[chord] node's identifier's problem

[william]

Hi
  About node's identifier,does it generate radomly?Or generate use
such as SHA-1 according node's IP address.
  If use such as SHA-1,it will confront a problem.Some nodes in
different network,but they use same private IP address,so their
identifier will be same.They will have collision about identifier.
  So which method that node generate identifier in chord?
  Thanks a lot.

Sincerely
William
5.11