CHAPTER 1

Hierarchical Network Design

Objectives
Upon completion of this chapter

What are the structured engineering principles of network design?

How do the modules of the Cisco Enterprise
Architecture model differ?

How do you apply the three hierarchical network layers in network design?

What are some trends that are challenging
enterprise network architectures?

What are the four basic modules in an enterprise campus network architecture that interconnect via the core?

How do the Borderless Network,
Collaboration Network, and Data Center/
Virtualization Network architectures address
the network challenges?

Key Terms
This chapter uses the following key terms. You can find the definitions in the glossary.
small network

page 3

medium-size network
large network

enterprise campus module
page 3

page 3

enterprise edge module
SP edge module

page 15

page 17

page 18

access layer page 6

enterprise branch module

distribution layer

enterprise teleworker module

page 22

enterprise data center module

page 22

core layer

page 7

page 9

three-tier hierarchical design page 10
two-tier hierarchical design page 10
collapsed core

page 10

modular network design page 11

page 21

Cisco Borderless Network Architecture
page 24
Cisco Collaboration Architecture

page 25

Cisco Data Center/Virtualization
Architecture page 26

Cisco Enterprise Architecture model
page 14

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2

Connecting Networks Companion Guide

Introduction (1.0.1.1)
Networks must meet the current needs of organizations and be able to support
emerging technologies as new technologies are adopted. Network design principles
and models can help a network engineer design and build a network that is flexible,
resilient, and manageable.
This chapter introduces network design concepts, principles, models, and architectures. It covers the benefits that are obtained by using a systematic design approach.
Emerging technology trends that will affect network evolution are also discussed.
Class Activity 1.0.1.2: Design Hierarchy

A network administrator is tasked with designing an expanded network for the
company.
After speaking with network administrators in other branches of the company, it was
decided to use the Cisco three-layer hierarchical network design model to influence the
expansion. This model was chosen for its simple influence upon network planning.
The three layers of the expanded network design include

Access

Distribution

Core

Hierarchical Network Design Overview (1.1)
The Cisco hierarchical (three-layer) internetworking model is an industry wide adopted model for designing a reliable, scalable, and cost-efficient internetwork. In this
section, you will learn about the access, distribution, and core layers and their role in
the hierarchical network model.

Enterprise Network Campus Design (1.1.1)
An understanding of network scale and knowledge of good structured engineering
principles is recommended when discussing network campus design.

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Chapter 1: Hierarchical Network Design

3

Network Requirements (1.1.1.1)
When discussing network design, it is useful to categorize networks based on the
number of devices serviced:

Small network: Provides services for up to 200 devices.

Medium-size network: Provides services for 200 to 1,000 devices.

Large network: Provides services for 1,000+ devices.

Network designs vary depending on the size and requirements of the organizations.
For example, the networking infrastructure needs of a small organization with fewer
devices will be less complex than the infrastructure of a large organization with a significant number of devices and connections.
There are many variables to consider when designing a network. For instance, consider
the example in Figure 1-1. The sample high-level topology diagram is for a large enterprise
network that consists of a main campus site connecting small, medium, and large sites.

Figure 1-1 Large Enterprise Network Design

Network design is an expanding area and requires a great deal of knowledge and
experience. The intent of this section is to introduce commonly accepted network
design concepts.
Note
The Cisco Certified Design Associate (CCDA®) is an industry-recognized certification for
network design engineers, technicians, and support engineers who demonstrate the skills
required to design basic campus, data center, security, voice, and wireless networks.

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To meet these fundamental design goals. 02_9781587133329_ch01.1. It breaks the complex problem of network design into smaller and more manageable areas. replacing major hardware devices).e.1. These principles include ■ Hierarchy: A hierarchical network model is a useful high-level tool for designing a reliable network infrastructure. data center.4 Connecting Networks Companion Guide Structured Engineering Principles (1.2) Regardless of network size or requirements. and core layers. ■ Flexibility: The ability to modify portions of the network. organizations now use a hierarchical network design as shown in Figure 1-3.2) This topic discusses the three functional layers of the hierarchical network model: the access. ■ Resiliency: The network must remain available for use under both normal and abnormal conditions. extreme traffic loads. Hierarchical Network Design (1.1. and Internet edge. Hubs and switches were added as more devices needed to be connected. add new services.1. ■ Modularity: By separating the various functions that exist on a network into modules. making the network unusable. Network Hierarchy (1. distribution. or increase capacity without going through a major forklift upgrade (i. Abnormal conditions include hardware or software failures. and other unplanned events. services block.2. response times degraded. Normal conditions include normal or expected traffic flows and traffic patterns.1) Early networks were deployed in a flat topology as shown in Figure 1-2. A flat network design provided little opportunity to control broadcasts or to filter undesirable traffic. including the enterprise campus. As more devices and applications were added to a flat network. as well as scheduled events such as maintenance windows. a network must be built on a hierarchical network architecture that allows for both flexibility and growth. A better network design approach was needed. For this reason. a critical factor for the successful implementation of any network design is to follow good structured engineering principles. denial-of-service (DoS) events. the network is easier to design.indd 4 3/13/14 2:43 AM . whether intentional or unintentional. Cisco has identified several modules. unusual traffic patterns..

