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Packet Classification on Multiple Fields

Packet Classification on Multiple Fields. 참고 논문: Pankaj Gupta and Nick McKeown SigComm 1999. IP Lookup. Longest-prefix address lookup. Rule: Each Prefix. Action: Next hop. Classifier: Forwarding table. Outline. Packet Classification Application, Information, Characteristics Design Goal

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Packet Classification on Multiple Fields

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  1. Packet Classification on Multiple Fields 참고 논문: Pankaj Gupta and Nick McKeown SigComm 1999

  2. IP Lookup • Longest-prefix address lookup • Rule: Each Prefix • Action: Next hop • Classifier: Forwarding table

  3. Outline • Packet Classification • Application, Information, Characteristics • Design Goal • Previous Work • Recursive Flow Classification (RFC)

  4. Packet classification(Application) • Packet Filtering • Deny all traffic from ISP3 destined to E2 • Accounting & Billing • Treat all video traffic to E1 as highest priority and perform accounting for the traffic sent this way

  5. Packet classification(Application)

  6. Packet Header http://vulcan.ee.iastate.edu/~dougj/class/580/index.htm

  7. Example

  8. Example (Cont.)

  9. Definition of Packet Classification • Each rule • Specifies a class • Based on criterion on F fields • Associates with an identifier, classID • i-th component of the rule R, R[i] • A regular expression on the i-th filed of the packet header

  10. Characteristics of P-C • 793 packet classifiers • 101 different ISP and enterprise networks • Total 41505 rules • ? Data representative? • Conclusion: Trivial or non-trivial?

  11. Distribution of total number of rules per classifier

  12. Characteristics 1 • The classifiers do not contain a large number of rules. • 0.7% of the classifiers contain more than 1000 rules • Mean number: 50 rules

  13. Characteristics 2 • The syntax allows a maximum of 8 fields to be specified: • Source/destination Network-Layer address(32-bits) • Source/destination Transport-layer port number(16-bits for TCP/UDP) • Type-of-service field(8-bits) • Protocol field (8-bits) • Transport-Layer protocol flags(8-bits)

  14. Characteristics 3-4 • Transport-Layer protocol field is restricted to a small set of values: • TCP, UDP, ICMP, IGMP, (E)IGRP, GRE and IPINIP or wildcard • Transport-layer fields • Many (10.2%) are range specifications

  15. Characteristics 5-6 • 14% of all the classifiers had a rule with a non-contiguous mask. • Many different rules share a number of field specifications.

  16. Characteristics 7 • Redundant • Backward redundancy • Rule T appears earlier than Rule R, and R is a subset of T. • Forward redundancy • Rule T apperas after R • R is a subset of T • R, T have the same action • Rules inbetween R and T • The same action • Disjoint from R. • 8% of the rules were redundant.

  17. Goals • Fast enough • Matching on arbitrary fields • Support general classification rules • Prefixes, operators(like range, less than, greater than…) and wildcards. • Suitable for software and hardware implementation • Memory efficient • Scalability • For steady classifier

  18. Previous Work • Sequential evaluations • Grid of Tries • Crossproducting • Bit-level parallelism • TCAM

  19. Abstract • The point location problem in multidimensional space • Find the enclosing region of a point, given a set of regions. • Complexity • O(logn) in time with O(nF) space • O(logF-1n) time with O(n) space

  20. Structure of classifiers

  21. Overlapping is small • For the biggest classifier with 1734 rules, the number of distinct overlapping regions in four dimensions to be 4316, compared to a worst possible case of approximately 1013.

  22. Recursive Flow Classification

  23. Chunks of Packet header

  24. Packet flow in RFC

  25. Phase number =3

  26. Phase number =4

  27. Select Phase number • Combine those chunks together which have the most “correlation”. • Combine as many chunks as possible without causing unreasonable memory consumption. • Best case: • P=3 Tree B • P=4 Tree A

  28. Performance (Storage requirement for P=2)

  29. Performance (Storage requirement for P=3)

  30. Performance (Storage requirement for P=4)

  31. Preprocess Time

  32. Hardware implementation

  33. Larger classifiers I • Concatenating the classifiers belonging to the same network.

  34. Larger classifiers II • Concatenate all the classifiers of a few (up to ten) different networks. • RFC frequently runs into storage problems for classifiers with more than 6000 rules.

  35. Variations • Process a larger number of fields in each packet header. • Use available fast lookup algorithms • Use Adjacency group

  36. Adjacency Groups • Two rules (R, S)are considered adjacent • R appears first • The same Action • All but one field have the same specification • All rules in between R and S • Either have the same action • Disjoint from R

  37. An example

  38. Storage (Adjacency groups)

  39. Comments • Trade off? • Memory, Speed, Dynamic Change, etc • Application and Demand oriented • Further discussion? • scai@ecs.umass.edu • Thank you!

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