service methodology, service description, service characteristics, performance characteristics, network supportability

1. CP7101 – DESIGN AND MANAGEMENT OF
COMPUTER NETWORKS
CSK / OXFORD ENGINEERING COLLEGE
Department of Information Technology

2. Course content
 Service methodology
 System description
 Service description
 Service characteristics
 Performance Characteristics
 Network supportability

3. Service methodology
 It is the activity of planning and organizing people, communication and
material components of a service in order to improve its quality and the
interaction between service provider and customers.
 we can explain our service methodology simply with the steps given
below
 information gathering : collecting information.
 problem analysis: finding solutions to problems.
 planning & designing: network planning(long-term and medium-term
short-term) an iterative process, composing( topological design)
 defining service level targets(1 year/ 3 year / 5 year)
 responsibilities and other specific requirements to manage the service.
 service level requirements(slr) : from a customer to a service provider
describing their service expectations.
 a service provider prepares a service level agreement (sla) based on
the requirements from the customer.
 Development & testing.
 maintenance and modification.

5. system descriptions
 A system is a set of components that work together to
provide connectivity, services and communications to
users.
Components of system includes:
 Users, hosts (PCs, laptops, handhelds).
 Devices : routers & switches.
 Links (wired, wireless).
 Protocols (IP, TCP,FTP,SNMP).
 Applications (E-mail, Remote login (Telnet) ,P2P file sharing,
Client/Server.

7. Service description
The organization has been developing service
descriptions for IP networks.
 IP networks : communication protocol.
 Encapsulated packet structures.(sends packet)
 Responsible for addressing hosts(source to destination).
 Version: (IPv4) – decimal (192.168.2.253)
 subnet mask: 255 255 255 0(class D)
 IP ranges: Cla s s A, Cla s s B, Cla s s C, Cla s s D.

8. Service description
We can look at this from two perspectives:
 Le ve ls o f p e rfo rm a nc e a nd
 Functions in the network.
 Levels of performance are described as
RMA (, Reliability, Maintainability, and Availability)
 s y s te m d e s ig n a ttribute s .
Re lia bility : to perform its required functions under stated conditions for
a specified period of time.(work simultaneously)
Ma inta ina bility : is us e d to m a inte na nc e the s y s te m s uch a s , repair or
replace faulty, prevent unexpected breakdowns.
Ava ila bility : to describe the amount of period that the system
resources is available.

9. Service description
 Functions are described as
 Accounting: to provide information about users
and their network resource usage(user accounts-login
details).
 Billing: Creating an invoice related to the use of
infrastructure and services(inbound/ outbound).
 Scheduling: processes or data flows are given
access to system resources (e.g. processor time,
communications)
 Management: coordinates the efforts of system to
accomplish goals and objectives.
 Security: give protection.

10. Service description
 Network services in most of today’s networks
are based on best-effort (unpredictable)
delivery.
 Network services are (hierarchical service
characteristics, and individual service
characteristics) can be grouped together to
form higher-level descriptions of a service.

12. Service characteristics
 One of the goals of network analysis is to be
able to characterize(give better) services so
that they can be designed into the network
and purchased from vendors and service
providers.
 Se rvic e cha ra c te ris tic s a re ind ividua l network
performance and functional parameters that
are used to describe services.

13. Service characteristics
 Service characteristics contains:
 Service levels
 System Components and Network
Services
 Service Requests & Requirements
 Performance Characteristics
 Service levels
 System Components and Network Services.
 Service Requests & Requirements.(user requirements,
application requirements, device requirements, and network
requirements.)
 Service offerings(Service offerings map to service requests and
thus can also be categorized as best effort, predictable, or
guaranteed.)
 Service metrics/activities.

14. Service levels
 Service characteristics can be grouped together
to form one or more service levels for the
network.
 There are many ways to describe service levels,
including:
 committed information rates (CIRs);
 levels of capacity;
 classes of service (CoSs);
 delay and capacity characteristics;
 types of service (ToSs);
 qualities of service (QoSs);

16. Service Requests & Requirements
 Service requests and requirements are, in part,
distinguished by the degree of predictability
needed from the service by the user,
application, or device making the request.
 Based on their predictability, service requests
are categorized as best effort, predictable, or
guaranteed.
 Best-effort service means that there is no
control over how the network will satisfy the
service request—that there are no guarantees
associated with this service.

17. Service Requests &
Requirements
 Guaranteed service:
 provides an assured level of bandwidth, with a firm end-to-end
delay bound and no queuing loss for conforming packets
of a data flow.
 predictable services:
 can provide services of predictable communication to
applications
 makes the development of new ones like an expensive and risky

18. Service Requests &
Requirements
 For service performance requirements and characteristics to be
useful, they must be configurable, measurable, and verifiable within
the system.
 Therefore, performance requirements and characteristics were
described in terms of service metrics(measurements), which are
intended to be:
 configurable, set a value for threshold/doorstep and limit
 measurable, by monitoring current state value.

19. Performance Characteristics
 Services may include one or more of the performance
characteristics:
 Capacity: is used as a label for the class of
characteristics that involves moving information from
place to place, including bandwidth, throughput, and so
forth.
 Delay: is a label for the class of characteristics that
includes end-to-end delay, round-trip delay, and delay
variation.
 RMA: is a label for the class of characteristics that
includes reliability, maintainability, and availability

20. Performance Characteristics
 Performance requirements can be combined
to describe a performance range for the system.
 A performance envelope is a combination of
two or more performance requirements, with
thresholds and upper and/or lower limits for each.
 Availability: Deals with the duration of up-time for operations and is
a measure of how often the system is alive and well.
 Throughput:
 the amount of work that a computer can do in a given time period
 the amount of processed data in communication networks.
 throughput is the rate at which a system achieves its goal.
 Utilization : Network utilization is the ratio of current network traffic
to the maximum traffic that the port can handle.
 Delay: the period or amount of time during which something
is delayed

22. Network Supportability
 Good network architects/designers take into
account the major factors that affect operability
and supportability as they make their decisions.
 The post-implementation phases of a network’s
life cycle can be broken into three elements:
 operations,
 maintenance, and
 human knowledge.

23. Network Supportability
 Key characteristics of a network architecture
and design that affect the post-implementation
costs include:
 Network and system reliability
 Network and system maintainability
 Training of the operators to stay within operational
 constraints
 Quality of the staff required to perform maintenance
actions

24. THANK
YOU