Bully Algorithm

#cse6603

See, Wikipedia, Bhanu Priya, colostate (good example)

• Select the process with the highest process-id.
• Any process can initiate an election if
  • it just recovered from a failure or
  • it suspects that the current coordinator has failed.
    • Cannot communicate with leader.
• Three types of messages are used: election, ok, and I won.

Bully Algo Steps

1. An initiating process p sends election messages to all processes with higher IDs and awaits for ok messages.
2. If a process receives an election message, it returns an ok message and starts an election.
   • election message comes from process of lower IDs.
   • Repeat step 1.
3. If it receives any ok messages, it drops out and waits for an I won message.
   • ok message comes from process having higher id.
4. If no ok messages are received, p becomes the coordinator and sends I won to all processes with lower IDs.
5. If a process receives an I won message, then the sender is the coordinator.