https://devzone.nordicsemi.com/f/nordic-q-a/69486/replay-protection-cache-entry-aging-outHello, I wanted to confirm my understanding of the Replay protection cache. In the code, the limit is set to REPLAY_CACHE_ENTRIES and there is a note that says: @note The number of entries in the replay protection list directly limits the numberen-USTelligent Community 13Tue, 15 Dec 2020 14:41:27 GMThttps://devzone.nordicsemi.com/thread/285122?ContentTypeID=1Tue, 15 Dec 2020 14:41:27 GMT137ad170-7792-4731-bb38-c0d22fbe4515:9bb38dba-a9b9-49c1-b82a-bc9ce7ee50d5tesc<p>Hi,</p> <p>The replay protection list is a table of element addresses and the highest known sequence number being received from that address. As you wrote, the IV Index lasts for at least 96 hours, often longer depending on how long it takes for the first node to run out of sequence numbers. I don&#39;t think there are any other protection mechanism that you are missing, no.</p> <p>In general it would then be wise to keep&nbsp;<span style="font-family:&#39;courier new&#39;, courier;">REPLAY_CACHE_ENTRIES</span> a bit higher than the expected number of elements sending messages to your node, to account for node replacements and network reconfigurations. (It would be a bit annoying to have to wait for the next IV Index rollover before the node can receive messages from new element addresses.)</p> <p>Regards,<br />Terje</p><div style="clear:both;"></div>