Explain why reversing the order of the lines ‘R-deliver m’ and ‘if ( q p ) then B-multicast(g, m); end makes the algorithm no longer satisfy uniform agreement. Does the reliable multicast algorithm based on IP multicast satisfy uniform agreement?

What will be an ideal response?

Reversing the order of those lines means that a process can deliver a message and then crash before sending it to the other group members – which might, in that case, not receive the message at all. This contradicts the uniform agreement property.

The reliable multicast algorithm based on IP multicast does not satisfy uniform agreement. A recipient delivers a message as soon as it receives it; if the sender was to fail during transmission and that same message was not to have reached the other group members then the uniform agreement property would not be met.