International Telecommunication Union Workshop on End-to-End Quality of Service.What is it? How do...
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International Telecommunication Union Workshop on End-to-End Quality of Service.What is it? How do we get it? Geneva, 1-3 October 2003 Service Level Service Level Agreements – What Agreements – What are the Goals? are the Goals? Alan Clark CEO, Telchemy Incorporated
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Transcript of International Telecommunication Union Workshop on End-to-End Quality of Service.What is it? How do...
International Telecommunication Union
Workshop on End-to-End Quality of Service.What is it? How do we get it?Geneva, 1-3 October 2003
Service Level Service Level Agreements – What Agreements – What
are the Goals?are the Goals?
Alan ClarkCEO, Telchemy Incorporated
21-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
Outline
o Services and Service Levelso SLA Agreements
• Customer objectives • Service provider objectives
o Defining meaningful SLAso Where are we today?
31-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
What is a “Service”
o “Service functionality”o Set of formal or informal
expectations with respect to:• Cost• Performance• Availability• Reliability• ……
41-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
“Service Levels”
o Abstract• Desired - expectation with regard to
some element of a service• Actual – perception that service is
“good” or “bad” with respect to expected level
o Concrete• Desired - measurable aspect of
service• Actual – measured aspect of service
51-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
A Classic SLA Agreement
o Availability o Capacity o Performance o Change notification o Help desk response timeo Billing/ Usage statistics
61-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
Customer objectives for SLAs
o Agreed level of service from vendor/ provider
o Means to hold service provider accountable when objectives not met
o Safety – confident in using critical applications that rely on service
o Prefer SLAs to be “narrow” – to reflect events that affect user experience of quality
71-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
Service Provider objectives for SLAs
o Clear delineation of service expected by customer
o SLA metrics can be used to set internal performance objectives
o Prefer SLAs to be “broader” - averaged, not specific to individual events, reflecting overall experience of quality
o Prefer that SLA measurements can be correlated with customer satisfaction – avoid “artificial” service quality problems
81-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
Why isn’t this easy?
o Easy if • service quality is uniformly good or bad• SLA expressed in terms of things that
are easy to measureo Unfortunately
• Problems may be intermittent/ irregular• Things that are easy to measure may
be difficult to relate to “actual” service quality
91-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
What should an SLA be
o Measurable• Countable, quantifiable
o Objective• Related to user perception of
service qualityo Comprehensive
• Address all aspects of service delivery
101-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
“Real World” SLA from a major service provider (Sept ’03)
o Availability – 100% uptimeo Packet loss – average monthly loss
rate 0.1%o Latency – average monthly latency
< 55mSo Jitter – average 500uSo Maximum jitter – exceeds 10mS
less than 0.1% of a calendar month
111-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
Example
0
20
40
60
80
100
0 50 100
Time
Inst
anta
neous
call
qualit
y
Average quality = 86
“Quality event” noticeableby the subscriber
121-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
Lesson
o Average quality level may be within limits
o User may be unhappy with service quality
o And worse - if the service provider only measures average service level • they may be unaware of widespread
problems• Problem diagnosis can be difficult
131-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
Recommendations
o With regard to call/ session performance metrics• If the customer’s perception of
service is affected by transient problems and
• If the service can experience transient problems then
• Measure service level in a way that reflects this.
141-3 October 2003 Workshop on End-to-End Quality of Service. What is it? How do we get it?
ITU-T
What should an SLA beHow do we measure up?
o Measurable• Countable, quantifiable
o Objective• Related to user perception of
service qualityo Comprehensive
• Address all aspects of service delivery
A
D
B+
