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Quality of SPC services
Claudio BortoneClaudio Bortone
IV seminar in
“ICT Service Oriented Network Architectures“
Universi...
Table of contents
• part 1:
– overview on ICT QoS management
• definition of a supply contract
• definition of an ICT serv...
ICT QoS management
Overview of quality management
of complex ICT services’ supply
Supply contract
Supply contract
• a supply contract is a costly deal:
– against the financial cost supported by the
supplier to provide th...
Supply conditions
• Supply conditions regulates:
– economical aspects
– delivery time
– mutual responsabilies
– involved r...
Supply subjects
• three kinds of supply subjects:
– supplier:
• the economical subject that provides the supply
– user:
• ...
Supply object
• the supply object can be:
– a product
• shoes
• food
• pencils
• personal computers
• …• …
– a service:
• ...
The difference between product and service
• product is tangible:
– omogeneous
– production and distribution differ from c...
Products and services overlapping
• a product can include more than one service erogation such as:
– for istance: mobile p...
Information and Communication
Technology (ICT) services
ICT services supply
• the contractor is generally the counterpart of an ICT
services supplier
• some examples of ICT servi...
ICT service supply life cycle: phases
• ICT service supply’s life cycle consists in 2
phases:
– phase 1: realization
• inc...
ICT service supply life cycle: transitions
• the passage between the 2 life cycle phases is
guaranteed by two transitions:...
ICT service supply life cycle : diagram
Rome, March 24th 2009 Quality of SPC services
Macro processes for ICT service supply
• the international standard ISO/IEC 20000 defines the
macro processes necessary to...
Quality of Service (QoS)
measure
General consideration on the quality of service
• the International Standardization Organization
(ISO), definines quality ...
Subjective quality
• the subjective QoS can be defined as the deviation
between perceived QoS and desired QoS:
– QoS desir...
Objective quality
• the objective quality can be defined as deviation
between designed QoS and erogated QoS:
– designed Qo...
Key Performance Indicators
• the Key Performance Indicators (KPIs) are tools used
to objectively measure QoS, during the l...
KPI determination
• the determination of a significant KPI often is a
challenging activity:
– it is necessary to avoid tha...
Service Level Agreement (SLA)
• in a service supply, the SLA is a condition that
establishes:
– the thresholds within whic...
Minimal requirements for SLA
• Minimal requirements for SLA are:
– service characterization
– involved KPIs list
– KPIs ag...
SLA target
• the SLA target represents the acceptable threshold
value within which the objective quality aspects
are measu...
SLA target rappresenting desired QoS
• it is crucial that the contractor defines SLA targets
in line with desired QoS:
– s...
SLA refining
• other useful information that can enrich the SLA
definition are:
– the erogation time slot (time during whi...
SLA classification
• the classification of a SLA in accordance with the
process that are involved in KPI is a best practic...
SPC network transport
QoS managementQoS management
QoS management of the network transport
service included in the SPC sup...
Elements for measuring
quality of network service
Tipical metrics
• Packet Loss
– percentage of packets that do not reach their destination
• Delay
– One-Way-Delay
• the ti...
Packet loss contributes
• network malfunctions
– link error
• significant bit error probability
• congestion
– network equ...
Delay contributes
• sending delay
– time between packet receiving and queuing on output interface
• queuing delay
– time e...
Jitter
• mathematical jitter
– standard deviation of one-way-delay
• it is the square root of variance (average of squares...
Inter-packet delay variation
Source
(Querier)
T1
P1 R1
T4 T5
P2 R2
T8
• Jitter SD = (T2 – T1) – (T6 – T5)
• Jitter DS = (T...
Charatteristics of SPC transport
service always-on
Always-on service
• technical specifications definition:
– “transport services allow linking to the
supplier’s network by ...
Transfer component
• different applications need different data transport
requirements:
– for each application and for eac...
Service class (CdS)
• 4 desired quality of transport requirement for a
CdT can be associated to 4 CdS:
– real time (RT)
• ...
Always-on network
transport SLA
Minimal requirements of SLA
• minimal requirements of SLA are:
– service characterization
– involved KPIs list
– KPIs aggr...
Service characterization
• one always-on service characterization:
– supply:
• Public Connectivity System
– service:
• alw...
Involved KPIs
• three tipical KPIs used for measuring quality of
transport services from source to destination:
– one way ...
Aggregation algorithm and SLA target
• the measures must be aggregated in “survey
intervals” with 24 hours duration (for C...
Reference time slot and penalties
• for each four-month period:
– SLA considers survey intervals out of SLA
target for eac...
