Connections
How the router connects to the Internet or other external network.
Almost all modern routers have
ethernet network connectors for this purpose, however, in addition to them, other connection options can be provided — both wired (
ADSL,
SFP / SFP + optics) and wireless (mobile access via
3G / 4G modem or
SIM card). Here are the features of each option:
— Ethernet. A standard LAN network cable connector (“twisted pair”) is the most popular modern wired connection format in computer networks. Widely used both in "local" and to provide access to the Internet. This standard is somewhat inferior to SFP / SFP + (see below) in terms of speed and noise immunity, but it is much cheaper. The speed of work in modern versions of Ethernet can reach 10 Gbps (see "Connection speed of WAN ports"), theoretically, a further increase in throughput is possible.
— SFP / SFP + (optics). A connector for transmitting network traffic over a fiber optic cable. The main advantage of such a cable is complete insensitivity to electromagnetic interference. And data transfer rates can reach 2.7 Gbps in the original SFP and 16 Gbps in SFP+. At the same time, maintaining this standard is not cheap, and the benefits mentioned are not often needed in fact. Therefore, SFP / SFP + is found mainly in mid-range a
...nd top-level routers.
— ADSL. Connecting to the Internet through a fixed telephone network using ADSL technology. The key advantage of this connection is the ability to use existing networks without laying additional wires; at the same time, Internet access is completely separated from telephone communication and traffic does not interfere with voice calls. On the other hand, the bandwidth of ADSL is very low by modern standards (less than 24 Mbps), moreover, the data transmission speed is noticeably lower than the reception speed. This can create problems for video communication and some other specific tasks. So nowadays ADSL is used less and less.
— 3G/4G modem (USB). Internet connection via mobile network using a separate 3G or 4G modem connected to the USB port. This feature can be useful where there is no full-fledged wired connection (for example, in rural areas), and also as a fallback option in case the main communication channel fails. And the type of network supported depends mainly on the modem used (the compatibility of the router with different models needs to be specified separately, but most often there are no problems with this). As for specific types of networks, most 3G modems work in UMTS networks (the same ones that are massively used by mobile phones); the data transfer rate in such networks can reach 75 Mbit / s (however, usually it is much lower). Less common are 3G modems for EV-DO networks based on CDMA — this standard has lower speeds (up to 14.7 Mbps) and not as extensive coverage as UMTS, however, both the equipment and the connection itself can be cheaper. And the designation "4G" means only one type of networks — LTE; it provides speeds up to 173 Mbps, but is not as widespread as 3G.
— SIM card. Another option for connecting to the Internet via mobile networks is its own SIM card slot provided in the design of the router. This option is convenient because you do not need to buy an additional device (modem) for mobile Internet — you just need to purchase an operator's SIM card. On the other hand, due to the built-in mobile communication modules, such routers themselves are more expensive than analogues for USB modems. In addition, the connectivity options in them are limited by the characteristics of the module: for example, a router for 3G networks will not be able to fully use 4G networks (whereas a USB modem can usually be changed to a more advanced one). As a result, this option is relatively rare in modern equipment.SFP (optics)
The number of optical network ports of the SFP standard provided in the design of the device. We emphasize that we are talking about "ordinary" SFPs; SFP+ data is usually listed separately.
Specifically, in switches, the marking “SFP” usually means a connector for fiber with a connection speed of 1 Gbps. Technically, this is not much compared to RJ-45 speeds; however, this connection format has a number of advantages. One of the main ones is a greater effective range: the mentioned gigabit standard works with a cable length of up to 550 m, and by the standards of optical fiber, this is still very little. True, the cable itself is sensitive to kinks and requires quite delicate handling; on the other hand, it is completely immune to electromagnetic interference. On the other hand, in general, the SFP format is noticeably less popular in network equipment than RJ-45; therefore, there are few ports of this type even in advanced devices (
1 port or
2 ports, less often more). It is also worth considering that there may be so-called combo connectors that combine SFP and RJ-45; the presence of such ports is specified in the notes, they are taken into account both in the calculation of RJ-45 and in the calculation of SFP.
USB ports
The number of
USB ports provided in the design of the router. USB is a universal interface used in computer technology to connect peripheral devices for various purposes. One of its uses is to connect a 3G modem (if provided, see “Data entry (WAN-port)”), but this is not limited to this: in fact, the options for using USB ports directly depend only on the capabilities specified in the router firmware. So, in some models, you can connect a flash drive or an external hard drive to this connector — to update the firmware or even organize an FTP server directly on the router. And for other peripherals — printers, cameras, etc. — USB connection can be used to work as network devices (however, such functions are rare in standard firmware).
RAM
The amount of random access memory (RAM) provided in the device. The amount of "RAM" is one of the indicators of the power of the device: the larger it is, the higher the speed and the better the device will cope with "heavy" tasks.
PoE outputs
The number of PoE-enabled outputs (see above) provided in the design of the router.
In theory, this number corresponds to the maximum number of network devices that can be powered via PoE. However, in practice, two more points should be taken into account. The first and foremost is the total power delivered by such ports; most often it is indicated in the item "Total PoE power", and for models with one output - in the item "Power per PoE output". In any case, if the power consumption of the connected equipment is higher than this value, at best, the power from the switch simply “does not start”, and at worst, overloads and equipment breakdowns are possible.
The second nuance concerns routers, which themselves can be powered using Power over Ethernet. Recall that the power of such a power supply is very limited, so when it is used, most of the power usually goes to the operation of the switch itself, and there is little (if any) left to supply the PoE outputs. So when a device is powered via PoE, its own PoE outputs, at best, greatly “sag” in terms of capabilities (maximum power decreases, the number of simultaneously powered devices decreases), and at worst, they completely turn into ordinary network ports, without additional power. So if you plan to fully use the PoE outputs, you should take care to connect the switch itself to the network; this is especially true for models where there is more than one such output.
PSU
—
Built -in. The built-in power supply does not take up space on the outside, but can significantly increase the size and weight of the entire router. Because of this, this option is quite rare — mainly among rack-mount models (see "Form factor"), where an external unit can create significant inconvenience, as well as among the most powerful desktop routers, for which dimensions and weight is not critical.
— External. Theoretically, the external placement of the power supply requires additional space, and therefore is not as convenient as the internal one. In fact, most blocks of this type are quite compact in size and are equipped with “plugs” for sockets right on the case — in other words, the block is installed on a socket, and from there the wire stretches to the router. And the absence of power circuits and transformers inside the routers has a positive effect on their compactness. Thanks to all this, this option is very popular among desktop models (see "Form factor"), primarily entry-level and mid-level.
