Networking Insights

Overview of Networking Insights, the network performance profiling tool

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Unreal Insights includes Networking Insights to analyze, optimize and debug network traffic. Users can record trace information to visualize network behavior with the following features:

  • Game Instance control to display visible machines during the network sessions being recorded

  • Connection Mode control to visualize outgoing or incoming data

  • Packet Overview panel that displays packet timelines (and sizes) being transmitted or received during a game

  • Packet Content panel that shows a packet's content, such as replicated objects, properties, and remote function calls

  • Net Stats panel that displays trace events for selected packets, including statistics about the total, maximum, and average exclusive (or inclusive) packet sizes.

NetworkingInsightsHero.png

Setup

Before continuing, ensure that you are running Unreal Insights.

Using Networking Insights

To analyze data start your project instances with the following command-line option:

-NetTrace=[VerbosityLevel] -trace=net

VerbosityLevel should be set to a value of greater than zero. For example, if a game instance starts with -NetTrace=1, Unreal Insights will collect and report network trace data for analysis by opening the session in Unreal Insights.

The editor runs its own data store for trace data, which means that you need to specify the tracehost in order to collect network trace data while running in the editor. To specify the tracehost, use: -NetTrace=1 -tracehost=localhost -trace=net

Networking Insights Window

The Networking Insights window is where you'll find networking session data.

For additional commands, tips, and information on other Unreal Insights windows , refer to the Reference documentation.

Overview of the entire Networking Insights window.

The Networking Insights window features the Connection Selection panel(1), the Packet Overview panel(2), the Packet Content panel(3), and Net Stats panel(4).

Packet Overview Panel

The Packet Overview panel displays a bar graph that shows the size (in bits) for every packet received or transmitted. This is useful for identifying large packets that need further investigation. Left-click the bar to select a packet.

The reported size of each packet is before compression, so the actual data on the wire may be smaller than what the report shows.

PacketOverviewPanel.png

Hovering over a packet displays its information. This information includes:

  • Packet Index

  • Sequence Number

  • Content Size in bits

  • Total Size in bytes, with unused bits

  • A timestamp for when the packet was sent or received

  • The packet's current status (delivered or undelivered)

  • The connection state in which the packet was received

  • Engine frame number of when the packet was sent or received

To select multiple packets, click to select an inital packet, then hold the Shift key and click other packets. Dropped packets display in red.

Packet Content Panel

The Packet Content panel displays the actual content of the currently selected packet. The packet's content displays as a hierarchical event graph starting with bit zero on the left side. This is the main tool to investigate the data contents in each packet down to the property level.

PacketContentPanel.png

The packet content panel displaying bunches of data contained in a packet. This includes information about replicated objects and properties.

The first level displays the bunches contained in a packet. Each bunch is named after the channel that it belongs to. If the reported bunch has its debug name set when reported, the debugname will be used instead of the channelname to provide additional context (where available).

The second level typically displays replicated objects contained in the bunch. If the event has an assigned NetId(NetGUID), the ID is on display as well.

Evemts further down the event hierarchy display replicated properties, including how many bits they wrote.

Hovering over an event displays all of the event's information.

The panel features controls to find a packet, or to find events belonging to a specific NetId.

You can navigate the Packet Content Panel and Packet Overview Panel using your keyboard. The up and down arrow keys will move between levels. The left and right arrow keys will move between events on the same level. If you hold the CTRL or CMD key and press the left or right arrow keys, you will move between packets.

Connection Selection Panel

The top of the Packet Overview panel has controls that let users select the data to display.

connection-drop-down-list

The connection dropdown lists located at the top of the Packet Overview panel. This example shows Player 0's connection in a server game instance, with incoming data selected.

Three dropdown lists are available in the Connection Selection panel:

Dropdown List

Description

Game Instance

Displays the created Game Instance for each unique NetDriver observed during a recording session. For example, when using PIE, there are separate instances for the server and each client.

Connection

This dropdown selects a specific connection, displaying every observed connection during the selected Game Instance's session.

Connection Mode

This dropdown controls whether to visualize incoming our outgoing data.

Net Stats Panel

The Net Stats panel lists all trace events for the selected packet range in the Packet Overview panel.

close-up-of-the-net-stats-panel-displaying-multiple-levels-of-data

The Net Stats panel with events grouped by level

In addition to aggregating data based on a selected range, users can sort the list in ascending or descending order by the values in any active column. Right-click anywhere in the list to change the sort order, or to activate or deactivate columns. The following columns are available:

  • Type

  • Level

  • Instance Count

  • Total Inclusive Size (bits)

  • Max Inclusive Size (bits)

  • Total Exclusive Size

  • Max Exclusive Size

To filter events by name, use the "search net events or groups" field. Users can group according to these event types:

Group Name

Description

Level

Creates one group for each level.

Flat

Creates a single group. Includes all Net Events.

Name

Creates one group for one letter

Grouping by Level helps users understand their data better because the same name can appear on different levels. The following table describes these levels:

Level

Description

0

Typically channel information that displays all bunches using the channel name.

1

Replicated Object (Actor), most events at this level show the serialized object.

2

Reports events originating from property replication or from RPCs.

3

Reports events when serializing properties.

4

Reports additional events when serializing properties, array content, and more.

The Net Stats panel features a !0 toggle to filter out event types that have no data in the selected range.

Example Data

Information about network packet content tracing macro is in the Unreal Insights Reference.

To better understand the data that Networking Insights visualizes, we offer the following examples:

Replicated Objects

Initial replication of a new Actor

This is the initial replication of a new Actor--ReplicationGraphDebugActor, NetGUID 10.

Before the bunch containing the new actor, there is a NetGUID bunch containing all of the exported references from the new Actor, including NetGUIDS.

RPCs

Example of an RPC called ClientAckGoodMove, which is part of a Character's movement system

This is an RPC named ClientAckGoodMove that targets PlayerPawn_C with NetGUID 14.

GUIDs must be mapped.

Split Bunches

Event data generated from transmitting a split bunch report with the first part--when receiving a split bunch, parts are reported first, and when all parts are received, events are reported with the final part.

Example of an outgoing bunch.

This is a split outgoing bunch. Note that the events in the bunch are larger than the Bunch.

The next few packets look like the following:

Example of a packet providing the rest of the data for the split bunch.

Incoming split bunches exhibit the opposite pattern, where events report with the last partial bunch.

SubObjects

Example of sub-objects sharing the same bunch as their owner

This is a SubObject example--note that the second Actor after BotPawn_C shares the same bunch.