Networking, Wi-Fi & Fibre Optics
A network switch is the box that connects the wired devices in a building so they can talk to each other and reach the internet. This guide explains how a switch decides where data goes, what PoE, uplinks and VLANs mean, and how to choose between managed and unmanaged models.
What you will learn
Applies to
Tools Required
No tools needed.
Before you start
Important
Step-by-Step Guide
1 / 10 steps
Step 1
Identify the switch components
A switch has a row of Ethernet ports, one or more uplink or SFP ports, port lights and a power input.
Expected result: You can tell the device ports from the uplink and fibre ports.
Each numbered port connects one wired device. The port light shows a link, and blinks when data moves.
Expected result: A lit port means a working cable and device.
Connect the uplink port to the router or to the next switch. This is the path to the rest of the network and the internet.
Expected result: Devices on the switch can reach the router.
Plug computers and printers into normal ports. The switch learns each device's MAC address from the first data it sends.
Expected result: The switch sends each device only the data meant for it.
IP cameras plug into PoE ports and send video through the switch to the NVR, which records it.
Expected result: Cameras appear on the NVR without separate power supplies.
When a PoE device is detected, the port supplies power and the PoE light comes on. Check the switch's total PoE budget.
Expected result: The PoE light is lit and the camera or access point starts up.
On a managed switch, put staff, guests and CCTV in separate VLANs. The tagged uplink carries all of them to the router.
Expected result: Guest devices cannot reach staff computers or the recorder.
Larger sites use a core switch in the main cabinet and edge switches on each floor, joined by uplinks or fibre.
Expected result: Each floor connects back to one central point.
An unmanaged switch has no settings. A managed switch has a page like this, where each port is set as tagged or untagged per VLAN.
Expected result: You know which features need a managed switch.
| Port | VLAN 10 | VLAN 20 | VLAN 30 | PVID |
|---|---|---|---|---|
| 1 (uplink) | Tagged | Tagged | Tagged | 1 |
| 2 | Untagged | - | - | 10 |
| 3 | - | Untagged | - | 20 |
| 4 | - | - | Untagged | 30 |
Generic sketch. Menu names differ by brand.
Router, managed PoE switch, computers, a printer, access points, cameras and an NVR, all in one cabinet on a UPS.
Expected result: A tidy layout you can expand and troubleshoot.
Interactive Demonstration
Add equipment, then connect two devices by selecting one and then the other. Press “Send data” to watch traffic flow from each device to the internet through the switch and router.
Start with a router, then add a switch.
Troubleshooting
Likely cause Faulty or unplugged cable, a dead device, or a broken port.
Solution Reseat both ends, try a known-good patch cable and another port, then test the cable run.
Likely cause A damaged cable, poor termination, or a device limited to 100 Mbps.
Solution Check the device's port speed, replace the patch lead and have the cable tested and reterminated.
Likely cause A network loop, often a cable plugged into two ports or between two switches twice.
Solution Unplug recently added cables one at a time. On managed switches, enable loop protection or spanning tree.
Likely cause The switch's PoE budget is exceeded, the port's PoE type is too low, or the cable is too long or poor.
Solution Check PoE use on the switch, compare with device data sheets, move devices to another switch or use a higher PoE type.
Likely cause The port is in the wrong VLAN, or the VLAN is not tagged on the uplink to the router.
Solution Check the port's untagged VLAN and PVID, and that the uplink carries that VLAN tagged.
Likely cause The computer is on a different VLAN or subnet, or the switch's address was changed.
Solution Connect to a port in the management VLAN and check the switch address with the vendor's discovery tool or controller.
In Depth
A network switch is the box that connects the wired devices in a building so they can talk to each other and reach the internet. This guide explains how a switch decides where data goes, what PoE, uplinks and VLANs mean, and how to choose between managed and unmanaged models.
Small offices often have one plastic box from the internet provider that does everything. As the network grows, the jobs split apart:
| Device | Its job |
|---|---|
| Router | Connects your network to the internet (or to other networks), hands out IP addresses and usually runs the firewall. |
| Switch | Connects many wired devices inside one network and passes data between them quickly. |
| Access point | Turns a cable from the switch into Wi-Fi for phones and laptops. |
A switch does not give you internet by itself. It extends the network that the router creates, so ten, twenty or forty devices can plug in where the router has only four or five ports.
Every network card has a MAC address, a hardware address unique to that device. When data arrives on a switch port, the switch reads the sender's MAC address and remembers which port it came from. Over a few seconds it builds a table of "this device lives on port 3, that printer lives on port 7".
When a frame arrives for a device the switch already knows, it sends it only out of that one port. When the destination is not in the table yet, the switch sends the frame out of every port except the one it came in on (this is called flooding), and the reply teaches it where that device is. Broadcasts, such as a computer asking for an IP address, always go to every port in the same network.
This is why a switch is much better than the old hubs it replaced: two pairs of devices can hold full-speed conversations at the same time without slowing each other down.
