Why do you need a switch in a local network? How is a switch different from a router? network hardware
The logical topology of an Ethernet network is a multi-access bus in which all devices share access to the same communication medium. This logical topology determines how nodes on a network view and process frames sent and received on that network. However, virtually all Ethernet networks today use a star or extended star physical topology. This means that in most Ethernet networks, end devices are typically connected to a Layer 2 LAN switch in a point-to-point manner.
A Layer 2 LAN switch performs switching and filtering based only on the OSI link layer MAC address. The switch is completely transparent to network protocols and user applications. The Layer 2 switch creates a table of MAC addresses, which it then uses to make packet forwarding decisions. Layer 2 switches rely on routers to transfer data between independent IP subnets.
Switches use MAC addresses to transmit data across the network through their switch fabric to the appropriate port towards the destination host. The switch fabric provides integrated channels and complementary machine programming tools to control the path of data through the switch. For a switch to know which port to use to transmit a unicast frame, it first needs to know what hosts are on each of its ports.
The switch determines how to process incoming frames using its own MAC address table. It creates its own MAC address table by adding the MAC addresses of hosts that are connected to each of its ports. After entering the MAC address for a particular host connected to a specific port, the switch will be able to send traffic intended for that host through the port that is associated with the host for subsequent transmissions.
If the switch receives a data frame for which there is no destination MAC address in the table, it forwards the frame on all ports except the one on which the frame was received. If a response is received from the destination host, the switch enters the host's MAC address into the address table using data from the frame's source address field. In networks with multiple connected switches, the MAC address tables contain multiple MAC addresses of the ports connecting the switches, which reflect elements outside the node. Typically, switch ports used to connect two switches have multiple MAC addresses entered into the corresponding table.
In the past, switches used one of the following forwarding methods to switch data between network ports:
Buffered switching
Switching without buffering
In buffered switching, when the switch receives a frame, it stores the data in a buffer until the entire frame is received. During storage, the switch analyzes the frame to obtain information about its destination. The switch also checks for errors using the tail of the Ethernet cyclic redundancy check (CRC) frame.
When using unbuffered switching, the switch processes data as it arrives, even if the transfer has not yet completed. The switch buffers just enough frames to read the destination MAC address so it can determine which port to forward the data to. The destination MAC address is specified in 6 bytes of the frame after the preamble. The switch looks up the destination MAC address in its switch table, determines the outgoing interface port, and routes the frame to its destination node through the switch's dedicated port. The switch does not check the frame for any errors. Because the switch does not have to wait for the entire frame to be buffered and does not perform error checking, switching without buffering is faster than switching with buffering. However, because the switch does not check for errors, it forwards corrupt frames throughout the network. During forwarding, damaged frames reduce throughput. Ultimately, the destination NIC rejects the corrupted frames.
Modular switches offer greater configuration flexibility. They typically come with varying chassis sizes to allow for multiple modular line cards to be installed. The ports are actually located on line cards. The line card is inserted into the switch chassis, similar to expansion cards installed in a PC. The larger the chassis, the more modules it supports. As shown in the picture, there are many different chassis sizes to choose from. If you purchased a modular switch with a 24-port line card, you can easily install another of the same card, increasing the total number of ports to 48.
Connecting the Internet to an apartment or private house always raises many questions. To begin with, we choose an Internet provider if there are plenty to choose from. Then we take a closer look at the tariffs, and only then try to find out how a switch differs from a router.
Equipment
Both devices belong to the category They are designed for the operation of computer networks. These include not only a switch and router, but also a hub, patch panel, etc. Anything can be assigned to one of the groups: active or passive. You need to understand what the difference between them is.
Active
These devices are built on electronic circuits that receive electrical power. Such equipment is designed to amplify and convert the signal. The main characteristic is the use of special algorithms for processing. What does it mean?
The Internet network works with batch sending of files. Each such set has its own technical parameters: this includes materials about its sources, purposes, data integrity, etc. These indicators make it possible to transfer packets to the desired address.
