New species: Evolution of layer-3 Exchange Technology

New species: the origin of layer-3 exchange technology, the origin of layer-3 exchange technology, with its innovative technical advantages, quickly replaced the pure layer-2 exchange technology, is widely used in various occasions. I will give my own views on the above issues.

Recently, the layer-3 switching technology has attracted more and more enterprise users and is widely used. For example, the network between the company and the campus is a layer-3 switching network, and the switch is a layer-3 switch. It can be seen that the layer-3 exchange technology is widely used in the network architecture of various large enterprises and campuses.

So what kind of technology is layer-3 Exchange Technology? How can it quickly become the main force for building multi-service converged networks in a few years? What changes have taken place in the origin of layer-3 switching technology? What is its development trend and future market? I will give my own views on the above issues.

Origin of layer-3 Switching Technology

L2 switching technology evolved from the earliest bridge to VLAN Virtual LAN) and has been widely used in LAN construction and transformation. Layer 2 switching technology works on the Layer 2 of the OSI Layer 7 network model, that is, the data link layer. It forwards data according to the target MAC address of the received data packet, which is transparent to the network layer or high-level protocols.

It does not process IP addresses at the network layer, does not process port addresses such as TCP and UDP on top protocols, and does not recognize protocols from the application layer. It only needs to know the physical address of the data packet, that is, the MAC address, data exchange is achieved by hardware alone. Its speed is quite fast, from 10 mb, 100 mb, to today's mb or higher, and its development is quite rapid, this is an obvious advantage of L2 switching.

However, it cannot process data exchange between subnets of different IP addresses. A traditional router can process a large number of packets that span the IP subnet, but its forwarding efficiency is much lower than that of the second layer. Therefore, to use the advantage of the second layer forwarding efficiency, the layer-3 switching technology has its roots in processing layer-3 IP data packets. With its innovative technological advantages, layer-3 exchange technology quickly replaces the pure layer-2 exchange technology and is widely used in various occasions.

Layer-3 Switching Technology

Layer-3 switching, also known as multi-layer switching technology, or IP address switching technology, is proposed relative to the concept of traditional switching. From its origins, We can summarize what layer-3 switching technology is. Simply put, the origin of layer-3 switching technology is layer-2 switching technology + layer-3 forwarding technology. It solves the network bottleneck caused by low speed and complexity of traditional routers.

Layer-3 switching is the layer-3 (Network Layer) in the OSI Layer-7 network model. It uses the IP packet header information in the layer-3 protocol to mark subsequent data services, A layer-3 switch does not need to detach packets to determine the route. Instead, it directly forwards the packets and exchanges the data streams, "switch everywhere" is the principle.

Comparison with vro 
 
Some people may ask, what do routers need to do with a layer-3 switch? Of course, a router has its own functionality. Vro has many port types, supports many layer-3 protocols, and has strong routing capabilities. Therefore, vro is suitable for interconnection between large networks, although many layer-3 switches or even layer-2 switches have heterogeneous network interconnection ports.

However, generally, there are not many interconnect ports in a large network. The main function of the interconnect device is not to fast exchange between ports, but to select the best path for load balancing, link backup and the most important routing information exchange with other networks. All these functions can be completed by routers.