1. Principle Of Network Switch

A network switch is a device that expands the network, which can provide more connection ports in the sub-network to connect more computers. With the development of the communication industry and the advancement of economic informatization, the network switch market is steadily rising. It is cost-effective, highly flexible, relatively simple, and easy to implement. Therefore, Ethernet technology has become the most important LAN networking technology today, and network switches have become the most popular switches.

2. Principle Of Router

A router is a hardware device that connects two or more networks. It acts as a gateway between networks. It is a dedicated intelligent network device that reads the address in each packet and then decides how to transmit it. It can understand different protocols, such as the Ethernet protocol used by a local area network and the TCP/IP protocol used by the Internet. In this way, the router can analyze the destination addresses of data packets from different types of networks, convert the addresses of non-TCP/IP networks into TCP/IP addresses, and then transmit each data packet according to the optimal route according to the selected routing algorithm to the designated location. So the router can connect non-TCP/IP networks to the Internet.

3. What Is The Difference Between A Network Switch And A Router

Working in different protocol layers

The network switch is a device at the data link layer, and some network switches can also implement the third layer of switching. Routers can solve the problem of forwarding packets between heterosexual networks and act on the network layer. In comparison, routers are more powerful than switches, but they are relatively slow and expensive. At the same time, the three-layer switch has the ability to forward packets at wire speed and the good control function of the router, so it is widely used.

Acting on different types of networks

Network switches are generally used for LAN-WAN connection and internal network communication. The router is used for the connection between WAN-WAN to realize the communication between different networks. The switch uses the switching technology to realize the rapid transmission of data within the network by using the MAC address. At the same time, it supports various technologies of security control and IP phone.

4. Some Characteristics Of Network Switches

As the main device for network connection, the switch determines the performance and stability of the network. With different size of the company, the network structure is also different, the switch used must also be determined according to the specific situation, but in order to bear a large amount of network data transmission and run stably and safely for the company’s network, it must be selected a gigabit switch with excellent performance and reasonable price that can meet the requirements. I have been working in this area for a period of time, and I have some basic views on the current network switch technology and performance. I hope to give you some reference. In recent years, many new technologies have appeared in switches industry, some of which are very useful.

Trunking technology can bundle multiple low-bandwidth switch ports of the switch into a high-bandwidth link without changing the existing network equipment and original wiring, and perform link load balancing through several ports, to avoid link congestion. This technology can be used in part of the company’s network backbone equipment: the network traffic is relatively large, but the actual situation does not allow the use of optical cables, using trunking can solve the bottleneck problem in data transmission.

5. The fourth layer switch developed on the basis of the third layer switch. This is a relatively new feature.

The data stream composed of data packets in the network can be identified at layer 2, 3 or 4 respectively. Each layer will provide more detailed information about the data flow. At layer 2, each data packet in the data stream is identified by the MAC address of the source site and destination site. In the broadcast domain, the layer 2 switching function is limited, because the source and destination MAC addresses are only a rough interpretation of the information in the data packet. Layer 2 switches can provide cheap, high-bandwidth network connections, but they cannot provide the necessary control capabilities for the backbone data flow. At layer 3, the data flow is identified by the source and destination network IP addresses, and the ability to control the data flow is limited to the source and destination address pair. If a client is using multiple applications on the same server at the same time, the layer 3 information will not describe each application flow in detail, so that it is impossible to identify different data flows. The fourth layer of the OSI model is the transport layer. It is responsible for coordinating the communication between network source and destination systems. Both TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are located on layer 4. At layer 4, each data packet contains information that can be used to uniquely identify the application that issued the packet. This is possible because the TCP and UDP headers contain “port numbers”, which can determine the application protocol contained in each packet. Combining the port number information of the layer 4 header and the source-destination information of the layer 3 header can achieve true precise control. The dialogue flow of the specific application program can be controlled between the client and the server. If the switching router is fully functional, all these tasks can be completed at wire speed.

A pair of client/server can open multiple different application sessions at the same time. Since an enterprise backbone network may contain thousands of client/server pairs, a backbone-level switching router must have a huge table capacity to store up to millions of Layer 4 streams. Because the transmission buffer is too burdened, and the performance of the backbone network is often degraded due to table errors in these routers, the layer 3 switches generally do not save information about the layer 4 data flow.