indd 5 3/13/14 2:43 AM . Hierarchical models apply to both LAN and WAN design. This helps the network designer and architect to optimize and select the right network hardware. The benefit of dividing a flat network into smaller. in the hierarchy provides specific functions that define its role within the overall network. For example. 02_9781587133329_ch01. more manageable blocks is that local traffic remains local. Only traffic that is destined for other networks is moved to a higher layer. or tier. in Figure 1-3 the flat network has now been divided into three separate broadcast domains. and features to perform specific roles for that network layer.Chapter 1: Hierarchical Network Design 5 Figure 1-2 Flat Switched Network Figure 1-3 Hierarchical Network A hierarchical network design involves dividing the network into discrete layers. Each layer. software.

While it is true that many campus networks are constructed using three physical tiers of switches. it may provide teleworkers or remote sites access to the corporate network across WAN connections.2) In a LAN environment. distribution. This is referred to as a collapsed core design. 02_9781587133329_ch01. this is not a strict requirement. the access layer highlighted grants end devices access to the network. Figure 1-4 Multi Building Enterprise Network Design Note There are no absolute rules for the way a campus network is physically built. The Access Layer (1.2. In the WAN environment. Notice that each building is using the same hierarchical network model that includes the access.6 Connecting Networks Companion Guide A typical enterprise hierarchical LAN campus network design includes the following three layers: ■ Access layer: Provides workgroup/user access to the network ■ Distribution layer: Provides policy-based connectivity and controls the boundary between the access and core layers ■ Core layer: Provides fast transport between distribution switches within the enterprise campus Another sample three-layer hierarchical network design is displayed in Figure 1-4.indd 6 3/13/14 2:43 AM .1. and core layers. the network might have two tiers of switches in which the core and distribution elements are combined in one physical switch. In a smaller campus.

02_9781587133329_ch01. the distribution layer is the boundary between the Layer 2 domains and the Layer 3 routed network. Figure 1-5 Access Layer The access layer serves a number of functions.1.3) The distribution layer aggregates the data received from the access layer switches before it is transmitted to the core layer for routing to its final destination. In Figure 1-6.Chapter 1: Hierarchical Network Design 7 As shown in Figure 1-5.2. including ■ Layer 2 switching ■ High availability ■ Port security ■ QoS classification and marking and trust boundaries ■ Address Resolution Protocol (ARP) inspection ■ Virtual access control lists (VACLs) ■ Spanning tree ■ Power over Ethernet (PoE) and auxiliary VLANs for VoIP The Distribution Layer (1.indd 7 3/13/14 2:43 AM . the access layer for a small business network generally incorporates Layer 2 switches and access points providing connectivity between workstations and servers.

■ Routing services between LANs and VLANs and between routing domains (e. The device acts as the demarcation point between broadcast domains. ■ A boundary for route aggregation and summarization configured on interfaces toward the core layer. EIGRP to OSPF).. ■ Broadcast domain control. 3/13/14 2:43 AM . ■ Redundancy and load balancing.indd 8 ■ Aggregation of LAN or WAN links. The distribution layer can provide 02_9781587133329_ch01. because routers or multilayer switches do not forward broadcasts. ■ Policy-based security in the form of access control lists (ACLs) and filtering. A distribution layer switch may provide upstream services for many access layer switches. Either a router or a multilayer switch is used to segment workgroups and isolate network problems in a campus environment.g.8 Connecting Networks Companion Guide Figure 1-6 Distribution Layer The distribution layer device is the focal point in the wiring closets.

