Authentication 4/9 Let's see what RFC 2082 states about sequence numbers: "The value used in the sequence number is arbitrary, but two suggestions are the time of the message's creation or a simple message counter" "If [...] the received sequence number is less than the last one received, the messege is discarded unprocessed" "When connectivity to the neighbor has been lost the receiver SHOULD be ready to accept [...] a message with a sequence number of zero"