2 Messages

In the DirectPlay 4 Protocol, the terms "frame" and "packet" are used interchangeably. Frames and packets refer to a single payload that is passed to a lower-layer transport, which is typically constrained by the maximum transmission unit (MTU) size of the network. Messages are higher-layer payloads that might be fragmented. Messages that do not fit in a single frame can span multiple frames.

The DirectPlay 4 Protocol supports three types of frames: Data, acknowledgment (ACK), and NACK.<2> The frame type is determined by the settings for the ACK (ACKNOWLEDGE) and EXT (EXTENSION) bits of the flags field, and the nNACK bits of the extended flags field in the packet.

Frame type

ACK bit

EXT bit

nNACK bits

Data Frame (section 2.2.2)

Not Set

Not Set

Not present

ACK Frame (section 2.2.4)

Set

Not Set

Not present

NACK Frame (section 2.2.3)

Set

Set

Non-zero

This protocol references commonly used data types as defined in [MS-DTYP].

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