Side_1_360

4 Interconnection – Agree-

ments, Brokering and A^3

4.1 SLS Negotiation

Having the capability to establish SLAs rapidly,
accurately and automaticallyis a significant
contribution to the efficiency of a provider. This
is particularly important when the number of
services and customers grow.

This is argued by the ever faster evolution of the
telecommunication market, leading to the intro-
duction of more services and mechanisms.
Another essential fact is that telecommunication
is steadily getting more important for the cus-
tomers. Hence, customers will look for service
guarantees to enable them to carry out their busi-
ness. Having adequate SLA-related mechanisms
is therefore considered as a competitive edge by
the providers/operators. As there are also depen-
dencies between the providers, the SLAs need
to be present throughout the set of providers
involved, not only towards the end customer.

Handling QoS and SLA in an efficient manner
introduces a number of challenges. An addi-
tional part is managing all relevant data; only a
few are illustrated in Figure 4. Several non-tech-
nical aspects will also be included in an agree-
ment between the actors. In addition to the data
transfer-related aspects, issues like customer
support and service provisioning will often be
covered.

The SLA template is used to capture a set of Ser-
vice Level Objectives for a service. A Service
Level Objective is a representation of the guar-
anteed level of service offered. It defines an indi-
vidual objective for example in terms of service
metric, threshold values and tolerances. A ser-
vice metric could be related to the entire service
bundle, to a service element or to a single ser-
vice interface, but is always related to something
visible to the customer.

When the provider depends on another provider
in order to fulfil the service delivery, the ques-
tion arises of how to relate the interfaces and
agreements as seen by that provider. This is
depicted in Figure 5.

In case the individual SLAs are reflected, a scal-
ability challenge would likely be faced.

The technical part of an SLA is called a Service
Level Specification, SLS, although the actual
relations between SLAs and SLSs can be more
involved. A service can be said to be provided
to a customer by a provider. Prior to service
delivery, a negotiation would commonly take
place. An example of a negotiation process is
depicted in Figure 6.

The provider describes the characteristic param-

eters of the service to be provided, as well as any

other conditions, by a Service Template Specifi-

cation, STS. After deciding upon the values of

the parameters, the customer returns a Service

Instance Specification, SIS. This is then

accepted or rejected by the provider. Any change

of the service delivery conditions can trigger an

update message from a provider. Then, the cus-

tomer, in principle also the provider, may initiate

a re-negotiation.

Figure 4 Some of the relevant data for managing SLAs and QoS

Figure 5 Reflecting individual SLAs (upper) or aggregating SLAs (lower)

Figure 6 Example of

negotiation process, [ID_sfsls]

Customer

data Customer and SLA

performance data SLA reports

Collected

performance

data

SLA

templates

Service

descriptions

SLA

SLAa

SLAb

provider 1 SLA1 provider 2

SLAa

SLAb

provider 1 SLA1 provider 2

SLA2

Customer Provider

Service Template Specification

Service Instance Specification

Accept/Reject

Update

Re-negotiate