TULIP Triangulation Algorithm

minRTT = propagation delay + extra delay (due to extra circular routes , congestion and router delays)

?T measured= ?t + ?t0  

(Pseudo-distance)

PD = ?T measured . ?

(Actual distance)

D = ?t . ?

PD = (?t + ?t₀). ?

PD = D + ?t0 . ?  .................................(1)

D = actual distance from the landmark.

C = speed of light

? = X(c) i.e. Speed of digital info in fiber optic cable

X = factor of c with which digital info travels in fiber optic cable.

?t = actual propagation delay along the greater circle router/paths.

?t₀ = the extra delay causing overestimation.

PD = pseudo distance

Graphically,

 
 H: host
L1: Landmark 1
L2: landmark 2
L3: landmark 3
 
Using distance farmula:
D1= ?¯? (XL1 - XH )² + (YL1 - YH)²    ............................................. (2)
FROM (1) & (2)

PD1= ?¯? (XL1 - XH )² + (YL1 - YH)²  +  ?t0 . ?     .................... (A)
Similarly for other 2 landmarks:
PD2 =  ?¯?  (XL2 - XH )² + (YL2 - YH)²  +  ?t0 . ?     .................... (B)
PD3 =   ?¯? (XL3 - XH )² + (YL3 - YH)²  +  ?t0 . ?   .....................(C)
We need to linearize (A), (B) & (C) to solve them