Comparison D-Link DGS-1510-52X vs D-Link DGS-1210-52/ME/A1A

— Unmanaged. The simplest kind of switch that does not have, as the name suggests, the ability to manage; and the possibilities of monitoring the state of the device are usually limited to the simplest indicators in the form of light bulbs (power supply, port activity). The advantages of such models are battery life, ease of use and low cost. The main disadvantage of this type is obvious — the impossibility of configuring the operation parameters. Unmanaged switches are well suited for small LANs like a home or small office where little administration tricks are required; but for large organizations they should not be used.

— Customizable. This category includes switches that allow you to change some of the operating parameters. At the same time, the possibilities for such changes are much narrower than in managed models, and the matter is usually limited to disabling individual ports, switching standard speeds for Ethernet connectors (for example, from 100 Mbps to 10 Mbps) and simple monitoring tools like browsing the network statistics. In addition, after reconfiguration, the device, usually, needs to be rebooted — in other words, it is impossible to control the operation of the switch on the fly. However, professional models designed for large networks can also belong to this type.

— Managed 2 levels. The term "managed" means that the switch has the ab...ility to reconfigure "on the fly" — in contrast to the configurable models described above. In addition, the overall functionality of such devices in most cases is noticeably wider. And "layer 2" means that the device supports only the second layer of the OSI network model — the channel, which is responsible for physical addressing. In fact, this means that the switch is able to work with the MAC addresses of connected devices, but IP addressing is beyond its capabilities.

— Managed 3 levels. A kind of managed switches (see above) that supports the third level of the OSI network model. This layer is responsible for logical addressing and route definition, which allows the device to work with IP addresses. Due to this, models of this type are considered the most advanced, they often provide not only the traditional features for "switches", but also individual functions of routers. On the other hand, the abundance of features significantly affects the price. These switches are commonly used in data centers, telecommunications companies, and other professional networking environments; it hardly makes sense to purchase such a device for a home or small office.

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 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.

The type of connector(s) used as the Uplink interface on the switch.

For more information about such an interface, see above; 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 cables) supporting speeds up to 100 Mbit/s. This speed is considered low by modern standards, while the Uplink port places increased demands on throughput - after all, traffic from all devices served by the switch passes through it. Therefore, in this role, Fast Ethernet ports are used mainly in inexpensive and outdated models.

— Gigabit Ethernet — LAN connector supporting speeds up to 1 Gbit/s. This speed is often sufficient even for a fairly extensive network, while the connectors themselves are relatively inexpensive.

— 2.5 Gigabit Ethernet — LAN connector supporting speeds up to 2.5 Gbit/s.

— 10Gigabit Ethernet — LAN connector supporting speeds up to 10 Gbit/s. 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. A connector for a fiber optic cable that supports speeds of about 1 Gbit/s. At the same time, over Gigabit Ethernet, which has a similar throughput, this connector has one noticeable advantage - a...longer connection range (usually up to 550 m).

- SFP+. Development of the SFP standard described above. Switches usually provide a connection speed of 10 Gbit/s; like the original standard, it noticeably exceeds the effective range of an Ethernet connection. On the other hand, the real need for such speeds does not arise so 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 Gbit/s.

- QSFP / QSFP+. The fastest SFPs up to 40 Gbit/s.

Note also 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 widespread. This provides versatility in connection, allowing you to use the most convenient type of cable 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 purchasing, it doesn’t hurt to clarify this nuance separately.

There are also switches that use a combination of two types of SFP - SFP/SFP+; however, there are few such models and they are mainly of 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.

— DHCP server. A feature that makes it easy to manage the IP addresses of devices connected to the switch. Without its own IP address, the correct operation of the network device is impossible; and DHCP support allows you to assign these addresses both manually and fully automatically. At the same time, the administrator can set additional parameters for the automatic mode (range of addresses, maximum time for using one address). And even in fully manual mode, work with addresses is performed only by means of the switch itself (whereas without DHCP, these parameters would also have to be specified in the settings of each device on the network).

— Stacking support. The ability to operate the device in stack mode. A stack consists of several switches that are perceived by the network as one “switch”, with one MAC address, one IP address, and with a total number of connectors equal to the total number of ports in all involved devices. This feature is useful if you want to build an extensive network that lacks the capabilities of a single switch, but do not want to complicate the topology.

— Link Aggregation. Switch support for link aggregation technology. This technology allows you to combine several parallel physical communication channels into one logical one, which increases the speed and reliability of the connection. Simply put, a switch with such a fun...ction can be connected to another device (for example, a router) not with one cable, but with two or even more at once. The increase in speed in this case occurs due to the summation of the throughput of all physical channels; however, the total speed may be less than the sum of the speeds — on the other hand, combining several relatively slow connectors is often cheaper than using equipment with a more advanced single interface. And the increase in reliability is carried out, firstly, by distributing the total load over individual physical channels, and secondly, by means of "hot" redundancy: the failure of one port or cable can reduce the speed, but does not lead to a complete disconnection, and when the channel is restored, the channel is switched on automatically.
Note that both the standard LACP protocol and non-standard proprietary technologies can be used for Link Aggregation (the latter is typical, for example, for Cisco switches). In addition, there are quite a few alternative names for this technology — port trunking, link bundling, etc.; sometimes the difference is only in the name, sometimes there are technical nuances. All these details should be clarified separately.

— VLAN. Support of the VLAN function by the switch — virtual local area networks. In this case, the meaning of this function is the ability to create separate logical (virtual) local networks within the physical "local area". Thus, it is possible, for example, to separate departments in a large organization, creating for each of them its own local network. The organization of VLAN allows you to reduce the load on network equipment, as well as increase the degree of data protection.

— Protection against loops. The switch has a loop protection function. The loop in this case can be described as a situation where the same signal is launched in the network in an endless loop. This may be due to incorrect cable connection, the use of redundant links and some other reasons, but anyway, such a phenomenon can “put down” the network, which means it is highly undesirable. Security prevents loops, usually by disabling looped ports.

— Limiting the speed of access. The ability to limit the data exchange rate for individual switch ports. Thus, it is possible to reduce the load on the network and prevent the "clogging" of the channel by individual terminals.

Note that the matter is not limited to this list: other features may be found in modern switches.