Side_1_360

7.2 Many-to-one Relationship

between SLA and SLS

In a many-to-one relationship case the SLA
gives the description of the service and all QoS
parameters necessary to describe the service to
be delivered at the service level, i.e. service A
with QoS guarantee QoSa at the service level.
The result is three SLSs for QoS description of
application service levels (e.g. VoIP, Video).
However, several services may be provided to
a user using the same IP network and the same
access. Therefore, an SLA may include a com-
mon SLS describing the common component,
i.e. IP connectivity, and its QoS description is
included in a separate SLS as illustrated in Fig-
ure 12 for the total set of services. In order to
guarantee the services and the QoS described in
separate SLAs the decision on the performance
needed from a common IP service should con-
sider these SLAs (service descriptions), QoS
descriptions and traffic profiles. Combining
these for the total set of services to be provided
using the same IP network service, the resulting
QoS parameters, QoSIPtot, may be found.

QoSIPtot is related to the IP level and should

be given in a separate SLS for the IP service.

Consider an example where SP B offers a ser-

vice B (e.g. VoIP) to the user, but without taking

care of the IP connectivity needed for the VoIP

service delivery. The user and SP B agree the

SLA, with the QoS description QoSb. At the

same time user A agrees delivery of service A

(e.g. VoD) with SP A as agreed in the SLA with

QoSa. In addition, the user makes an SLA with

the NO for the IP connectivity as illustrated in

Figure 13. This service will be used for delivery

of services A and B, i.e. typically there will be

several services using the same resources towards

the same user. Having a situation like this, it is

very complex for the NO to monitor the service

delivery and SLA assurance, and to report to

each of the SPs the performance of their particu-

lar services. The problems are partially solved

if the SPs make SLAs with NO for IP services

delivered to the user (thus hiding NO from the

user, and including the relevant information in

the user’s SLA), but even then the situation is

not simple.

+

Service B

SLS

QoSb

Service A

SLS

QoSa

IP

SLS:

QoSIPtot

Service C

SLS

QoSc

Figure 12 Many-to-one

relation

Service Provider B

(SP B)

Network operator (NO)

QoSb

QoSIPtot

Service Provider A

(SP A)

QoSa

= SLA

Figure 13 Several services delivered over the same access