Reporting modalities
• for each four-month period will be produced a report
that represents:
– the four-month period under...
Thanks
Claudio Bortone
e-mail: claudio@bortone.it
web-site: http://www.linkedin.com/in/claudiobortone
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Quality Of Spc Services

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Overview of ICT services QoS management such as SPC

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Quality Of Spc Services

  1. 1. Quality of SPC services Claudio BortoneClaudio Bortone IV seminar in “ICT Service Oriented Network Architectures“ University of Rome La Sapienza March 24th 2009
  2. 2. Table of contents • part 1: – overview on ICT QoS management • definition of a supply contract • definition of an ICT service • definitions and tools for measuring QoS• definitions and tools for measuring QoS • part 2: – SPC network transport QoS management: • elements for measuring network transport QoS • a network transport service of SPC: always-on • always-on network transport SLA Rome, March 24th 2009 Quality of SPC services
  3. 3. ICT QoS management Overview of quality management of complex ICT services’ supply
  4. 4. Supply contract
  5. 5. Supply contract • a supply contract is a costly deal: – against the financial cost supported by the supplier to provide the supplied object, corresponds a patrimonial benefit for the same supplier due to the object delivery to thesupplier due to the object delivery to the counterpart • a supply contract defines: – conditions – subjects – characteristics of supply’s object Rome, March 24th 2009 Quality of SPC services
  6. 6. Supply conditions • Supply conditions regulates: – economical aspects – delivery time – mutual responsabilies – involved resources– involved resources – … – service levels – … Rome, March 24th 2009 Quality of SPC services
  7. 7. Supply subjects • three kinds of supply subjects: – supplier: • the economical subject that provides the supply – user: • the user or beneficiary of the object of the supply• the user or beneficiary of the object of the supply – contractor: • in some context, it is the direct interlocutor of the supplier instead of the user • a contractor can be a user Rome, March 24th 2009 Quality of SPC services
  8. 8. Supply object • the supply object can be: – a product • shoes • food • pencils • personal computers • …• … – a service: • professional training • catering • library (keeping) • web site hosting • … Rome, March 24th 2009 Quality of SPC services
  9. 9. The difference between product and service • product is tangible: – omogeneous – production and distribution differ from consumption – a thing, an object – customers don’t partecipate to the production process – it can be stored – property transfer • service si untangible: – eterogeneous – production and consumption are not separable – an activity, a process – customers partecipate to the production process – it cannot be stored – there’s not property transfer Rome, March 24th 2009 Quality of SPC services
  10. 10. Products and services overlapping • a product can include more than one service erogation such as: – for istance: mobile phone • ... • power supply • software • battery • … • often a service can be “realized” by supplying more than one product – for istance: network data transport • … • connection • switch • router • … Rome, March 24th 2009 Quality of SPC services
  11. 11. Information and Communication Technology (ICT) services
  12. 12. ICT services supply • the contractor is generally the counterpart of an ICT services supplier • some examples of ICT services supply: – connectivity – security– security – VoIP – system management – web site design – asset management – … Rome, March 24th 2009 Quality of SPC services
  13. 13. ICT service supply life cycle: phases • ICT service supply’s life cycle consists in 2 phases: – phase 1: realization • includes activities for implementing the new service and delivery predispositionand delivery predisposition – phase 2: operation • includes activities for service erogation, change management, problem mangement Rome, March 24th 2009 Quality of SPC services
  14. 14. ICT service supply life cycle: transitions • the passage between the 2 life cycle phases is guaranteed by two transitions: – from phase 1 to phase 2: test • service must be realized under the conditions specified in the supply contract (verified and tested)specified in the supply contract (verified and tested) – from phase 2 to phase 1 : design review • information on some troubles resolution or on changes managed in the operation phase, can be used as input for reiterating the realization phase Rome, March 24th 2009 Quality of SPC services
  15. 15. ICT service supply life cycle : diagram Rome, March 24th 2009 Quality of SPC services
  16. 16. Macro processes for ICT service supply • the international standard ISO/IEC 20000 defines the macro processes necessary to a ICT service supply: – for the realization phase: • Planning and Implementing New or Changed Services • Service Delivery Processes – for the operation phase: • Release Processes • Resolution Processes • Relationship Processes • Control Processes (activate the Design Review) Rome, March 24th 2009 Quality of SPC services
  17. 17. Quality of Service (QoS) measure
