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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)
2 Orange Group restricted
1
Agenda
Problem to solve
Encoding Algorithms
Conclusion
Segment Routing ?
2
3
4
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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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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
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