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23-04-2012

Chapter 1 LAN Design

CCNA3-1

Chapter 1

Objectives
• Describe how a hierarchical network supports the voice, video and data needs of a small and medium-sized business. Match the appropriate Cisco switch to each layer in the hierarchical network design model

CCNA3-2

Chapter 1

LAN Design

Switched LAN Architecture

CCNA3-3

Chapter 1

1

• Each layer has a specific purpose.23-04-2012 Switched LAN Architecture • When building a LAN that satisfies the needs of a small or medium-sized business. CCNA3-6 Chapter 1 2 . bridges. your plan is more likely to be successful if a hierarchical design model is used. performance. wireless access points. • Provides a means of connecting and controlling which devices are allowed to communicate on the network. • Divided into discrete layers. CCNA3-4 Chapter 1 Switched LAN Architecture CCNA3-5 Chapter 1 Access Layer • Interfaces with end devices. switches. • Becomes modular – maintenance. • Routers.

Routing of VLANs (Virtual LANs). Must be highly available and redundant.23-04-2012 Distribution Layer • • • • Aggregates (funnels) Access Layer traffic. Defines broadcast domains. Must be capable of quickly forwarding large amounts of data. Smaller networks – collapsed model (Core and Distribution). Controls traffic flow with security or routing policies. Chapter 1 CCNA3-8 Medium Sized Business Logical Layout Physical Layout CCNA3-9 Chapter 1 3 . Chapter 1 CCNA3-7 Core Layer • • • • High speed backbone of the network.

23-04-2012 Benefits of a Hierarchical Network • Benefits: • Scalability • Redundancy • Performance • Security • Manageability • Maintainability CCNA3-10 Chapter 1 Benefits of a Hierarchical Network Scalability Hierarchical Networks can be expanded easily. CCNA3-11 Chapter 1 Benefits of a Hierarchical Network Redundancy CCNA3-12 Redundancy at the core and distribution layers ensure availability. Chapter 1 4 .

23-04-2012 Benefits of a Hierarchical Network Performance CCNA3-13 Link aggregation and high performance distribution and core layer switches provide near-wire speed at all layers. Chapter 1 Benefits of a Hierarchical Network Security CCNA3-14 Port security at the access layer and policies at the distribution layer make the network more secure. Chapter 1 Benefits of a Hierarchical Network Manageability Configurations Additional Switch Functionality Rapid Recovery Easier Troubleshooting CCNA3-15 Consistency among switches at each layer makes management more simple. Chapter 1 5 .

• Each switch introduces some latency. Chapter 1 Principles of Hierarchical Network Design • Just because a network is hierarchical. • In this case. • Bandwidth Aggregation: • After the bandwidth requirements of the network are known. CCNA3-17 Chapter 1 Principles of Hierarchical Network Design More on • Network Diameter: this in • For PC1 to Chapter 5 communicate with PC3.23-04-2012 Benefits of a Hierarchical Network Maintainability CCNA3-16 The modular design allows a network to scale easily without becoming over-complicated or burdensome. network diameter is always going to be a predictable number of hops between the source and destination devices. the data must traverse 6 intermediate switches. it doesn’t mean it’s well designed. links between specific switches can be aggregated or combined to provide higher bandwidth. • Redundancy: • The practice of providing multiple paths to a destination or multiple instances of a device. • Network Diameter: • The number of devices that a packet has to cross before it reaches its destination. • In a hierarchical network. CCNA3-18 Chapter 1 6 . the network diameter is 6.

• The determining factor is using link aggregation is the requirements of the user applications. CCNA3-20 Chapter 1 What is a Converged Network? • A Converged Network is one where voice and video communications have been combined on a single data network. CCNA3-19 Chapter 1 Principles of Hierarchical Network Design • Redundancy: • Redundancy is one part of creating a highly available network. • Multiple links between switches or multiple devices. • It can get expensive and most likely will not be done on the access layer because of the cost and variety of devices. • Legacy Equipment: • Until now.23-04-2012 Principles of Hierarchical Network Design • Bandwidth Aggregation: • Link aggregation allows multiple switch port links to be combined so as to achieve higher throughput between switches. CCNA3-21 Chapter 1 7 . • It is feasible at the distribution and core layers. mainly feasible on large enterprise networks.

