System Board Components
Inside a wireless router is a purpose-built system, complete with a processor, memory, power circuitry and a printed circuit board. These are all proprietary components, with closed specifications, and are not upgradeable.
The above image shows the internals of Netis' N300 Gaming Router (WF2631). We see the following components:
- Status LEDs that indicate network/router activity
- Heat sink for the processor—these CPUs don't use much power, and are cooled without a fan
- Antenna leads for the three external antennas to connect to the PCB
- Four Ethernet LAN ports for the home network
- WPS Button
- Ethernet WAN port that connects to a provider's modem
- Power jack
- Factory reset button
- 10/100BASE-TX transformer modules — these support the RJ45 connectors, which are the Ethernet ports.
- 100 Base-T dual-port through-hole magnetics. These are designed for IEEE802.3u (Ethernet ports).
- Memory chip (DRAM)
As routers send and receive data across the 2.4 and 5GHz bands, they need antennas. There are multiple antenna choices: external versus internal designs, routers with one antenna and others with several. If a single antenna is good, then more must be better, right? And this is the current trend, with flagship routers like the Nighthawk X6 Tri-Band Wi-Fi Router featuring as many as six antennas, which can each be fine-tuned in terms of positioning to optimize performance. A setup like that facilitates three simultaneous network signals: one 2.4GHz and two 5GHz.
While a router with an internal antenna might look sleeker, these designs are built to blend into a living area. The range and throughput of external antennas are typically superior. They also have the advantages of reaching up to a higher position, operating at a greater distance from the router's electronics, reducing interference, and offering some degree of configurability to tune signal transmission. This makes a better argument for function over form.
The more antennas you see on a router, the more transmit and receive radios there are, corresponding to the number of supported spatial streams. For example, a 3x3 router employs three antennas and handles three simultaneous spatial streams. Using current standards, these additional spatial streams account for much of how performance is multiplied. The Netis N300 router, pictured on the left, features three external antennae for better signal strength.
While the wireless aspect of a wireless router gets most of the attention, a majority also enable wired connectivity. A popular configuration is one WAN port for connecting to an externally-facing modem and four LAN ports for attaching local devices.
The LAN ports top out at either 100 Mb/s or 1 Gb/s, also referred to as gigabit Ethernet or GbE. While older hardware can still be found with 10/100 ports, the faster 10/100/1000 ports are preferred to avoid bottlenecking wired transfer speeds over category 5e or 6 cables. If you have the choice between a physical or wireless connection, go the wired route. It's more secure and frees up wireless bandwidth for other devices.
While four Ethernet ports on consumer-oriented routers is standard, certain manufacturers are changing things up. For example, the TP-Link/Google OnHub router only has one Ethernet port. This could be the start of a trend toward slimmer profiles at the expense of expansion. The OnHub router, pictured on the right, features a profile designed to be displayed, and not hidden in a closet, but this comes at the expense of external antennas, and the router has only a single Ethernet port. Asus' RT-AC88U goes the other direction, incorporating eight Ethernet ports.
Some routers come with one or two USB ports. It is still common to find second-gen ports capable of speeds of up to 480 Mb/s (60 MB/s). Higher-end models implement USB 3.0, though. Though they cost more, the third-gen spec is capable 5 Gb/s (640 MB/s). The D-Link DIR-820L features a rear-mounted USB port. Also seen are the four LAN ports, as well as the Internet connection input (WAN).
One intended use of USB ports is to connect storage. All of them support flash drives; however, some routers output enough current for external enclosures with mechanical disks. If you don't need a ton of capacity, you can use a feature like that to create an integrated NAS appliance. In some models, the storage is only accessible over a home network. In other cases, you can reach it remotely.
The other application of USB on a router is shared printing. Networked printers make it easy to consolidate to just one peripheral. Many new printers do come with Wi-Fi controllers built-in. But for those that don't, it's easy to run a USB cable from the device to your router and share it across the network. Just keep in mind that you might lose certain features if you hook your printer up to a router. For instance, you might not see warnings about low ink levels or paper jams.