Detailed description of how LAN switches work

LAN switches are the "cornerstone" for building network platforms. LAN switches require less configuration, less space, less wiring, cheaper prices, and provide higher and more reliable performance, enterprise-level switches are both rack-mounted and department-level switches can be rack-mounted.

For example, we have sent a batch of packets specially sent to someone. If it is in a network environment using a general hub, everyone can see this packet. In the network environment where a vswitch is used, the vswitch analyzes the packet to whom it is sent, and then packs and encrypts it. At this time, only the packet recipient can receive the packet.

In a broad sense, there are two types of switches: WAN switches and LAN switches. WAN switches are mainly used in the telecom field to provide basic communication platforms. LAN switches are used in local networks to connect terminal devices, such as PCs and network printers.

The transmission media and transmission speed can be divided into Ethernet switches, Fast Ethernet switches, Gigabit Ethernet switches, FDDI switches, ATM switches, and wildcard ring switches. Large-scale applications can be divided into enterprise-level switches, department-level switches, and working group switches.

Generally, enterprise-level switches are rack-mounted, and department-level switches can have fewer rack-mounted slots) or fixed configurations, the working group-level switch is relatively simple with fixed configurations ).

On the other hand, from the perspective of application scale, enterprise-level switches support large enterprise applications with more than 500 information points as enterprise-level switches, and department-level switches support Switches of medium enterprises with less than 300 information points, switches that support less than 100 information points are working group-level switches. Unless otherwise stated below, all the mentioned switches refer to LAN switches.

As we all know, switches work on the data link layer, the second layer of the OSI reference model. Their main functions include physical addressing, network topology, error verification, frame sequence, and traffic control. The physical addressing corresponds to the network addressing) defines the addressing method of the device on the data link layer;

The network topology includes the description of the data link layer, which defines the physical connection mode of the device, such as the star topology or bus topology. The error verification sends an alarm to the upper-layer protocol that has a transmission error; re-organize and transmit the data frame sequence except the sequence;

Throttling can delay data transmission so that the receiving device does not crash because it receives information that exceeds its processing capability at a certain time point. At present, the switch also has some new functions, such as VLAN support, link aggregation support, and even some firewall features. This is the function of the layer-3 switch. The layer-3 Switch adds the routing function when dividing VLAN based on the protocol.

Analysis of Switch Technology Status and Trends layer-3 switching is the key to adopting Intranet. It combines the advantages of layer-2 switches and layer-3 routers into a flexible solution, provides line rate performance at all levels. This integrated structure also introduces policy management attributes.

It not only associates Layer 2 with Layer 3, but also provides traffic priority processing, security, and a variety of other flexible functions, such as link aggregation, dynamic deployment of VLAN and Intranet. Layer-3 LAN switches are divided into three parts: interface layer, switch layer, and route layer.

The interface layer includes all important LAN interfaces: 10/100 M Ethernet, Gigabit Ethernet, FDDI, and ATM. The switching layer integrates multiple LAN interfaces with policy management. It also provides link aggregation, VLAN, and Tagging mechanisms.

The routing layer provides the main LAN routing protocols: IP, IPX, and AppleTalk. Through policy management, the routing layer provides the traditional routing or pass-through layer-3 forwarding technology. Policy management and administrative management enable the network administrator to adjust the network according to the specific needs of the enterprise.

Compared with Layer 3, the level 2 Adoption determines the so-called network control classification. A pure Layer 2 solution is the cheapest solution, however, it provides the least control over subnet division and broadcast restrictions. Layer-3 switches provide dynamic integration support for all levels in the classification.

Traditional general-purpose routers and external switches can also achieve this goal, but compared with this solution, layer-3 LAN switches require less configuration, less space, and less wiring, cheaper and more reliable performance.

A layer-3 Switch has all the functions of a traditional switch. The layer-3 Switch prevails. The specific technical implementation of the switch includes:

1. Programmable ASIC
ASIC is a dedicated Integrated Circuit dedicated to optimizing Layer 2 processing. It is the core of today's networking solutions and integrates multiple functions on one chip, it has the advantages of simple design, high reliability, low power consumption, higher performance and lower cost.

2. Distributed Pipeline
With the distributed pipeline, multiple distributed forwarding engines can quickly send data packets independently. In a single pipeline, multiple ASIC chips simultaneously process multiple frames. This concurrency and pipeline improves the forwarding performance to a new level: On-Demand Unicast, Broadcast, and Multicast on all ports.

3. dynamically Scalable Memory
For advanced LAN switching products, the real performance is built on an intelligent storage system. The layer-3 LAN switch directly associates a part of the memory with the forwarding engine. More interface modules are added, including their respective forwarding engines, and memory is also expanded accordingly. It also uses streamlined ASIC processing to dynamically construct the cache, which increases the memory usage. The system can also handle large burst data streams without packet loss.

4. Advanced queue mechanism
Even if the network device has outstanding performance, it will be damaged by the congestion on the connected network segment. Traditionally, the traffic through a port must be stored in the cache of only one output queue. No matter how high its priority is, it must also be processed in the first-in-first-out mode.

When the queue is full, any excess parts will be discarded. In addition, when the queue grows, the latency also increases. This feature makes it very difficult to run real-time transaction processing and multimedia applications on Traditional Ethernet. For this reason, many network device manufacturers have developed new technologies that provide different service levels on an Ethernet segment and control latency and jitter at the same time. In this way, the mechanism of queues of different levels is introduced for each port.

1. Correct Interpretation and test of vswitch Port
2. Summarize the market status of high-end Switches
3. Resolve core layer switch faults
4. PythonAndroid: Learn how to select a 24-port Gigabit Switch
5. Let's talk about the stacking of Ethernet switches.