I am doing some analysis to identify the data overhead of the OTA updates to minimize the data consumption. As we would use modem for the OTA we would like to understand the data sizes and the time it takes for the typical update to ensure the updates can be reliably transmitted and also do not consume a lot of data.
I did some analysis by capturing packets to first check the data transmission for polling the OTA system. I see that for every poll the system exchanges 110 to 112 packets which include the DNS + the actual communication with the OTA system. This amounts to around 12-14 Kbytes per poll which is huge from our perspective.
Another this which I noticed is that for each polling interval 4 transactions of same set of packets are repeated. May be there is a way to avoid.
@jeremias.tx @drew.tx @andrecurvello.tx Can you please help me understand this and identify possible way to reduce the transactions?
pcap file of the tcpdump on the device capture
Just a heads up we brought this question up to our OTA team to look at. We’ll let you know once we hear back from them on this.
Hi @gauravks the only real option here is to reduce the polling interval. The amount of data transferred for update checks is constrained by Uptane security requirements. Establishing the mutual TLS session takes some bytes, and then you need to send the device manifest and download the appropriate metadata.
Thanks for the response.
Yeah I just don’t understand why they are repeated 4 times? Are these 4 transactions different in that case why they require 4 time DNS resolution?
We don’t have a definite answer on that. Can you clarify a bit which packets you see are repeating? I took a look at the pcap file but if you can help me narrow in a bit that would be helpful.