Multi-layer network switching makes routers "smart"

In today's world, the network is getting higher and higher, and communication methods between people and devices are changing with each passing day. Some of these communication types are well known, such as IP voice VoIP, digital images, multicast, on-demand video, peer-to-peer file sharing, and remote video conferencing. However, all these applications share a common feature, that is, the demand for network bandwidth can be described by the word "greedy.

In the long run, the bandwidth itself is always insufficient. Therefore, the smart devices behind the network infrastructure, that is, the switches and routers must undertake the difficult task of keeping up with bandwidth requirements in an intelligent way. Applications such as video and digital X-light always require a larger and more intelligent "transmission pipeline", while VoIP applications require low latency, response time, and consistent transmission rate. In the middle of the 1990s s, with the decline of traditional switches, people began to compete for switches and routers that develop faster and more intelligent. A group of talents in Silicon Valley saw this market opportunity. As a result, they invented network hardware and related software based on a new concept called "multi-layer switching routing. Compared with software-based routers at the time, these new "smart" switches/routers can provide faster speed and shorter latency, while combining the functions of multiple network devices.

Originally, when the network bandwidth needs to be increased, the network administrator often designs the network to avoid the bottleneck of the router. The server is often reinstalled closer to the user without passing through the router. In large enterprises, users are usually divided into smaller network subnets that implement interconnection through routers ). This classification is generally based on the region, the type of running application, the required data volume, and security factors. For example, the finance department is often arranged in its own group because it aims to effectively protect the company's financial records, rather than taking into account the bandwidth used. VoIP phones are often placed in their own networks because they can bypass the bottleneck of traditional routers.

When a computer needs to communicate with a computer other than its local network, to send packets to the outside of the group, they must first send the packets to the nearest router. Vro provides connections and security boundaries between the company and the Internet, as well as Intranet connections between the company's internal groups ).

Traditional routers are used only when absolutely necessary, such as connecting to a remote office through a WAN, connecting to the Internet, or isolating groups with high bandwidth requirements in the company. Traditional routers are very expensive, but they still do not have much progress compared with the original design. The components used are similar to those of a standard PC, use multiple interface cards to run dedicated software.

In contrast, a multi-layer Switch Router integrates all the functions of a traditional router on a dedicated Integrated Circuit ASIC. ASIC is cheaper than the CPU of traditional routers and is usually distributed on multiple network ports. Currently, a typical vswitch/vro may contain 50 ASIC instances and support hundreds of interfaces. In addition, the new ASIC allows smart switches/routers to forward data as quickly as possible on all ports. Regardless of the network traffic type, it can be said that they are often called line speeds at actual interface speeds) forward data. Currently, new switches/routers on the market for enterprise LAN) can forward data on a single interface with a 10 Gigabit bandwidth OC-192 per second.

Stepping out of the old age and entering new world of exchange

Because a centralized architecture is used, traditional routers generally lack scalability. For a traditional router, all data packets arriving at the router must be sent to a region for processing. In this way, the more interfaces you have, the heavier the system load, resulting in excessive resource occupation. This greatly limits the services provided by the network, such as VoIP.

When a router that uses a centralized architecture needs to process traffic beyond its processing capacity, it will start to discard packets. When network applications or computers fail to receive response information, they send more data packets and attempt to resume the session. In this way, the situation gets worse, because it can easily lead to cross-session overload. In this case, the overloaded router may selectively discard data packets based on the application, user priority, or network destination/source address. Obviously, we need a new method to meet the traffic growth requirements.