Note A switch works with MAC addresses inside one network. Moving traffic between different networks or VLANs, and out to the internet, is the router's or firewall's job (or a "Layer 3" switch's).
| Unmanaged switch | Managed switch | |
|---|---|---|
| Set-up | Plug in and it works | Needs configuring through a web page, app, controller or command line |
| VLANs | No | Yes (IEEE 802.1Q) |
| Monitoring | Port lights only | Port status, errors, PoE use, traffic per port |
| PoE control | Automatic, if PoE model | Turn PoE on, off or restart per port, set priorities |
| Security | None to configure | Admin password, port security, firmware updates |
| Best for | A few desks at home or a small room | Offices, hotels, schools, CCTV systems |
Some vendors also sell "smart" or "easy smart" switches: a cut-down managed switch with VLANs and basic monitoring but fewer advanced features. If you will ever want to separate guest Wi-Fi, staff and CCTV, buy at least a switch that supports 802.1Q VLANs.
PoE sends electrical power down the same cable as the data, so IP cameras, access points, IP phones and intercoms need no separate power socket. The switch (the PSE, power sourcing equipment) only applies power after it detects a PoE device on the port, so plugging a normal laptop into a PoE port is safe with standard PoE.
The IEEE standards define these power levels per port:
| Standard | Type | Power from the switch port | Power guaranteed at the device |
|---|---|---|---|
| IEEE 802.3af (PoE) | Type 1 | 15.4 W | about 13 W |
| IEEE 802.3at (PoE+) | Type 2 | 30 W | 25.5 W |
| IEEE 802.3bt | Type 3 | up to 60 W | up to 51 W |
| IEEE 802.3bt | Type 4 | up to 90 W | up to 71.3 W |
The difference between the two columns is lost as heat in the cable over a full-length run. Types 1 and 2 use two of the four pairs in the cable; 802.3bt can use all four.
The power budget matters as much as the per-port figure. A switch with sixteen PoE+ ports rarely has sixteen times 30 W of total power. Check the total PoE budget in the data sheet, add up what your cameras and access points actually draw (with infrared on at night for cameras), and leave spare headroom. Our PoE budget calculator does the arithmetic.
Warning "Passive PoE" injectors used by some outdoor radios are not the IEEE standard. They push voltage without checking what is connected and can damage equipment that is not designed for it. Match the PoE type to the device's data sheet.
An uplink is the port that connects a switch to the router or to another switch. Many switches have one or two faster ports for this, such as Gigabit uplinks on a Fast Ethernet camera switch, or 10 Gigabit uplinks on an office switch.
An SFP port is an empty cage that accepts a small plug-in module. The module decides the connection type: a copper module for a normal Ethernet cable, or a fibre module for links longer than copper allows, or between buildings. The module must match the fibre type, the speed and the module at the other end. See Fibre optic internet vs traditional Ethernet for how those links work.
A VLAN (virtual LAN, standardised as IEEE 802.1Q) splits one physical switch into several separate networks. Devices in the CCTV VLAN cannot reach devices in the staff VLAN unless the router or firewall allows it.
A typical small business uses VLANs for staff, guests, CCTV and payment terminals. A guest's infected phone should never be able to see your recorder or the accounts computer.
The simplest reliable layout is a router or firewall connected to a managed PoE switch in a network cabinet. Computers and printers plug into the switch, ceiling access points and IP cameras take power and data from it, and the NVR records the cameras on the same switch. Everything in the cabinet runs on a UPS, which matters in Zanzibar where short power cuts are common. The interactive topology builder on this page lets you connect these devices and see how data moves.
Keep each copper cable run within 100 metres from switch to device. Label both ends of every cable and keep a simple diagram showing which port goes where.
If your network has grown into a tangle of small switches, or you are adding CCTV, access points or guest Wi-Fi, our networking, Wi-Fi and cabling team can design and install a tidy, documented switch and VLAN layout. Contact us to arrange a visit.
This guide is general information. Procedures, product features and firmware change, so check your own equipment's documentation before you start.
FAQs
No. A router connects your network to other networks such as the internet and hands out addresses. A switch connects many devices inside your network. Most offices need both.
Yes. Link them with a cable from an uplink or normal port. Avoid connecting two switches with two cables unless they are managed and configured for it, because a loop can flood the network and stop everything working.
Standard IEEE PoE (802.3af, at or bt) only powers a port after it detects a PoE device, so normal equipment is safe. Passive PoE injectors are different and should only be used with devices made for them.
It depends on the switch's total PoE budget and what each camera draws, not just the number of ports. Add up the maximum draw of each device from its data sheet and keep spare capacity.
If you only have a few computers and no guest Wi-Fi or CCTV, an unmanaged switch is fine. Once you add guest Wi-Fi, cameras or payment terminals, a managed switch with VLANs keeps them apart.
Each port can run at up to 1 Gbps. A Gigabit switch still connects older 100 Mbps devices, which run at their own lower speed on that port.
Not usually. The internet speed is set by your connection. A better switch speeds up transfers inside the building, such as to a file server or NVR, and makes the network more reliable.
We design, cable and configure routers, switches and firewalls that stay up, with documentation you can hand to the next engineer.
Ask for clarification, tell us a problem this did not solve, or suggest a topic. An engineer reads every message, and we use them to improve the Knowledge Center.
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