IN THIS ARTICLE

AzNetworking and Multiplayer Gem Settings

Overview

This page documents console variables (CVARs) and other settings that can control Networking and Multiplayer behavior in Open 3D Engine (O3DE).

Networking commands

Use the following console functor (cfunc) commands to control the connection of clients to servers for networked games or simulations.

Setting	Description	Parameters	Notes
host	Opens a multiplayer connection as a host for other clients to connect to.
connect	Opens a multiplayer connection to a host.	(Optional) IP address and port, separated by ‘:’. For example, `0.0.0.0:1234`.	Defaults to `cl_serveraddr`:`cl_serverport`.
disconnect	Disconnects any open multiplayer connections.
LoadLevel	Unloads the current level and loads a new one with the given asset name. Used to setup the initial level for the game or simiulation.	(Required) Path to a level file.	Command is not specific to network or multiplayer but used for all games and simulations.
sv_launch_local_client	Launches a local client and connects to this host server.		Only works if currently hosting.

These console commands can be executed dynamically via the console command line or placed within a console command configuration file.

When using a console command configuration file, it is common practice to place the file in the project root directory. Use .cfg as the filename suffix. Commands will be executed in the order written.

For a networked game or simulation, a typical server configuration file should contain:

host
LoadLevel <path to Level>

A typical client configuration file should contain:

connect

Console commands in configuration files can be passed to client and server launchers using the console-command-file option. Example:

MultiplayerSample.ServerLauncher.exe --console-command-file=launch_server.cfg

Client settings

The cl CVARs control client behavior.

Setting	Description	Default
cl_clientport	The port to bind to for game traffic when connecting to a remote host, a value of 0 will select any available port.	0
cl_serveraddr	The address of the remote server or host to connect to.	LocalHost
cl_serverport	The port of the remote host to connect to for game traffic.	33450
cl_InputRateMs	Rate at which to sample and process client inputs.	33 ms
cl_MaxRewindHistoryMs	Maximum number of milliseconds to keep for server correction rewind and replay.	2000 ms
cl_renderTickBlendBase	The base used for blending between network updates, 0.1 will be quite linear, 0.2 or 0.3 will slow down quicker and may be better suited to connections with highly variable latency.	0.15

Client to server connection settings

Setting	Description	Default
cl_ClientEntityReplicatorPendingRemovalTimeMs	How long to wait prior to removing an entity for the client through a change in the replication window, entity deletes are still immediate.	10000 ms
cl_DefaultNetworkEntityActivationTimeSliceMs	Max Ms to use to activate entities coming from the network, 0 means instantiate everything.	0 ms
cl_ClientMaxRemoteEntitiesPendingCreationCount	Maximum number of entities that we have sent to the client, but have not had a confirmation back from the client.	4294967295

Debug settings

Setting	Description	Default	Notes
cl_DebugHackTimeMultiplier	Scalar value used to simulate clock hacking cheats for validating bank time system and anticheat.	1.0	Non-release builds
cl_EnableDesyncDebugging	If enabled, debug logs will contain verbose information on detected state desyncs.	True	Non-release builds
cl_DesyncDebugging_AuditInputs	If true, adds inputs to audit trail.	False	Non-release builds
cl_PredictiveStateHistorySize	Controls how many inputs of predictive state should be retained for debugging desyncs.	120	Non-release builds only

Server settings

The sv CVARs control server behavior.

Setting	Description	Default	Notes
sv_map	The map the server should load.	None
sv_port	The port that Multiplayer Gem will bind to for game traffic.	33450
sv_portRange	The range of ports the host will incrementally attempt to bind to when initializing.	999
sv_protocol	This flag controls whether we use TCP or UDP for game networking.	Udp
sv_DedicatedCPUPercent	Target CPU usage when running as a dedicated server.	0	Disabled by default.
sv_DedicatedCPUVariance	How much the CPU can vary from `sv_DedicatedCPUPercent`.	10
sv_DedicatedMaxRate	Maximum update rate when running as a dedicated server.	30
sv_isDedicated	Whether the host command creates an independent or client hosted server.	True
sv_isTransient	Whether a dedicated server shuts down if all existing connections disconnect.	True
sv_serverSendRateMs	Minimum number of milliseconds between each network update.	50 ms
sv_versionMismatch_autoDisconnect	Determines if a mismatched connection will automatically terminate. It’s recommended to keep this true; even minor differences between the version of a multiplayer component can cause unexpected behavior.	True

Server to client connection settings

Setting	Description	Default
sv_ClientEntityReplicatorPendingRemovalTimeMs	How long to wait prior to removing an entity for the client through a change in the replication window, entity deletes are still immediate.	10000 ms
sv_ClientMaxRemoteEntitiesPendingCreationCount	Maximum number of entities that we have sent to the client, but have not had a confirmation back from the client.	4294967295
sv_ClientMaxRemoteEntitiesPendingCreationCountPostInit	Maximum number of entities that we will send to clients after gameplay has begun.	4294967295