2. As shown in Figure 1-7. Considerations at the core layer include 02_9781587133329_ch01. fast transport) ■ Providing reliability and fault tolerance ■ Scaling by using faster. Figure 1-7 Core Layer The core should be highly available and redundant.. The core aggregates the traffic from all the distribution layer devices. or other processes 3/13/14 2:43 AM . quality of service (QoS) classification.1.Chapter 1: Hierarchical Network Design 9 The Core Layer (1. the data center.indd 9 ■ Providing high-speed switching (i.e. the core layer is critical for interconnectivity between distribution layer devices (for example. inspection. The core layer consists of high-speed network devices such as the Cisco Catalyst 6500 or 6800.4) The core layer is also referred to as the network backbone. service modules. These are designed to switch packets as fast as possible and interconnect multiple campus components. such as distribution modules. interconnecting the distribution block to the WAN and Internet edge). so it must be capable of forwarding large amounts of data quickly. and not more. equipment ■ Avoiding CPU-intensive packet manipulation caused by security. and the WAN edge.

However. A “collapsed core” is when the distribution layer and core layer functions are implemented by a single device.indd 10 3/13/14 2:43 AM . 02_9781587133329_ch01.2. many small enterprise networks do not grow significantly larger over time. while maintaining most of the benefits of the three-tier hierarchical model. Figure 1-8 Two-Tier Hierarchical Design The hierarchical network model provides a modular framework that allows flexibility in network design and facilitates ease of implementation and troubleshooting. The primary motivation for the collapsed core design is reducing network cost.1.6: Identify Hierarchical Network Characteristics Go to the course online to perform this practice activity.10 Connecting Networks Companion Guide Two-Tier Collapsed Core Design (1. Cisco Enterprise Architecture (1. Interactive Graphic Activity 1.5) The three-tier hierarchical design maximizes performance. This section identifies enterprise architecture modules that are commonly found in medium-to-large organizations. Therefore.2) The Cisco Enterprise Architecture is a modular approach to network design. a two-tier hierarchical design where the core and distribution layers are collapsed into one layer is often more practical. and the ability to scale the network design.2. network availability.1. The example in Figure 1-8 has collapsed the distribution layer and core layer functionality into multilayer switch devices.

1. or the introduction of new services can be made in a controlled and staged fashion. networks have become more sophisticated and complex. it became necessary to adjust the network design to one that uses a more modular approach.1) While the hierarchical network design works well within the campus infrastructure. Using a modular approach has several benefits. As shown in Figure 1-9. Large organizations may also require dedicated connections to offsite data centers. A modular network design separates the network into various functional network modules. They designate where different functions occur in the network. networks have expanded beyond these borders. 3/13/14 2:43 AM . ■ Network changes. upgrades. including 02_9781587133329_ch01. allowing greater flexibility in the maintenance and operation of the campus network. The modules represent areas that have different physical or logical connectivity. Figure 1-9 Expanding Beyond the Campus Infrastructure As the complexity of the network increased to meet these demands.indd 11 ■ Failures that occur within a module can be isolated from the remainder of the network.Chapter 1: Hierarchical Network Design 11 Modular Design (1. The central campus site now requires connections to branch sites and support for teleworking employees working from home offices or other remote locations. providing for simpler problem detection and higher overall system availability. each targeting a specific place or purpose in the network.2.

Modules in the Enterprise Architecture (1.12 Connecting Networks Companion Guide ■ When a specific module no longer has sufficient capacity or is missing a new function or service. 3/13/14 2:43 AM . and more (see Figure 1-11). this is the most familiar element and fundamental component of a campus design (see Figure 1-10). Basic network modules include ■ Access-distribution: Also called the distribution block. unified communications services. policy gateways. These basic modules are connected together via the core of the network. Figure 1-10 Access-Distribution Module ■ 02_9781587133329_ch01. it can be updated or replaced by another module that has the same structural role in the overall hierarchical design. ■ Security can be implemented on a modular basis allowing for more granular security control. The use of modules in network design enables flexibility and facilitates implementation and troubleshooting.indd 12 Services: This is a generic block used to identify services such as centralized Lightweight Access Point Protocol (LWAPP) wireless controllers.2.2) A modular approach to network design further divides the three-layer hierarchical design by pulling out specific blocks or modular areas.1.

Chapter 1: Hierarchical Network Design 13 Figure 1-11 Services Module ■ Data center: Originally called the server farm. collaborate. Figure 1-12 Data Center Module 02_9781587133329_ch01. partners.indd 13 3/13/14 2:43 AM . and customers rely on data and resources in the data center to effectively create. and interact (see Figure 1-12). This block is responsible for managing and maintaining many data systems that are vital to modern business operations. Employees.

