Totally-ordered Multicast practice problem

2019/02/20

In class, we discussed how a Totally Ordered Multicast protocol could be implemented using Lamport Clocks. Consider that a bank has two branch offices: Branch 1 is in Los Angeles (represented by P1), and branch 2 is in Seattle (represented by P2). The one-way propagation delay between these branches is defined in this table:

Los Angeles Seattle
Los Angeles 0 25ms
Seattle 25ms 0

Imagine that each branch issues transactions, represesnted as Ti. Consider this sequence of transactions:

  1. Seattle (P2) issues T1 at t=0ms
  2. Los Angeles (P1) issues T2 at t=10ms
  3. Seattle (P2) issues T3 at t=40ms

In what order do the transactions execute?

At what time does T1 execute in Seattle?

At what time does T3 execute in Los Angeles?