Slides used for a presentation at MPLS SDN congress in March 2014. This describes advantages and applicability of Topology independent LFA.

1. Topology Independent LFA
Orange use case & applicability
Stéphane Litkowski, Orange Expert
Bruno Decraene, Orange Expert
MPLS 2014

2. 2 TI-LFA
Orange Business Service
MPLS 2014
One of the largest dedicated network for business
•Worldwide :
• 172 countries, 900+ cities
•France :
• more than 2 million business clients, SMBs and
companies in France
IP VPN
Ethernet
Internet
Cloud
Voice & Telepresence
High value: availability,
security, SLA

3. 3 TI-LFA MPLS 2014
Agenda
 Requirements
 Topology Independent LFA
 Applicability on Orange topologies
 Simulation results

4. 4 TI-LFA MPLS 2014
Agenda
 Requirements
 Topology Independent LFA
 Applicability on Orange topologies
 Simulation results

5. 5 TI-LFA MPLS 2014
Why using Fast Reroute ?
 Fast convergence is below 1sec BUT:
– hard to have the same performance on all nodes
– hard to maintain convergence time while network is growing
 Applications are more and more sensitive (VoIP, CRM, Sync, transport)
 Customers do not want to rewrite or customize their applications code
to handle network failures 

6. 6 TI-LFA
FRR issue
MPLS 2014MPLS 2014MPLS 2014

7. 7 TI-LFA
FRR issue Primary path
MPLS 2014MPLS 2014MPLS 2014
South
East
5ms

8. 8 TI-LFA
FRR issue Primary path Backup path
MPLS 2014MPLS 2014MPLS 2014
South
East
8ms

9. 9 TI-LFA MPLS 2014
FRR issue
MPLS 2014MPLS 2014

10. 10 TI-LFA MPLS 2014
FRR issue
MPLS 2014MPLS 2014
Primary path
5ms

11. 11 TI-LFA MPLS 2014
FRR issue
MPLS 2014MPLS 2014

12. 12 TI-LFA MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR
33ms

13. 13 TI-LFA
Backup
8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR
33ms

14. 14 TI-LFA
Backup
8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR
33ms
COMPLETELY
UNOPTIMAL !!!!

15. 15 TI-LFA
Backup
8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR
33ms
COMPLETELY
UNOPTIMAL !!!!
DAMAGE NETWORK

16. 16 TI-LFA
Backup
8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR
33ms
COMPLETELY
UNOPTIMAL !!!!
DAMAGE NETWORKDAMAGE CUSTOMER
SERVICE

17. 17 TI-LFA
Backup
8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR
33ms
COMPLETELY
UNOPTIMAL !!!!
DAMAGE NETWORKDAMAGE CUSTOMER
SERVICEFRR

18. 18 TI-LFA MPLS 2014
How to improve ?
 Requirements
– 100% coverage link and node protection
– No transient congestion
– Optimal routing
– Simple solution to operate and understand
– Scalable solution

19. 19 TI-LFA MPLS 2014
 What is the more optimal and natural path upon a failure ?
 Post-convergence path from the PLR
 Benefits of using Postconvergence path :
– Policy compliant and optimized
– Well sized
– Well known
D
S Potential backup
Path
Postconvergence
Path
How to use Post-convergence path for
FRR ?
How to improve ?

20. 20 TI-LFA
Agenda
 Requirements
 Topology Independent LFA
 Applicability on Orange topologies
 Simulation results

21. 21 TI-LFA
 Providing 100% coverage (node/link/SRLG)
 Segment Routing Fast-Reroute solution
– SR allows to use « unlimited » number of paths
 encoding any FRR path by using Segment Routing blocks :
– any Service Provider policy (LFA policy framework)
– including post-convergence path as new criteria
 Primary traffic does not require to be SR :
– IP or LDP can be protected by SR
MPLS 2014
Topology Independent LFA

22. 22 TI-LFA MPLS 2014
Topology Independent LFA
 Cannot use a strict only Explicit Path due to depth of segment
stack
 We need to compress the stack
 Done by reusing rLFA/dLFA building blocks (P & Q space)
S R1 R2 R3 D
R4 R5 R6
MPLS MPLS MPLS MPLS
2
MPLS
AdjR5
AdjR6
AdjR3
MPLS
AdjR6
AdjR3
MPLS
AdjR3
MPLS
Primary
TI-LFA

23. 23 TI-LFA
MPLS 2014
Topology Independent LFA
 FRR path is computed as follows :
– Compute postconvergence shortest path (new SPF)
– Enforce loop-freeness by :
– finding a P node on the path
– finding a Q node on the path after P (P and Q may be equal)
– Only P to Q path would be explicit and may be additionnaly
compressed using nodal segments
S R1 R2 R3 D
R4 R5 R6
MPLS MPLS
2
MPLS
NodeR5
MPLS
NodeR5
MPLS
MPLS
PQ
S R1 R2 R3 D
R4 R5 R6
MPLS MPLS
2
MPLS
NodeR5
MPLS MPLS
MPLS
P
50
Q
AdjR6
NodeR5
AdjR6 AdjR6

24. 24 TI-LFA MPLS 2014
Agenda
 Requirements
 Topology Independent LFA
 Applicability on Orange topologies
 Simulation results

25. 25 TI-LFA
Analysis on topologies : case #1
TI-LFA for path optimality
Paris Paris
Paris Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
Primary
MPLS 2014
Paris
Out of
transit
node