The active device not only finds the signal, but also processes these technical parameters. It directs them through streams in accordance with built-in algorithms. This ability allows the device to be called as such.
Passive
This group does not receive the necessary power from the electrical network. Works with distribution and reduction of signal levels. Such devices can easily include cables, plug and socket, balun, patch panel. Some attribute this to telecommunication cabinets, cable trays, etc.
Variety
Since the network is active mainly thanks to the first group of devices, we will talk about it. This includes ten devices of different types. For example, a network adapter that is located in the computer itself. Network equipment of this type is now found in all PCs and helps connect to a LAN.
The repeater should also be included here. The device has two ports and works with signal duplication. Thus, it helps to increase the size of the network segment. A concentrator is also an active piece of equipment, sometimes called a hub. It operates with 4-32 channels and serves for the interaction of all participants in the network.
Well, finally, we come to the question of how a switch differs from a router. Although besides them, there is also a repeater, media converter, bridge and network transceiver.
Router
So let's start with this device. People simply call it a router. It serves to forward packets between different network segments. At the same time, it is guided by rules and routing tables. The device connects networks with different architectures. In order to carry out the process correctly, it studies the typology and determines the rules that the administrator has set.
To understand the question of how a switch differs from a router, it is important to understand the operating principles of one and the other device. So, the router first studies information about the recipient: looks at his address and the name of the set. Then it goes to and identifies the path for transferring files. If the tables do not contain the necessary information, data packets are discarded.
Sometimes other methods may be used to select the desired path. For example, the sender's address, upper-level protocols and all data that is hidden behind the name of the set are studied.
Routers interact with address translation, filter transit streams according to prescribed rules, and encrypt or decrypt transmitted files.
Switch
A network switch or switch is a device that interacts with the connection of several PC network nodes. The entire process does not extend beyond several or one part of the network.
This equipment also belongs to the active group. It operates at the OSI data link layer. Since the switch was initially configured to work with bridge parameters, it can be considered as a multiport bridge. To combine several lines at the network level, a router is used.
The switch has no control over the propagation of traffic from one gadget to the rest. It conveys information only to the right person. The process has good performance and ensures the security of the Internet network.
The job of the switch is to store the switching table and, using it, determine the mappings between MAC addresses. When the equipment is connected, the table is empty and is filled in as the device learns itself.
Files that arrive on one of the ports are immediately sent over other channels. The device begins to examine the frames and, after determining the sender's addresses, temporarily enters the information into the archive. When a port receives a frame whose address has already been recorded, it will be transmitted along the path specified in the configuration.
Difference
How is a switch different from a router? At first glance, it is definitely worth saying that the main differences between these devices lie in the principles of operation. There is a rather interesting analogy that easily explains the difference.
Let's say we have a corporate mail server. The employee sent a file that should reach the recipient through an internal or local delivery system. In this case, the switch is a mail server, and the router is a local one.
What we have? The switch does not analyze the content of mail and its type. It stores a list of all employees of the company, the addresses of their offices. Therefore, its main task is to transfer mail to a specific recipient.
In this whole story, the router works as a postman delivering information to people who work outside the company. He checks the contents and can independently change the delivery rules if any additional information is found in the letter.
The disadvantage of a router compared to a switch lies in the difficult and costly administration. Specialists who work with this equipment must master a huge number of parameters. In this case, the configuration must always be consistent with another configuration on the network.
conclusions
Most companies are trying to modernize their network, so they replace outdated equipment with a switch between routers and networks. New devices help improve productivity, while their older counterparts continue to improve security.
Setting up a router and switch is not easy. It is better for the average user not to go here at all. When setting up a home network, specialists come to install this equipment and configure it at the same time. This process is not easy. It is individual for each provider and specific network.
If any failures occur, then you need to contact your Internet provider, because if there are problems with the setup, then you will not be able to cope without it.
