Bandwidth
The bandwidth of a switch is the maximum amount of traffic that it can handle. Specified in gigabits per second.
This parameter directly depends on the number of network ports in the device (excluding Uplink). Actually, even if the bandwidth is not given in the specifications, it can still be calculated using the following formula: the number of ports multiplied by the bandwidth of an individual port and multiplied by two (since both incoming and outgoing traffic are taken into account). For example, a model with 8 Gigabit Ethernet connectors and 2 SFP ports will have a bandwidth of (8*1 + 2*1)*2 = 20 Gbps.
The choice for this indicator is quite obvious: you need to evaluate the expected traffic volumes in the serviced network segment and make sure that the switch's bandwidth will cover it with a margin of at least 10-15% (this will give an additional guarantee in case of emergency situations). At the same time, if you plan to often work at high, close to maximum, loads, it will not hurt to clarify such a characteristic as the internal bandwidth of the switch. It is usually given in a detailed technical description, and if this value is less than the total throughput, serious problems may arise under significant loads.
MAC address table size
The maximum number of MAC addresses that can be stored in the Switch's memory at the same time. Specified in thousands, for example, 8K — 8K.
Recall that the MAC address is the unique address of each individual network device used in physical routing (at layer 2 of the OSI network model). Switches of all types work with such addresses. And it is worth choosing a switch according to the size of the table, taking into account the maximum number of devices that are supposed to be used with it (including based on the possible expansion of the network). If the table is not enough, the switch will overwrite new addresses over the old ones, which can noticeably slow down the work.
SFP (optics)
The number of optical network ports of the SFP standard provided in the design of the switch. 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 used in switches works with a cable length of up to 550 m, and by the standards of 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. So, solutions for
2 or
4 SFP connectors are most widely used, although there are more - 6, 8, or even 10 or more. It is also worth considering that the so-called combo connectors can be used in switches, combining 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.
To clarify, Uplink inputs also often use this type of connector; however, their
...number is specified separately (see below).Uplink
The number of Uplink connectors provided in the design of the switch.
“Uplink” in this case is not a type, but a connector specialization: this is the name of the network interface through which the switch (and network devices connected to it) communicate with external networks (including the Internet) or network segments. In other words, this is a kind of "gate" through which all traffic from the network segment served by the switch is transmitted further. Uplink, in particular, can be used to connect to a similar "switch" (for horizontal network expansion) or to a higher level device (like a core switch).
Accordingly, the number of Uplink connectors is the maximum number of external connections that the switch can provide without using additional equipment. The specific type of such a connector may be different, but this is usually one of the varieties of LAN or SFP; see "Uplink type" for details.
Uplink type
The type of connector(s) used in the switch as an Uplink interface.
See above for details on such an interface; here we note that the same network ports are usually used as Uplink, as for connecting individual devices to the switch. Here are the main options for such connectors:
- Fast Ethernet - LAN network connector (for "twisted pair") with support for speeds up to 100 Mbit. Such a speed is considered low by modern standards, while the Uplink port puts forward increased bandwidth requirements - after all, traffic from all devices served by the switch goes through it. Therefore, in this role, Fast Ethernet ports are used mainly in inexpensive and outdated models.
- Gigabit Ethernet - LAN connector with support for speeds up to 1 Gb / s. Such a speed is often enough even for a fairly extensive network, while the connectors themselves are relatively inexpensive.
- 2.5 Gigabit Ethernet - LAN connector with support for speeds up to 2.5 Gbps.
- 10Gigabit Ethernet - LAN connector with support for speeds up to 10 Gbps. Such features allow you to work comfortably even with very large volumes of traffic, but they significantly affect the price of the switch. Therefore, this option is rare, mainly in high-end models.
— SFP. Socket for fiber optic cable that supports speeds of about 1 Gb / s. At the same time, over Gigabit Ethernet, which has a similar bandwidth, this connector has one noticeable advantage - a lon...ger connection range (usually up to 550 m).
- SFP+. An evolution of the SFP standard described above. The switches usually provide a connection speed of 10 Gb / s; like the original standard, it noticeably outperforms an Ethernet connection in terms of effective range. On the other hand, the real need for such speeds does not arise very often, and SFP+ is quite expensive. Therefore, the presence of such Uplink connectors is typical mainly for high-end models with a large number of ports.
— SFP28. Another development of SFP with increased throughput up to 25 Gbps.
— QSFP / QSFP+. The fastest SFPs up to 40 Gbps.
We also note that the connectors described above (except perhaps Fast Ethernet) are rarely used as the only type of Uplink input. Combinations of electrical and fiber optic ports - SFP / Gigabit Ethernet and SFP + / 10Gigabit Ethernet - have become noticeably more common. This provides versatility in connection, allowing you to use the type of cable that is most convenient in a given situation; and if necessary, of course, you can use all Uplink inputs at once. However, it is worth considering that in some models, Ethernet and SFP interfaces can be combined in one physical connector. So before buying this nuance does not hurt to clarify separately.
There are also switches that use a combination of two types of SFP - SFP/SFP+; however, there are few such models and they mainly belong to the professional level.