26. 26 TI-LFA
Analysis on topologies : case #1
TI-LFA for path optimality
Paris Paris
Paris Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
Primary
MPLS 2014
Paris
Out of
transit
node

27. 27 TI-LFA
Analysis on topologies : case #1
TI-LFA for path optimality
Paris Paris
Paris Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
Primary
Backup
MPLS 2014
Paris
Out of
transit
node

28. 28 TI-LFA MPLS 2014
Analysis on topologies : case #1
TI-LFA for path optimality
Paris Paris
Paris Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
FRR path
Paris
Out of
transit
node

29. 29 TI-LFA MPLS 2014
Analysis on topologies : case #1
TI-LFA for path optimality
Paris Paris
Paris Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
MRT
FRR path
Paris
Out of
transit
node

30. 30 TI-LFA MPLS 2014
Analysis on topologies : case #1
TI-LFA for path optimality
Paris Paris
Paris Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
MRT
FRR path
RSVP-TE link
protection (1:n)
Paris
Out of
transit
node

31. 31 TI-LFA MPLS 2014
Analysis on topologies : case #1
TI-LFA for path optimality
Paris Paris
Paris Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
LFA
MRT
FRR path
RSVP-TE link
protection (1:n)
Paris
Out of
transit
node

32. 32 TI-LFA
Analysis on topologies : case #1
TI-LFA for path optimality
Paris
1
Paris
2
Paris
3
Paris
5
STR
STR
Dijon
Lyon
Lyon
Paris
4
Lyon
Poitiers
EPC FRR
Nodal
EPC stack composed of one segment
Protection stack
Node_Paris
4
MPLS 2014
Paris
Out of
transit
node

33. 33 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments

34. 34 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments

35. 35 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments

36. 36 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments
P
Q

37. 37 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments
P
QProtection stack (PQ)
Adj_R3
Adj_R4
Adj_R6
Adj_R7
Adj_PE3
Top
Bottom

38. 38 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments
Protection stack
compressed
P
QProtection stack (PQ)
Adj_R3
Adj_R4
Adj_R6
Adj_R7
Adj_PE3
Top
Bottom

39. 39 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments
Protection stack
compressed
Node_R3
P
QProtection stack (PQ)
Adj_R3
Adj_R4
Adj_R6
Adj_R7
Adj_PE3
Top
Bottom
Top
Nodal to R3
Nodal to PE3

40. 40 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments
Nodal to PE3
Protection stack
compressed
Node_R3
Node_PE3
P
QProtection stack (PQ)
Adj_R3
Adj_R4
Adj_R6
Adj_R7
Adj_PE3
Top
Bottom
Top
Bottom
Nodal to R3
Nodal to PE3

41. 41 TI-LFA MPLS 2014
Analysis on topologies : case #2
TI-LFA using multiple segments
PE1
R1
PE2
R2
R3
R4 R5
R6
R7
PE3
1
7
3
3
3
1
1 1
11
2
100 100
Primary
Backup
SR
Segments
Nodal to PE3
Protection stack
compressed
Node_R3
Node_PE3
P
QProtection stack (PQ)
Adj_R3
Adj_R4
Adj_R6
Adj_R7
Adj_PE3
Top
Bottom
Top
Bottom
Nodal to R3
Nodal to PE3

42. 42 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
Primary
Backup
SR
Segments

43. 43 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
Primary
Backup
SR
Segments

44. 44 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
P
Q
Protection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2
Primary
Backup
SR
Segments
Top
Bottom

45. 45 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
P
Q
Protection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2 Node_R3
Primary
Backup
SR
Segments
Top
Bottom

46. 46 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
P
Q
Protection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2
Node_R5
Node_R3
Primary
Backup
SR
Segments
Top
Bottom

47. 47 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
P
Q
Protection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2
Node_R5
Node_R6
Node_R3
Primary
Backup
SR
Segments
Top
Bottom

48. 48 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
P
Q
Protection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2
Node_R5
Node_R6
Node_R3
Adj_PE2
Primary
Backup
SR
Segments
Top
Bottom

49. 49 TI-LFA MPLS 2014
Analysis on topologies : case #3
Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5
R6
10
0
10
0
2
1
2
3
3
1
3
1
3
1000
P
Q
Protection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2
Protection stack
compressed
Node_R5
Node_R6
Node_R3
Adj_PE2
Primary
Backup
SR
Segments
Top
Bottom Top
Bottom

50. 50 TI-LFA MPLS 2014
Agenda
 Requirements
 Topology Independent LFA
 Applicability on Orange topologies
 Simulation results

51. 51 TI-LFA MPLS 2014
Simulations results on 11 Orange Networks
Depth of protection stack
11 topologies have been
analyzed including multiple
network types and size

52. 52 TI-LFA
Simulations results on 11 Orange Networks
MPLS 2014
80% of nodes have 12 or less distinct repair_lists

53. 53 TI-LFA
 100% FRR link/node protection is a requirement
 Current FRR technics may cause some side effects :
– Transient network congestion
– Additionnal management for selection of the backup path
 Topology Independent LFA :
– Scalable : no additional state in the network
– Simple to compute
– Provides 100% link/node protection
– Prevents any side effect by using a well sized and optimal
path
– Simple to understand : well known pathMPLS 2014
Conclusion

54. Thank you !