Modernization of the local computer networkenterprises - a task that all system administrators sooner or later face. Improved interaction of computers among themselves will create optimal conditions for the work of employees and in the future will lead to an increase in the company's success.
The switch is a device that providesCombining several computers into a single local network and serving to improve the quality of the transmitted signal. Exactly the same functions are performed by other network equipment - the hub (with the English Hub - the node of any network). However, when choosing professionals for a long time recommend giving preference to the switches. What is the reason for this?
The work of the hub can be compared with the functioningthe usual repeater - it receives a signal and forwards it to all connected computers, regardless of which PC the information stream was intended for. As a result of such a "mass mailing" the local network quickly "clogged", the transmission rate as a whole decreased. In addition, the more hubs you installed on the network, the higher the probability of a packet storm - a situation where a large number of parasitic packets were sent over the network.
Ordinary and gigabit switches right afterConnections do not differ from the hub. However, over time, they form a switching table, or an ordered list of MAC addresses of computers, according to which in the future packet data is sent. Thus, optimal network functionality is maintained.
LAN performance directlydepends on the parameters of the switch. Even the cheapest devices have a large set of functions that distinguish them among other representatives of this price category. However, when choosing one should pay attention to only a few of the most important parameters. The first is the number of ports. It determines the number of network devices that can be connected to the switch. Usually the number of ports varies from 5 to 48. Another important parameter is the data transfer rate - the speed at which each gigabit port on the switch functions. In our case, this is not less than 1000 Mb / sec. But most often the equipment supports the standard IEEE 802.3 Nway - automatic detection of packet transmission speed.
Bandwidth is the product of the numberports to the maximum data transfer rate. This parameter determines the performance of the system at the peak load moment. It is optimal if this indicator is higher than the data stream transmitted from all PCs simultaneously.
The performance of the network depends on the agreementFull-duplex and Half-duplex. In the Full-duplex mode, the transfer of data packets occurs simultaneously in two directions - from the switch to the computer and vice versa. In Half-duplex mode, the signal is transmitted only to one side. The built-in reconciliation function avoids conflicts during the operation of network devices using different modes.
When choosing a switch, it is important to pay attention tothe dimensions of the switching table, in which the "names" of the ports correspond to the MAC addresses of the computers. This parameter must be determined with the number of PCs on your network. In cases where there is no room in the memory for recording a new network device, it will delete the address of the rarely used PC, and after that it will start searching for it again. This significantly reduces performance.
Flow Control must have all gigabitswitches, because it provides protection against data loss. With its help, two devices "agree" with each other, in what sequence and when to send a signal.
By type of management switches are divided into twospecies - uncontrollable and manageable. In the first case, we have a completely autonomous device without tools for manual adjustment and calibration. It is better suited for a small office network or for a home, since it has low cost, does not require human intervention. Its main drawback is low productivity, which does not allow it to be used in a large enterprise.
In a highly competitive environment, it is important to be able toquickly make decisions and give orders. To make this possible, it is necessary to equip the enterprise with high-speed switches providing data transmission at speeds up to 10 Gb / s. It is worth mentioning that such devices appeared on the market more than 10 years ago. However, they are still relevant, and they have not yet been replaced.
To connect a 10 Gigabit switch, you canuse a fiber-optic cable, twinnaxial or conventional copper wire standard UTP / FTP. Today, the most popular devices are connected by a conventional copper wire. They provide data transfer using 10GBASE-T technology, have low cost and make the network as flexible as possible. Separately, it should be noted backward compatibility with gigabit networks.
Our list is opened by Alcatel-Lucent.Its family of OmniSwitch devices is designed for building medium and large, as well as for building a core of small corporate networks. In the OmniSwitch 6850E, the 10 Gigabit switching function is available as an option, but the OmniSwitch 6900 already has 64 ports for high-speed packet transfer.
The company D-Link has in its range onlytwo representatives of this category of devices. Its 8-port Gigabit desktop switch DXS-3600-16S provides PC connectivity through a fixed port SFP +, but in the DXS-3600-32S there are already 24 similar connectors. Both devices have a slot for the expansion module, through which it will be possible to connect to the network using 10GBASE-T technology.
Фирма Cisco не может порадовать полноценным equipment. However, it offers a more advantageous solution in the form of removable modules, for example, Nexus and Catalyst. Such "extensions" can be used to connect to the network both via copper cable and through fiber.
Корпорация НР предлагает свои гигабитные switches for the needs of medium and small businesses. One of the brightest representatives is HP 6125G / XG, which is a hybrid device - a 1/10-gigabit switch. Only 10-gigabit switches are represented by the models of the series 5820. They support this speed at the SFP + landing sites. However, among the devices you can find the PoE-Gigabit switch of the industrial series HP 5920.
If you use a wireless connection foruniting devices into a home network is impossible or unacceptable due to the low data transfer rate, it is better to use unmanaged switches. First, they are cheaper. Secondly, they are easy to connect and configure, do not require intervention from the user.
If you want, you can choose for yourselfOptical gigabit switch manufactured by TRENDnet or ASUS. The cost of such devices is at an acceptable level, and their functionality is sufficient to meet the needs of the home network.
