Re: linux-ipsec: what is the idea behind Pluto's EVENT_CLEANUP?

Is this to avoid the last-ack problem?

In any exchange of packets, there's going to be one un-acknowledged packet -- the last one sent. There's no way to acknowledge it (any such ack would then be the "last packet" rather than this packet being the "last packet"). Protocols should be designed so that if the "last packet" is lost, the other side will repeatedly ask for it again, or both sides will just revert to a clean state after a timeout.

I haven't looked recently at the specific packets or protocols you mention as having a CLEANUP rather than a RETRANSMIT action; this is just a guess.

        John Received on Wed Oct 21 04:59:27 1998