Page 539 - Handbook of Modern Telecommunications

4-70 CRC Handbook of Modern Telecommunications, Second Edition

priority packets always being served before lower-priority packets, both for packet processing
and transmission on outbound links. Scheduling mechanisms ensure that different connec-
tions obtain their promised share of the resources, such as processing and link bandwidth. This
mechanism also ensures that any spare capacity is distributed in a fair manner.
• Signaling protocols: To obtain the required QoS from a network, systems need to signal the
network regarding the desired QoS as well as the anticipated offered traffic profile. Scalability
and the corresponding capabilities to signal different QoS needs are issues under current
examination.
• Queuing: Some network elements allow for fair queuing algorithms. This ensures that a misbe-
having application will not punish other, better-behaved applications, and that the average of
dropped packets is evenly distributed across flows and queues.

4.4.5.5 SLA Procedures
This area involves policy determinations for controlling service quality. This quality has been defined
and agreed upon in the SLA between the contracting partners. The following procedure steps are rec-
ommended for certification.
Definition of data sources: The following options are considered as data sources: Managed Objects
(MO), Element Management Systems, traps, and SLA probes. In certain cases, manual logs and notifica-
tions from the help desk and hotline may be considered.
Determination of raw data to be collected: MIB-II entries using SNMPv1 and SNMPv3, and the remote
monitoring (RMON)1 and RMON2 standards.
Determination of the mediation functions: The current focus of the telecommunications industry on SLA
and QoS as a method of differentiating service providers creates a completely new mediation challenge:
nonbilling transactions have the potential, when a series of conditions are met, to trigger a billing action.
Figure 4.4.6 shows an example of the impact of the new data flows generated by the addition of SLA
agreements and an SLA manager that provides billing adjustment information to the billing system.
The same is true with settlements among multiple providers. It becomes even more challenging when
the information that triggers the billing action originates on a network element that belongs to another

Invoice
Generation Record
Archives
Trouble
Record SLA Manager Ticketing &
Rating Dispatch

Record Network Operating Network-
Planning
Formatting Center (NOC)

Operational data

Raw billing records
Mediation Traditionally
data flows
New data
flows
Access and
Transport Network

FIGu RE 4.4.6 Impact of SLA on data flows.