Computer Network Module 5 : Enterprise Network Design

Computer Network Module 5 : Enterprise Network Design The Cisco Service Oriented Network Architecture, Network Design
Methodology, Top-Down vs Bottom up Approach to Network Design, Classic
Three-Layer Hierarchical Model: Core, Access and Distribution Layers,
Campus Design Considerations, Designing a Campus Network Design

Cisco Service Oriented Network Architecture (SONA)

The Cisco Service-Oriented Network Architecture (SONA) is a conceptual architecture that describes how to design networks to be more agile, efficient, and scalable.

SONA is based on the principles of service orientation, which means that the network is designed to provide services to applications rather than just providing connectivity. This means that the network is more flexible and can be more easily adapted to changing business needs.

SONA consists of three layers:

  1. The Network Infrastructure Layer: The Network Infrastructure Layer is the foundation of the SONA architecture. It provides the physical and virtual resources that are used to deliver network services. This layer is made up of the following components:
    • Network devices: Network devices such as routers, switches, and firewalls are responsible for routing traffic, providing security, and other network functions.
    • Servers: Servers are responsible for running applications and providing storage.
    • Clients: Clients are the devices that users use to access the network, such as computers, laptops, and smartphones.
  2. The Interactive Services Layer: The Interactive Services Layer provides the network services that are used by applications. This layer is made up of the following components:
    • Application services: Application services are the network services that are used by applications to perform specific tasks, such as security, mobility, and storage.
    • Business services: Business services are the network services that are used by business processes to support their operations, such as customer relationship management (CRM) and supply chain management (SCM).
    • Collaboration services: Collaboration services are the network services that are used by users to collaborate with each other, such as video conferencing and instant messaging.
  3. The Applications Layer: The Applications Layer is the top layer of the SONA architecture. It contains the applications that are used by users. Applications can be anything from web applications to mobile apps to desktop applications.

Benefits of the Cisco Service-Oriented Network Architecture (SONA)

There are many benefits to using the Cisco Service-Oriented Network Architecture (SONA). Some of the key benefits include:

  • Increased agility: SONA helps to make networks more agile by making it easier to add, move, and change network services.
  • Improved efficiency: SONA helps to improve network efficiency by centralizing the management of network services.
  • Increased scalability: SONA helps to make networks more scalable by making it easier to add new users and devices.
  • Reduced costs: SONA can help to reduce costs by simplifying the network and making it easier to manage.
  • Improved security: SONA can help to improve security by making it easier to implement and manage security policies.
  • Reduced downtime: SONA can help to reduce downtime by making it easier to identify and resolve network problems.

SONA is a powerful tool that can help organizations to improve their networks and their businesses.

Network Design Methodology

The network design methodology presented in this section is derived from the Cisco Prepare, Plan,

Design, Implement, Operate, and Optimize (PPDIOO) methodology, which reflects a network’s lifecycle. The following sections describe the PPDIOO phases and their relation to the network design methodology, and the benefits of the lifecycle approach to network design. Subsequent sections explain the design methodology in detail.

Figure 2.3. PPDIOO Network Lifecycle Influences Design

The following describes each PPDIOO phase:

Prepare phase: The Prepare phase involves establishing the organizational (business) requirements, developing a network strategy, and proposing a high-level conceptual architecture, identifying technologies that can best support the architecture. Financial justification for the network strategy is established by assessing the business case for the proposed architecture.

Plan phase: This phase involves identifying the network requirements, which are based on

the goals for the network, where the network will be installed, who will require which network services, and so forth. The Plan phase also involves assessing the sites where the network will be installed and any existing networks, and performing a gap analysis to determine if the existing system infrastructure, sites, and operational environment can support the proposed system. A project plan helps manage the tasks, responsibilities, critical milestones, and resources required to implement the changes to the network. The project plan should align with the scope, cost, and resource parameters established in the original business requirements. The output of this phase is a set of network requirements.

Design phase: The initial requirements determined in the Plan phase drive the network design specialists’ activities. These specialists design the network according to those initial requirements, incorporating any additional data gathered during network analysis and network audit (when upgrading an existing network) and through discussion with managers and network users. The network design specification that is produced is a comprehensive detailed design that meets current business and technical requirements and incorporatesspecifications to support availability, reliability, security, scalability, and performance. This design specification provides the basis for the implementation activities.