  18. 18. General consideration on the quality of service • the International Standardization Organization (ISO), definines quality as: – “the level with which a set of charateristics (of product, of system, or process) satisfies the requirements”requirements” • the satisfation level of a user/contractor can be evaluated in two ways: – subjectively – objectively Rome, March 24th 2009 Quality of SPC services
  19. 19. Subjective quality • the subjective QoS can be defined as the deviation between perceived QoS and desired QoS: – QoS desired: • it is the quality level determined by explicit or implicit needs or by user desireimplicit needs or by user desire – QoS perceived: • it is the quality level that the user can be evaluate by using service and by comparing the (actual or potential) service performance with his desire Rome, March 24th 2009 Quality of SPC services
  20. 20. Objective quality • the objective quality can be defined as deviation between designed QoS and erogated QoS: – designed QoS: • it is the quality level taken as reference (project requirement) during the realization; it regulates therequirement) during the realization; it regulates the organizational system, the service realization modalities, and the functioning conditions – erogated QoS: • it is the quality level objectively measured in the operational phase by adeguated measuring tools Rome, March 24th 2009 Quality of SPC services
  21. 21. Key Performance Indicators • the Key Performance Indicators (KPIs) are tools used to objectively measure QoS, during the life cycle of the supply: – one or more KPIs can be determined for each supply sub-process – KPIs can be put together to built another KPI • constant monitoring of KPIs is an important activity: – it allows the supplier to identify precisely the processes that need to be fine tuned to increase the satisfaction level – it allows the user/contractor to measure more objectively the erogated QoS Rome, March 24th 2009 Quality of SPC services
  22. 22. KPI determination • the determination of a significant KPI often is a challenging activity: – it is necessary to avoid that: • it consists in a statistic data that is not rappresentativerappresentative • it is defined in a vage and interpretable way – the requirements for a good KPI designer are: • technical and managerial skills which must be reliable and horizontal • capability analysis and affective reporting for all the factors which affect the indicator evaluation Rome, March 24th 2009 Quality of SPC services
  23. 23. Service Level Agreement (SLA) • in a service supply, the SLA is a condition that establishes: – the thresholds within which the objective quality aspects (measured by KPI) are accettableaccettable – the penalities agreed with the supplier in case of established thresholds are exeded Rome, March 24th 2009 Quality of SPC services
  24. 24. Minimal requirements for SLA • Minimal requirements for SLA are: – service characterization – involved KPIs list – KPIs aggregation algorithm – SLA target– SLA target – the referencing time slot – modality of evaluation and penalty payment – reporting modalities Rome, March 24th 2009 Quality of SPC services
  25. 25. SLA target • the SLA target represents the acceptable threshold value within which the objective quality aspects are measured by one or more KPIs • the supplier uses the SLA targets as quality level• the supplier uses the SLA targets as quality level reference (project requirements) during the relization phase Rome, March 24th 2009 Quality of SPC services
  26. 26. SLA target rappresenting desired QoS • it is crucial that the contractor defines SLA targets in line with desired QoS: – strict SLA targets imply an increase of referring desired quality levels while designing – strict project requirements imply a non– strict project requirements imply a non proportional increase of performance price Rome, March 24th 2009 Quality of SPC services
  27. 27. SLA refining • other useful information that can enrich the SLA definition are: – the erogation time slot (time during which the service are erogated) – SLA updating modalities – … Rome, March 24th 2009 Quality of SPC services
  28. 28. SLA classification • the classification of a SLA in accordance with the process that are involved in KPI is a best practice • some example of classification are: – delivery– delivery – assurance – performance – … Rome, March 24th 2009 Quality of SPC services
  29. 29. SPC network transport QoS managementQoS management QoS management of the network transport service included in the SPC supply
  30. 30. Elements for measuring quality of network service
  31. 31. Tipical metrics • Packet Loss – percentage of packets that do not reach their destination • Delay – One-Way-Delay • the time elapsing between the packet departure and arrival – Round-Trip-Delay • the time elapsing between the packet departures and its acknowledgement • Jitter – delay variation between two subsequent packets Rome, March 24th 2009 Quality of SPC services
  32. 32. Packet loss contributes • network malfunctions – link error • significant bit error probability • congestion – network equipement that does not have enough resources to manage incoming packetsresources to manage incoming packets – memory resource shortage of interface output queue • transients – transient and incoherent network configurations due to routing protocol convergence • packets dropped for TTL zero value Rome, March 24th 2009 Quality of SPC services
