In-depth introduction to the technical trend of the low-end Layer-3 Switch

With the rapid development of China's exchange industry, it also promotes the upgrade of the Third-layer switch technology. Here we mainly analyze the technical trend of the low-end third-layer switch. In the switch market, layer-3 switching devices have gradually become mainstream products. 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, which not only associate Layer 2 with Layer 3, but also provides traffic prioritization, security, and a variety of other flexible functions, such as link aggregation, dynamic deployment of VLAN and Intranet. At the same time, the market puts forward higher security performance requirements for layer-3 switches. Due to the continuous improvement of network security performance requirements, VPN technology and security authentication technology will be widely used. Layer-3 switching devices work on layer-3 of the OSI model and have all the functions of traditional switches. Take the layer-3 switch as the standard. The specific technical implementation of the switch includes:

◆ 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.

◆ Distributed Pipeline

With the distributed pipeline, multiple distributed forwarding engines can quickly send data packets independently. In the pipeline, multiple ASIC chips simultaneously process multiple frames. This concurrency and pipeline can bring forward performance to a new height, achieving the line rate performance of on-demand (Unicast), Broadcast (Broadcast), and Multicast (Multicast) on all ports.

◆ Dynamically Scalable Memory

For advanced LAN switching products, the real performance is built on an intelligent storage system. The layer-3 Switch directly associates a portion of the memory with the forwarding engine. More interface modules are added, including their respective forwarding engines, and memory is also expanded accordingly. With streamlined ASIC processing, the dynamic cache structure increases memory usage, and the system can also handle large burst data streams without packet loss.

◆ 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 to provide different service levels on an Ethernet segment, while also providing control over latency and jitter, in this way, each port has a queue mechanism of different levels.

◆ Automatic traffic classification

Some data streams are more important than other data streams. With Automatic traffic classification, the layer-3 switch can instruct the data packet assembly line to differentiate user-specified data streams to achieve low-latency, high-priority transmission, and avoid congestion.

◆ Intelligent permission Control

The layer-3 Switch provides multiple security mechanisms and uses a traffic classifier. administrators can restrict any identified data streams, including restricting access to servers and eliminating useless protocol broadcasts. This is a breakthrough in the network technology field, that is, providing a line rate firewall.

◆ Dynamic Traffic Monitoring

Traffic classification, priority processing, and resource retention enable enterprise network and Intranet administrators to focus on more important things, that is, traditional and next-generation applications. But one thing still needs to be done is traffic monitoring. Traffic monitoring cannot be regarded as a policy mechanism because it is actually a protection mechanism. It monitors traffic and network congestion conditions and responds dynamically to these conditions to ensure that all network elements end users and networks themselves are under control and can run best.

Many layer-3 switches use the IEEE 802.1p service level for priority processing on congested LAN. To avoid congestion, the high-performance Layer-3 Switch even uses more advanced technologies to dynamically monitor the size of the output queue, so as to detect whether a port will become congested. By controlling the queue size and congestion, the network can maintain the limit required for latency-sensitive data streams.

◆ Scalable RMON implementation

RMON support has become an indispensable part of active and extensive network management. The MIB defined in RFC 1757 contain statistics on the physical layer and MAC layer. The RMON 2 defined in RFC 2021 extends the collection of statistics to the network layer.

◆ Vector Processing Technology

Vector processing technology is used to accelerate the processing speed of data frames. The architecture of the layer-3 Switch not only adds the control capability of the layer-3 on the layer-2, but also adds multi-faceted vector control, thus greatly enhancing the vector processing capability.

◆ Multi-TTL Processor

In a layer-3 Switch with high reliability, a dedicated high-performance RISC processor is absolutely required. In fact, the combination of frame Processing Unit (FP) and Vector Logic provides unparalleled performance. An independent application processor (AP) can assist FP. Like FP, AP is also a high-performance CPU. AP controls all operations except Frame Forwarding: High-Level bridging and routing, such as Spanning Tree and OSPF protocols, SNMP and HTTP operations.

Through the above technical analysis, we can easily see that high performance, security, ease of use, manageability, stackability, service quality and fault tolerance are the technical features of the current layer-3 switch. As video conferencing, real-time multicast, network calls, program-controlled switching, and automatic call forwarding demonstrate the emergence of a new generation of applications in the multimedia era, high bandwidth, security, service quality, and intelligence should be the technical direction of the next generation of layer-3 switches.