This topic discusses the enterprise campus module.2. Cisco Enterprise Architecture Model (1. Cisco Enterprise Architecture Model (1. These blocks offer connectivity to voice. Figure 1-13 Enterprise Edge Module Interactive Graphic Activity 1. and the service provider edge module.14 Connecting Networks Companion Guide ■ Enterprise edge: Consists of the Internet edge and the WAN edge.2. and facilitates the design of larger. video. enterprise edge module. Cisco developed the Cisco Enterprise Architecture model.2. 02_9781587133329_ch01.2) The Cisco Enterprise Architecture is a modular approach to network design.3: Identify Modules in a Network Design Go to the course online to perform this practice activity.1) To accommodate the need for modularity in network design. The modularity that is built in to the architecture allows flexibility in network design and facilitates implementation and troubleshooting.1. and data services outside the enterprise (see Figure 1-13).indd 14 3/13/14 2:43 AM . The Cisco Enterprise Architecture model separates the enterprise network into functional areas that are referred to as modules. This model provides all the benefits of the hierarchical network design on the campus infrastructure. more scalable networks.2.

SOHOs. Regional offices. The enterprise campus module describes the recommended methods to create a scalable network while addressing the needs of campus-style business operations.2.indd 15 3/13/14 2:43 AM . an industrial complex or business park environment). but it can span several neighboring buildings (for example. 02_9781587133329_ch01. and mobile workers may need to connect to the central campus for data and information.Chapter 1: Hierarchical Network Design 15 As shown in Figure 1-14.2. including ■ Enterprise branch ■ Enterprise teleworker ■ Enterprise data center Cisco Enterprise Campus (1. the following are the primary Cisco Enterprise Architecture modules: ■ Enterprise campus ■ Enterprise edge ■ Service provider edge Figure 1-14 Cisco Enterprise Architecture Modules Connected to the service provider edge are the remote modules. A campus is generally limited to a fixed geographic area.2) A campus network is a building or group of buildings connected into one enterprise network that consists of many LANs.

As shown in Figure 1-15. viruses. and automatic procedures for reconfiguring network paths when failures occur. 02_9781587133329_ch01. and other attacks on the network.16 Connecting Networks Companion Guide The architecture is modular and can easily expand to include additional campus buildings or floors as the enterprise grows. mobility.indd 16 3/13/14 2:43 AM . and advanced security ■ Utilize multicast traffic and QoS to optimize network traffic ■ Provide increased security and flexibility using access management. VLANs. and IPsec VPNs The enterprise campus module architecture provides the enterprise with high availability through a resilient multilayer design. the enterprise campus module consists of the following submodules: ■ Building access ■ Building distribution ■ Campus core ■ Data center Figure 1-15 Enterprise Campus Module Together these submodules ■ Provide high availability through a resilient hierarchical network design ■ Integrate IP communications. Integrated security protects against and mitigates the impact of worms. even at the switch port level. redundant hardware and software features.

troubleshooting. print. email. As shown in Figure 1-16. and Domain Name System (DNS) services to internal users. The data center module typically also supports network management services for the enterprise.2.Chapter 1: Hierarchical Network Design 17 A high-capacity.2. The data center submodule typically contains internal email and corporate servers that provide application. logging. file.indd 17 3/13/14 2:43 AM . centralized data center module can provide internal server resources to users. including monitoring. and other common management features from end to end. This module often functions as a liaison between the enterprise campus module and the other modules. the enterprise edge module consists of submodules providing ■ E-commerce services ■ Internet connectivity ■ Remote access and VPN access ■ WAN site-to-site VPN access Figure 1-16 Enterprise Edge Submodules 02_9781587133329_ch01.3) The enterprise edge module provides connectivity for voice. Cisco Enterprise Edge (1. and data services outside the enterprise. video.

Frame Relay. Metro Ethernet. PPP.indd 18 ■ Internet service providers (ISPs) ■ WAN services such as Frame Relay. and MAN ■ Public switched telephone network (PSTN) services 3/13/14 2:43 AM . the SP edge module can include 02_9781587133329_ch01. FTP and HTTP servers. SMTP relay servers.18 Connecting Networks Companion Guide Specifically. ATM. ATM. ■ Remote access and VPN: The VPN/remote access submodule of the enterprise edge provides remote-access termination services. and wireless. It uses the high-availability designs of the data center module. email. Devices located in the e-commerce submodule include web. firewall and firewall routers. Components of this submodule include firewalls. Service Provider Edge (1. and DNS. and network intrusion prevention system (IPS) appliances. Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH).2. As shown in Figure 1-17. cable. and network intrusion prevention systems (IPS). dial-in access concentrators. including authentication for remote users and sites.4) Enterprises use service providers (SPs) to link to other sites. Components of this submodule include firewall and firewall routers. digital subscriber line (DSL). Connectivity to one or several Internet service providers (ISPs) is also provided. and database servers. application. leased lines. and DNS servers. ■ Internet connectivity and demilitarized zone (DMZ) : The Internet submodule of the enterprise edge provides internal users with secure connectivity to Internet services such as public servers. these submodules consist of: ■ E-commerce networks and servers: The e-commerce submodule enables enterprises to support e-commerce applications through the Internet. Internet edge routers. Cisco Adaptive Security Appliances (ASA).2. Enterprise WAN links include technologies such as Multiprotocol Label Switching (MPLS). ■ WAN: The WAN submodule uses various WAN technologies for routing traffic between remote sites and the central site.

