Experience case of handling the problem of Comware V7 switch interface receiving a large number of aborts frames

Not involving

Comware V7 platform switch equipment, packet loss occurs when forwarding data packets. Using display interface, you can see that there are a large number of aborts in the inbound direction of the interface.

Input (total):  263629831 packets, 216666337351 bytes

         160591963 unicasts, 50472988 broadcasts, 33998440 multicasts, 0 pauses

Input (normal):  245063391 packets, - bytes

         160591963 unicasts, 50472988 broadcasts, 33998440 multicasts, 0 pauses

Input:  18566440 input errors, 0 runts, 0 giants, 0 throttles

         0 CRC, 0 frame, - overruns, 18566440 aborts

         - ignored, - parity errors

This problem can usually be optimized by enabling the burst-mode enable function on the device. The specific function and meaning of this command are explained as follows:

Before formally introducing the meaning of the burst-mode enable function, you need to first understand the meaning and function of "data buffer" to facilitate subsequent understanding of related knowledge.

Introduction to data buffer

Data buffers temporarily store packets to avoid packet loss.

The following data buffers are available:

·     Ingress buffer—Stores incoming packets when the CPU is busy.

·     Egress buffer—Stores outgoing packets when network congestion occurs.

Burst-mode enable command function

Normally, the buffer size of a device is a fixed value, and its specifications are determined by the chip type. The chip will allocate corresponding buffer space to each port of the device, and the remaining buffer space will be allocated in real time by the chip.

The burst-mode enable command can be used to adjust the buffer space allocation method, cancel the fixed allocation of ports, and allocate the entire buffer space in real time to enhance the fault tolerance of burst traffic.

Note

The burst-mode enable automatically allocates buffer space only for known unicast packets.

Burst-mode enable command deployment usage scenario

This command is mainly available for the following scenarios:

l  When the business traffic flow is N:1, for example: messages enter the device from multiple interfaces of the same speed at the same time and are forwarded by an interface of the same speed. At this time, deploying the burst-mode enable command can increase the buffer of "1" and reduce the probability of "packet loss events" caused by sudden traffic bursts.

l  Business traffic enters the device from a high-speed link interface and is subsequently forwarded by a low-speed link interface. At this time, deploying the burst-mode enable command can increase the buffer size of the low-speed link interface, and similarly reduce the probability of "packet loss events" caused by sudden traffic bursts.

Note

If the business flow direction is N:N, it is not recommended to configure the "burst-mode enable" command easily, because it may cause a port to occupy the entire chip buffer due to excessive traffic, resulting in other interfaces unable to obtain buffer resources, thereby increasing the probability of "packet loss events".