Maybe this idea works:

Assuming finite bandwidth b, unique node-id for each node, packet size p << b * latency, nodes can fill the channel and random() function on robots (these assumptions are real life true generally so):

Each node fills the channel with its own packets (his node-id) or forwards other nodes packets as follows:

    Always fill the channel with my own packets except:
    if I receive a packet from another node then
       Evenly randomly choose to 
              either forward that packet
              or drop the packet

Since A's bandwidth*delay product is higher because delay is higher A will manage to have more packets succesfully received than B, therefore *each Node can know who he is in the diagram*.

Furthermore, with enough convergence time of running above if the above holds then the proportion of packets of A vs B will denote the *actual proportion of RTT delay of A vs B therefore the desired OTT*.

Even if bandwidths between the links are different the above method could still hold (although one will have to think about it more to be more certain) by using packet pairs to figure out bandwidth estimates and then just apply to the proportion equation above.