Replication window settings

Setting	Description	Default
sv_ReplicateServerProxies	Enable sending of ServerProxy entities to clients.	True
sv_MaxEntitiesToTrackReplication	The default max number of entities to track for replication.	512
sv_MinEntitiesToReplicate	The default min number of entities to replicate to a client connection.	128
sv_MaxEntitiesToReplicate	The default max number of entities to replicate to a client connection.	256
sv_PacketsToIntegrateQos	The number of packets to accumulate before updating connection quality of service metrics.	1000
sv_BadConnectionThreshold	The loss percentage beyond which we consider our network bad.	0.25
sv_ClientReplicationWindowUpdateMs	Rate for replication window updates.	300 ms
sv_ClientAwarenessRadius	The maximum distance entities can be from the client and still be relevant.	500.0

Rewind settings

Setting	Description	Default	Notes
sv_RewindVolumeExtrudeDistance	The amount to increase rewind volume checks to account for fast moving entities.	50

Editor server settings

The editorsv settings control how a server will be launched during the “play-in-editor” (CTRL+G) mode.

Setting	Description	Default	Notes
editorsv_isDedicated	Whether to init as a server expecting data from an Editor. Do not modify unless you’re sure of what you’re doing.	False
editorsv_port	The server port the Editor will connect to when entering play-mode.	33450	Only valid when `editorsv_enabled` is true.
editorsv_serveraddr	The address of the server the Editor will connect to when entering play-mode.	LocalHost	Only valid when `editorsv_enabled` is true.
editorsv_process	The file path to your project’s ServerLauncher. If `editorsv_enabled` and `editorsv_launch` is true, the Editor will attempt to launch its own server when entering game mode. By default it looks for the ServerLauncher executable inside the same folder where Editor lives; `editorsv_process` overrides that path.	""
editorsv_rhi_override	If `editorsv_launch` is true, the server will use the same render hardware interface (rhi) that the editor is using. For example, if the editor is using DX12, then the new server will be launched using DX12. `editorsv_rhi_override` can be used to override the rhi.	""	If you don’t need to see the launched server’s graphics then set `editorsv_rhi_override=null`, the null renderer.
editorsv_enabled	If true the Editor will attempt to connect to a Multiplayer server upon entering game mode.	False
editorsv_clientserver	Whether the Editor should act as the server and a client at the same time, without launching a dedicated server process.	False	Only applies if `editorsv_enabled` is also true.
editorsv_hidden	If true the Editor will automatically launch a server upon entering game mode. Set `editorsv_hidden` to true if you want the launched server to be started as a background process without any visible window.	False
editorsv_launch	If true the Editor will automatically launch its own server upon entering game mode.	True	Only applies if `editorsv_enabled` is also true. If starting your own editor-server remember to set `editorsv_isDedicated` to true on the server
editorsv_connectionMessageFontSize		0.7

Dual client server settings

The bg settings control behavior on both the client and server.

Setting	Description	Default
bg_RewindDebugDraw	If true enables debug draw of rewind operations.	False
bg_replicationWindowImmediateAddRemove	Update replication windows immediately on visibility Add/Removes.	True
bg_multiplayerDebugDraw	Enables debug draw for the Multiplayer Gem.	False
bg_replicationWindowImmediateAddRemove	Update replication windows immediately on visibility Add/Removes.	True
bg_RewindPositionTolerance	Don’t sync the NVIDIA PhysX entity if the square of delta position is less than this value.	0.001
bg_AssertNetBindOnDeactivationWithoutMarkForRemoval		False
bg_hierarchyEntityMaxLimit		16
bg_DrawArticulatedHitVolumes	Enables debug draw of articulated hit volumes.	False
bg_DrawDebugHitVolumeLifetime	The lifetime for hit volume draw-debug shapes.	0.0
bg_RewindOrientationTolerance	Don’t sync the NVIDIA PhysX entity if the square of delta orientation is less than this value.	0.001

Networking settings

The net settings control networking behavior.