To create a local or home network, you need special devices. From this article you will learn a little about them. I will try to explain as simply as possible so that everyone can understand.
Purpose .
Hub, switch and router are designed to create a network between computers. Of course, after creation, this network will also function.
Difference .
What is a hub
A hub is a repeater. Everything that is connected to it will be repeated. One is given to the hub and therefore everything is connected.
For example, you connected 5 computers through the Hub. To transfer data from the fifth computer to the first, the data will pass through all the computers on the network. It's like a parallel phone - any computer can access your data, and so can you. Due to this, the load and distribution also increases. Accordingly, the more computers are connected, the slower the connection will be and the greater the load on the network. This is why nowadays fewer and fewer hubs are being produced and less and less are being used. Soon they will completely disappear.
What is a switch?
The switch replaces the hub and corrects the shortcomings of its predecessor. Each connected to the switch has its own separate IP address. This reduces the load on the network and each computer will receive only what it needs and others will not know about it. But the switch has a disadvantage associated with dignity. The fact is that if you want to divide the network into more than 2 computers, then you will need more IP addresses. This usually depends on the provider, and they usually only provide one IP address.
What is a router?
Router - it is often also called a router. Why? Yes, because it is a link between two different networks and transmits data based on a specific route specified in its routing table. To put it very simply, the router is an intermediary between your network and Internet access. The router corrects all the mistakes of its predecessors and that is why it is the most popular nowadays. Especially considering the fact that routers are often equipped with Wi-Fi antennas for transmitting the Internet to wireless devices, and also have the ability to connect USB modems.
The router can be used either separately: PC -> router -> Internet, or together with other devices: PC -> switch/hub -> router -> Internet.
Another advantage of the router is its easy installation. Often, only minimal knowledge is required from you to connect, configure a network and access the Internet.
So. Let me summarize briefly.
All these devices are needed to create a network. Hub and switch are not very different from each other. A router is the most necessary and convenient solution for creating a network.
The choice of router to use is determined by the Ethernet interfaces that match the switch technology at the center of the LAN. It is important to note that routers offer many LAN services and features.
Each LAN has a router, which is used as a gateway to connect the LAN to other networks. A LAN has one or more hubs or switches to connect end devices to the LAN.
Routers are the main devices used to connect networks. Each port on the router connects to a different network and routes packets between networks. Routers can break up broadcast and collision domains.
Routers are also used to connect networks that use different technologies. They can have both LAN and WAN interfaces.
The LAN interfaces of routers allow them to connect to LAN media. Typically these are UTP cable connections, but modules can be added to allow fiber optics. Depending on the series or model of routers, they may have several types of interfaces for WAN and LAN cable connections.
Intranet devices
To create a LAN, we must select appropriate devices to connect the end nodes to the network. The two most common devices used are hubs and switches.
Hub
The hub receives the signal, regenerates it and sends it to all ports. The use of hubs creates a logical bus. This means that the LAN uses the media in multi-access mode. The ports use a bandwidth sharing approach, which often results in reduced performance on the LAN due to collisions and recovery. Although multiple hubs can be connected, there will still be a single collision domain.
Hubs are less expensive than switches. A hub is usually chosen as an intermediary device for a very small LAN that has low bandwidth requirements, or where finances are limited.
Switch
The switch receives the frame and regenerates each bit of the frame to the corresponding destination port. This device is used to segment the network into multiple collision domains. Unlike a hub, a switch reduces the number of collisions on the LAN. Each port on the switch creates a separate collision domain. This creates a logical point-to-point topology for the device on each port. In addition, the switch provides dedicated bandwidth on each port, which can improve LAN performance. A LAN switch can also be used to connect network segments at different speeds.
In general, switches are chosen to connect devices to the LAN. Although a switch is more expensive than a hub, its improved performance and reliability make it cost-effective.
There is a whole range of switches available with a variety of features that allow you to connect many computers in a typical enterprise LAN setup.