MTU discovery using EDT
Enlightened Data Transport (EDT) is a Citrix-proprietary transport protocol built on top of the UDP protocol. It delivers superior user experience on challenging long-haul connections while maintaining server scalability. EDT improves data throughput for all ICA virtual channels on unreliable networks, providing a better and more consistent user experience.
When Adaptive Transport is enabled, EDT is the preferred protocol.
Note:
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Session Reliability must be enabled to use MTU Discovery and EDT with NetScaler Gateway and Citrix Gateway Service.
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Packet fragmentation can cause performance degradation or even failure to open sessions in some cases. To prevent this, you must adjust the EDT MTU to a value adequate for your networks. You can use EDT MTU Discovery or a manual workaround described in How to configure MSS when using EDT on networks with non-standard MTU.
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For details on enabling the use of EDT with NetScaler Gateway, see Configure NetScaler Gateway to support Enlightened Data Transport.
EDT MTU Discovery
MTU Discovery allows EDT to automatically determine the Maximum Transmission Unit (MTU) when establishing a session. Doing so prevents EDT packet fragmentation that might result in performance degradation or failure to establish a session.
MTU Discovery is enabled by default. If you need to disable it, run the following command in the terminal.
create -k "HKLM\System\CurrentControlSet\Control\Terminal Server\Wds\icawd" -t "REG_DWORD" -v "MtuDiscovery" -d "0x00000000" --force
In scenarios where dynamic routing through asymmetrical paths may cause the MTU for the session to change, MTU rediscovery can also detect and adjust the session’s MTU accordingly. Rediscovery is enabled by default.
To disable it, run the following command in the terminal.
create -k "HKLM\System\CurrentControlSet\Control\Terminal Server\Wds\icawd\MtuReDiscovery" -t "REG_DWORD" -v "MtuDiscovery" -d "0x00000000" --force
Note:
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Session Reliability must be enabled for MTU Discovery to work.
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MTU rediscovery is available with VDA versions 2603 and later.