Wireless Datagram Protocol (WDP) works as the transport layer of WAP. WDP processes datagrams from upper layers to formats required by different physical datapaths, bearers, that may be for example GSM SMS or CDMA Packet Data. WDP is adapted to the bearers available in the device so upper layers don't need to care about the physical level.

Connectionless Broadband Data Service. European highspeed, packet-switched, datagram-based WAN networking technology. Similar to SMDS.

Logical grouping of information sent as a network layer unit over a transmission medium without prior establishment of a virtual circuit. IP datagrams are the primary information units in the Internet. The terms frame, message, packet, and segment are also used to describe logical information groupings at various layers of the OSI reference model and in various technology circles.

It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header

The data unit created at the application layer is called a message, at the transport layer the data unit created is called either a segment or an user datagram, at the network layer the data unit created is called the datagram, at the data link layer the datagram is encapsulated in to a frame and finally transmitted as signals along the transmission media.

Switched Multimegabit Data Service (SMDS) is a high-speed, packet-switched, datagram-based WAN networking technology used for communication over public data networks (PDNs)

Datagram Delivery Protocol. Apple Computer network layer protocol that is responsible for the socket-to-socket delivery of datagrams over an AppleTalk internetwork.

The ndd Command
Several of the network settings discussed in this article are configured using the ndd command. It is used to examine and set kernel module parameters, namely the Transmission Control Protocol/Internet Protocol (TCP/IP) drivers. Most kernel parameters accessible through ndd can be modified without rebooting the system.
To see which parameters are available, use the following ndd commands:
# ndd /dev/arp \?
# ndd /dev/icmp \?
# ndd /dev/ip \?
# ndd /dev/tcp \?
# ndd /dev/udp \?These commands list the parameters for the
Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), IP, TCP, and User Datagram Protocol (UDP) drivers. In this updated BluePrint OnLine article, the various drivers are listed in alphabetic order.
The Solaris 8 and 9 OE releases include support for the next version of the Internet Protocol suite (IPv6) and the Internet Protocol Security architecture (IPsec). These have additional drivers. A list of parameters for these drivers can be found with the following commands:
# ndd /dev/ip6 \?
# ndd /dev/icmp6 \?
# ndd /dev/tcp6 \?
# ndd /dev/udp6 \?
# ndd /dev/ipsecesp \?
# ndd /dev/ipsecah \?The IPv6 parameters for the ICMP, IP, TCP, and UDP drivers are also listed in the standard (IPv4) parameter lists. This article does not discuss IPsec, but the parameters are listed here for completeness. Neither IPv6 nor IPsec support will be supported in any Solaris OE release earlier than Solaris 8 OE.
There are also network interface device drivers with parameters that can be adjusted using the ndd command. The following command will list the parameters for the hme (FastEthernet) device driver:
# ndd /dev/hme \?The "\?" string is required to prevent the shell from interpreting the "?" as a special character. Using "\?" will list all parameters for the driver and indicate whether the parameter is read only, write only, or
read and write. The current parameter value or status information can be read by specifying the driver and
parameter names.
This example shows the output of a ndd command examining the debugging status of the ARP driver. (The output "0" indicates that the option is disabled.)
# ndd /dev/arp arp_debug
0ndd-specified parameter values are integers with "0" meaning disable, "1" meaning enable, or a large integer to set a time or size value. Setting parameters requires the "-set" option, the driver name, the parameter name, and the new value.
For example, to enable debugging mode in the ARP driver use this ndd command:
# ndd -set /dev/arp arp_debug 1Notes on Parameter Changes Previously, only some ndd parameter documentation was available from Sun. This has been a known problem. Since the release of the Solaris 8 OE, there is now documentation of selected tunable TCP/IP parameters. The book is the Solaris Tunable Parameters Reference Manual and is available on the docs.sun.comSM web site. Most of the parameter information for the Solaris 9 OE is also applicable to previous releases.
Network parameters set with the ndd command apply to the currently running Solaris instance; parameter changes do not last past system reboots. Once a system is booted, the default parameters will be used. To provide a simple method of setting the ndd network parameters mentioned in this article at Solaris boot time, a system init script has been created and is described in "Sample System nddconfig init Script."
Setting driver parameters involves making trade-offs. Most parameters involve changing the default Solaris OE configuration. The default settings are optimal for most situations. Adjusting parameters might affect normal system operation, so Sun does not encourage parameter changes.
All ndd parameter changes suggested in this article include a discussion of trade-offs, where appropriate. Some settings change the expected operation of systems; these are noted. Most of these recommended parameter changes are being actively used on production systems at customer sites.
Sun sometimes alters parameter names or adds additional parameters between releases of the Solaris OE. Most of the IPv4 parameters described in this article are used consistently across Solaris OE releases. When there are exceptions, the text for the parameter specifically mentions the OE differences.

no connection is required because datagram itself act as a call establishment signal

SNMP is a management tool.
Whenever SNMP communicates with managed devices it will take the help of other protocols ie., UDP( user datagram protocol).