Topology Independent LFAOrange use case & applicability
Stéphane Litkowski, Orange ExpertBruno Decraene, Orange ExpertMPLS 2014
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 VPNEthernetInternetCloudVoice & TelepresenceHigh value: availability, security, SLA
3 TI-LFA MPLS 2014
Agenda
Requirements
Topology Independent LFA
Applicability on Orange topologies
Simulation results
4 TI-LFA MPLS 2014
Agenda
Requirements
Topology Independent LFA
Applicability on Orange topologies
Simulation results
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
8 TI-LFA
FRR issue Primary path Backup path
MPLS 2014MPLS 2014MPLS 2014
South East
8ms
14 TI-LFA
Backup8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR33msCOMPLETELY
UNOPTIMAL !!!!
15 TI-LFA
Backup8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR33msCOMPLETELY
UNOPTIMAL !!!!DAMAGE NETWORK
16 TI-LFA
Backup8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR33msCOMPLETELY
UNOPTIMAL !!!!DAMAGE NETWORKDAMAGE CUSTOMER
SERVICE
17 TI-LFA
Backup8ms
MPLS 2014
FRR issue
MPLS 2014MPLS 2014
FRR33msCOMPLETELY
UNOPTIMAL !!!!DAMAGE NETWORKDAMAGE CUSTOMER
SERVICEFRR
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 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 PathHow to use Post-convergence path
for FRR ?
How to improve ?
20 TI-LFA
Agenda
Requirements
Topology Independent LFA
Applicability on Orange topologies
Simulation results
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 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
AdjR5AdjR6AdjR3
MPLS
AdjR6AdjR3
MPLSAdjR3
MPLS
Primary
TI-LFA
23 TI-LFAMPLS 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
MPLSNodeR5
MPLSNodeR5
MPLS
MPLS
PQ
S R1 R2 R3 D
R4 R5 R6
MPLS MPLS
2
MPLS
NodeR5
MPLS MPLS
MPLS
P50 Q
AdjR6
NodeR5AdjR6 AdjR6
24 TI-LFA MPLS 2014
Agenda
Requirements
Topology Independent LFA
Applicability on Orange topologies
Simulation results
25 TI-LFA
Analysis on topologies : case #1TI-LFA for path optimality
Paris
Paris
Paris
Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
Primary
MPLS 2014
Paris
Out of transitnode
26 TI-LFA
Analysis on topologies : case #1TI-LFA for path optimality
Paris
Paris
Paris
Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
Primary
MPLS 2014
Paris
Out of transitnode
27 TI-LFA
Analysis on topologies : case #1TI-LFA for path optimality
Paris
Paris
Paris
Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
Primary
BackupMPLS 2014
Paris
Out of transitnode
28 TI-LFA MPLS 2014
Analysis on topologies : case #1TI-LFA for path optimality
Paris
Paris
Paris
Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
FRR path
Paris
Out of transitnode
29 TI-LFA MPLS 2014
Analysis on topologies : case #1TI-LFA for path optimality
Paris
Paris
Paris
Paris STR
STR
Dijon
Lyon
Lyon
Paris
Lyon
Poitiers
MRT
FRR path
Paris
Out of transitnode
30 TI-LFA MPLS 2014
Analysis on topologies : case #1TI-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 transitnode
31 TI-LFA MPLS 2014
Analysis on topologies : case #1TI-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 transitnode
32 TI-LFA
Analysis on topologies : case #1TI-LFA for path optimality
Paris1
Paris2
Paris3
Paris5 STR
STR
Dijon
Lyon
Lyon
Paris4
Lyon
Poitiers
EPC FRR
Nodal
EPC stack composed of one segment
Protection stackNode_Pari
s4
MPLS 2014
Paris
Out of transitnode
33 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 1
11
2
100 100
Primary
Backup
SR Segments
34 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 1
11
2
100 100
Primary
Backup
SR Segments
35 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 1
11
2
100 100
Primary
Backup
SR Segments
36 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 1
11
2
100 100
Primary
Backup
SR Segments
P
Q
37 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 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 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 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 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 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 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 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 TI-LFA MPLS 2014
Analysis on topologies : case #2TI-LFA using multiple segments
PE1
R1
PE2
R2R3
R4 R5
R6
R7
PE3
1
7
3
3
311 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 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
Primary
Backup
SR Segments
43 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
Primary
Backup
SR Segments
44 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
P
QProtection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2
Primary
Backup
SR Segments
Top
Bottom
45 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
P
QProtection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2 Node_R3
Primary
Backup
SR Segments
Top
Bottom
46 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
P
QProtection stack (PQ)
Node_R3
Adj_R4
Adj_R5
Adj_R6
Adj_PE2
Node_R5
Node_R3
Primary
Backup
SR Segments
Top
Bottom
47 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
P
QProtection 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 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
P
QProtection 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 TI-LFA MPLS 2014
Analysis on topologies : case #3Maximum observed stack depth
PE1
PE2
R1
R2
R3
R4
R5R6
100
100
21
23
3
1
3
13
1000
P
QProtection 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 TI-LFA MPLS 2014
Agenda
Requirements
Topology Independent LFA
Applicability on Orange topologies
Simulation results
51 TI-LFA MPLS 2014
Simulations results on 11 Orange NetworksDepth of protection stack
11 topologies have been analyzed including multiple network types and size
52 TI-LFA
Simulations results on 11 Orange Networks
MPLS 2014
80% of nodes have 12 or less distinct repair_lists
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 path
MPLS 2014
Conclusion
Thank you !