The backplane bandwidth of an industrial switch is the larger amount of information that can be throughput between the industrial switch socket CPU or interface card and the system bus. The backplane bandwidth indicates the total data transmission capacity of the industrial switch. The unit is Gbps, which is also called interchange network bandwidth. The backplane bandwidth of general industrial switches varies from several Gbps to hundreds of Gbps. The higher the bandwidth of the backplane of an industrial switch, the stronger the ability to solve data information, but the higher the cost of the design solution. Next, we will introduce the backplane bandwidth of industrial switches in detail for everyone, and those who are interested can take a look!
Generally speaking, the calculation method is as follows:
1) Wire-speed backplane bandwidth
Investigate the total network bandwidth that all port numbers on the industrial switch can show. The calculation method is the number of ports*relative port number speed*2 (full-duplex mode). If the total network bandwidth ≤ the allowable backplane bandwidth, then the backplane bandwidth is line-speed.
2) Layer 2 packet forwarding wire speed
Layer 2 packet forwarding rate = total number of gigabit network card port numbers×1.488Mpps+total number of 100M port numbers*0.1488Mpps+number of other types of ports*relative calculation method, if this speed can be less than the tolerance of Layer 2 packet forwarding speed, then the industry The switch can guarantee the line speed in the case of the second layer interchange.
3) Layer 3 packet forwarding wire speed
The third layer packet forwarding rate = the total number of gigabit network card port numbers × 1.488Mpps + the total number of 100M port numbers * 0.1488Mpps + the number of other types of ports * relative calculation method, if this speed can be less than the tolerance of the three-layer packet forwarding speed, then the industry The switch can guarantee the line speed in the case of the third layer interchange.
So, how did you get 1.488Mpps?
The evaluation index of the packet forwarding line speed is based on the number of 64-byte data files (the most packet) pushed in a unit time as the measurement standard. For Gigabit Ethernet, the calculation method is as follows: 1,000,000bps/9ait/(64＋8＋12) byte=1,488,095pps, indicating that when the Ethernet interface frame is 64byte, the 9ayte frame header and 12byte The fixed cost of the frame gap. Therefore, a wire-speed Gigabit Ethernet port number has a packet forwarding rate of 1.488Mpps when sharing 64byte packets. The wire-speed port number packet forwarding rate of the Rapid Ethernet interface is exactly one-tenth of that of the Gigabit Ethernet, which is 148.9kpps.
* For 10 Gigabit Ethernet interfaces, the packet forwarding rate of a wire-speed port number is 14.88Mpps.
* For Gigabit Ethernet, the packet forwarding rate of a wire-speed port number is 1.488Mpps.
* For 100M Ethernet interface, the packet forwarding rate of a wire-speed port number is 0.1488Mpps.
* For the POS port number of OC-12, the packet forwarding rate of a wire-speed port number is 1.17Mpps.
* For the POS port number of OC-48, the packet forwarding rate of a wire-speed port number is 468MppS.
Therefore, if the above three standards can be considered, then everyone will say that this industrial switch truly guarantees linearity and no blockage.
The utilization rate of backplane bandwidth resources is closely related to the internal structure of industrial switches. At this stage, the internal structure of industrial switches has the following key types: One is the shared memory structure. This type of structure relies on the exchange module of the management center to show the excellent connection of the full port number, and the key module checks each input packet to determine the router.
This type of method requires very large memory bandwidth and high period cost, especially with the increase of industrial switch port numbers, the price of the intermediate running memory will be very high, so the core of the industrial switch becomes a short board of feature completion; Cross structure, it can create an immediate point-to-point connection between port numbers, which is very good for multicast characteristics, but it is not suitable for more transmission; third is the hybrid cross structure, which is a hybrid cross system bus completion Method, its design concept is to divide the integrated cross-type system bus drainage matrix into a small cross-type drainage matrix, which is connected according to a system bus with excellent performance in the middle. Its advantage is to reduce the number of cross-type system buses, reduce costs, and reduce system bus contention; but the system bus connected to the cross-type drainage matrix has become a new feature short board.
Well, the above content is the detailed introduction of Feichang Technology on the bandwidth of the industrial switch backplane, I hope it can be helpful to everyone! Feichang Technology has been specialized in the R&D, production and sales of industrial communication equipment such as optical transceivers, industrial-grade switches, optical fiber transceivers, and protocol converters for 20 years. Welcome to come to understand and exchange ideas.