I have read this about INT and was wondering... where is all the INT data saved?

Is it in the packet metadata? and if so, does metadata count as a part of the total packet length? I know metadata isn't a part of the packet per-se (hence the name META) but there is actual data there that needs to be sent.

Theoretically speaking there could be an infinite number of INT-capable devices between the INT-source and the INT-sink (i.e. INT-hops). Where do we save all that data?

A detailed explanation of INT in general will be appreciated also.


  • 1
    You might want to ask the authors directly. This really isn't in implemented anywhere.
    – Ron Trunk
    Commented Jun 13, 2017 at 2:34
  • @RonTrunk Actually it is already implemented and even deployed in data center. For example, in Alibaba.
    – qin
    Commented Mar 9, 2018 at 3:44

3 Answers 3


INT data is saved in the packet. P4 can handle any type of packet. So the packet maybe looks like:




If you try to use INT, you must change the date in the packet and you must change the router in your network.

  • Change the date in the packet and change the router? This doesn't make any sense. Could you please elaborate? Commented May 9, 2018 at 5:54

INT's authors leave these question explicitly open. The INT data can be added to a packet anywhere you can fit it. You can add it to options fields, increasing the sizes of the already present headers, append it the the actual data, tunnel the actual data and add INT data outside the tunnel, ...

The only thing you have to make sure is that the sinks are able to retrieve the metadata and remove it in case the transport method isn't compatible with the end nodes.


According to the P4 paper found here

Inband Network Telemetry (“INT”) is a framework designed to allow the collection and reporting of network state, by the data plane, without requiring intervention or work by the control plane. In the INT architectural model, packets contain header fields that are interpreted as “telemetry instructions” by network devices.

Inband Network Telemetry works with packets, but their implementation is "intentionally generic". These packets contain the information about the state of other systems as queried through the INT architectural model.

The INT packets are described as any packet which contains an INT header which, depending if you are querying the data, would contain the information you are asking. However, if it's an instruction, data would also be collected from the INT header.

Metadata is a way of "daisy chaining" the messages as a Legal Hold Record which would describe what exactly happened to that data.

More information may be found on the research paper.

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