Implement phase: Implementation and verification begins after the design has been approved. The network and any additional components are built according to the design specifications, with the goal of integrating devices without disrupting the existing network or creating points of vulnerability.

Operate phase: Operation is the final test of the design’s appropriateness. The Operate phase involves maintaining network health through day-to-day operations, which might include maintaining high availability and reducing expenses. The fault detection and correction and performance monitoring that occur in daily operations provide initial data for the network lifecycle’s Optimize phase.

Optimize phase: The Optimize phase is based on proactive network management, the goal of which is to identify and resolve issues before real problems arise and the organization is affected. Reactive fault detection and correction (troubleshooting) are necessary when proactive management cannot predict and mitigate the failures.

Top-Down vs Bottom up Approach to Network Design

CriteriaTop-Down ApproachBottom-Up Approach
InitiationStarts with broader vision and overall business goals.Begins with specific components or technical details.
Strategic vs TacticalMore strategic, focusing on the big picture.More tactical, addressing specific technical aspects.
Comprehensive ViewTakes a holistic view of the entire system.Builds up from individual components to the system.
Complexity HandlingHandles complexity through abstraction and hierarchy.Deals with complexity by solving specific issues first.
Risk ManagementIdentifies risks early in the planning phase.Risks are identified and mitigated as implementation progresses.
AdaptabilityMay require adjustments as detailed planning progresses.Can adapt quickly to specific technical challenges.
Time EfficiencyPotentially longer planning phase due to strategic considerations.Quick identification and resolution of specific issues.
User InvolvementUser needs are considered in the overall vision.Users may be involved as issues are addressed incrementally.
Change ManagementEasier to manage changes as they are part of the overall vision.Changes may be more challenging as they are integrated incrementally.

Examples of Top-Down Approach:

  • Designing a new corporate network for a large organization
  • Implementing a new cloud-based infrastructure for a small business
  • Deploying a new wireless network for a university campus

Examples of Bottom-Up Approach:

  • Troubleshooting a network issue and replacing a faulty router
  • Gradually upgrading network components to improve overall performance
  • Integrating new network devices and applications into an existing network

Classic Three-Layer Hierarchical Model

The classic three-layer hierarchical model is a common network design model. It consists of the following three layers:

  1. Core layer: The core layer is the backbone of the network. It is responsible for routing traffic between the different layers of the network .
  2. Distribution layer: The distribution layer is responsible for distributing traffic to the access layer. It also provides some security and filtering services.
  3. Access layer: The access layer is responsible for providing connectivity to end devices

Benefits of the Three-Layer Hierarchical Model:

There are a number of benefits to using the three-layer hierarchical model, including:

  • Improved scalability: The three-layer hierarchical model can be easily scaled to accommodate a growing number of users and devices.
  • Increased security: The three-layer hierarchical model can help to improve security by isolating different layers of the network from each other.
  • Simplified management: The three-layer hierarchical model can simplify network management by making it easier to troubleshoot problems and make changes to the network.

Campus Design Considerations

There are a number of factors to consider when designing a campus network, including:

  • The size and layout of the campus: The size and layout of the campus will affect the type of network design that is used.
  • The number and type of users: The number and type of users will affect the bandwidth requirements of the network.
  • The applications that will be used: The applications that will be used will affect the security and performance requirements of the network.

Designing a Campus Network Design Topology

The campus network design topology is the layout of the network devices and cables. There are a number of different campus network design topologies

The type of campus network design topology that is used will depend on the specific requirements of the campus network.

Additional Considerations

In addition to the factors mentioned above, there are a number of other considerations that should be taken into account when designing a campus network. These include:

  • The budget for the network: The budget for the network will affect the type of equipment that can be purchased.
  • The expertise of the network staff: The expertise of the network staff will affect the complexity of the network design.
  • The future needs of the network: The future needs of the network should be considered when designing the network to ensure that it can be easily and cost-effectively scaled to meet future demands.

Other Modules

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