redundant connections to a single ISP can include 02_9781587133329_ch01. enterprise branch. video. As shown in Figure 1-18. redundancy or failover should be considered. The SP edge module ■ Spans across large geographic areas in a cost effective manner ■ Converges voice. and data services over a single IP communications network ■ Supports QoS and service level agreements ■ Supports security using VPNs (IPsec / MPLS) over Layer 2 and Layer 3 WANs When acquiring Internet services from an ISP.Chapter 1: Hierarchical Network Design 19 Figure 1-17 Service Provider Edge Module The SP edge provides connectivity between the enterprise campus module to the remote enterprise data center. and enterprise teleworker modules.indd 19 ■ Single-homed: A single connection to an ISP ■ Dual-homed: Two or more connections to a single ISP 3/13/14 2:43 AM . Redundant Internet connections vary depending if the enterprise is connecting to a single ISP or multiple ISPs.

20 Connecting Networks Companion Guide Figure 1-18 Connecting to a Single ISP Alternatively. Options for connecting to multiple ISPs include ■ Multihomed: Connections to two or more ISPs ■ Dual-multihomed: Multiple connections to two or more ISPs Figure 1-19 Connecting to Multiple ISPs 02_9781587133329_ch01. as shown in Figure 1-19. it is possible to set up redundancy using multiple ISPs.indd 20 3/13/14 2:43 AM .

The edge device connecting the remote site to the central site varies depending on the needs and size of the site.2. These locations are typically responsible for providing security. and mobility options to employees. Cisco Unified Communications. telephony. These remote sites rely on the SP edge to provide services and applications from the main site. to the remote branches. as shown in Figure 1-20. and advanced application performance. it also has an Internet link as a backup.Chapter 1: Hierarchical Network Design 21 Remote Functional Area (1. as well as general connectivity into the campus network and the different components located inside the enterprise campus. The enterprise branch module allows enterprises to extend head-office applications and services. while smaller sites may use an ISR G2 router.5) The remote functional area is responsible for remote connectivity options and includes the following modules. 02_9781587133329_ch01.indd 21 3/13/14 2:43 AM . In Figure 1-20. Figure 1-20 Remote Connectivity Areas Enterprise Branch The enterprise branch module includes remote branches that allow employees to work at noncampus locations. The Internet link uses site-to-site IPsec VPN technology to encrypt corporate data. the enterprise branch module connects to the enterprise campus site primarily using a WAN link.2. However. Large remote sites may use high-end Cisco Catalyst switches. such as security.

Interactive Graphic Activity 1. hotels.3.1) As businesses have grown more dependent on networks for success. Integrated security. including home offices.3) New technologies are constantly challenging network administrators. data. Enterprise Data Center The enterprise data center module is a data center with all of the same functional options as a campus data center. IT Challenges (1. This solution allows the enterprise to scale without major changes to the infrastructure. Evolving Network Architectures (1. or customer/client sites. such as cable modem or DSL.2. Users could only access network resources with company-owned computers. but exists at a remote location. This provides an added layer of security as the offsite data center can provide disaster recovery and business continuance services for the enterprise. Redundant data centers provide backup using synchronous and asynchronous data and application replication. The network had distinct borders and access requirements. users. network architectures have evolved over the years. High-end switches such as the Cisco Nexus series switch use fast WAN services such as Metro Ethernet (MetroE) to connect the enterprise campus to the remote enterprise data center.2. The teleworker module recommends that mobile users connect to the Internet using the services of a local ISP. Maintaining 02_9781587133329_ch01. Traditionally. This section discusses new networking architecture trends.6: Identify Modules of the Cisco Enterprise Architecture Go to the course online to perform this practice activity. Additionally.indd 22 3/13/14 2:43 AM .22 Connecting Networks Companion Guide Enterprise Teleworker The enterprise teleworker module is responsible for providing connectivity for workers who operate out of different geographically dispersed locations.1.and identitybased networking services enable the enterprise to extend campus security policies to the teleworker. the network and devices offer server and application load balancing to maximize performance. VPN services can then be used to secure communications between the mobile worker and central campus. and applications were housed on premise. Staff can securely log in to the network over the VPN and gain access to authorized applications and services from a single cost-effective platform.

