Null (00h)

Isotropic Sensor Network Specifications, Null: Ping and Padding Layer

OSI: Transport Layer

Keywords: keep-alive, padding in framing, encapsulation, low communication overhead, sensors, internet of things, embedded systems, sensor networks

Document: ISN-Null-1.0 released on September 15, 2018 by Isotel, (c) All Rights Reserved

Creative Commons License
Isotropic Network Specifications: Null Layer 1.0 by Isotel is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.
Permissions beyond the scope of this license may be available at

Note: Any adaptations to this specifications made by groups, individuals or companies are according to the license not allowed for general publication, but we strongly encourage you to send your modifications back to us for further consideration for the next releases.


The scope of this project is to define the Isotropic Sensor Network User layers 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.


The purpose of this specifications is to provide a standard for low complexity, low cost, and low power (aware) consumption devices (sensors) to provide keep alive capability and padding for frame and packet alignment.

Definitions, Acronyms and Abbreviations

An entity containing this protocol implementation. Also referred as sensor device or just sensor or device.
The format of aggregated bits that are transmitted together in time.
The format of aggregated bits that are transmitted together in time across the physical medium.

Packet Format

Fields Protocol ID
Bits 8
Value 00h
Protocol ID:
defines the unique protocol identification number of the application protocol specific format

Keep alive

In many cases the underlying media cannot provide information whether a device is alive or not, or looking from a device side, whether host (peer) is connected or does it exist.

The device and host should thus support keep-alive capability in which, after reception of the packet with Null protocol only, then the queried device should respond either with some valid message or Null.


Some devices may due to internal optimization require padding bytes to align data structure to i.e. 32-bit boundaries. And in other cases packets may need to be filled to account a fixed size. In such cases the Null is used as a padding byte.

Document Changes

Date Release Changes
September 15, 2018 1.0 Initial Specifications



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