Devices and components of the data link layer are those devices or components that have both physical layer and data link layer functions. The devices and components of the data link layer mainly include network cards, bridges, and switches.
What are the data link layer devices - network cardThe network card is an interface that provides various network devices and network communication media in the local area network. The full name is a network interface card, also called a network adapter. The quality and quality of the network directly affect the performance of the network and the effect of the software running on the network. As an I/O interface card, the network card is inserted into the expansion slot of the motherboard. The basic structure includes interface control circuit, data buffer, data link control, codec circuit, internal transceiver, and media interface device. .
The NIC is used for the physical layer and the data link layer. At the data link layer, the NIC contains the physical address of the device for performing the data formatting operations and media access operations required by the particular network system architecture. A device driver that acts as an interface between the operating system and the network card is also part of the data link layer.
All kinds of network cards are similar in appearance, but the performance of different types of network cards is very different, and even cannot be replaced and compatible with each other. It is a basic requirement to ensure that the type of network card matches the type of network used. According to the network technology classification network card can be divided into Ethernet card, token ring network card, FDDI network card, etc. According to the transmission rate classification network card can be divided into 10Mb/s, 100Mb/s, 1000Mb/s and 10Gb/s and other network cards.
(2) NIC driverA driver is a set of software systems that connect operating systems and hardware devices. The NIC driver is part of the data link layer and can be found on the network control panel and controls the NIC. Most of the data link layer work is done by chips inside the network card or switch. However, the device driver acts as part of the data link layer and is primarily used as an interface between the network card and the network layer. Therefore, the proper configuration and optimization of the NIC driver for operations in the network is particularly important.
(3) The working mode of the network cardSome network cards can work in many modes. Such a network card can be designed to automatically select the best mode of operation depending on the connected device. Network cards are generally compatible with the following modes of operation: 10Mb/s half-duplex, 10Mb/s full-duplex, 100Mb/s half-duplex, 100Mb/s full-duplex.
(4) NIC MAC addressEach NIC is assigned a globally unique address identifier at the factory. This nickname is called a NIC address or media access control address. Since the address is hardened on the NIC, it is also called a physical address or hardware address. . The NIC consists of a 48-bit binary number.
Bridge is an early two-port Layer 2 network device used to connect different network segments. The two ports of the bridge each have an independent switching channel, instead of sharing a backplane bus, the collision domain can be isolated. The bridge performs better than the hub, and each port on the hub shares the same backplane bus. Later, the bridge was replaced by a switch with more ports and also can isolate the collision domain.
(1) Basic characteristics of the bridge1. The bridge implements local area network interconnection on the data link layer;
2. The bridge can interconnect two networks with different data link layer protocols, different transmission media and different transmission rates.
3. The bridge implements communication between the interconnected networks by means of receiving, storing, address filtering and forwarding;
4. The network that the bridge needs to interconnect uses the same protocol above the data link layer.
5. Bridges can separate the traffic between two networks, helping to improve the performance and security of the interconnected network.
(2) Bridge principleThe bridge connects two similar networks and manages the flow of network data. It works at the data link layer, which not only extends the distance or range of the network, but also improves the performance, reliability, and security of the network. After the network 1 and the network 2 are connected through the bridge, the bridge receives the data packet sent by the network 1, and checks the address in the data packet. If the address belongs to the network 1, it gives up the packet. On the contrary, if it is the address of the network 2, it Continue to send to the network 2. This can use the bridge isolation information to divide the same network number into multiple network segments (belonging to the same network number), isolate the security network segment, and prevent users in other network segments from illegally accessing. Due to the segmentation of the network, the network segments are relatively independent (belonging to the same network number), and the failure of one network segment does not affect the operation of another network segment.
The bridge can be a dedicated hardware device, or it can be implemented by a bridge software installed on the computer. At this time, multiple network adapters (network cards) are installed on the computer.
The function of the bridge is similar to the repeater in extending the span of the network, however it can provide intelligent connection services, ie forwarding and filtering according to which network segment the frame's destination address is in. The bridge knows the network segment where the site is located by "self-learning", and has a transparent bridge, a conversion bridge, a package bridge, and a source routing bridge. The bridge is shown in Figure 1.
Figure 1
The switch is also a network interconnection device working at the data link layer, and is one of the most commonly used and most important network devices in the LAN network. There are many types of switches, such as Ethernet switches, FDDI switches, Frame Relay switches, ATM switches, and token switches.
(1) Switch function
The basic functions of all switches are the same, that is, receiving frames, looking for ports to the destination address, and sending frames.
(2) How the switch works
Some switches can help the network check for more frame information before sending a frame, not just checking the source and destination addresses. It is based on these differences that switches have four ways.
1) Direct exchange
2) Fragmentless frame exchange
3) store-and-forward exchange
4) Adaptive switching
5) Comparison of switches and hubs
Portable power system ,Portable power storage,Portable solar system, Outdoor power station, Portable power station
SHENZHEN CHONDEKUAI TECHNOLOGY CO.LTD , https://www.szfourinone.com