1. SDN in IP/MPLS Networks
Mochammad Irzan
m.irzan@gmail.com
irzan@juniper.net

2. Agenda
● IP/MPLS in the Service provider Network
● Planning tool
● SDN in IP/MPLS a.k.a PCE
● Use cases

3. IP Network
● Packet forwarding based on packet's header
and routing table
● Distributed control plane
– Routing protocol : OSPF, ISIS, BGP, RIP
– Hop-by-hop routing information propagation
– Distributed calculation
● Best path based on metric

4. IP Network
R1 R2 R3 R4
R5 R6
A B

5. IP Network (...)
R1 R2 R3 R4
R5 R6
A B
Routing protocol

6. IP Network (...)
R1 R2 R3 R4
R5 R6
A B
Routing protocol

7. IP Network (...)
R1 R2 R3 R4
R5 R6
A B
Routing protocol
Prefix Outgoing Intf Metric
B 2 3
… … ….

8. IP Network (...)
● Packet forwarding follow the best path
● Explicit routing/Traffic Engineering is
complicated/difficult
– Policy based routing
– Metric manipulation

9. IP Network (...)
R1 R2 R3 R4
R5 R6
A B

10. IP Network (...)
R1 R2 R3 R4
R5 R6
A B

11. IP/MPLS Network
● Packet forwarding is based on label information
● Used the existing IP routing infrastructure
● Label distribution protocol
– MP-BGP, LDP, RSVP
● Traffic Engineering/Explicit routing is easier
● Multiservice network

12. IP/MPLS Network
R1 R2 R3 R4
R5 R6
A B
LER LER
LSR

13. IP/MPLS Network (...)
● LER (Label Edge Router)
– Push/Pop Label
● LSR (Label Switch Router)
– Label Swapping

14. MPLS label
MPLS label (20 bit) Exp. Bit (3 bit) Stack bit (1 bit) TTL (8 bit)
L2 Header MPLS Label L3 Header Payload
L2 Header Label 1 Label 2 L3 Header Payload
L2 Header Label 1 ... Label N L3 Header Payload

15. Label Distribution Protocol
● LDP
– Follow IP Routing protocol
● RSVP
– Explicit path/Traffic Engineering
● MP-BGP
– L3VPN, L2VPN, VPLS, EVPN

16. IP/MPLS Network (...)
R1 R2 R3 R4
R5 R6
A B
LER LER
LSR
prefix Label in Label out Out. intf. Metric
B Null 100 2 3
... ... …. ... ...
Routing Table

17. IP/MPLS Network (...)
R1 R2 R3 R4
R5 R6
A B
LER LER
LSR
Label in Label out Out. Intf.
100 120 2
... ... ...
Label Table

18. IP/MPLS Network (...)
R1 R2 R3 R4
R5 R6
A B
LER LER
LSR
Label in Label out Out. Intf.
120 100 2
... ... ...
Label Table

19. IP/MPLS Network (...)
R1 R2 R3 R4
R5 R6
A B
LER LER
LSR
prefix Label in Label out Out. intf. Metric
B 100 null 2 3
... ... ... ... ...
Routing Table

20. Explicit Routing/Traffic Engineering
R1 R2 R3 R4
R5 R6
A B
LER LER
LSR
prefix Label in Label out Out. intf. Metric
B null 100 LSP1 3
... ... ... ...
Routing Table

21. MPLS Use Case 1, IP routing
R2 R3 R4/LER
R5 R6
A B
R1/LER
LSReBGP eBGP
iBGP

22. MPLS Use Case 1 (...)
R2 R3 R4/LER
R5 R6
A B
R1/LER
LSReBGP eBGP
iBGP
Prefix Next-hop metric
B1 X1 1
B2 X2 1
… 1
Bn Xn 1

23. MPLS Use Case 1 (...)
R2 R3 R4/LER
R5 R6
A B
R1/LER
LSReBGP eBGP
iBGP
Prefix Next-hop metric Label
B1 R4 1 100
B2 R4 1 100
… ... ... ...
Bn R4 1 100

24. MPLS Use Case 1 (...)
R2 R3 R4/LER
R5 R6
A B
R1/LER
LSReBGP eBGP
iBGP
Prefix Label in Label out Out. Intf.
R4 100 120 2
… ... ... ...

