Slow reaction to link failures Start with d3=1 and d2=100 After one iteration node 2 receives d3=1 and D2=min[1+1,100=2 100 In practice, link lengths occasionally change Suppose link between 3 and fails(Le, d31=infinity) Node 3 will update D3= d32+D2= 3 In the next step node 2 will update: D2=d23+D3=4 It will take nearly 100 iterations before node 2 converges on the correct route to node 1 Possible solutions: Propagate route information as well Wait before rerouting along a path with increasing cost Node next to failed link should announce d=infinity for some time to prevent loopsEytan Modiano Slide 9 Slow reaction to link failures • Start with D3=1 and D2=100 – After one iteration node 2 receives D3=1 and D2 = min [1+1, 100] = 2 • In practice, link lengths occasionally change – Suppose link between 3 and 1fails (I.e., d31=infinity) – Node 3 will update D3 = d32 + D2 = 3 – In the next step node 2 will update: D2 = d23+D3 = 4 – It will take nearly 100 iterations before node 2 converges on the correct route to node 1 • Possible solutions: – Propagate route information as well – Wait before rerouting along a path with increasing cost Node next to failed link should announce D=infinity for some time to prevent loops 3 2 1 1 1 1 100