1. 1 May 13, 2004 IFIP Networking 2004 L ink-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)

2. 2 May 13, 2004 IFIP Networking 2004 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

3. 3 May 13, 2004 IFIP Networking 2004 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

4. 4 May 13, 2004 IFIP Networking 2004 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

5. 5 May 13, 2004 IFIP Networking 2004 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)

6. 6 May 13, 2004 IFIP Networking 2004 Link-Based Fair Aggregation (LBFA): Motivation and Idea Motivation The considered flow Flows from the same input link as the considered flow 1HH- 1 2 Idea –Aggregate link-level input flow aggregates “fairly”. –Use Fair Queueing with Shaping (FQ-S) to aggregate link-level aggregates.

7. 7 May 13, 2004 IFIP Networking 2004 Link-Based Fair Aggregation (LBFA): Detailed Approach (1/2) Aggregator …… … … Class-based scheduling Class-based flow aggregation Separator Output link server Input Links Output Links........ FIFO queue

8. 8 May 13, 2004 IFIP Networking 2004 Link-Based Fair Aggregation (LBFA): Detailed Approach (2/2) … … … Class-based schedulingClass-based link-level flow aggregation: FQ-S Shaper Output link server From input links after separator Output Links.... FQ scheduler....

9. 9 May 13, 2004 IFIP Networking 2004 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

10. 10 May 13, 2004 IFIP Networking 2004 > 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):

11. 11 May 13, 2004 IFIP Networking 2004 Comparison ApproachPFFQ IntServFIFO DiffServSCORELBFA GranularityFlow levelClass levelPacket levelLink level GuaranteesTh. 1-3Th. 4-6Th. 7-9Th. 10-12 LimitationnoyesYes *no Flow states (FS) StatefulCore-stateless # of FSO(N)no Impl. Complex.O(log(N))/O(1)straightforwardO(log(M))O(I) / O(1) Packet stateno yesno

12. 12 May 13, 2004 IFIP Networking 2004 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

13. 13 May 13, 2004 IFIP Networking 2004 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.