02_9781587133329_ch01. These architectures must account for the network design principles established in the Cisco Enterprise Architecture. the network border has shifted. Cisco has introduced the following three network architectures: ■ Cisco Borderless Network Architecture ■ Collaboration Architecture ■ Data Center/Virtualization Architecture Note Network architectures continually evolve. To address these emerging network trends. Networks are transforming from a data-only transportation system of connected LAN devices to a system that enables the connections of people.Chapter 1: Hierarchical Network Design 23 security. and information in a media-rich. There are several new networking trends that continue to effect organizations and consumers. Some of the top trends include ■ Bring your own device (BYOD) ■ Online collaboration ■ Video communication ■ Cloud computing These trends. As new technologies and end-user devices come to market. Today.1. while allowing for more advanced services than ever before. converged network environment. and services was simpler. new business network architectures are necessary. devices. The intent of this section is to provide an introduction and overview of emerging architecture trends.2) The speed of change in market and business environments is requiring IT to be more strategic than ever before.3. To meet this need. Evolving business models are creating complex technology challenges that IT must address. creating new challenges for IT departments. productivity. Emerging Enterprise Architectures (1. as well as the overlaying policies and technologies that allow organizations to support emerging trends in a safe and manageable way. also introduce new security risks that IT must address.indd 23 3/13/14 2:43 AM . businesses and consumers must continue to adjust to this ever-changing environment.

24 Connecting Networks Companion Guide Emerging Network Architectures (1. In doing this. switching. For example. security. as shown in Figure 1-21. It is based on wired. and application optimization devices working in harmony to help IT balance demanding business challenges and changing business models. and the Data Center and Virtualization Architecture. ■ Borderless network services: As highlighted in Figure 1-22. policy-based connection for a seamless user experience. Cisco Borderless Networks (1. and seamlessly to the corporate network in a BYOD environment. and seamless access to resources from multiple locations.indd 24 ■ Borderless end-point/user services: As highlighted in Figure 1-21. reliably. borderless end-point/user services connect the various devices to provide access to network services. wireless. and seamless user experiences in a world with many new and shifting borders. reliable. It securely connects internal users and remote users and provides access to network resources.2) Cisco has been at the forefront of network design for decades. This topic introduces the Cisco Borderless Network Architecture. Specifically. It removes the location and device borders. the Collaboration Architecture. reliable. End-point/user services define the user experience and enable the attributes of secure. 3/13/14 2:43 AM . most smartphones and tablets can download and use the Cisco AnyConnect software.1) The Cisco Borderless Network Architecture is a network solution that allows organizations and individuals to connect securely. and to applications that can be located anywhere. routing. it provides secure. borderless network services unify the approach to securely deliver applications to users in a highly distributed environment. reliable.3. It enables an IT department to architect and deploy its systems and policies efficiently to all end user devices that require connection to the network. providing unified access to wired and wireless devices. It enables the device to establish a secure. from multiple devices. They consistently adopt existing networks and develop new network architectures. but an evolving solution to help IT evolve its infrastructure to deliver secure.3. the Cisco Borderless Network Architecture delivers two primary sets of services: 02_9781587133329_ch01.2. It is not a static solution. The crucial element to scaling secure access is a policy-based architecture that allows IT to implement centralized access controls. Devices that can connect to the borderless network can range from PCs to tablets and smartphones. persistent. and seamless performance on a broad range of devices and environments.

to work together.3. including BYOD. 02_9781587133329_ch01. software development kits (SDKs).indd 25 3/13/14 2:43 AM . to cooperate and contribute to the production of something. and APIs. It needs to be flexible enough to scale in its support for future growth in terms of business expansion. applications. The individual components work together to provide a comprehensive solution. The Cisco Collaboration Architecture comprises a portfolio of products.2) Working in a collaborative environment helps increase productivity. and to innovate. Collaboration and other types of groupware are used to bring people together for one reason or another: such as to socialize. high-performing network that is accessible to a wide range of devices. mobility and cloud computing and must be able to support the growing requirements for online voice and video.2. Collaboration Architecture (1.Chapter 1: Hierarchical Network Design 25 Figure 1-21 Borderless Network Architecture Figure 1-22 Services Supported in Borderless Networks The borderless network architecture supports a highly secure.

