Configuration Settings

In addition to the basic interface controls, various aspects of ExpeDat Desktop's setup and network behavior can be adjusted for unusual conditions.  These settings may be applied using the Options dialog, or embedded in the executable using the DropDat master application.

In most cases, the default configuration will provide the best performance and there is no need to adjust these settings.  Incorrect settings may severely degrade performance or disrupt the network.  Take the time to understand what these settings do before experimenting with them.

The default values shown below apply to unmodified configurations.  Your application may have different defaults depending on the server configuration and embedded settings.  See the Priority chapter to learn how the setting values are negotiated.


These settings affect the behavior of the ExpeDat Desktop client itself.

Default Folder <pathname>
Choose the folder which will be initially displayed in the local browser upon startup.  All web-downloads will be saved to this location regardless of the current Local Folder path.  Not available for DropDat embeddingDefault: None.

Debug <level>
Enable diagnostic messages.  Level 1 will display configuration information and report additional details about network activity.  Immediately after startup, a section labeled "Configuration Settings" will show detailed information about what options are set and where.  Debug levels above 1 will produce copious output which may severely degrade performance and overflow the message box.  It is best to enable a Log File when debugging is enabled.  Default: 0.

Log File <pathname>
When a log file is specified, message box output will be copied to the file and all diagnostic messages will be written exclusively to the file.  Session logs are appended to the end of any existing data, so the file may grow quite large over time.  Setting this as a default via the DropDat interface is not recommended because the pathname may not be valid on the end-user's system and the file may grow arbitrarily large.  Default: None.

Server Handlers <Handler List>
ExpeDat servers can be configured to access object storage and workflow automation systems, in addition to regular files.  Server Object Handlers, such as CloudDat, route ExpeDat Desktop requests to external scripts and applications.  To access object handlers, enter the list of handler action codes supported by your servers.  Each code must be separated by a comma, without spaces.  A new "Handlers" menu will appear in the main window where you can choose from the list or select "None" to access the server filesystem.  For example, clients interacting with a CloudDat for S3 would typically have "S3" here.  Default: None.

Streaming Folders <On or Off>
When checked, the contents of folders will be transferred as a real-time data stream.  When unchecked, the contents of folders will be transferred individually, one-at-a-time.  See Copying Folders for very important details.  This is "Off" by default, but the default can be changed to "On" with DropDat embeddingDefault: Off.

Show Hidden <On or Off>
By default, files which the operating system would normally hide are not included in folder listings or transfers.  Checking this box will include hidden files in folder listings and folder transfersDefault: Off.

Limit Prompts <On or Off>
Do not prompt for confirmation when overwriting local files or resuming transfers.  This may be useful for unattended downloads of multiple files.  Default: Off.

Startup Message <Text>
This text will be displayed at startup.  You may find it useful for custom branding, user instructions, administrative contacts, or any other text message.  Checking "Lock" will caused the text to be displayed in a modal dialog which the user must dismiss before using the application.  This option is only available with DropDat embeddingDefault: None.

Require Encryption <On or Off>
When checked, the Encryption option will be locked "On".  This option is only available with DropDat embeddingDefault: Off.


These settings change the default network characteristics of new transactions.

Aggression <-3 to 5>
Aggression is a scalable means of adjusting how ExpeDat Desktop's network activity affects other network traffic.  When third party-traffic is present, increased Aggression may improve ExpeDat Desktop's performance by slowing down the other traffic.  Decreasing Aggression may reduce ExpeDat Desktop's performance which may allow other traffic to go faster.  Do not use Aggression level 5 unless your entire network supports Jumbo Ethernet Frames.  See the Performance section for critical information about this and other performance adjustments.  Default: 2.

Default Server Port <UDP Port Number>
Specify the default UDP port number of the server.  Use this option if many of your servers are running on a port other than the default 8080.  Note that the end-user can always type a different port number in the Server field, even if the default port is locked.  Default: 8080.

Expire <seconds>
Sets how long ExpeDat Desktop should wait without hearing from the server before it gives up and begins Automatic RetryDefault: 40.

Compression / Streaming Buffer <Megabytes>
Sets the number of megabytes to use for buffering network data when compression or Streaming Folders are in use. The buffer should be at least twice the bandwidth-delay-product of your network path.  (Multiply the path bandwidth in bits-per second by the latency in milliseconds, then divide by 4194304000.  The result is the minimum number of megabytes recommended.)  If you increase this value, you should also increase the server's StreamSize setting to match.  Default: 64.


These settings restrict MTP/IP's network behavior.  They may be useful to optimize performance in unusual environments or to achieve specific performance goals.  It is extremely rare for these settings to require adjustment.

Maximum Data Rate <kilobits per second>
Do not allow data to be transferred across the network faster than this many kilobits per second.  This limit applies to actual network speed: data compression may make the net transfer speed appear to be faster.  Setting this to a value at or above the hardware speed of the path will have no effect.  The limit applies to the peak speed of a transfer, the average may be less.  Combining a limit below the hardware speed with an Aggression setting of 4 may provide an average that is closer to the limit.  Default: None.

Maximum Round Trip Time <milliseconds>
Slow down if the path latency ever exceeds this many milliseconds.  This setting may be used if there is latency sensitive traffic sharing the network path.  Make sure this value is significantly higher than the baseline latency of the path, as measured by a ping utility when the path is idle.  Remember that different servers may have very different minimum latencies.  Default: None.

Minimum Round Trip Time <milliseconds>
Advise MTP/IP of operation on a path with very high latency.  The value should be the minimum observed round trip time of the path, in milliseconds.  This setting will have no effect for RTTs less than 500ms and has little effect for RTTs less than 2000ms.  Default: None.

Maximum Datagram Payload <bytes>
Limit the size of network datagram payloads to no more than this amount.  The full IP datagram size will be at least 56 bytes larger when MTP/UDP/IP headers are included.  Tunneling, VPNs, IPsec, MPLS and other encapsulations will add more.  If you are experiencing performance or connectivity problems on a network with an MTU much less than 1500 bytes or on a multigigabit path with Jumbo datagrams disabled, try setting a value of 1408, 1280, 1024, or 512Default: None.

Minimum Datagram Payload <bytes>
Use network datagram payloads of at least this size.  If your network path is very fast (gigabit or more) and every device along that path supports Jumbo frames (MTU 9000), you may be able to improve performance by setting this to 8192.  Even larger values, up to 61440 may be used on networks which support Super Jumbo frames (e.g. InfiniBand).  Settings above 1408 without Jumbo frames fully supported may cause severe performance problems or loss of connectivity.  Note that setting MinDatagram will increase the minimum throttling limit discussed in the Performance chapter.  Default: None.

Noise Ratio <4 to 5000>
MTP/IP normally regards packet loss as an indication of network congestion.  This option will cause MTP/IP to ignore packet losses up to a rate of one in N, for a given number N.  For example, a value of 100 will cause MTP/IP to ignore a loss rate of up to 1%.  This option should only be used on noisy data paths where loss is occurring due to uncorrected bit errors (e.g. raw satellite or radio links).  Improper use of this option may severely disrupt the network and result in a loss of performance or connectivity, especially when Aggression is elevated.  Default: None.