think, for example, the traffic that is generated during the sending of files that must be backed up to a storage system such as a NAS server …) and to/from the Internet.

With the increasing spread of ultra-wideband connections, having a switch that avoids bottlenecks and avoids local network congestion is essential today.

What are PoE Ports?

Power over Ethernet or PoE is a technique that allows you to power network equipment using the same cable that connects it to the Ethernet network.

Examples of devices are antennas that can be installed on the roof of the home or business to transfer data at high speed, many IP cameras, video surveillance and access control systems, smart lighting systems, telephones and VoIP devices, some wireless access points.

Two standards are currently supported: PoE and PoE+. The first (IEEE 802.3af specification) allows you to deliver up to 15.4 W DC on each Ethernet port while with PoE+ (IEEE 802.3at) you can go further.

Newer ProSAFE Netgears, for example, allow up to 30 W per port, making them ideal for powering PoE devices.

The advantage of these switches is that they can be used to remotely turn on or off PoE devices connected to various ports. Netgear’s ProSAFE switches clearly indicate when the device is being powered and signal any problems.

The most important functionalities, for each port – in case a PoE powered device is connected – from the administration interface of the ProSAFE device you can define the power required.

How to manage the bandwidth occupied by the devices connected to the switch?

When choosing an Ethernet switch, one of the features that can never be missing is the QoS (Quality of Service) support. In this way, the network administrator can decide which important activities should never be penalized: Netgear’s managed web switches allow you to optimize network performance based on the traffic generated by certain devices or by certain types of services and applications.

In this way it is possible to create both port-based rules, i.e. to give a higher or lower priority to the traffic in transit on a certain Ethernet port or a group of them, or to use the 802.1p protocol to classify the traffic on the basis of different classes of service and, consequently, to define different levels of priority according to the type.

For example, an access point or another switch, even an unmanaged one, can be connected to one of the switch ports and it can be established that – in the case of a very busy network – these devices will have the right to engage much less bandwidth than the others.

Thanks to the use of QoS it will be possible, for example, to avoid those situations in which even a simple heavy upload to the network tends to block – even in downstream – the entire local network.

The switches also allow you to set strict limits in terms of bandwidth occupied by connected devices: by defining a maximum ceiling (egress rate) rather conservative compared to the bandwidth available in upload as the best effort for the connection in use, you will avoid much of the congestion phenomena with which you often have to deal even in the business environment.

How to Duplicate the Bandwidth Available on a Port With a Gigabit Ethernet Switch?

The so-called pork trunking or LAG (Link Aggregation) allows you to increase throughput by combining multiple Ethernet ports of the switch.

This technique extends the connection speed beyond the limits of the individual Ethernet cable and increases redundancy for higher availability.

If the managed web switch is to interconnect distributed networks across multiple floors (think of a company with a large IT infrastructure), the link to the switch on another floor can be made using two or more Ethernet cables. In this way, the “subnet” will not suffer from any bottleneck and the workstations belonging to it will be able to make the best use of the connection.

The trunking port, however, can also be used – always with the devices that support it – with data storage systems. Netgear’s ReadyNAS, for example, can transfer data at a higher speed using link aggregation and, as a result, exploit more bandwidth.

How do I Create Virtual Subnets With a Switch?

Instead of installing new hardware to physically segment a network, more comprehensive switches such as Netgear’s ProSAFE web managed allow you to do so logically by acting on the administration interface.

VLANs (Virtual LANs) allow you to separate groups of devices by completely isolating them from the rest of the local network.

This approach brings with it countless advantages in terms of both security (the resources shared in one network or another are not mutually visible and accessible) and traffic management (a QoS policy will apply more easily and quickly to an entire VLAN).

It is not necessarily necessary to manage a medium-sized network in order to use VLANs.

Providing “guest” access (e.g. via a wireless access point) to any facility means that devices belonging to third parties must be separated from the rest of the network.

Not to mention the scenarios in which VoIP telephony, video surveillance, control and lighting systems are used. These devices must always be working, they must be guaranteed enough bandwidth and their operation must therefore not be affected by the rest of the network traffic.

Here are some examples of Netgear ProSAFE switches that integrate advanced VLAN management.

What Guarantees Does Netgear Offer on its ProSAFE Switches?

The advantage of Netgear ProSAFE switches is that they have been designed and developed with the higher standards required for enterprise-class networks in mind.

Netgear offers the original purchaser a lifetime hardware warranty for ProSAFE products such as switches, firewalls and wireless access points.

This means that Netgear is committed to replacing the ProSAFE device in the event of damage for as long as it is being used by the customer, upon presentation of the original proof of purchase.

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