Is the backboard bandwidth sufficient? Vswitch board bandwidth

The backboard bandwidth of A vswitch is the maximum amount of data that can be transferred between the vswitch interface processor or interface card and the data bus. The backboard bandwidth indicates the total data exchange capability of a vswitch. The unit is Gbps. It is also called the switching bandwidth. The bandwidth of A vswitch ranges from several Gbps to hundreds of Gbps. The higher the bandwidth of A vswitch, the stronger the ability to process data, but the higher the design cost.

The utilization rate of the backboard Bandwidth Resources is closely related to the internal structure of the vswitch. The internal structure of a vswitch is as follows:

The first is the shared memory structure, which relies on the central exchange engine to provide high-performance connections across the port. The core engine checks each input packet to determine the route. This method requires a lot of memory bandwidth and high management costs. Especially with the increase of switch ports, the price of the central memory will be very high, so the switch kernel becomes a bottleneck for performance implementation.

The second is the cross-bus structure, which can establish direct point-to-point connections between ports, which is good for single-point transmission performance, but not suitable for multi-point transmission.

The third is the hybrid cross-bus structure. This is a hybrid cross-bus implementation method. Its design idea is to divide the integrated cross-Bus Matrix into small cross matrices, it is connected through a high-performance bus. The advantage is that the number of Cross buses is reduced, the cost is reduced, and the bus contention is reduced. However, the bus connected to the cross matrix becomes a new performance bottleneck.

We purchased the best performance of the transfer plane, that is, the switch is required to achieve linear non-blocking transmission. How can we check whether the backboard bandwidth of A vswitch is sufficient? How can we determine whether the design of the switch you bought is reasonable and there is a blocking structure design?

Obviously, the estimation method is useless. I think we should consider the following two aspects:

1. The sum of the total port capacity X ports should be 2 times smaller than the backboard bandwidth, enabling full-duplex non-blocking switching, proving that the switch has the conditions to maximize the data exchange performance.
2. Full configuration throughput (Mbps) = number of fully configured GE ports × 1. 488 Mpps. The theoretical throughput of One gigabit port when the packet length is 64 bytes is 1.488 Mpps. For example, A vswitch that can provide up to 64 Gigabit ports must have a full configuration throughput of 64 × 1.488 Mpps = 95.2 Mpps to ensure that all ports are working at the same speed, provides non-blocking packet switching.

If a vswitch can provide a maximum of 176 Gigabit ports and the declared throughput is less than 261.8 Mpps (176x1.488 Mpps = 261.8 ), the user has reason to think that the switch adopts a blocking structure design.

Generally, the switches that both meet the requirements are qualified switches.

For vswitches with relatively large backboards and low throughput, the software efficiency/dedicated chip circuit design is not a problem, but the backboard is relatively small. The overall performance of vswitches with relatively high throughput is relatively high. However, the Board bandwidth can be believed by the manufacturer, but the throughput cannot be believed by the manufacturer. because the latter is a design value, the test is very difficult and the significance is not great.

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