CCNAv5 - S4: Chapter 1 Hierarchical Network Design

© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 1
Chapter 1: Hierarchical
Network Design
Connecting Networks

Presentation_ID 2© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 1
1.0 Introduction
1.1 Hierarchical Network Design Overview
1.2 Cisco Enterprise Architecture
1.3 Evolving Network Architectures
1.4 Summary

Chapter 1: Objectives
 Describe how a hierarchical network model is used to design
networks.
 Explain the structured engineering principles for network design:
Hierarchy, Modularity, Resiliency, Flexibility.
 Describe the three layers of a hierarchical network and how they are
used in network design.
 Identify the benefits of a hierarchical design.
 Describe the Cisco Enterprise Architecture model.
 Describe the three new business network architectures: borderless
network architecture, collaboration network architecture, and the
data center or virtualization network architecture.

1.1 Hierarchical Network
Design Overview

Enterprise Network Campus Design
Network Requirements
 Small network – Provides services for 1 to 200 devices.
 Medium-sized network – Provides services for 200 to 1,000 devices.
 Large network – Provides services for 1,000+ devices.

Enterprise Network Campus Design
Structured Engineering Principles

Hierarchical Network Design
Network Hierarchy
 Access layer – Provides workgroup or user access to the network.
 Distribution layer – Provides policy-based connectivity.
 Core layer – Provides fast transport between distribution switches.

Access Layer
 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

Distribution Layer
 Aggregation of LAN or WAN links
 Policy-based security in the form of access control lists (ACLs) and
filtering
 Routing services between LANs and VLANs and between routing
domains (e.g., EIGRP to OSPF)
 Redundancy and load balancing
 A boundary for route aggregation and summarization configured on
interfaces toward the core layer

Core Layer
 Provides high-speed switching (i.e., fast transport)
 Provides reliability and fault tolerance
 Scales by using faster, and not more, equipment
 Avoids CPU-intensive packet manipulation caused by security,
inspection, quality of service (QoS) classification, or other processes

Two-Tier Collapsed Core Design
 A two-tier hierarchical
“collapsed core” is when
the distribution layer and
core layer functions are
implemented by a single
device.
 Used by smaller
businesses to reduce
network cost while
maintaining most of the
benefits of the three-tier
hierarchical model.

1.2 Cisco Enterprise
Architecture

Modular Network Design
Modular Design
 As the complexity of networks increased, a modular network design
has been implemented.
 Modular design separates the network into various functional network
modules.

Modular Network Design
Modules in the Enterprise Architecture
 Access-distribution
module – Also called the
distribution block.
 Services module – A
generic block used to
identify services, such as
centralized Lightweight
Access Point Protocol
(LWAPP).
 Data center module –
Originally called the
server farm.
 Enterprise Edge module
– Consists of the Internet
Edge and the WAN
Edge.

Cisco Enterprise Architecture Model

Cisco Enterprise Campus

Cisco Enterprise Edge

Service Provider Edge

Cisco Enterprise Data Center

Cisco Enterprise Branch

Cisco Enterprise Teleworker

1.3 Evolving Network
Architectures

Cisco Enterprise Architectures
IT Challenges
Some of the top trends include:
 Bring Your Own Device
(BYOD)
 Online collaboration
 Video communication
 Cloud computing

Cisco Enterprise Architectures
Emerging Enterprise Architectures

Emerging Network Architectures
Cisco Borderless Networks

Collaboration Architecture
Cisco’s collaboration architecture
is composed of three layers:
 Application and Devices –
Unified communications and
conference applications, such as
Cisco WebEx Meetings, WebEx
Social, Cisco Jabber, and
TelePresence.
 Collaboration Services –
Supports collaboration
applications.
 Network and Computer
Infrastructure – Allows
collaboration anytime, from
anywhere, on any device.

Data Center and Virtualization
The data center architecture consists of three components:
 Cisco Unified Management Solutions – Simplifies and automates
the process of deploying IT infrastructure and services with speed and
enterprise reliability.
 Unified Fabric Solutions – Delivers network services to servers,
storage, and applications, providing transparent convergence, and
scalability.
 Unified Computing Solutions – Cisco’s next-generation data center
system unites computing, network, storage access, and virtualization
into a cohesive system designed to reduce total cost of ownership
(TCO).

1.4 Summary

Chapter 1: Summary
This chapter:
 Introduced the structured engineering principles of good network
design that include hierarchy, modularity, resiliency, and flexibility.
 Explained that the typical enterprise hierarchical LAN campus
network design incorporates the access layer, distribution layer, and
the core layer.
 Identified that smaller enterprise networks may use a “collapsed
core” hierarchy, whereas the distribution and core layer functions are
implemented in a single device.
 Described the benefits of a hierarchical network as scalability,
redundancy, performance, and ease of maintenance.

Chapter 1: Summary (cont.)
 Explained that a modular design, which separates the functions of a
network, enables flexibility and facilitates implementation and
management.
 Discussed that the Cisco Enterprise Architecture modules are used
to facilitate the design of large, scalable networks.
 Identified the primary modules, including the Enterprise Campus,
Enterprise Edge, Service Provider Edge, Enterprise Data Center,
Enterprise Branch, and Enterprise Teleworker.

CCNAv5 - S4: Chapter 1 Hierarchical Network Design

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CCNAv5 - S4: Chapter 1 Hierarchical Network Design