Transport Layer (7Eh) and (7Dh)
OSI: Transport Layer
Keywords: Connection/-less network, flow control, reliable transport service, low communication overhead, sensors, internet of things, embedded systems, sensor networks
Scope
The scope of this project is to define the Isotropic Sensor Network Transport layer for broadcast and peer to peer connection in distributed sensor area network, wired or wireless, low and high data rate devices, battery powered devices, short-range devices with short operational space, low-cost devices to support trivial sensors, besides the fully featured devices.
Purpose
The purpose of this specifications is to provide a standard for low complexity, low cost, and low power (aware) consumption devices (sensors) to provide a connection-less and reliable connection-oriented network in combination with a Sensor Frame layer.
Key features
Adds Logical Ports and Sequence Counters
Basic Hand-Shaking
Low-Cost and Compact Implementation
Definitions, Acronyms and Abbreviations
- device
An entity containing this protocol implementation. Also referred as sensor device or just sensor or device.
- frame
The format of aggregated bits that are transmitted together in time.
- packet
The format of aggregated bits that are transmitted together in time across the physical medium.
- LSB
least significant byte/bit
- MSB
most significant byte/bit
Packet Formats
Protocol defines short and long frame formats:
short frame format supports connection-less network, with up to 64 logic ports and 2 pending transactions
long frame format supports connection-oriented network, with up to 256 logic ports, 8 pending transactions, and flow-control acknowledge bits
Both protocol can be nested to address larger space and more complex structures.
Short Frame Format (16-bits)
Fields |
Protocol ID |
Port |
Counter |
Payload |
Bits |
8 |
6 |
2 |
N |
Value |
0x7E |
0-63 |
0-3 |
user |
- Protocol ID:
defines the unique protocol identification number
- Port:
logical port 0..31
- Counter:
packet counter 0..3
- User Payload:
of arbitrary length, typically defined by upper or nested Frame Layers (80h+, 10h+ and 20h+)
Long Frame Format (24-bits)
Extends the Short Frame format and adds optional hand-shaking with two acknowledge bits.
Fields |
Protocol ID |
Port |
Counter |
Ack |
Payload |
Bits |
8 |
8 |
14 |
2 |
N |
Value |
0x7D |
0-255 |
0-16383 |
user |
- Protocol ID:
defines the unique protocol identification number
- Port:
logical port 0..255
- Counter:
packet counter 0..16383
- User Payload:
of arbitrary length, typically defined by upper or nested Frame Layer
Opening and Closing Port
Opening a port starts with a first message from or to selected port and non-empty message.
Any side may close the port by sending an empty message, a message which does not contain any user payload.
Packet Counter
In general counter is incremented after every transmission of a packet,
Acknowledge Bits
To be revised.
Document Changes
Date |
Release |
Changes |
January 17, 2015 |
Initial specifications. |
|
February 21, 2016 |
1.0 |
Public version of Renewed Sensor Transport Layer |
September 15, 2018 |
1.x |
Reviewing in progress |