Yuming Jiang Centre for Quantifiable Quality of Service in Communication Systems (Q2S)

1. Link-Based Fair Aggregation: A Simple Approach to Scalable Support of Per-Flow Service Guarantees Yuming Jiang Centre for Quantifiable Quality of Service in Communication Systems (Q2S) Centre of Excellence Norwegian University of Science and Technology (NTNU) IFIP Networking 2004

2. Outline • Current Approaches for Internet Service Guarantees • Integrated Services (IntServ) • Differentiated Services (DiffServ) • Stateless Core (SCORE) • Link-Based Fair Aggregation (LBFA) Approach • Motivation and Idea • Per-Flow Service Guarantees • Comparison • Conclusion IFIP Networking 2004

3. Current Approaches for Internet Service Guarantees: (1) IntServ • Introduction • Per-flow resource reservation • Stateful: Each router maintains per-flow states for flow classification and resource allocation. • Per-Flow Fair Queueing (PFFQ) for per-flow resource allocation • Granularity of nodal service guarantees: flow level • Per-flow service guarantees: • Rate Guarantee: Theorem 1 • Bounded Delay Guarantee: Theorem 2 • Throughput Guarantee: Theorem 3 IFIP Networking 2004

4. Current Approaches for Internet Service Guarantees: (2) DiffServ • Introduction • Per-class resource reservation at each node (Per-Hop Behaviour) • Core-Stateless: Only ingress edge routers possibly maintain per-flow states for flow classification; core routers do not. • First-In-First-Out (FIFO) for forming class-level aggregate at each node. • Granularity of nodal service guarantees: class level • Per-flow service guarantees: • Bounded Delay Guarantee: Theorem 4 • Rate Guarantee: Theorem 5 • Throughput Guarantee: Theorem 6 IFIP Networking 2004

5. Current Approaches for Internet Service Guarantees: (3) SCORE • Introduction • Per-packet resource allocation and scheduling based on Packet State (PS) • Core-stateless: Only ingress edge routers maintain per-flow states; core routers do not. PS is inserted to each packet used as a basis for resource allocation and scheduling; PS may be updated by core routers. • Core-Stateless Guaranteed Rate (CSGR) for scheduling at each router • Granularity of nodal service guarantees: packet level • Per-flow service guarantees: • Rate Guarantee: Theorem 7 (same as PFFQ IntServ) • Bounded Delay Guarantee: Theorem 8 (same as PFFQ IntServ) • Throughput Guarantee: Theorem 9 (same as PFFQ IntServ) IFIP Networking 2004

6. Flows from the same input link as the considered flow The considered flow 1 2 H-1 H Link-Based Fair Aggregation (LBFA): Motivation and Idea • Motivation • Idea • Aggregate link-level input flow aggregates “fairly”. • Use Fair Queueing with Shaping (FQ-S) to aggregate link-level aggregates. IFIP Networking 2004

7. Class-based flow aggregation Class-based scheduling Input Links Output Links FIFO queue Aggregator … … Separator … Aggregator . . . . … Separator Output link server Link-Based Fair Aggregation (LBFA): Detailed Approach (1/2) IFIP Networking 2004

8. From input links after separator Class-based link-level flow aggregation: FQ-S Class-based scheduling FQ scheduler Output Links Shaper . . … … … Shaper . . Output link server Link-Based Fair Aggregation (LBFA): Detailed Approach (2/2) IFIP Networking 2004

9. Link-Based Fair Aggregation (LBFA): Summary • Introduction • Hierarchical link sharing: per-class input link-level resource allocation and scheduling • (Core-)Stateless: Ingress edge routers may maintain per-flow states; core routers do not. • Fair Queueing with Shaping (FQ-S) to aggregate link-level flow aggregates at each router • Granularity of nodal service guarantees: link level • Per-flow service guarantees • Rate Guarantee: Theorem 10 • Bounded Delay Guarantee: Theorem 11 • Throughput Guarantee: Theorem 12 IFIP Networking 2004

10. Link-Based Fair Aggregation (LBFA): A Comparison of Per-Flow Service Guarantees with IntServ • Assumptions: • Both PFFQ IntServ and LBFA adopt hierarchical link-sharing. • LBFA adopts per-flow fair queueing for flow aggregation at ingress edge. • Theorem 1 (for PFFQ IntServ): • Theorem 10 (for LBFA): > IFIP Networking 2004

11. Comparison IFIP Networking 2004

12. Integration of LBFA with IntServ / DiffServ • View PFFQ, FIFO and LBFA as flow aggregation approaches. • PFFQ IntServ • Use PFFQ to aggregate flows and form the class level aggregate • Problem: stateful • FIFO DiffServ • Use FIFO to aggregate flows and form the class level aggregate • Problem: link utilization is limited to ensure deterministic guarantees • Integration of LBFA with IntServ or DiffServ • LBFA IntServ: Preserve (and may even improve) per-flow service guarantees and is core-stateless. • LBFA DiffServ: Solve the link utilization problem and improve per-flow service guarantees IFIP Networking 2004

13. Conclusion • Introduced from service guarantee granularity perspective the three current approaches: IntServ, DiffServ and SCORE. • Proposed the Link-Based Fair Aggregation (LBFA) approach. • Analyzed per-flow service guarantees by LBFA. • Compared LBFA with IntServ, DiffServ and SCORE. • Discussed possible integration of LBFA with IntServ and DiffServ to solve their specific problems: scalability problem with PFFQ IntServ and link utilization problem with FIFO DiffServ. IFIP Networking 2004