Datagram – Datagram service

Agents offering the Datagram service support messages to transmit and receive datagrams. Such agents may offer some optional capabilities:

Capability Description
FRAGMENTATION Capable of fragmentation/reassembly of datagrams
RELIABILITY Capable of link-level reliability
PROGRESS Capable of reporting progress via DatagramProgressNtf messages
CANCELLATION Capable of cancelling queued datagram transmission
PRIORITY Capable of honoring datagram priority
TTL Capable of honoring datagram time-to-live settings


A large number of agents provide the Datagram service. Specifically, any agent providing Physical, Link, Routing or Transport services support this service.

Requests and Responses

Request Possible Responses Description
DatagramReq AGREE, REFUSE, FAILURE Transmit a datagram
DatagramCancelReq AGREE, REFUSE, NOT_UNDERSTOOD Cancel a datagram transmission
ParameterReq ParameterRsp Get/set/list parameters
CapabilityReq CONFIRM, DISCONFIRM, CapabilityListRsp Check/list capabilities


If reliability is supported, a reliable datagram is specified by setting the reliability property of the DatagramReq. If an agent does not support reliability, it would respond with a REFUSE performative to such a request.


A NOT_UNDERSTOOD response for the DatagramCancelReq request indicates that the agent does not support the CANCELLATION capability.


Notification Topic Description
DatagramNtf default Notification of a received datagram
DatagramDeliveryNtf requester Notification of successful delivery of reliable datagram
DatagramFailureNtf requester Notification of unsuccessful delivery of reliable datagram
DatagramProgressNtf requester/default Periodic notifications of datagram transfer progress
ParamChangeNtf PARAMCHANGE Notification about the modified parameter


The DatagramProgressNtf message is sent by agents supporting PROGRESS capability on a periodic basis. On the transmission end, this message is sent to the originator of the DatagramReq for which the progress is reported. On the reception end, this message is sent to the default notification topic of the agent.


Parameter r/w Description
MTU rw Maximum datagram size in bytes