Ouroboros Praos: Slots, Epochs, Leader Selection


#1

I want to know how the slots, epochs and leader selection work on decentralized version of Cardano. Praos talks about epochs being 24K deep. I have seen alternative information on this forum on epochs being 21.6K slots deep and epochs themselves lasting 5 days.

Can you point me to an authoritative source that describes what exactly will be implemented?

I have read this resource, which is a great way to start getting your head around how the protocol works. Kudos to the person who posted it on the forum!

Thanks,


#2

24K is not a slot measure. It’s just a way to say: “imagine epoch being equally divided into 24 parts”. Original Ouroboros, for example, talks about epoch being 10K, but it’s not relevant to slots. It just means - whatever your length of epoch is in slots - divide it in 10 parts.

At the moment there are exactly 21600 slots in each epoch, which makes epoch to be 5 days at 20 seconds per slot. With Praos implementation it might change, since Praos allows for shorter slots.


#3

Thanks for the clarification.

About he 20 second slot: Does the current data support this empirically? I wonder if there is a way to interrogate the network. Can’t find this on cardanoexplorer or adatracker.

Also, what’s your best guess to what the time slot interval might look like when we have Shelley?


#4

What do you mean? You can see the 20 second intervals in the explorer:

And you always can find this info in the genesis block in the field "slotDuration": https://github.com/input-output-hk/cardano-sl/blob/8d25c2ad3ca2354af8f8c43a2972d1b9a31bf440/scripts/prepare-genesis/README.md

My best guess is that time slots might be 20 seconds or less when we have Shelley.


#5

Sorry I must have totally missed this. Thank you again, Ruslan.