How to Diagnose Network Congestion with Ax3soft Unicorn

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What is network congestion?

In data networking and queuing theory, network congestion occurs when a link or node is carrying so much data that its quality of service deteriorates. Typical effects include queuing delay, packet loss or the blocking of new connections. A consequence of these latter two is that an incremental increase in offered load leads either only to a small increase in network throughput, or to an actual reduction in network throughput.

Fault description

Network activity of host (MAC: 00:0D:61:E2:76:02) is abnormal, to sent a large number of broadcast packets. Please see the figure below:

Figure 1: Diagnose network congestion in the Nodes tab

Switch to summary tab, we found that these packets which’s size is in between 66-127 accounted a large proportion of total traffic.  Please see the figure below:

Diagnose Network Congestion

To analyzed packets sent by the host (MAC: 00:0D:61:E2:76:02), we found that the host constantly query domain and the DNS server returned back a name error response. Next, the host broadcast wins packets to query domain, please see the figure below:


The host query a domain which don’t exists and sent a large of packets, to waste network resources. we found the host and clear these malware. The fault was resolved and network returned to normal.

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