Describes the key parameters of a data center switch.

With the explosive growth of data traffic, the construction standards of data centers are constantly improving. Obviously, common switches cannot meet the needs of data centers, the data center switch has high capacity, large cache, virtualization, layer-2 TRILL and other technical features to meet your needs. What key parameters should a data center switch have?

Port line rate forwarding:The current data center switch, port line rate Forwarding is the most basic requirement, the new backplane technology can also meet. A Data Center switch is an important component of a data center and an indispensable device for Data Center interaction with external information. Since its appearance, the data center has grown to the fourth generation, and the switches in the data center are constantly improving. Although many new features have emerged in the data center field, such as FCoE, TRILL, EVI, XVLAN, and SPB, the criteria that really determine the performance and quality of switches are still the basic parameters. The basic function of a vswitch is switching, so the switching performance is still the key parameter of the vswitch. In addition to the exchange performance requirements, there are more technical parameters for the data center switch. The following describes the key parameters of the data center switch, for reference when purchasing, using, and resizing data center networks.

Data Centers are also divided into two types: Box switches and rack-mounted switches. A box switch is a switch with a fixed number of ports and sometimes with a small number of expansion slots. A rack-mounted switch is a slot-type switch that is highly scalable and supports different network types and networks with higher port density. Generally, a box switch is used in the access layer of the data center. Some of the box switches have only two-layer functions, and some also support three-layer functions, which are basically two-layer. Rack-mounted switches are used in data center aggregation and core egress. Compared with box switches, rack-mounted switches have three-tier functions and require more attention to key parameters.

The reason why such a network device is called a switch is that it has a powerful switching function.The parameters used to measure the switching performance of a vswitch include the backboard bandwidth, port density, and switching capacity.

Board bandwidthIt is the maximum data throughput between the vswitch interface processor and the data bus. The higher the backboard bandwidth, the stronger the data processing capability. The backboard bandwidth is the technical parameter of the rack-mounted switch, there is no backboard bandwidth concept for a vswitch. Generally, the bandwidth of a backboard ranges from several Gbps to several hundred Gbps. The higher the bandwidth, the better. As long as the port line rate Forwarding is met, the design is too high, resulting in a waste of costs. The early backplane technology was not high enough to satisfy all backboards of devices that could not reach the full line speed. The calculation of the backplane bandwidth is related to the internal implementation, such as how many slots can provide up to the bandwidth for each slot, in this way, the backboard bandwidth is obtained. For a vswitch that supports wire rate forwarding, the bandwidth calculation method of the backplane is very simple: the number of ports * the corresponding port rate * 2 (full duplex mode), of course, the backplane can also be designed into a redundant mode, some backboard bandwidth can be provided, so that the forwarding between slots has multiple backboard channels. If some of the backboard channels are faulty, the service will automatically switch to achieve redundant backup. Now, the bandwidth of the high-end vswitch backboard in the data center is no longer T-level.

Port DensityIs a key parameter of a data center switch, representing the forwarding capability of the switch. For example, a box switch can provide 0.48 million m ports, a rack-mounted switch can provide 24 40g plug-in cards, and a rack-mounted switch can provide 18 slots. The higher the port density, the higher the forwarding capability of the device. The higher the port speed, the higher the processing performance of the device. With the popularization of 40G/G ports, data center switches can provide rack-mounted switches with eight ports of G boards and 24 ports of 40G boards with a single slot that is close to 1 TB. In the future, with the improvement of optical module technology and smaller optical modules, the 0.48 million g port density that a single slot can provide will be higher. Now, rack-mounted switches with single slot providing M ports will become popular. Due to the limited cabinet size of the data center, the width of the rack-mounted switch cannot be expanded. Therefore, the 0.48 million MB port can be provided to the limit. In addition, the more module types are supported, the more practical the device is, the more suitable it can be applied to different network environments, such as LAN interfaces, WAN interfaces, and ATM interfaces. The more abundant the port bandwidth type, the better. That is, it supports 40G and G High-Speed ports, and also supports G and 1G low-speed ports, that is, XFP supports multiple optical interface types, including SFP, SFP +, and CFP. These are important considerations for vswitches.

The data center switches are basically layer-2 and layer-3 based forwarding switches.Ii. Capacity of three-tier forwarding table itemsThe number of users that the device can host. The current vswitch can basically reach 32 K in the L2 MAC address table, which means that the vswitch can contain up to 30 thousand L2 user addresses and a l3 route table with 16 K entries. This means that the vswitch can learn more than 10 thousand routes. The specification of the current vswitch is getting bigger and bigger, and the MAC address and IP address routing can basically exceed 128 K, or even reach 1 M, this allows the data center to be scaled up and used without worrying about the capabilities of network devices. Another specification is also very important for vswitches, namely the ACL, the access control list. With ACL, You can flexibly deploy services and restrict network attacks, allowing vswitches to work more flexibly. Generally, the specification of the commercial Chip Switch ACL is not high (less than 10 KB), and there are many restrictions. For example, if Cisco uses its own chip, it can say that the ACL specification is very large and the one hundred k acl specification can be provided.

Manage data center SwitchesIt refers to how the vswitch controls the user's access to the vswitch, and the user's degree to the vswitch. The management capability of a vswitch is reflected in the CPU and Memory parameters. Generally, the switch is at a cost. It does not use a CPU with a high processing speed. The CPU of the switch mainly performs device management, monitoring, and layer-3 Table learning, the real data forwarding is not completed by the CPU, so you do not need to run the CPU at a high speed. As the CPU cost is getting lower and lower, the CPU of the switch is also growing. At present, the average CPU clock speed of high-end switches is above MHz. The same is true for Memory. From 64 M to 256 M, 1g, and so on, 5g ultra-large Memory switches are even emerging. These performance parameters are also an important embodiment of the performance of a switch.

As a data center switch, you must have some features of the data center itself. Over the past few years, new technologies have emerged in the data center. virtualization, XVLAN, TRILL, SDN, EVI, SPB, FCOE, and other technologies are unique to the data center. For example, a virtual machine has more than one virtual machine.Virtualization TechnologySome box switches can even provide 10 devices to virtualize one device, while some rack switches can provide one device to virtualize more than 10 independent devices. Data center switches must be able to deploy these new technologies to play a better role in the future data centers.

The switch in the data center has many device parameters. The parameters described in this article are the most important and key parameters. These parameters can often represent the comprehensive capabilities of the device, we must carefully study and focus on equipment procurement, data center expansion, and usage. Each parameter affects the performance, functions, and different integration features of the vswitch.