3. Cisco’s collaboration architecture is composed of three layers: ■ Application and Devices: This layer contains unified communications and conference applications such as Cisco WebEx Meetings. computing. It includes virtual machines. Figure 1-23 Cisco Collaboration Architecture Data Center and Virtualization (1. on any device. and virtualization platforms together.3) The Cisco Data Center/Virtualization Architecture is built upon Cisco Data Center 3. client frameworks. from anywhere. and TelePresence. These applications include voice. session management. It comprises a comprehensive set of virtualization technologies and services that bring the network. ■ Collaboration Services: This layer supports collaboration applications including the following services: presence. contact management. ■ Network and Computer Infrastructure: This layer is responsible for allowing collaboration anytime. 3/13/14 2:43 AM . the network. messaging. The Data Center Architecture consists of three components. mobile applications. storage. web conferencing. WebEx Social. video. Cisco Jabber.2. and enterprise social software. location. tagging. as shown in Figure 1-24: ■ 02_9781587133329_ch01. and storage. and policy and security management.indd 26 Cisco Unified Management Solutions: Management solutions simplify and automate the process of deploying IT infrastructure and services with speed and enterprise reliability.26 Connecting Networks Companion Guide As shown in Figure 1-23. The applications within this layer help users stay connected and productive. Solutions operate transparently across physical and virtual resources in cloud environments.0.

Cisco Fabric Manager. storage access.4) These three architectures are built on an infrastructure of scalable and resilient hardware and software. and provide organizations with the services they need. ■ Unified Computing Solutions: Cisco’s next-generation data center system unites computing. and virtualization into a cohesive system designed to reduce total cost of ownership (TCO) and increase business agility. Expanding the Network (1. Components of the architecture come together to build network systems that span an organization from network access to the cloud.2. providing transparent convergence.Chapter 1: Hierarchical Network Design 27 ■ Unified Fabric Solutions: Flexible network solutions deliver network services to servers. and sophisticated intelligence. storage. network. scalability.3: Cisco Unified Fabric Video Go to the course to see a short video on the Cisco Unified Fabric. adding features and functionality in an integrated solution.indd 27 3/13/14 2:43 AM .2. The Cisco Unified Computing System (Cisco UCS) is built with blade servers.3. organizations can use these network architectures to grow their network over time.3. fabric interconnects. Solutions include Cisco Nexus switches. and applications. and virtual interface cards (VICs). and Cisco NX-OS software. 02_9781587133329_ch01. Figure 1-24 Components of the Data Center Architecture Video 1. Catalyst switches. Building off the basic network infrastructure. rack-mount servers.

indd 28 Video 1.2. 3/13/14 2:43 AM .2.3.3. Activity 1.28 Connecting Networks Companion Guide One of the first steps in growing the network is expanding from the campus infrastructure to a network that connects remote sites through the Internet and through the WAN. Interactive Graphic Interactive Graphic 02_9781587133329_ch01.4: Evolution of a Corporate WAN Go to the course to see a short video on the evolution of a network to a WAN infrastructure.5: Identify Evolving Network Architecture Terminology Go to the course online to perform this practice activity.

and flexibility. Packet Tracer Activity Packet Tracer Activity 1. and the other half uses IPv6 addressing. 02_9781587133329_ch01.4.1: Borderless Innovations .4.1.indd 29 3/13/14 2:43 AM . You are tasked with completing upgrades to the network infrastructure that has two locations.Chapter 1: Hierarchical Network Design 29 Summary (1. which includes dual-stacked IPv4 and IPv6 as well as a variety of addressing and routing technologies. The structured engineering principles of good network design include hierarchy. While planning for network policies and services.to medium-size business. The requirements also include a variety of routing and switching technologies. Borderless network services interest you as you plan your network’s future.3: Skills Integration Challenge .Everywhere You are the network administrator for your small. resiliency.1. Therefore. modularity. this leads you to consider the following Cisco borderless services as possible options for your business: Packet Tracer Activity ■ Security: TrustSec ■ Mobility: Motion ■ Application performance: App Velocity ■ Multimedia performance: Medianet ■ Energy management: EnergyWise Packet Tracer Activity 1. Your business has just expanded into a different town and needs to expand its presence across the Internet. Half of the enterprise network uses IPv4 addressing.4) Class Activity 1.4.EIGRP You are a network technician new to a company that has lost its last technician in the middle of a system upgrade. you realize that your wired and wireless networks need manageability and deployment design.1.2: Skills Integration Challenge This Packet Tracer Activity provides an opportunity to review skills from previous coursework. You are tasked with completing the upgrades to the enterprise network.

