1. Load Sharing with 1:1 Protection Switching Alan McGuire IEEE 802.1 Eilat

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

3. Load sharing with protection AB Link 1 Link 2 Link 3 1 1 1/3 + 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

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

5. What about conventional 1:1 protection? AB Link 1 Link 2 Link 3 1 1 0.5 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

6. 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

7. What about uneven load in 1:1? AB Link 1 Link 2 Link 3 1 1 0.8 0.2 TEPG Working Protection Total capacity = 1.8

8. What about uneven load sharing? AB Link 1 Link 2 Link 3 1 1 0.8 + ½(0.1) 0.1 + ½(0.8) Total capacity = 0.805 + 0.5+0.5 = 1.805

9. 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