title: under what scenarios does SERVER REFLEXIVE and PEER REFLEXIVE addresses/candidates differ from each other?
body: <p>I was going through the ICE/STUN specification and had a question.
  If I am located behind a NAT which could be a Full Cone, Restricted or Port Restricted but not a symmetric NAT and considering I am using UDP, then in this case my SERVER REFLEXIVE and PEER REFLEXIVE addresses/candidates will be same, right?  I am not able to imagine under what scenarios (for the above mentioned NAT types) they'll be different from each other?  Or if they are really different then it can only mean that my NAT is symmetric one?</p>