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IP Performance Metrics: Definitions and Implementation Examples

IP Performance Metrics: Definitions and Implementation Examples. Al Morton AT&T Labs. Outline. Performance Management Framework Relationship to the E2E QoS goal IP Parameters/Metrics Summary In-progress Metric Development Implementations Service Providers Customers 3rd Parties

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IP Performance Metrics: Definitions and Implementation Examples

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  1. IP Performance Metrics:Definitions and Implementation Examples Al Morton AT&T Labs

  2. Outline • Performance Management Framework • Relationship to the E2E QoS goal • IP Parameters/Metrics Summary • In-progress Metric Development • Implementations • Service Providers • Customers • 3rd Parties • Performance for MPLS-enabled IP Nets Workshop on End-to-End Quality of Service. What is it? How do we get it?

  3. Network Performance Management Framework • Fault Monitoring -- failure detection • Passive Info Collection (single point) • Read MIB counters or control data • Sample Traffic • Active Measurements • Synthetic Traffic Dedicated to meas. • Customer Measurements • Live or Synthetic traffic Workshop on End-to-End Quality of Service. What is it? How do we get it?

  4. Relationship to E2E QoS: Provide answers to ... • Network Provider • Is the design meeting requirements for various traffic classes or applications? • How can I demonstrate the superior performance of my service offering? • Customer • Is Network Performance  Agreement? • 3rd Parties • What does “the net” look like? Hot spots? • What Network Provider is “best”? Workshop on End-to-End Quality of Service. What is it? How do we get it?

  5. IPRE 1 ingress MP egress MP Packet Perf. Parameters IPRE 2 Successful Valid header and £ t T IP packet outcome error-free payload max IPRE 1 IPRE 2 Errored Corrupted header or t T £ IP packet outcome errored payload max Spurious IPRE 2 IP packet outcome (Note) IPRE 1 Never delivered or Lost delivered to an unpermitted IP packet outcome egress MP IPRE 1 t > T max Lost IPRE 2 IP packet outcome (Note) NOTE – Outcome occurs independent of IP packet contents Workshop on End-to-End Quality of Service. What is it? How do we get it?

  6. Metric/Parameter Definition Summary Workshop on End-to-End Quality of Service. What is it? How do we get it?

  7. Comparison of IETF and ITU-T Delay Variation Metrics IETF IPDV is a measure of transfer delay variation w.r.t. previous packet. For Packet n, IPDV(n) = Delay(n) - Delay(n-1) or = R(n) - R(n-1) - T(n) - T(n-1) If the nominal transfer time is  =10msec, and packet 2 is delayed in transit for an additional 5 msec, then two IPDV values will be affected. IPDV(2) = 15 - 10 = 5 msec IPDV(3) = 10 - 15 = -5 msec IPDV(4) = 10 - 10 = 0 msec ITU-T SG 13 PDV is delay w.r.t. a reference, usually minimum delay. PDV(n) = Delay(n) - Min[Delay(*)] PDV(1,3,4)=0 PDV(2)=5 Tx Rcv Playout 1  2 Inter packet arrival time, longer than send interval 1 3 t 2 4 3 4 Time spent in: Transit Rcv Buffer Workshop on End-to-End Quality of Service. What is it? How do we get it?

  8. Transient Delay Variation caused by burst traffic ITU PDV IETF Workshop on End-to-End Quality of Service. What is it? How do we get it?

  9. Packet Metrics for VoIP and other voiceband applications • *new* metrics in G.IPP • Consecutive Packet Loss • Degraded Seconds • Short-term Delay Variation • Overall VoIP Parameters • Alan Clark’s Presentation Workshop on End-to-End Quality of Service. What is it? How do we get it?

  10. What is Packet Reordering? • Packets arrive at Dst, but not in send order. • 1, 2, 3, 7, 8, 9, 10, 11,... Loss,no reordering • 1, 2, 3, 7, 8, 9,4, 5, 6, 10, 11,...reordering • In the “world of order” all these packets are of interest. • 1, 2, 3, 7, 8, 9,4, 5, 6, 10, 11,... • | Early | Late | • No reordering until Late Packets Arrive • # of Early Packets => Reordering Extent Workshop on End-to-End Quality of Service. What is it? How do we get it?

  11. Affect of Reordered Packets on most applications • Receivers must perform work to restore order 1, 2, 3, 7, 8, 9,10,4, 5, 6, 11, 12,... | Buffered ||Reordered| Dst Time axis 1 2 3 7 8 9 10 4 5 6 11 Higher layers 1 2 3 4 5 6, 11 (& 7 to 10) Workshop on End-to-End Quality of Service. What is it? How do we get it?

  12. Definition of Reordered Packet • Packet n is designated reordered when its sequence number is less than the Next Expected threshold (set by the arrival of a previous packet). Next Expected Workshop on End-to-End Quality of Service. What is it? How do we get it?

  13. Failure Recovery Time • When recovery was a simple outage, characterization was simple, too. • IETF Benchmarking Methodology WG has identified 5 possible recovery scenarios: Lost packets Induced delay 4 3 2 1 7 6 2 1 Out-of-order packets Errored packets Duplicate packets 7 5 6 3 4 2 1 2 1 6 5 3 7 6 2 1 4 4 Workshop on End-to-End Quality of Service. What is it? How do we get it?

