Discussion Items for InterProvider 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
• 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