A Conceptual Model for Diffserv Routers

1. 4190.704 통신 네트워크특강 논문발표 A Conceptual Model for Diffserv Routers Y. Bernet, A. Smith and S. Blake Internet Draft, October 1999 draft-ietf-diffserv-model-01.txt 2000년 3월 10일 전기공학부 데이터통신망연구실 99420-813 김 진 호

2. Introduction • Differentiated Services • offers differing levels of network QoS • A conceptual model of a Diffserv router • helps cohesive management and configuration tools to be developed. • abstracts away implementation details.

3. Contents • Introduction • Conceptual Model • Basic Elements • Classifiers • Meters • Action Elements • Queues • Traffic Conditioning Blocks • Open Issues

4. Conceptual Model • Elements of a Diffserv Router • Basic traffic classification components • Basic traffic traffic conditioning components • Combinations of the above components • Queuing components

5. Diffserv Router major functional blocks Mgmt Diffserv configuration & Management interface SNMP, COPS Etc. Ingress I/F Classification TC Queuing Routing Core Egress I/F Classification TC Queuing Data RSVP (optional) RSVP cntl msgs

6. Traffic conditioning and Queuing Elements Interface A Interface B Ingress I/F Classification Meter Action Queuing Routing Core Egress I/F Classification Meter Action Queuing Egress I/F Classification Meter Action Queuing Ingress I/F Classification Meter Action Queuing

7. Example of Traffic Conditioning Block to Queue A (not shown) meter monitor dropper Submitted traffic A B C X to Queue B (not shown) marker shaper queue BA classifier to Queue C (not shown) meter mux marker to Queue D (not shown)

8. Hierarchical Model of Diffserv components • Interfaces • TCB • Groups of functional elements interconnected in a directed acyclic graph(DAG) • Individual functional Elements

9. Classifiers • Classifier element • performs classification. • parameterized by • Filters • Output streams • Fan-out element

10. Unclassified traffic Classified traffic Match Filter1 output A Classifier Match Filter2 output B no match output C

11. Filters • Match • Exact, prefix, range, masked and wildcard • Overlapping Filters • Ordering mechanisms must be supported by the configuration and management protocols.

12. Filter Groups

13. Examples • Behavior Aggregate (BA) Filter • Multi-Field (MF) Filter

14. IEEE802 MAC Address Filter • Free-form Filter

15. Meters • Meter element • monitors packets and determines the level of conformance of each packet to a pre-established traffic profile • parameterized by • Temporal profile • Conformance levels • Fan-out element • Datapath element • It differs from that described in [DSARCH]. • More powerful

16. Unmetered traffic Metered traffic conformanceA Meter conformanceB conformanceC

17. Examples • Average Rate Meter

18. Exponential Weighted Moving Average (EWMA) Meter • avg_rate(t) = (1 - Gain) * avg_rate(t’) + Gain * rate(t) • t = t’ + gain • For a packet arriving at time t : if ( avg_rate(t) > AverageRate ) non-conforming else conforming

19. Two-Parameter Token Bucket Meter

20. Multi-Stage Token Bucket Meter

21. Null Meter • Always conforming • When the configuration or management interface doest not have the flexibility to omit a meter in a datapath segment.

22. Action Elements • Marker • sets the DSCP in an IP header. • may act on unmarked packets or re-mark previously marked packets. • 1:1 element

23. Dropper • simply discards packets • Shaper • embedded in a queue. • Mirroring • mirrors data traffic on one or more interfaces for data collection purposes. • Mux • Fan-in element

24. Enqueuing element • executes buffer management algorithm. • Fan-in element • Monitor • Octet counter • Packet counter • Null Action • When the configuration or management interface does not have the flexibility to omit an action element in a datapath segment.

25. Queues • Queue Sets and Scheduling • Queues serviced using a common scheduling algorithm • Minimal set of queue parameters • Minimum service rate • Strict service priority • Maximum service rate (optional) • Additional Parameters are dependent on the particular scheduling algorithm implemented.

27. Shaping • Implemented by using a non-work conserving queue • can utilize buffer management algorithms.

28. Traffic Conditioning Blocks • TCB • Group of functional datapath elements interconnected in such a way as to perform a specific set of traffic conditioning functions on an incoming traffic stream • Abstraction of a functional element • Blackbox with a single input and output

29. Simple TCB • Classifier stage • Enqueuing stage • Queuing stage • More general TCB • Classifier stage • Metering stage • Action stage • Queuing stage

30. Example TCB to Queue A (not shown) meter monitor dropper Submitted traffic A B C X to Queue B (not shown) marker shaper queue BA classifier to Queue C (not shown) meter mux marker to Queue D (not shown)

31. SLS:

32. Example of a Multi-Customer TCB Submitted traffic A B C X TCB1 TCB2 TCB3 Dropper4 BA classifier

33. Example of a Marking and Traffic Isolation TCB marker meter dropper MF classifier to TCB2 marker meter mux dropper

34. Open Issues • Token bucket behavior difference between this document and [DSMIB] • To demonstrate how the [TRTCM] meter could be implemented • Are the queue parameters defined sufficient? • Does Queue and QueueSet really belong in the model? • Should a classifier be part of TCB? • Is the description of a shaper sufficient?