4. where the distribution layer and core layer functions are implemented in a single device.4.1. distribution layer.EIGRP 02_9781587133329_ch01. A modular design that separates the functions of a network enables flexibility and facilitates implementation and management.OSPF Packet Tracer Activity 1. scalable networks. and maintainability. a “collapsed core” hierarchy.Everywhere Packet Tracer Activity Packet Tracer Activities Packet Tracer Activity 1. service provider edge. performance. enterprise edge. and the core layer. The Labs and Class Activities are available in the companion Connecting Networks Lab Manual (978-1-58713-331-2). The basic module blocks that are connected by the core include the access distribution block. enterprise branch. The Cisco Enterprise Architecture modules are used to facilitate the design of large. Class Activities Class Activity 1.2: Design Hierarchy Class Activity 1. The primary modules include the enterprise campus. the services block.2: Skills Integration Challenge .1: Borderless Innovations . and the enterprise edge.indd 30 3/13/14 2:43 AM . The Packet Tracer Activity PKA files are found in the online course. enterprise data center. the data center. In smaller enterprise networks. Practice The following activities provide practice with the topics introduced in this chapter. and enterprise teleworker. can be more practical.1.1.0.4. redundancy.30 Connecting Networks Companion Guide A typical enterprise hierarchical LAN campus network design includes the access layer.3: Skills Integration Challenge . The benefits of a hierarchical network include scalability.1.

” lists the answers. Cisco Enterprise Data Center Architecture E. Cisco Enterprise Teleworker module 02_9781587133329_ch01. What are the four structured design principles? A. modularity. and security E. Workgroup 3. resiliency. Flexibility. resiliency D. Cisco Collaboration Architecture B. resiliency. modularity. Flexibility. and security 2. WAN F.Chapter 1: Hierarchical Network Design 31 Check Your Understanding Questions Complete all the review questions listed here to test your understanding of the topics and concepts in this chapter. Which layer of the hierarchical network design model is often called the backbone? A. Distribution D. Which network architecture combines individual components to provide a com- prehensive solution allowing people to cooperate and contribute to the production of something? A. Hierarchy. modularity. modularity. hierarchy. Modularity. and security G. Access B. Availability. and security B. Availability. quality of service (QoS) C. flexibility. Cisco Enterprise Branch Architecture D. “Answers to the ‘Check Your Understanding’ Questions. 1. Hierarchy. modularity. and security F. resiliency. hierarchy. The appendix. Core C. Network E. quality of service (QoS). resiliency. Cisco Borderless Network Architecture F.indd 31 3/13/14 2:43 AM . Cisco Enterprise Campus Architecture C. quality of service (QoS).

It is used to establish a secure.) A. It is used to connect from anywhere.) A. policy-based connection.32 Connecting Networks Companion Guide 4. 6.indd 32 3/13/14 2:43 AM . D. Also called a two-tier hierarchical network design B.) A. Core D. Network 5. It is used to connect without an Internet connection. Consists of the access layer and distribution layer in one device D. Access B. Which two statements correctly describe a collapsed core network design? (Choose two. Firewall appliance B. C. persistent. Application C. Consists of the access layer and core layer in one device E. Wireless access point 7. At which layer of the hierarchical network model do users connect to the net- work? A. It is used to connect any device to the network. E. Also called a three-tier hierarchical network design C. It is part of the borderless end-point/user services. Consists of the distribution and core layer in one device 02_9781587133329_ch01. Which two statements regarding the Cisco AnyConnect software are true? (Choose two. Layer 2 switch C. It is part of the borderless network services. F. Which three devices are found in the access layer of the hierarchical network model? (Choose three. Layer 3 switch D. Distribution E. Modular multilayer switch E. VoIP phones F. B.

Size of the network E. tagging. location. B. C. and policy and security management. contact management. Connectivity to the data center B. It satisfies telephony requirements for users who are located at medium to large enterprise sites. What does the application and device layer of the Cisco Collaboration Architecture do? A. It contains applications such as Cisco WebEx Meetings. session management. Type of security implemented F. it forces users who are located at main sites to log on to resources. Cisco Borderless Network B. D. security. It allows the enterprise to add large branch sites that span geographic areas.indd 33 3/13/14 2:43 AM . wireless. Which goal can be accomplished by implementing the Cisco enterprise telework- er module? A. Type of applications 10. Cisco Enterprise Campus D. It allows the enterprise to deliver secure voice and data services to workers no matter where or when they work. It is responsible for allowing collaboration anytime. 9. Which network architecture functions through a combination of technologies that include wired. from anywhere. and TelePresence to help users stay connected and productive. 02_9781587133329_ch01.Chapter 1: Hierarchical Network Design 33 8. It supports collaboration applications with presence. Cisco Jabber. To reduce remote security threats. Cisco Enterprise Edge E. Cisco Enterprise Teleworker 11. client frameworks. and more? A. C. B. on any device. Cisco Enterprise Branch C. What should be considered first when starting the network design? A. Protocols required D. Connectivity to the branch site C.

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