Side_1_360

nents need to be bought from sub-providers in
order to satisfy users’ demands. As an output of
running the procedure, the complete business
model will be known (all the partners and the
customers’ segments will be decided upon) as
well as the content of SLAs, e.g. QoS objectives,
reaction pattern, etc.

This paper addresses issues related to the SLAs
and SLSs. First of all, in Chapter 2, the relation-
ships between different types of agreements pre-
sent in today’s IP-aware telecom market are dis-
cussed. In Chapter 3, basics of SLA, its types,
structure and applicability are presented from a
generic perspective. A suggestion for the generic
structure of the QoS-related part of a technical
portion of an SLA is presented, offering a possi-
bility for providers to reuse the same structure
each time the situation changes for them (either
in the business or technical sense). The generic
principles are elaborated further, specifically
SLAs related to IP, as presented in Chapter 4.
Some examples of SLAs offered in today’s mar-
ket for various IP-based services are presented
in Chapter 5, followed by the status of the work
undertaken in various standardisation bodies
given in Chapter 6. A discussion on the mapping
between SLAs and SLSs is conducted in Chapter

7. Finally, the paper concludes by analysing the
   future and possible evolution paths for SLAs and
   SLSs in IP-based networks.

2 Agreements and specifica-

tions – BLA, SLA, SLS, TCA

Various types of agreements/specifications that
are discussed nowadays are depicted in Figure 2.
These are all referring to relations between pairs

of actors, pointing to the service provision con-

figuration.

Generally, the agreement made between any user

and any provider represents the harmonised

understanding between these two parties by

formally comprising/expressing the way they

should behave. Their behaviour is described via

a set of expressed duties, rights, and obligations.

Three types of agreements present in today’s

business and technical research – a Business

Level Agreement (BLA), an SLA, and a Traffic

Conditioning Agreement (TCA) – are described

in this chapter. The original definitions made

by the bodies/fora introducing these terms are

quoted if available. In addition to the agreements

Figure 1 Handling SLAs –

input needed by the provider

results in SLAs

Figure 2 Illustrating relation-

ships between BLA, SLA, SLS,

TCA ans TCS2)

1)Discussions on the procedure and trade-off/strategic decision undertaken by provider are given in [Tele0200].
2)Note that any of the hierarchically superior agreements may contain a set of inferior agreements/ specifications. For example, a BLA

may contain more than one SLA, e.g. if a service packet is subject to provision, or an SLA may contain multiple SLSs, etc. as illus-

trated in Figure 2.

Charging

schemes

SLA / SLSL

monitoring

QoS Parameters

and values

Business

Model

Entities

Roles

Relationships

Service

Desription

Agreement

Service

Desription

QoS

Desription

SLA USER PROVIDER

TCS

TCA

SLS

SLA

BLA