Segment routing

1. Label Encoding Algorithm for MPLS Segment
Routing
Rabah Guedrez*, Orange Laps
Olivier Dugeon , Orange Labs
Samer Lahoud, IRISA/Rennes 1 University
Géraldine Texier, IRISA/Telecom Bretagne
The 15th IEEE International Symposium on Network Computing and Applications
(NCA 2016)

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Orange Group restricted
1
Agenda
Problem to solve
Encoding Algorithms
Conclusion
Segment Routing ?
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What is Segment Routing ?
It is not a NEW PROTOCOL
It is a new architecture that leverages the source routing paradigm
Can be implemented over two data planes (MPLS & IPv6)
Standardized by the IETF SPRING Working Group
Segment Routing
Choose your data plane
IPv6 MPLS
SR-IPv6 SR-MPLS

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A segment can represent a node, link ,etc
SIDs are interpreted by the forwarding plane as:
Node-SID: “forward the packet using the IGP shortest path”
Adj-SID: “forward the packet using a specific interface”.
:100
:8000
What is Segment Routing ?
SR-MPLS
SID is a 20 bit label
SR Paths are encoded as a stack of labels

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SR Strict Path Encoding (No stack optimization)

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Problem : Maximum Stack Depth (MSD)
Limitation
It is a physical limitation on the routers
The maximum number of labels a router can push onto the header of packet
Results: paths expressed with a label stack > MSD are unusable
=> a sub-optimal network utilization
Percentage of useable paths

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SR Paths Label Encoding Algorithm (SR-LEA)

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SR Paths Label Encoding Algorithm (SR-LEA)
5037

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SR-LEA with Global Adj-SIDs

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Simulation Results
Useable paths

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Simulation Results

12. Conclusion
The MSD limitation slows the deployment of Segment Routing
The proposed algorithms are proven to slacken the impact of the MSD limitation
Implementation
Quagga-SR an open source SR-MPLS implementation with Global Adj-SID
ELENAOR an SDN base implementation of the proposed algorithms

13. Thank You