Discussion Items for Inter-Provider Service Performance Metrics

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Discussion Items for Inter-Provider Service
Performance Metrics

• Ralph Santitoro
• CTO Office
• rsantito_at_nortelnetworks.com
• Inter-Provider QoS Workshop at MIT
• October 20-21, 2004

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Key Service Performance Metrics

• Rate of Service (RoS) / Bandwidth Profile
• Octet count per UNI/NNI, CoS aggregate or Flow
  per time
• Performance of Service (PoS)
• One Way Packet Delay (also looking at Round Trip)
• Packet Delay Variation
• Packet Loss Ratio
• Availability of Service (AoS)
• of time PoS PMs are met over time interval

Need Common Terminology, Definitions and
Parameters
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Bandwidth Profile Parameters

• Lets agree on some common definitions for rate
  enforcement parameters
• 4 main parameters for each type of bandwidth
  profile
• ltCIR, CBS, EIR, EBS, CMgt
• CIR/CBS determines packet delivery per PoS
  objectives
• EIR/EBS determines amount of excess packet
  delivery
• CM (Color Mode) determines the whether packet
  color markings per CoS should be honored or
  ignored
• EIR ? PIR, EBS ? PBS
• PIR CIREIR

Common Definitions and Terms for Rate Enforcement
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Color Indications

• Green
• Packets conformant to CIR/CBS and SLA applicable
  per PoS parameters (delay, delay variation and
  loss)
• Yellow
• Packets not conformant with CIR/CBS but
  conformant with EIR/EBS and SLA not applicable
• Packets admitted to network but may be dropped
  under congestion
• Red
• Packets not conformant to CIR/CBS or EIR/EBS
• Packets typically dropped but may be admitted to
  network
• Red packets get dropped ahead of yellow packets

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Rate Enforcement / Color from a Token Bucket
Perspective

• Common parameters / definitions result in
  consistent service performance
• Metro Ethernet Forum trTCM algorithm for Ethernet
  services
• MEF 5 tech. spec. http//www.metroethernetforum.or
  g/PDFs/Standards/MEF5.pdf
• http//www.ietf.org/internet-drafts/draft-aboulmag
  d-trtcm-inprofile-01.txt
• Applicable to Ethernet and IP services

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NNI Bandwidth Profiles

• MEF has defined these for UNI. Some possible NNI
  variants below
• BW Profile to use depends upon type of service
  supported at NNI

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Performance of Service (PoS)

• Packet Delay (One Way)
• P percentile of the delay of all successfully
  delivered Green packets per CoS over time
  interval T
• E.g., PD 100ms 99.9 over 5 min. intervals
• Packet Delay Variation (a.k.a. jitter)
• P percentile of the difference of delays of green
  packet pairs within time interval T with
  inter-packet time interval of ?t
• Selection of ?t related to application
• E.g., PDV 5ms 99.9 over a 5 min. intervals, ?t
  5ms
• Packet Loss Ratio
• Ratio of number of discarded green packets during
  time interval T to number of ingress green
  packets during the time interval T
• E.g., PLR 0.1 over a 5 min. intervals

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POS PM Zoning

• Zoning used with PoS PMs to factor in delay
  introduced due to distance

PoS PMs in SLA based on Zone
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Performance of Service (PoS) Time Sync / Stamping

• Critical for one way delay/delay variation
  measurements
• IEEE 1588 highlights (http//ieee1588.nist.gov)
• Provides a deterministic injection and extraction
  of timestamp information at source and
  destination MACs to distribute frequency
  optional phase aligned clock reference
• Sync messages sent at source (master) to end
  points (slaves)
• MAC injects precision timestamp or-
• Follow-up message sent containing precise master
  sending time
• All slaves compute offset and correct their
  clocks
• Can be sent as UDP/IP packets or as native
  Ethernet packets

Stratum traceable reference over a packet network
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Availability of Service (AoS)

• Calculated via the following over time interval T
• Packet Delay, Delay Variation and Loss Ratio
  performance objectives being met
• UNI or NNI (L1) availability
• E.g., AoS 99.9 calculated over 15 minute
  intervals
• Would be useful to have BCP guidelines for
  interval T / CoS
• T differs depending upon CoS performance
  objectives

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PM Service Attribute Summary
Service Attribute PM description Parameters
PoS Packet Delay (ms) P percentile, T measurement interval
PoS Packet Delay Variation (ms) P percentile, T measurement interval
PoS Packet Loss Ratio () P percentile, T measurement interval ?t inter-packet time interval
RoS Bandwidth Profile per NNI ltCIR, CBS, EIR, EBS, CMgt
RoS Bandwidth Profile per CoS Aggregate ltCIR, CBS, EIR, EBS, CMgt
RoS Bandwidth Profile per Subscriber CoS ltCIR, CBS, EIR, EBS, CMgt
AoS PD, PDV, PLR SLOs being met () T measurement interval