Page 542 - Handbook of Modern Telecommunications

Network Organization and Governance 4-73

TABl E 4.4.10 Performance Metrics of International Carriers
Carrier Cable and Wireless AT&T UUNet
Intra-U.S. Less than 55 ms Less than 60 ms Less than 65 ms
Intra-Europe Less than 60 ms Less than 65 ms Less than 65 ms
Trans-Atlantic Less than 100 ms Less than 120 ms Less than 120 ms
Trans-Pacific Less than 130 ms Less than 130 ms Less than 150 ms
Note: Informal examples.
4.4.6.3 Assistance of SLAs in Settlements
SLAs can support a fair and mutually acceptable settlement between service providers by using accurate
measurement data. Settlements are business agreements between service providers that may support the
same clients with their service portfolios.
All revenues generated for certain clients should be subdivided between service providers following
mutually agreed rules. Criteria for these rules are:

• Accuracy: Settlements should be based on measured data; the level of detail should be reasonable.
• Simplicity: Settlements must be simple and easy to implement and call for the use of very
simple metrics.
• Periodicity: The timeframes of settlements should be agreed upon. They could be very differ-
ent. Common sense should dictate the decision. Experiences show timeframes from one week to
three months.
The first and second items are slightly contradictory, and compromises are required.
SLAs are signed to help clients. Clients are usually interested in signing end-to-end SLAs, but in such
cases, multiple service providers may be included. Multiprovider models are addressed in other APs.
Basically, we should consider:
• Bilateral SLAs between clients and service providers: In this case, SLAs are rarely used for settle-
ments because they have been signed for individual use. Settlements are important, but they are
not impacted by the SLAs.
• The client and the main service provider sign an SLA: There are multiple SLAs between the main
service provider and other service providers (subcontractors). In this case, SLAs have a great
impact on settlements because the business relationships are built hierarchically. An SLA viola-
tion may trigger a chain reaction of events.

Metrics, agreed upon in SLAs, may be used for the settlement (mutual billing) between service pro-
viders. The most important metrics are:
• Throughput: Transferred bytes, messages, and transactions in both directions
• Trouble statistics that are the basis for availability calculations
• Performance metrics that determine the service quality
• Security metrics that determine the level of protection in the networking segments of service
providers
The supervision of SLAs is supported by measurements accomplished by standardized and certified
measurement tools. They are able to provide the measurement results for throughput rates, error rates,
response time, delays, latencies, and eventually security violations. When all or some of these metrics
may be utilized for settlements between service providers, savings may be accomplished in the area of
data collection tools and of generating special settlement-oriented reports.
Settlement between service providers are functioning as follows: