Business Network Switch Buyers Guide

A network switch connects multiple PCs, workstations, servers or storage devices within a business environment, enabling them to communicate within an organisation and share and access an Internet connection to the wider world. Switches often also connect other network capable or IP (Internet Protocol) devices such as wireless access points, surveillance cameras, phones and video conferencing systems.

Switches increase in functionality depending on where in the network they are intended for so it is important to get the correct feature set. This guide will take you through which network switch will suit a particular environment, how to ensure compatibility with the rest of your network and what management features you should consider

Types of Network Switch

Switches sit at the heart of any LAN (Local Area Network) and depending on where the switch is situated will determine its tasks and naming convention - a switch at the edge of the network will act to provide access to desktop and workstation users, IP phones and wireless users (via wireless access points), whereas a switch at the centre of the network will sit in the back end of the infrastructure and communicate with each other and the servers and storage appliances.

Typically the speed of switches in the core is greater than at the edge, as the majority of data traffic to regular users may just be emails and small files. An edge switch may be deployed at the same speed as core switches if for example you have high demand graphical users, who you want to be able to access large file sizes from the servers. Core switches will also deal with access to the servers from remote workers and external users via the router and over the Internet. The below diagram demonstrates a typical mid-sized organisation’s network - larger organisations may have an additional layer of switches in an ‘aggregation’ layer to consolidate traffic from the edge switches.

It is worth at this stage just reiterating the difference between a switch and a router - essentially a switch allows communication between devices on a network or LAN, whereas a router allows communication between separate networks, sometimes referred to as a WAN (wide area network).

Network Switch Technology and Interfaces

There are two main types of networking protocols in use today - Ethernet and InfiniBand. Both act to do the same job - transmitting data packets from one device on the network to another - however, they differ in the ways they do this and the associated resources they use to do it. You may occasionally come across older technologies such as Fibre Channel or Intel OmniPath, but due to development in the capabilities in Ethernet and InfiniBand, these have largely fallen out of favour.

Ethernet

Ethernet is the most common network protocol delivering speeds starting at 100Mbps (megabits per second) and 1000Mbps or 1Gbps (gigabits per second) often written as 1GbE. In a corporate network, 1GbE has long been the standard, with faster 10GbE, 25GbE, 40GbE and 50GbE speeds also being available. The last few years have seen speeds of Ethernet increase to 100GbE, 200GbE, 400GbE and recently 800GbE, using similar offloading techniques to InfiniBand. Although all these speeds are delivered over Ethernet, the distance of connection and speed required have an impact on the interfaces and the types of cabling used. Up to 10GbE speeds the RJ45 connector is used designed to take a copper cable. Above 10GbE it is more common to see an SFP (small form-factor pluggable) port.

InfiniBand

InfiniBand is an alternative technology to Ethernet, usually found in HPC (high-performance compute) applications where high bandwidth and low latency are key requirements. InfiniBand historically achieved improved throughput by not needing to use the server CPU to control data transmission, hence latency is reduced by removing this step. Like Ethernet there have been several generations of starting with SDR (Single Data Rate) providing 8Gbps throughput. This has since been superseded by DDR (Double) at 16Gbps, QDR (Quad) at 32Gbps, FDR (Fourteen) at 54Gbps, EDR (Enhanced) at 100Gbps, HDR (high) at 200Gbps, NDR (Next) at 400Gbps and recently XDR (Extended) at 800Gbps. As with the higher speeds of Ethernet, differing SFP modules are used depending on the speed and distance required.

SFP and QSFP Transceiver Modules

For RJ45 Ethernet connections the maximum distance data can be transmitted is 100m, which has limitations when looking at networks in large buildings, campuses or even city-wide. The SFP port allows for fibre optic cabling to be employed, which suffers less data loss and can achieve much higher throughput speeds. It is worth mentioning that although traditionally Ethernet has lagged behind Infiniband speeds, this is now changing, due to increased common SFP interface use by the likes of NVIDIA Networking - perhaps driven by the much larger install base of Ethernet technology in the market and the opportunity for upgrade.

Ethernet Switch

InfiniBand Switch

SFP transceivers offer both multi-mode and single-mode fibre connections (the latter being designed for longer distance transmission) ranging from 550m to 160km. These are older technology standards but still available in either 100Mbps or 1Gbps versions. SFP+ transceivers are an enhanced version of the SFP that support up to 16Gbps fibre throughput. Like SFP multi-mode and single-mode options are available to cover distances up to 160km. SFP28 is a 25Gbps interface which although faster is identical in physical dimensions to SFP and SFP+. SFP28 modules exist supporting single- or multi-mode fibre connections, active optical cable (AOC) and direct attach copper (DAC).

QSFP transceivers are 4-channel versions of SFPs and are available, like SFPs, in a number of versions. Rather than being limited to one connectivity medium, QSFPs can transmit Ethernet and Infiniband. The original QSFP transceiver specified four channels carrying 1GbE or DDR InfiniBand. QSFP+ is an evolution of QSFP to support 10GbE or QDR InfiniBand. The QSFP28 standard carries 100GbE or EDR InfiniBand, with the QSFP56 carrying 200GbE or HDR InfiniBand, and the latest QSFP112 carrying 400GbE or NDR InfiniBand.

Power over Ethernet

Power over Ethernet (PoE) is a feature of many network switches that enable the delivery of enough power through the Ethernet cable connection to power the device connected to it. This has the advantage of only needing a single cable running to the device - delivering both power and data - and removes the need to have a standard plug socket nearby everything you wish to power and be on the wired network. Examples of PoE devices would be ceiling mounted wireless access points (WAPs) or outdoor mounted surveillance cameras, where in both instances running power to them may be very awkward - PoE capability provides flexibility in the placement of devices.

