Wireless Datagram Protocol (WDP):
The Wireless Datagram Protocol(WDP) provides a UDP-like service to non-IP bearers. On IP-enabled bearers (like IP or GSM Circuit-Switched Data (CSD) or even GPRS) WDP is identical to UDP, hence people often talk about the "WDP-UDP" protocol.
WDP provides 16-bit port multiplexing and 8-bit data transport in the same way UDP does.
Note that WDP is not a real dissector in Wireshark, but some dissectors (like the GSM SMS User Data dissector) will hand off protocol data to WAP dissectors as if it was handed off to a WDP dissector.
Wireless Datagram Protocol,how does work.
Provides a network and bearer independent interface to higher layers
Provides port level addressing
Provides segmentation and reassembly
For link layers that support IP, UDP is used as the Wireless Datagram Protocol layer
Wireless Datagram Protocol architecture:
The Wireless Data Protocol acts as the communication layer between the upper level protocols (WTLS, WTP, and WSP), and the bearer services. WDP allows the upper layers to function independently from the wireless network at hand, as long as the WTP layer is specifically set to the settings of the bearer settings.
The function of the WDP is to provide a stable environment so that any of the underlying bearers can operate using WAP. WDP can be adapted to different bearers with different services however the services offered by WDP remains constant thus providing a continuous interface to the upper layers of the WAP stack.
The bearers of WAP are the products or other types of medium that implements WAP in their network and in their technology, such as CDPD, Mobitex, and GSM.