UDP TunnelMicrosoft has added several new and innovative features to its Windows Server 2012 R2 edition. Notable among them is the ability to switch between Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) or UDP tunnel in the remote desktop component. This protocol switch is based on the availability of bandwidth to the RDP client, and results in delivery of a rich user experience over the remote session.

TCP/IP protocol

Transmission Control Protocol is the client-server communication language on the internet. This is a two-layer protocol, with communication occurring primarily from point to point. The higher layer TCP protocol breaks the message into smaller packets, while the receiving TCP protocol reassembles the message. The Internet Protocol (IP) works in the lower layer to handle the address part of each packet so that the message is delivered to the right destination. Higher layer application protocols such as HTTP, HTTPS, FTP, Telnet and SMTP use TCP/IP for communication.

UDP Tunnel – User Datagram Protocol (UDP)

UDP is another communication protocol, an alternative to TCP. It is a connection-less protocol whereby one computer sends loads of information to another computer and ends the relationship. All packets are independent of each other and the application layer has to reorganize them at the receiving end. UDP tunnel is used by DNS, DHCP, SNMP and VOIP protocols.


The good thing about UDP is that it is lightweight, fast and efficient. There is no acknowledgment and no handshake, which is especially beneficial for playing games or streaming media. However, there is no flow control, ordering of messages or tracking connections. It does error-checking, but there is no recovery option, and although fast and streaming RDP connections can be made, data security and integrity are concerns.

TCP is heavyweight and requires three packets to set up a connection before the actual data are sent. Reliability and congestion control are handled effectively. Although the speed is slow when compared to UDP, TCP guarantees that data are sent in the right order and arrive in the same order. TCP is suited for applications that require high reliability where transmission time is not a concern.

In an RDP/VDI environment, it is important for businesses to be able to switch between UDP and TCP for seamless and secure delivery of applications to remote users. In times of low bandwidth, switching to UDP tunnel would be beneficial, but applications that require a reliable connection should stick with TCP.

UDP Tunneling with Parallels RDP

Parallels RAS provides a comprehensive platform for businesses to effectively manage all aspects of a VDI/RDS environment. The Parallels RDP client is able to contemplate UDP tunneling and switch over for the best user experience when necessary. Taking advantage of this feature, the user gets the best performance over the remote session based on the bandwidth available to the RDP client. This option must be enabled on the 2X SecureClientGateway and occurs without the users knowledge, providing a seamless and smooth experience.

Easy to install, configure and use, Parallels RAS provides the flexibility for businesses to optimize resources according to changing business needs. Moreover, Parallels RAS is the only solution that offers a range of RDP tools within the standard license.


UDP Tunnel: Improve the Windows Server 2012 Remote Desktop experience by using UDP | glennmatthys.wordpress.com

Performing UDP tunneling through an SSH connection: http://zarb.org

UDP Tunnel: TCP vs. UDP | skullbox.net
UDP Tunnel: TCP vs. UDP | diffen.com
UDP Tunnel: TCP/IP (Transmission Control Protocol/Internet Protocol) | searchnetworking.techtarget.com
UDP Tunnel: [MS-RDPEUDP]: Remote Desktop Protocol: UDP Transport Extension | msdn.microsoft.com

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