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NetFlow collects the Packet source, Port number, Destination Packet size, and Protocol number. Understanding what ports are commonly used on your network can help you in determining if abnormal activity is coming through. Using the Conversation Summary feature in opFlow allows for a detailed look into all conversations happening on your network. There may be a lot of conversations happening across your network, in Figure 1 below, you can see that the ports are filtered to only show Src Port 443 allowing you to see specific and relevant traffic easier. These packets can be sorted in ways that help you view and understand the information more clearly. In this example, packets received are sorted in descending order to see if the packet count is any higher than normal; this is why understanding what normal packet sizes are as well as their ports/sources on your network is important for any network engineer.

To view the Conversation Summary page navigate to menu -> Views -> Conversation Summary. The filter is added by simply typing the desired port in the box in the top right hand corner of the Conversation Summary page. The drop down menu to the right of the search box allows you to search for the specific Application, Source, Src Port, Destination, and Dst Port.


Figure 1 - Conversation Summary

The default landing page for opFlow displays the Top 10 App Sources as shown in Figure 2 below. This shows the applications that are generating the most flow data displaying their Source, Application, Bits, and Pkts. In this example, these sources are mostly coming from known servers and routers having conversations with each other. However, the application generating the most Bits is clearly Other. Other is defined by all of the other applications that are not on the Top 10 Apps list which in this case is quite a lot. To get a clearer view of all the applications that are grouped in Other, the Conversation Summary view is recommended. If you wanted an application that is defined in the Other category to be recognized as a known application by you, you can create a Custom Application. Custom Application creation is detailed Here: Creating Custom Applications

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Figure 2 - Top 10 App Sources