	PoE	PoE+	PoE++	PoE++
IEEE Standard	802.3af	802.3at	802.3bt	802.3bt
Type	Type 1	Type 2	Type 3	Type 4
Maximum Power per Port	15.4W	30W	60W	100W
Maximum Power to Device	12.95W	25.5W	51W	71W
Typical Devices	Static Cameras, IP Phones, WAPs	PTZ Cameras, Video IP Phones, Alarm Systems	Heated Cameras, Laptops, Info Kiosks	TVs, High Power, WAPs

If you are considering using PoE switches in any part of your network then you should check the power draw of the devices you want to connect and ensure the class of switch you choose will support the number and type of devices you require. You should also check that each device is capable of being powered by PoE.

Network Switch Management

Although the job of a network switch is to transfer data from one device to another using their IP addresses, there are additional management tools that can enhance switch performance. This is especially important in a busy network as it ensures certain types of network traffic such as voice and video can be prioritised over less important data such as email, so applications runs smoothly. To fully understand network management it is key to be aware of the seven layers of OSI (Open Systems Interconnection) network traffic topology, as summarised below.

Level	Layer	Function
L1	Physical Layer	If you've ever had to troubleshoot anything electronic, Layer 1 is where you'd answer the question, "Is it plugged in?" Layer 1 also includes layouts of pins, voltages, radio frequency links, and other physical requirements. It's a media layer used to transmit and receive symbols, or raw bits of data, which it converts into electrical, radio, or optical signals.
L2	Data Link Layer	This digital stratum is all about media, acting as an avenue for node-to-node data transfers of frames—simple containers for single network packets—between two physically connected devices. It's where you'll find most of the switches used to start or end communication between connected devices.
L3	Network Layer	Another media layer, Layer 3 is home to IP addresses and routers that look for the most efficient communication pathways for packets containing control information and user data, also known as a payload. If a packet is too large to be transmitted, it can be split into several fragments which are shipped out and then reassembled on the receiving end.
L4	Transport Layer	Layer 4 is a host layer that generally functions as a digital post office coordinating data transfers between systems and hosts, including how much data to send, the rate of data transmission, data destinations, and more.
L5	Session Layer	Layer 5 is a host layer that acts like a moderator in that it controls the dialogue between computers, devices, or servers. It sets up pathways, limits for response wait time, and terminates sessions.
L6	Presentation Layer	This host layer is where data is translated and formatted so applications, networks, and devices can understand what they're receiving. Characters are encoded and data compressed, encrypted, and decrypted on Layer 6.
L7	Application Layer	This top-of-stack host layer is familiar to end users because it's home to Application Programming Interfaces (API) that allow resource sharing, remote file access, and more. It's where you'll find web browsers and apps like email clients and social media sites.

The majority of switch management takes place in layers 2-4 of the above model, so look out for abbreviations like ‘L2’, ‘L3’ or ‘L2-L4’ in switch descriptions. Switch management falls into one of four categories as summarised in the diagram and tabs below.

Unmanaged Switches

An Unmanaged switch is designed so that you can simply plug them in and no configuration is required. Unmanaged switches are suitable for small office networks or wherever a few more ports are needed, such as in a conference room.

As more and more devices become network enabled, it may be wise investing in smart switches even in a small office as this will give you some degree of future proofing. At some point you are likely to benefit from some traffic management and the price delta between unmanaged and smart-managed is often minimal.

Switch Resiliency

In addition to the management features mentioned above, there are various additional ways to improve the performance of a network, increase its residency and remove potential single points of failure.

Stacking

When using standalone switches, each switch is managed and configured as an individual entity. In contrast, stackable switches provide a way to simplify and increase the availability of the network. For example, instead of configuring, managing, and troubleshooting eight 48-port switches individually, you can manage all eight like a single unit, so the total 384 ports function as a single switch providing valuable operational advantages. Additionally, if a cable, port or entire switch fails, the stack will automatically route around that failure, with microsecond failover speeds.

Redundancy

Redundancy in a switch can refer to two things. Firstly, how a switch is connected to others, whereby using multiple cables not only balances the load of data being transferred it also protects against a single cable failure. Multiple cable connections between switches can be used in a small network or in conjunction with stacking in a very large network. Secondly, within higher end switches redundant power supplies are common. Each of the power supplies will have the capacity to run the device on its own, so if one fails the switch can still operate normally.

Switch Accessories

The very nature of a network is that no device works standalone, so there are a number of areas you should consider when buying new network switches for your business, as highlighted in the tabs below.

Network Interface Cards

Although not part of the switch directly, it is vital to ensure that servers and storage devices have compatible network interface cards (NICs) with the switches that they are to be connected to. For example if Infiniband switches are being employed for HPC or AI workloads, then all the servers must have Infiniband NICs with the correct SFP or QSFP modules to ensure proper connections. You can learn more about choice of switches in our dedicated NETWORK CARDS BUYERS GUIDE.

Ready to buy?

Browse our range of network switches:

UNMANAGED ETHERNET SMART ETHERNET MANAGED ETHERNET CONFIGURABLE ETHERNET / INFINIBAND

Alternatively, if you have any further questions you’d like answering about network switches for your business or organisation, don’t hesitate to call one of our friendly advisors on 01204 474747 or [email protected].