1.
Introducing Network
Design Concepts
Designing and Supporting Computer Networks – Chapter 1
Version 4.0 © 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 1

2.
Objectives
 Explain how a hierarchical network design creates a stable,
reliable, scalable network
 Explain what factors need to be considered when the Core Layer
of a network is designed and implemented
 Explain which factors need to be considered when the
Distribution Layer of a network is designed and implemented
 Explain which factors need to be considered when the Access
Layer of a network is designed and implemented
 Describe the benefits and security implications of creating server
farms
 Describe the considerations of an implementation of a wireless
network design
 Describe the factors that affect the implementation of VPNs,
including how remote workers can be supported
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 2

3.
Explain How a Hierarchical Network Design
Creates a Stable, Reliable, Scalable Network
Network requirements:
 Ease of management
 Fast recovery
 Application response time
 Fast troubleshooting
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 3

4.
Explain How a Hierarchical Network Design
Creates a Stable, Reliable, Scalable Network
Four fundamental network design goals:
 Scalability
 Availability
 Security
 Manageability
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 4

5.
Explain How a Hierarchical Network Design
Creates a Stable, Reliable, Scalable Network
 Core Layer: connects Distribution Layer devices
 Distribution Layer: interconnects smaller LANs
 Access Layer: provides connections for hosts and end
devices
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 5

6.
Explain How a Hierarchical Network Design
Creates a Stable, Reliable, Scalable Network
Subdividing the three-layer model into modular areas:
 Enterprise campus
 Server farm
 Enterprise edge
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 6

7.
Explain How a Hierarchical Network Design
Creates a Stable, Reliable, Scalable Network
Steps in network design projects:
 Identify the network requirements
 Characterize the existing network
 Design the network topology and solutions
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 7

8.
Explain what Factors Need to be Considered
when Designing the Network Core Layer
 Network backbone
 Goals of the Core Layer
Provide 100% uptime
Maximize throughput
Facilitate network growth
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 8

9.
Explain what Factors Need to be Considered
when Designing the Network Core Layer
 Combining routing and switching in the same device
 Redundancy and load balancing
 High-speed and aggregate links
 Quick convergence
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 9

10.
Explain what Factors Need to be Considered
when Designing the Network Core Layer
 Full mesh topology
 Partial mesh topology
 Failure prevention
 Reducing human error
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 10

11.
Explain which Factors Need to be Considered when
Designing the Distribution Layer of a Network
 Filtering and managing traffic flow
 Access control policies
 Route summarization
 Isolating Core Layer from Access Layer failures
 Routing between VLANs
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 11

12.
Explain which Factors Need to be Considered when
Designing the Distribution Layer of a Network
 Explain how redundant links improve network reliability
and stability
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 12

13.
Explain which Factors Need to be Considered when
Designing the Distribution Layer of a Network
 Explain how ACLs filter traffic for security and traffic
management
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14.
Explain which Factors Need to be Considered when
Designing the Distribution Layer of a Network
 Explain the concept of route summarization and
describe how it is implemented at the Distribution Layer
of the network
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 14

15.
Explain which Factors Need to be Considered
when Designing the Access Layer of a Network
 Physical location of equipment
 Wiring closets
 Converged networking
 Availability
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 15

16.
Explain which Factors Need to be Considered
when Designing the Access Layer of a Network
 Naming structures
 VLAN architecture
 Traffic patterns
 Prioritization strategies
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 16

17.
Explain which Factors Need to be Considered
when Designing the Access Layer of a Network
 Star topologies
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 17

18.
Explain which Factors Need to be Considered
when Designing the Access Layer of a Network
Functions of VLANs:
 Separate and classify traffic
 Control broadcasts
 Contain VLANs within a single wiring closet
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 18

19.
Explain which Factors Need to be Considered
when Designing the Access Layer of a Network
QoS at the network edge:
 Classification
 Assigned priority
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 19

20.
Explain which Factors Need to be Considered
when Designing the Access Layer of a Network
Security risks at the network edge:
 Authentication
 Wireless security
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 20

21.
Explain which Factors Need to be Considered
when Designing the Access Layer of a Network
Security measures at the Access Layer:
 Physical security
 Strong passwords
 SSH
 Disabling unused ports
 Security policy
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 21

22.
Describe the Benefits and Security
Implications of Creating Server Farms
 Defined entry and exit points for network traffic
 Redundant, high-capacity links
 Load balancing and failover
 Lower cost of providing services
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 22

23.
Describe the Benefits and Security
Implications of Creating Server Farms
 Firewalls
 LAN switch security features
 Intrusion and prevention systems
 Load balancers
 Network analysis and management devices
 DMZs
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 23

24.
Describe the Benefits and Security
Implications of Creating Server Farms
 Building in redundancy for high availability
 Virtualization
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 24

25.
Describe the Considerations of an Implementation
of a Wireless Network Design
Customer requirements:
 Roaming
 Authentication
 Services and applications
 Encryption
 Coverage and number of users
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 25

26.
Describe the Considerations of an Implementation
of a Wireless Network Design
 Physical WLAN design
 Site survey
 Logical WLAN design
 Open guest access vs. secured employee access
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 26

27.
Describe the Factors that Affect the
Implementation of VPNs
 Cost of bandwidth
 QoS
 Security
 Remote access
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 27

28.
Describe the Factors that Affect the
Implementation of VPNs
Interconnection options:
 Traditional WAN technologies
 Newer WAN technologies
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 28

29.
Describe the Factors that Affect the
Implementation of VPNs
 Explain ways to provide redundant connectivity to
remote sites
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 29

30.
Summary
 The four fundamental technical requirements of
network design are scalability, availability, security and
manageability.
 Network projects involve identifying the requirements,
characterizing the existing network, and designing the
network topology and solutions.
 Redundancy at the Core Layer keeps the network
functioning even when a device or link fails.
 Routing efficiency at the Distribution Layer isolates the
Core from Access Layer failures.
 Using VLANs and IP subnets is the most common way
to segregate user groups and traffic within the Access
Layer.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 30

31.
© 2006 Cisco Systems, Inc. All rights reserved. Cisco Public 31