Very often, "distance" between two points is only measured as the number of hops required, through the network, and that's an adequate measure. But if you want actual distances, and you don't have the distances between nodes pre-measured, perhaps the best technique is to compute the round trip time (RTT) between nodes. To do this, the source node places a timestamp on a query packet, the packet is reflected by adjacent nodes, with that timestamp unchanged, and the source node checks the time elapsed from transmission to reception of the response.

This approach is good enough, if the time required to process these queries, by each node, is known. If not, then you use something like NTP or IEEE 1588. These protocols require each node to add a timestamp when they receive the query, and add another timestamp when they transmit the response. The source node can then subtract, from the total delay from query to response, the amount of time spent waiting for the queried node to reply, after it had received the query. (Note that the two timestamps of the queried node do not need to be synchronized in any way, with the timestamps of the querier. The only function of the two timestamps added by the queried node is to compute the lag before it responds.)

Yet another way, if you know the transmit power of each node, might be to measure the propagation loss, when the source node receives the response. But this would also be a function of the number of connections in the path.

See this, if you want to know more about NTP and IEEE 1588 computations.

https://www.eecis.udel.edu/~mills/ptp.html

http://ieeexplore.ieee.org/abstract/document/1578993/

http://ieeexplore.ieee.org/abstract/document/4212088/

http://ieeexplore.ieee.org/document/605303/

by sending a control packet  and wait for its return ,   by calculating the  time of propagation  , you can conclude the distance

by measuring propagation delay between two nodes(routers)

Dear Bassam 

          please have a look at this paper 

On calculating connected dominating set for efficient routing in ad hoc wireless networks

http://dl.acm.org/citation.cfm?id=313261

Dear Bassam Ali,

for this you can use the Timestamps option in the IPv4 header

Greetings and success

See:

https://tools.ietf.org/rfc/rfc781.txt

https://people.eecs.berkeley.edu/~justine/honorsthesis_slides_long.pdf

http://www.academia.edu/10351526/Covert_Channel_using_the_IP_Timestamp_Option_of_an_IPv4_Packet

See pages 73 and 74 in the book:

https://www.researchgate.net/publication/281104658_Technik_der_IP-Netze_Internet-Kommunikation_in_Theorie_und_Einsatz

Book Technik der IP-Netze, Internet-Kommunikation in Theorie und Einsatz

distance = sqrt((Pt * Gt * Gr) / (L * Pr)) * lambda / (4 * PI);