1. Replace the OS with Centos 5.8. The problem is solved.
The network interface card (NIC) driver provided by Centos 5.8 is of the 3.06k2-2 version.
2. Download the latest NIC driver of the 3.3.6 version from the Intel website and update it to Centos 6.2. After testing, the problem is solved, as shown in Figure 2.
Figure 2 Traffic information after NIC driver replacement