25. MPLS Use Case 1 (...)
R2 R3 R4/LER
R5 R6
A B
R1/LER
LSReBGP eBGP
iBGP
Prefix Label in Label out Out. Intf.
R4 120 110 2
… ... ... ...

26. MPLS Use Case 1 (...)
R2 R3 R4/LER
R5 R6
A B
R1/LER
LSReBGP eBGP
iBGP
Prefix Label in Label out Out. Intf.
R4 110 null 2
… ... ... ...

27. MPLS Use Case 1 (...)
R2 R3 R4/LER
R5 R6
A B
R1/LER
LSReBGP eBGP
iBGP
Prefix Label in Label out Out. Intf.
R4 110 null 2
… ... ... ...
Prefix Next-hop metric
B1 X1 1
B2 X2 1
… 1
Bn Xn 1

28. MPLS Use Case 2, VPN services
R2 R3 R4/LER
R5 R6
A1
B1
R1/LER
LSR
eBGP OSPF
MP-BGP
B2A2

29. MPLS Use Case 2 (...)
● Two Label
– Label 1 : VPN label
– Label 2 : Egress LER
● Label 1 is used at the egress LER
● Label 2 is used for label swapping in the
IP/MPLS core (LSR)

30. MPLS Use Case 3
R1
R2
R3 R4
R6
R7
5G
5G 5G
3G5G
2G
2G

31. MPLS Use Case 3 (...)
R1
R2
R3 R4
R6
R7
5G
5G 5G
3G5G
2G
2G
LSP R1-R6 : 2G

32. MPLS Use Case 3 (...)
R1
R2
R3 R4
R6
R7
5G
5G 5G
3G5G
2G
2G
LSP R1-R6 : 2G
LSP R2-R6 : 3G

33. MPLS Use Case 3 (...)
● The LSP tunnel configuration is distributed and
independent
● Result might be different on different time
● Can be resolved using LSP priority and
preemption
● Can be complex to deploy

34. MPLS Use case 4
R1
R2
R3
R4
R6
R7
R5
R8

35. MPLS Use case 4 (...)
R1
R2
R3
R4
R6
R7
R5
R8
S1
S2
S3 S5
S7
S6

36. MPLS Use case 4 (...)
● Packet and optical network are not fully
overlapping
● Multiple L3 link may overlap on the optical
transmission
● L3 link R3-R5 and R4-R7 share the same
optical transmission S3-S7

37. Planning tool
● Centralized optimization engine
● What-if scenario
● Identify potential bottleneck
● Planning and design
● Off-line tool

38. Path Computation Element
PCC
PCE
PCC
PCC
PCEP PCEP
PCEP
RFC5440

39. Path Computation Element
Topology Discovery
Path calculation
Path InstallationBGP-LS
OSPF
ISIS
etc
PCEP
Netconf/
Yang

40. Use case 1, Path Diversity
LSP1
LSP2

41. Use case 2, TE++
R1
R2
R3 R4
R6
R7
5G
5G 5G
3G5G
2G
2G
LSP R1-R6 : 2G
LSP R2-R6 : 3G
Dynamic LSP create/tear down
based on traffic load

42. Use case 3, Bandwidth Calendaring

43. Use Case 4, Programmable path
cost function
● Home grown CSPF algorithm
● IGP Metric tuning
● Controlling exit point

44. Use Case 5, Packet Optical
Integration
R1
R2
R3
R4
R6
R7
R5
R8
S1
S2
S3 S5
S7
S6
PCE

45. Thank You