  14. Implementations: Customers, Service Providers & 3rd Parties $ ping R2 (or R3) R3 • Select Ping Target - make Round-trip connectivity and RTT measurement • Accuracy Issues include path through router, path through net (asymmetries), response time at target, sampling rates • Compare to current perf. to “normal” or R2 R1 or R4 Workshop on End-to-End Quality of Service. What is it? How do we get it?

  15. Beyond ping: ICMP Timestamp or Timestamp Reply Message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identifier | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Originate Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Receive Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Transmit Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ • Time spent processing packet at target can be removed, for more accurate RTT. R3 Originate Code=13 Receive R2 R1 Transmit Code=14 R4 Workshop on End-to-End Quality of Service. What is it? How do we get it?

  16. Implementations:AT&T Global IP Measurements AT&T GLOBAL IP BACKBONE INFRASTRUCTURE BR (City 1) BR (City n) BR (City 2) MEASUREMENT COLLECTION SERVER (MCS) Measurement Probes Measurement probe AGGREGATED MEASUREMENT DATA http://www.att.com/ipnetwork WEB CLIENTS (for report viewing) MEASUREMENT AGGREGATION & REPORTING SERVER (MRS) Workshop on End-to-End Quality of Service. What is it? How do we get it?

  17. AT&T’s IP Measurement Design 24 hours . . . 15 minutes • Poisson Sequence (RFC2330) • 15 minute duration •  = 0.3 pkts/sec • Type UDP, IPv4 • 278 bytes total • ~300 packets sent • unbiased sample • Periodic Sequence (RFC3432) • 1 minute duration • Random Start Time • 20 ms packet spacing • Type UDP, IPv4 • 60 bytes total • ~3000 packets sent Workshop on End-to-End Quality of Service. What is it? How do we get it?

  18. Len Ciavattone George Holubec Madhukar Kshirsagar Ron Kulper Arvind Ramarajan Gomathi Ramachandran Technical Collaborators at AT&T Workshop on End-to-End Quality of Service. What is it? How do we get it?

  19. New Measurement Challenges for MPLS-enabled IP Networks • Most (all?) IP/Packet Network challenges • Two main categories of MPLS Domains: • LDP-based, connection-less • Traffic Engineering, connection oriented • Label Switched Paths are Unidirectional • point to point and multi-point to point • Many options for Failure Recovery • LSP identity optionally removed (PHP) • Work in progress in SG 13 = Y.MPLSperf Workshop on End-to-End Quality of Service. What is it? How do we get it?

  20. New Measurement Challenges for MPLS-enabled IP Networks MPLS Domain Scope of OA&M Measurements: single Network Section or MPLS Domain MPLS Domain Network Network section section Exchange Exchange link link Exchange Network link section Exchange link Exchange link MPLS Edge Node, or MPLS Ingress Node, or MPLS Node LSR if both IP and MPLS are enabled Label Switched Paths Network Section Ensemble (NSE) MPLS Network Workshop on End-to-End Quality of Service. What is it? How do we get it?

  21. New Measurement Challenges for MPLS-enabled IP Networks • New Protocols = New Opportunities to Blackhole Traffic • Detect this new class of failures with • Y.1711 MPLS OA&M Connectivity Verific. • First version approved, adding fast failure detection • LSP-Ping, Like ICMP Echo Request, plus • One-way Delay measurement possible • LSP Traceroute possible Workshop on End-to-End Quality of Service. What is it? How do we get it?

  22. New Measurement Challenges for MPLS-enabled IP Networks • New Availability Definition? Crossroad: • Connection-Oriented Transport has used a 10 second sliding window • Connection-Less Packet Transport has used a 5 minute fixed window • MPLS Networks => both transport types • When Connection-oriented Services use a Connection-less transport, which precedent should the Availability Definition follow? Workshop on End-to-End Quality of Service. What is it? How do we get it?

  23. Summary • Performance Management Framework • Measurement Systems are a key step toward the goal of E2E QoS • Summary of existing Parameters/Metrics • In-progress Metric Development • Active Measurement Implementations • Ping for connectivity and ... • Dedicated Measurement Systems • Parameter Framework for MPLS has new challenges Workshop on End-to-End Quality of Service. What is it? How do we get it?

  24. L. Ciavattone, A. Morton and G. Ramachandran, "Standardized Active Measurements on a Tier 1 IP Backbone," IEEE Communications Magazine, June 2003. Geoff Huston, “Measuring IP Network Performance,” The Internet Protocol Journal, vol 6, no.1, March 2003 http://www.cisco.com/ipj X.Xiao, et al., “A Practical Approach for Providing QoS in the Internet Backbone,” IEEE Communications Magazine, December 2002. D. Meyer, et al., “Trends in Measurement and Monitoring of Internet Backbones,” Panel at NANOG 26, slides etc. at http://www.nanog.org/mtg-0210/measurement.html ITU-T Rec. Y.1540, “Internet Protocol Data Communication Service – IP Packet Transfer and Availability Performance Parameters,” 2003. IETF IP Performance Metrics Working Group, links to RFC 2330, other IPPM RFCs and Internet Draft on Reordering: http://www.ietf.cnri.reston.va.us/html.charters/ippm-charter.html Draft New Recommendation Y.MPLSperf, “Performance and Availability Parameters for MPLS Networks” Draft New Recommendation G.IPP, “Performance Parameter Definitions for Quality of Speech and other Voiceband Applications Utilising IP Networks” RFC 792, “Internet Control Message Protocol,” J. Postel, September 1981. Resources and References Workshop on End-to-End Quality of Service. What is it? How do we get it?

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