# Queries about digest messages

**URL:** https://forum.p4.org/t/queries-about-digest-messages/923
**Category:** Getting Started with P4
**Created:** [August 24, 2023, 9:25pm UTC](https://forum.p4.org/t/queries-about-digest-messages/923 "2023-08-24T21:25:20Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![kpapad](https://avatars.discourse-cdn.com/v4/letter/k/3e96dc/32.png) [@kpapad](https://forum.p4.org/u/kpapad)
#### Post date: [August 24, 2023, 9:25pm UTC](https://forum.p4.org/t/queries-about-digest-messages/923/1 "2023-08-24T21:25:20Z")

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Greetings to all,

I have a few queries about digest messages.  
Can I capture a digest message with ie. Wireshark?  
Can a digest messages be sent over to another node of the network, where the controller resides?  
The digest extern seems to only send messages to a local controller.

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### Author: ![andyfingerhut](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.p4.org/andyfingerhut/32/17_2.png) [@andyfingerhut](https://forum.p4.org/u/andyfingerhut)
#### Post date: [August 24, 2023, 11:38pm UTC](https://forum.p4.org/t/queries-about-digest-messages/923/2 "2023-08-24T23:38:28Z")

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If you use the P4Runtime API to configure a device, then Digest messages created by the data plane will typically first go to a local CPU running driver software, and then they will be sent over a TCP connection from the P4Runtime API server to the P4Runtime API client that should receive the Digest messages.

That TCP connection could be a local connection between a client and server running on the same host, or it could be between two different hosts.

If it is running on a different host, one could imagine using a packet capture program to see all of the packets in that TCP connection. However, since it is a TCP connection, the Digest messages might be split across 2 or more TCP packets due to TCP segmentation. Or there could be multiple Digest messages in a single packet, again due to TCP segmentation decisions made in the TCP implementation.

You could write a P4Runtime API client program that writes the Digest messages to a local file, or sends them in packets that it generates, or anything else you can imagine a program to do with the data in those messages.
