Comparison Cisco CBS250-48T-4G vs Aruba Instant On 1930-48G-4SFP+

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.

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.

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).

The number of optical SFP+ ports provided in the design of the switch. Let's clarify right away that we are talking about ordinary network ports; Uplink inputs can also use this interface, however their number is specified separately even in this case (see below).

The general advantages of optical fiber over conventional Ethernet cable are longer communication range and insensitivity to electromagnetic interference. Specifically, SFP+ is a development of the original SFP standard; in switches, such connectors typically operate at a speed of 10 Gbps. As for the number of such ports, for all its advantages, fiber optics in network equipment is still used quite rarely. Therefore, the most common switches are 1 - 2, less often 4 SFP + connectors, although there are 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+.

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.

The switch has a console port. This connector is used to control the device settings from a separate computer, which plays the role of a control panel — a console. The advantage of this format of operation is that access to the functions of the switch does not depend on the state of the network; in addition, special utilities can be used on the console that provide more extensive capabilities than a regular web interface or network protocols (see "Management"). Most often, the console port uses an RS-232 connector.

Management methods and protocols supported by the switch.

— SSH. Abbreviation for Secure Shell, i.e. "Safe shell". The SSH protocol provides a fairly high degree of security, because. encrypts all transmitted data, including passwords. Suitable for managing almost all major network protocols, but requires a special utility on the host computer.

— Telnet. A network management protocol that provides configuration using a text-based command line. It does not use encryption and does not protect transmitted data, and is also devoid of a graphical interface, which is why in many areas it has been supplanted by more secure (SSH) or more convenient (web interface) options. However, it is still used in modern network equipment.

— Web interface. This function allows you to open the management interface of the switch in a common Internet browser. The main convenience of the web interface is that it does not require additional software — a browser is enough (and it is available in any "self-respecting" modern OS). Thus, knowing the device address, login and password, you can manage the settings from almost any computer on the network (unless, of course, otherwise specified in the access parameters).

— SNMP. Abbreviation for Simple Network Management Protocol, i.e. "simple network control protocol". It is a stan...dard part of the common TCP/IP protocol on which both the Internet and many local networks are built. It uses two types of software — "managers" on control computers and "agents" on managed computers (in this case, on a router). The degree of security is relatively low, but SNMP can be used for simple management tasks.

Note that this list is not exhaustive — modern switches may provide other management options, for example, support for proprietary utilities and special technologies from the same manufacturer.

Power consumed by network equipment during operation. Knowing the indicator of energy consumption, you can, for example, calculate the battery life of equipment from an uninterruptible power supply or choose a suitable “uninterruptible power supply”.

The range of operating temperatures allowed for the switch, in other words, the air temperature at which the device is guaranteed to remain operational.

All modern switches are able to normally endure conditions that are comfortable for a person. Therefore, you should pay attention to this indicator, first of all, in cases where the conditions at the installation site of the switch will differ markedly from home / office; a typical example is the placement of ISP equipment in the attic of a multi-storey building. At the same time, special attention should be paid to the lower limit of the temperature range — not every device is able to operate at sub-zero temperatures. If we talk about specific numbers, then for an unheated room frost resistance is desirable at least at the level of -5 °C, and ideally — — 20 °C(although, of course, this also depends on the climate).

Also note that, in addition to temperature, most switches have restrictions on the relative humidity of the air; these restrictions are usually specified in the documentation.