AzNetworking layer

Setting	Description	Default	Notes
net_maxPacketTrackTimeMs	Maximum time to track any particular packet ID before giving up.	2000
net_rttIncreaseOnPacketLoss	Scalar amount to increase round trip time estimates by on packet loss.	1.2
net_TcpCompressor	TCP compressor to use. WARNING: Similar to encryption this needs to be set once and only once before creating the network interface.	None
net_TcpUseEncryption	Enable encryption on TCP-based connections.	False
net_UseDtlsCookies	Enables DTLS cookie exchange during the connection handshake.	False
net_UdpMaxUnackedPacketCount	Maximum packets to receive before forcing a heartbeat packet for acking.	10
net_UdpFragmentTimeoutMs	Milliseconds to retain chunks of incomplete unreliable fragmented packets before timing them out.	5000 ms
net_UdpCompressor	UDP compressor to use. WARNING: Similar to encryption this needs to be set once and only once before creating the network interface.	None
net_MinPacketTimeoutMs	Minimum time to wait before timing out an unacked packet.	200 ms
net_UdpDefaultTimeoutMs	Time in milliseconds before we timeout an idle UDP connection.	10 * 1000 ms
net_UdpPacketTimeSliceMs	The number of milliseconds to allow for packet processing.	8 ms
net_UdpTimeoutConnections	Should code hold timeout UDP connections.	True
net_UdpUseEncryption	Enable encryption on UDP-based connections.	False
net_RttFudgeScalar	Scalar value to multiply computed RTT by to determine an optimal packet timeout threshold.	2.0
net_MaxTimeoutsPerFrame	Maximum number of packet timeouts to allow to process in a single frame.	1000
net_FragmentedHeaderOverhead	A fudge overhead value to take out of fragmented packet payloads.	32
net_SslInflationOverhead	A SSL fudge overhead value to take out of fragmented packet payloads.	32
net_UdpUnackedHeartbeats	The number of heartbeats to attempt to send to keep a connection alive before giving up.	5
net_UdpMaxReadTimeMs	The amount of time to allow the reader thread to read data off registered sockets.	10 ms
net_MaxReliablePacketsInWindow	The maximum number of reliable packets to allow to be queued up before triggering a disconnect.	16384
net_UdpIgnoreWin10054	If true, will ignore 10054 socket errors on windows.	True
net_UdpRecvBufferSize	Default UDP socket receive buffer size.	1 * 1024 * 1024
net_UdpSendBufferSize	Default UDP socket send buffer size.	1 * 1024 * 1024
net_validateSerializedTypes	Causes an Assert when an attempt at `TypeValidatingSerializer` serialization results in a type or variable name mismatch.	False	Increases bandwidth utilization to support mismatch detection.

Multiplayer layer

Setting	Description	Default	Notes
net_EntityReplicatorRecordsMax	Number of allowed outstanding entity records.	45	Requires Multiplayer Gem
net_DefaultEntityMigrationTimeoutMs	Time to wait for a new authority to attach to an entity before we delete the entity.	1000 ms	Requires Multiplayer Gem
net_EntityReplicatorRecordsMax	Number of allowed outstanding entity records.	45	Requires Multiplayer Gem
net_DebugEntities_ShowBandwidth	Display bandwidth information.	False
net_DebutAuditTrail_HistorySize	Size of audit history.	20
net_DebugEntities_WarnAboveKbps		10.f
net_DebugEntities_BelowWarningColor		Grey
net_DebugEntities_WarningColor		Red
net_DebugEntities_ShowAboveKbps		1.f

TLS/DTLS certificate settings

Setting	Description	Default
net_SslCertCiphers	The cipher suite to use when using cert based key exchange.	ECDHE-RSA-AES256-GCM-SHA384
net_SslExternalCertificateFile	The filename of the EXTERNAL (server to client) certificate chain in PEM format.	""
net_SslExternalContextPassword	The password required for the EXTERNAL (server to client) private certificate.	""
net_SslExternalPrivateKeyFile	The filename of the EXTERNAL (server to client) private key file in PEM format.	""
net_SslInternalCertificateFile	The filename of the INTERNAL (server to server only) certificate chain in PEM format.	""
net_SslInternalContextPassword	The password required for the INTERNAL (server to server only) private certificate.	""
net_SslInternalPrivateKeyFile	The filename of the INTERNAL (server to server only) private key file in PEM format.	""
net_RotateCookieTimer	Number of milliseconds to wait before generating a new DTLS cookie for handshaking.	50 ms
net_SslAllowSelfSigned	If enabled, self-signed certs will not cause a validation error if they are otherwise considered trusted.	True
net_SslEnablePinning	If enabled, the public certificates on the local and remote endpoints will be compared to ensure they match exactly.	True
net_SslValidateExpiry	If enabled, expiration dates on the certificate will be checked for validity.	True
net_SslMaxCertDepth	The maximum depth allowed for cert chaining validation.	3

Debug settings

Setting	Description	Default	Notes
net_DebugCheckNetworkEntityManager	Enables extra debug checks inside the NetworkEntityManager.	False	Requires Multiplayer Gem
sv_versionMismatch_sendManifestToClient	Determines if the server will send all its individual multiplayer component version information to the client when there’s a mismatch. Upon receiving the information, the client will print which components are different to the console. It’s recommended to set to false for release builds. This is to prevent clients having knowledge to any multiplayer component information that should be kept private (component names and version hashes).	True

Other useful settings

The following settings can be passed as command line arguments to control server performance.

Setting	Description
rhi	Add `-rhi=null` to the server launcher args to turn on null renderer to avoid rendering costs.
NullRenderer	Add `-NullRenderer` to the server launcher args to turn off RPI ticking to save on performance when using null renderer.