Differences between layer-4 switching technology and other layer Switches

As technology continues to develop and networks naturally become technology leaders, we have to consider layer-4 switches to meet the needs of policy-based scheduling, QoS, and security services, the following articles describe in detail.

With the popularization of broadband and the deepening of various network applications, our local network is undertaking heavy business traffic. The amount of transmitted audio, video, data, and other information in the network system is full of bandwidth, and we have to provide differentiated services for these data traffic.

Differences between Layer 2, Layer 3 and Layer 4 Switching

Layer-2 exchange enables fast information exchange between hosts in the LAN. layer-3 Exchange is a perfect combination of exchange technology and routing technology, the layer-4 switching technology can provide optimal allocation for network application resources to achieve application service quality, load balancing, and security control. The layer-4 switching is not a replacement. In fact, the layer-2 switching and layer-3 switching are now integrated into the layer-4 switching technology.

The second layer switch performs end-to-end data exchange based on the MAC address and MAC address table of the second layer data link layer. The second layer switch only needs to identify the MAC address in the data frame and forward it directly based on the MAC address, which is very easy to implement using ASIC dedicated chip. The second-layer switch solution is a "Everywhere switch" solution. Although it can also divide subnets, restrict broadcast, and establish VLANs, it has low control capabilities and is not flexible enough, it cannot control traffic and lacks the routing function.

A layer-3 Switch performs end-to-end data exchange based on the layer-3 network layer IP address. It is mainly used for routing between different VLAN subnets. After the first data stream of a certain information source performs layer-3 switching routing, the switch generates a MAC ing table between the MAC address and IP address.

Store the table. If subsequent data streams from the same information source enter the vswitch again, the vswitch directly transmits the source address to the destination address from the second layer based on the address ing table generated and saved for the first time, no longer processed by the third route system, which improves the data packet forwarding efficiency and solves the speed bottleneck caused by traditional routers when information is transmitted between VLAN subnets.

The layer-4 switch not only performs end-to-end switching, but also determines or limits the switching traffic based on the Application Characteristics of the port host. To put it simply, the layer-4 switch is based on the packet exchange process at the transport layer. It is a new type of LAN switch based on the Application exchange requirements at the TCP/IP application layer.

The layer-4 switch supports all protocols below the layer-4 of TCP/UDP. You can distinguish the application types of data packets based on the TCP/UDP port numbers to achieve access control at the application layer and ensure service quality. You can view the source address and target address of the third-level data packet header.

You can take appropriate actions based on the observed information to achieve bandwidth allocation, fault diagnosis, and access control for TCP/IP application data streams. The layer-4 switch optimizes the network through task allocation and Server Load balancer, and provides detailed traffic statistics and accounting information, in this way, network congestion, network security, and network management are solved at the application level, so that the network can be intelligent and manageable.

Introduction to layer-4 Switching Technology

The fourth layer of the OSI network reference model is the transport layer. The transport layer is responsible for end-to-end communication, that is, coordinated communication between the network source and the target system. In the IP protocol stack, This is the protocol layer of TCP transmission control protocol) and UDP User Datagram Protocol.

TCP and UDP contain port numbers, which uniquely differentiate which application protocols are contained in each packet, such as HTTP, FTP, and telnet ). The additional information provided by TCP/UDP port numbers can be used by network switches. layer-4 switches use this information to distinguish packet data, which is the basis of layer-4 switching.

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