How does Cisco switch realize the speed limit of a single port?

There are too many steps. You can read this post or look at the documents inside. /thread-1696-1-1.html or search this forum for the technical configuration of Cisco Huawei.

Port speed limit must start QOS on the switch.

Switch (configuration) #mls qos // Start qos on the switch.

Here are the specific implementation steps.

First, create ACL.

Because this is a three-layer switch, although the port is limited in speed, the network address passing through this port should be considered. In this example, we choose to speed limit the 22nd port of CISCO3550 switch, which belongs to VLAN66 and the IP address segment is 10.66/ 16, so we should create an ACL first, as shown below:

Conference room 3550

Enter configuration commands, one per line. It ends with cntl/z.

3550 (Configuration) # Access List 15 License 10. 66. 0. 0 0. 255. 255

Second, create a class map.

Conference room 3550

Enter configuration commands, one per line. It ends with cntl/z.

3550 (configuration) #class-map dkxs

3550 (Configuration -cmap)# Matching Access Group 15

The main purpose of this step is to create a class map, in which we refer to our pre-created ACL 15 so that we can operate port 22 in the future.

Third, create a policy map

For testing purposes, we created several policy maps and set different bandwidth limits, such as 80k, 1m, 5m and 10m, as shown below:

Conference room 3550