All about the network switch

by sogrow team

All about the network switch

Network switches or switches connect network segments and thus ensure full-duplex communication, good traffic performance, and efficient use of bandwidth. 

Networks are essential today to support business activities, ensure communication, provide entertainment, etc. But none would be possible without a fundamental element common to all networks and connects devices to share resources: the network switch.

What is a network switch

A network switch is a device that operates at the second link layer of link-layer 2 under the seven layers of the OSI (Open Systems Interconnection) model. It receives the packets sent by the devices connected to its physical ports and forwards them again, but only on the ports that go to the devices that the packets are supposed to reach. Switches are a common component of Ethernet, Fiber Channel, Asynchronous Transfer Mode (ATM), and InfiniBand networks, among other things. However, most switches these days generally use Ethernet.

How does a network switch work? 

As soon as a device connects to a switch, the switch remembers its MAC (Media Access Control) address, also known as a physical address. This is a code embedded in the device's network interface card (NIC), which connects to the switch with an Ethernet cable. The switch uses the MAC address to identify the connected device, from which outgoing packets are sent and incoming packets. Therefore, the MAC address identifies the physical device in contrast to the network layer (layer 3) IP address, which is dynamically assigned to a device and can change over time. When a device sends a packet to another device, it enters the switch, and it reads its header to determine what to do with the data packet.

To reduce the risk of collision between network traffic entering and leaving a switch at the same time and a connected device, most switches provide full-duplex functionality. Packets coming to and from a device have access to the full bandwidth of the switch connection. (You can compare this to two people talking on a cell phone instead of a walkie-talkie.) While most switches operate at the Layer 2 level, some can also operate at the Layer 3 level. These are rightly called Layer 3 switches and offer additional features such as Layer 3 switches. Virtual Local Area Network (VLAN) configurations capabilities.

Differences between switches and hubs 

A hub or hub can also connect multiple devices to share resources. Devices connected to a hub are called LAN segments. The difference between a hub and a switch is that packets sent by any of the connected devices are sent to all the devices connected to the hub. With a switch, packets are only forwarded to the port that leads to the device they are going to. Switches are typically used to connect the segments of the LAN network to which hubs connect. The switches filter traffic destined for devices on the same LAN segment. With this intelligence, the switches use their processing resources more efficiently.

Differences between switches and routers 

Switches are sometimes confused with routers. These also allow the transmission and routing of network traffic, hence their name. But their purpose is not the same, and they work on a different level. This is because routers operate at layer 3 of the network layer and are used to connect networks to other networks. The nature of the LAN or WAN network makes it easy to distinguish between switches and routers. The devices are locally connected by switches. In extended WAN mode, on the other hand, networks are connected to other networks through routers. The route that a data packet can take to reach the Internet, for example, Device> Hub> Switch> Router> Internet, also helps to differentiate.

Of course, there are cases where the switching functionality is built into the router hardware, and the router also acts as a switch. The most common and simple example is the home wireless router. It connects to a broadband connection through its WAN port, but it usually has additional Ethernet ports that can be used to connect an Ethernet cable to a computer, TV, printer, or even a game console. Even if other devices on the network, for example, other laptops and phones, connect through the WLAN router, it still offers switching functions over the LAN. Therefore, the router is also a switch.

The Different Types of Switches 

The sizes of the switches vary depending on the number of devices to be connected in a given area and the type of network speed and bandwidth that those devices require. A switch with four or eight ports is usually sufficient for a small office or home office, but for larger deployments, some switches can have up to 128 ports. A small switch easily fits in an office, but larger switches can be rack-mounted and placed in a closet, data centre, or server farm. Rack switch sizes can range from 1U to 4U, but larger sizes are also available. There are also speed differences between the switches. There are Fast Ethernet (10/100 Mbit / s), Gigabit Ethernet (10/100/1000 Mbit / s), 2.5 Gigabit (2500 Mbit / s), 10 Gigabit (10/100/1000/10000 Mbit / s)) switches and even 40 / 100GB / s. Speed ​​depends on the performance required for supported tasks.

The switches also differ in their capabilities. Here are three typical models.

  • Unmanaged Switches

  • Unmanaged switches are the simplest, and you cannot change their configuration. In general, they are "plug and play", which means that they offer the user little or no choice. They are often provided with default settings for the quality of service features, but they cannot be changed. The advantage of unmanaged switches is that they are relatively inexpensive, but their lack of functionality makes them unsuitable for most business uses.

  • Managed switches

  • Managed switches offer more functionality and features to IT professionals and are the most popular in enterprises. Managed switches are equipped with command-line interfaces (CLI), which allows their configurations to be changed. They support simple Network Management Protocol (SNMP) agents that provide information that can be used to troubleshoot network problems. They can also support VLANs, VLANs, QoS settings, and IP routing. Security is also better, and they can protect all kinds of traffic they handle. Due to their advanced capabilities, managed switches cost significantly more than unmanaged switches.

  • Say Smarts Switches  

  • Smart Type Switches are simplified managed switches that offer more functionality than unmanaged switches but less functionality than managed switches, thus being more sophisticated than unmanaged switches but less expensive than fully managed switches. They generally do not support Telnet access and have graphical web interfaces instead of command-line interfaces (CLI). Other options, such as VLANs, may not have as much functionality as supported by fully managed switches. However, being less expensive, they can be used in smaller networks, companies with fewer financial resources, or fewer functional requirements.

  • Management Features

  • The list of features and functions for a network switch varies by switch manufacturer and bundled software, but in general, a switch allows those skilled in the art to: 

    • enable and disable specific ports
    • configure the duplex parameters (half or full) and the bandwidth
    • defines the Quality of Service (QoS) levels for a specific port
    • Enables MAC filtering and other access control functions
    • configures SNMP monitoring of devices, including link status
    • Configure port mirroring to monitor network traffic. 

    Other uses 

    In larger networks, switches are often used to offload traffic for analysis. This feature can be important for security, as a switch can be placed in front of a WAN router before traffic is transmitted to the local network. This can facilitate intrusion detection, performance analysis, and firewall configuration. Quite often, port mirroring is used to mirror the data flowing through the switch before sending it to an intrusion detection system or packet sniffer. However, the basic task of a network switch is to quickly and efficiently deliver packets from computer A to computer B, whether the computers are across the hall or the world. Of course, several other devices contribute to data transmission, but the switch is an essential part of the network architecture.