A network switch is a device that expands the network and can provide more connection ports in the sub-network to connect more computers. It has the characteristics of high performance-price ratio, high flexibility, relatively simple, and easy to implement. So, what is the role of the network switch in the data center?

When the network switch interface receives more traffic than it can handle, the network switch will choose to either cache it or the network switch to discard it. The cache of the network switch is usually caused by the different network interface speed, the traffic of the network switch suddenly bursts or the many-to-one traffic transmission.

The most common problem that causes buffering in network switches is sudden changes in many-to-one traffic. For example, an application is built on multiple server cluster nodes. If one of the nodes simultaneously requests data from the network switches of all other nodes, all replies should arrive at the network switch at the same time.  When this happens, the traffic flood of all network switches will flood the port of the requester’s network switch. If the network switch does not have enough egress buffers, the network switch may discard some traffic, or the network switch may increase application delay. Enough buffers of the network switch can prevent packet loss or network delay caused by low-level protocols.

The most modern data center switching platform solves this problem by sharing the switching buffer of the network switch. The network switch has a buffer pool space allocated to a specific port. The shared exchange buffers of network switches vary greatly among different vendors and platforms.

Some network switch manufacturers sell network switches designed for specific environments. For example, some network switches have larger buffer processing, which is suitable for many-to-one transmission scenarios in the Hadoop environment. In an environment capable of distributing traffic, network switches do not need to deploy buffers at the switch level.

The buffer of the network switch is very important, but there is no correct answer to how much space do we need for the network switch. The huge network switch buffer means that the network will not discard any traffic, and it also means that the network switch delay is increased-the data stored by the network switch needs to wait before being forwarded. Some network administrators prefer smaller buffers of network switches to allow application or protocol processing to reduce some traffic. The correct answer is to understand the traffic pattern of the application’s network switch and choose a network switch that suits these needs.