Application layer control has the following advantages: The true quality of service strategy meets the needs of all communication traffic in the network by providing wire-speed bandwidth and low latency for all applications. However, when a certain output port of the switch is overloaded and the internal buffer is full, the quality of service should be required to establish priority rules or “policies” in order to prioritize network traffic. Switching routers allow setting quality of service policies for application layer traffic, so that network managers can fully control the bandwidth usage in the network backbone. In layer 2 and 3 switching, quality of service policies can only be applied to network traffic based on source or destination addresses. The use of quality of service policies for layer 4 application traffic means that individual host-to-host application conversations can also be prioritized.

6. Support for multiple routing protocols.

Switching routers have greatly improved their performance and functions through hardware measures, but routing processing is still based on software. The original switched routers only supported Router Information Protocol (RIP). For a simple network, RIP is generally sufficient. But more complex networks require more complex routing protocols. Switched routers designed for large networks require the use of an open shortest path first (OSPF) routing protocol. As applications requiring Multicast support become more popular, switching routers should be able to implement a full set of standards-based multicast protocols, such as distance vector multicast routing protocol (DVMRP) and scalability Stronger protocol-independent multicast protocol (PIM). For example, Cabletron’s smart switch router SmartSwitchRouter (SSR) can provide layer 2, 3, and 4 switching functions at a gigabit per second rate on all ports. The high-speed dedicated ASIC chip realizes the forwarding of the data packet by searching the headers of the second, third, and fourth layers of the data packet. In addition, intelligent switching routers can achieve bandwidth allocation, fault diagnosis and access control to TCP/IP application data streams by exchanging data packets at layer 4, and provide detailed traffic statistics and accounting information, applications Layer QoS policies and access control capabilities. Many company networks use static routing, which is due to the current network topology determined by the star nature. When the network structure becomes complicated, the company network must consider the use of dynamic routing protocols to provide network redundancy.

7. IEEE802.1X protocol

This protocol is used for user authentication, which can improve the security of the network. On switches that support this protocol, only users who have passed system authentication can send and receive information, and authentication information is kept on a dedicated server for easy query. Companies should try their best to select switches that support 802.1X, and use switches that support transparent transmission of authentication information close to the user end, which can significantly improve network security and manageability.

Considerations For Choosing The Best Gigabit Switch

Combining the above points, and considering the traditional performance parameters of the network switch, we can get the parameters that should be considered in practical applications of the gigabit switch.

  1. Backplane bandwidth, Layer 2/3 switching throughput rate. This determines the actual performance of the network. No matter how convenient of the switch functions and management, if the actual throughput does not increase, the network will only become congested. So these three parameters are the most important parameters for a network switch. The backplane bandwidth includes the switching bandwidth between switch ports, the data exchange bandwidth between the ports and the switch, and the data exchange bandwidth within the system.
  2. VLAN type and quantity, a switch supports more VLAN types and quantity, it will be more convenient to design and realize the network topology.
  3. TRUNKING, current switches support this function, and it is not widely used in practical applications, so I personally think that as long as switch supports this function, it does not require the binding of the maximum number of lines.
  4. The number and type of switch ports, different applications have different needs, which should be determined according to specific conditions.
  5. Protocols and methods that support network management. The switch is needed to provide more convenient and centralized management.
  6. Qos, 802.1q priority control, 802.1X, 802.3X support, these are the development direction of the network switch, these features can provide better network flow control and user management, we should consider purchasing switches that support for these features.
  7. Stacking support. When the number of users increases, stacking becomes very important. The general method for companies to expand switch ports is to connect sub-switches to each port of a main switch, so that the maximum data transmission rate between the sub-switch and the main switch is only 100M, which greatly affects the switching performance. If the stack mode can be used, it will be Gigabit Bandwidth for the unit.
  8. For the three-layer network switch, the 802.1d production tree is also an important parameter. This feature allows the network switch to learn the network structure, which is also very helpful to the performance of the network.


Through the above introduction, I believe it will be helpful for you to choose the best gigabit switch. Choosing the right network switch is actually not that complicated.