  33. 33. Delay contributes • sending delay – time between packet receiving and queuing on output interface • queuing delay – time elapsed while packets remain in queue • line delay – time needed to write a packet on the line • it depends on the packet dimension and from the bit rate (technological facility) • it can be reduced increasing resources• it can be reduced increasing resources • propagation delay – time needed for the signal to cover the distance from source to destination • it depends on the light speed • it cannot be decreased • ritrasmission delay – time needed to ritransmit a lost packet • only for links that provide ritrasmission feature Rome, March 24th 2009 Quality of SPC services
  34. 34. Jitter • mathematical jitter – standard deviation of one-way-delay • it is the square root of variance (average of squares of average deviation) • inter-packet delay variation• inter-packet delay variation – defined in RFC 3393 – average of interarrival times difference • let ti the time necessary to a packet i to reach destination, it will be calculated the average of |ti+1 – ti| Rome, March 24th 2009 Quality of SPC services
  35. 35. Inter-packet delay variation Source (Querier) T1 P1 R1 T4 T5 P2 R2 T8 • Jitter SD = (T2 – T1) – (T6 – T5) • Jitter DS = (T2 – T1) – (T6 – T5) Rome, March 24th 2009 Quality of SPC services Destination (Responder) T2 T3 T6 T7
  36. 36. Charatteristics of SPC transport service always-on
  37. 37. Always-on service • technical specifications definition: – “transport services allow linking to the supplier’s network by a technology that provides permanent access (link xDSL, SDH, etc.)”etc.)” • technical specifications also define the service access point “Punto di Accesso al Servizio” (PAS) such as: – “every service will be erogated by one or more phisical user interface called PAS” Rome, March 24th 2009 Quality of SPC services
  38. 38. Transfer component • different applications need different data transport requirements: – for each application and for each PAS the supplier can provide one or more transfer components “Componente di Trasferimento “ (CdT)(CdT) – every CdT is characterized by: • a scope • guaranteed amount of access bandwidth “Banda Massima in Accesso” (BMA) • a service class “Classe di Servizio” (CdS) Rome, March 24th 2009 Quality of SPC services
  39. 39. Service class (CdS) • 4 desired quality of transport requirement for a CdT can be associated to 4 CdS: – real time (RT) • low delay and low jitter – mission critical (MC)– mission critical (MC) • low delay and low packet loss – streaming (ST) • low jitter – best effort (BE) • no specific requirements Rome, March 24th 2009 Quality of SPC services
  40. 40. Always-on network transport SLA
  41. 41. Minimal requirements of SLA • minimal requirements of SLA are: – service characterization – involved KPIs list – KPIs aggregation algorithm– KPIs aggregation algorithm – SLA target – the referencing time slot – modality of evaluation and penalty payment – reporting modalities Rome, March 24th 2009 Quality of SPC services
  42. 42. Service characterization • one always-on service characterization: – supply: • Public Connectivity System – service: • always-on (AON)• always-on (AON) – service characteristic: • one transport component with a real time service class Rome, March 24th 2009 Quality of SPC services
  43. 43. Involved KPIs • three tipical KPIs used for measuring quality of transport services from source to destination: – one way delay (OWD) – packet loss – jitter • KPIs measuring modalities: – each equipement that realizes the PAS will measure constantly sending 10 packets with a 40 bytes dimension toward the QXN border router – this measure will be done for each minute of the day, and for each CdT with a RT CdS Rome, March 24th 2009 Quality of SPC services
  44. 44. Aggregation algorithm and SLA target • the measures must be aggregated in “survey intervals” with 24 hours duration (for CdT BGA) • SLA target for each KPI in each “survey interval” is: – for OWD: • < 40 ms for 99% of packets – for Packet Loss: • < 0,15% of packets – for Jitter: • average value < 15 ms Rome, March 24th 2009 Quality of SPC services
  45. 45. Reference time slot and penalties • for each four-month period: – SLA considers survey intervals out of SLA target for each KPI • the penalty for each four-month period under• the penalty for each four-month period under check will be: – 1% of monthly charge of each survey interval out of SLA target in four months Rome, March 24th 2009 Quality of SPC services
  46. 46. Reporting modalities • for each four-month period will be produced a report that represents: – the four-month period under check – the identificative of service – the measure of each KPI (PL, OWD, Jitter) – the number of intervals out of SLA target– the number of intervals out of SLA target – monthly charge – percentage of monthly charge used for calculating penalty – economical value of penalty Rome, March 24th 2009 Quality of SPC services
  47. 47. Thanks Claudio Bortone e-mail: claudio@bortone.it web-site: http://www.linkedin.com/in/claudiobortone

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