Load Sharing with 1:1 Protection Switching Alan McGuire IEEE Eilat

Load sharing without protection AB Link 1 Link 2 Link /3 Distribute traffic between links

Load sharing with protection AB Link 1 Link 2 Link /3 + ½(1/3) Total capacity = 3(1/3) (working) + 3(½(1/3)) (protection) = 1½ If one link fails then traffic is shared over remaining links 3 TESIs 1 Protection Group

Capacity as a function of number of links Let there be N links For load sharing the capacity on each link is

What about conventional 1:1 protection? AB Link 1 Link 2 Link TEPG Working Protection Total capacity = 1.5 As mechanism is 1:1 protection capacity is not used until required – so can overlap in middle link So can obtain B/W reuse in 1:1 and as such effectively load share

Capacity as a function of number of links with 1:1 Let there be N links For load sharing the capacity on each link is

What about uneven load in 1:1? AB Link 1 Link 2 Link TEPG Working Protection Total capacity = 1.8

What about uneven load sharing? AB Link 1 Link 2 Link ½(0.1) ½(0.8) Total capacity = = 1.805

Conclusions Load sharing can be achieved with conventional 1:1 by allowing overlapping protection capacity Overlapping capacity reduces total B/W required Protection TESIs can overlap Therefore do not need two mechanisms to achieve the same thing Conventional 1:1 provides load sharing in line with PAR