CCNA3-23 Chapter 1 LAN Design Matching Switches to Specific LAN Functions Traffic Flow Analysis User Community Analysis Data Stores and Data Servers Analysis Topology Diagrams Switch Features CCNA3-24 Chapter 1 8 . • Benefit: • Only one network to manage. • Add a webcam and video conference.23-04-2012 What is a Converged Network? • Advanced Technology: • More popular to medium and small sized businesses. CCNA3-22 Chapter 1 What is a Converged Network? • New Options: • You can now tie voice and video communications directly into an employee's personal computer system. • Can be a difficult decision considering current investments in technology. • Software integrated on a PC eliminates an expensive handset.

CCNA3-27 Chapter 1 9 . CCNA3-26 Chapter 1 Considerations for Network Switches • Data Stores and Data Servers Analysis: • When analyzing traffic on a network. consider the location of the data stores and data servers. • Consider both client-server and server-server traffic. CCNA3-25 Chapter 1 Considerations for Network Switches • User Community Analysis: • The process of identifying various groupings of users and their impact on network performance. • Performance tuning. • Hardware improvement decisions.23-04-2012 Considerations for Network Switches • Traffic Flow Analysis: • The process of measuring the bandwidth usage on a network and analyzing the data. • Capacity planning.

CCNA3-28 Chapter 1 Switch Features • Switch Form Factors: • When selecting a switch. • Aggregated ports and redundant paths. • Stackable or non-stackable. • Switch connections with port numbers.23-04-2012 Considerations for Network Switches • Topology Diagram: • A graphical representation of a network infrastructure. • Shelf in a central area. • Could contain user information. • You cannot add features or options to the switch beyond those that originally came with the switch. • Wiring closet with limited space. you need to decide between • Fixed configuration or modular configuration. • Identify configuration by switch name. • The switch form factor (physical size) is important depending upon where the switch will be installed. • Computer room with free standing racks. CCNA3-29 Chapter 1 Switch Features • Fixed Configuration Switches: • Fixed in their configuration. CCNA3-30 Chapter 1 10 .

CCNA3-32 Chapter 1 Switch Performance • When selecting a switch for the access. • The line cards actually contain the ports. larger switch. consider the ability of the switch to support: • Port Density. • Forwarding Rate. CCNA3-33 Chapter 1 11 . • Bandwidth Aggregation Requirements. distribution. • Typically come with different sized chassis that allow for the installation of different numbers of modular line cards. CCNA3-31 Chapter 1 Switch Features • Stackable Switches: • Interconnected using a special backplane cable that provides high-bandwidth throughput between the switches (Cisco StackWise). or core layer.23-04-2012 Switch Features • Modular Switches: • Offer more flexibility. • Desirable when fault tolerance and bandwidth availability are critical and a modular switch is too costly to implement. • The stacked switches effectively operate as a single.

lower performing switches at the access layer. • Allows the use of: • Less expensive. Catalyst 6500 . CCNA3-35 Chapter 1 Switch Performance • Forwarding Rate: • Access layer switches typically do not need to operate at full wire speed because they are physically limited by their uplinks to the distribution layer.000 Ports CCNA3-34 Chapter 1 Switch Performance • Forwarding Rate: • Defines the processing capabilities of a switch by rating how much data the switch can process per second. • If the switch forwarding rate is too low.23-04-2012 Switch Performance • Port Density: • Port density is the number of ports available on a single switch. 24 Port 48 Port Very high density. • A 48 port Gigabit switch is capable of switching 48 Gigabits of traffic. higher performing switches at the distribution and core layers. CCNA3-36 Chapter 1 12 . where the forwarding rate makes a bigger difference. • More expensive. it cannot accommodate full wire-speed communication across all of its switch ports.1.

you should determine if there are enough ports on a switch to aggregate to support the required bandwidth.1 Gigabit 8 Gigabits. 24 Port Gigabit Up to 8 ports bound together to provide up to Single Port . BOTTLE NECK CCNA3-37 Chapter 1 Switch Performance • Power over Ethernet (PoE): • Allows the switch to deliver power to a device over the existing Ethernet cabling.23-04-2012 Switch Performance • Link Aggregation: • As part of bandwidth aggregation. Adds considerable cost to the switch. CCNA3-38 Chapter 1 Switch Performance • Layer 3 Functionality: • Switches typically operate at Layer 2 of the OSI Model. CCNA3-39 Chapter 1 13 .

23-04-2012 Switch Features – Hierarchical Network • Access Layer Switch Features: Port Security Link Aggregation VLANs PoE FastEthernet/Gigabit Quality of Service (QoS) CCNA3-40 Chapter 1 Switch Features – Hierarchical Network • Distribution Layer Switch Features: Layer 3 Support High Forwarding Rate Link Aggregation Redundant Components Gigabit/10 Gigabit Quality of Service (QoS) Security Policies CCNA3-41 Chapter 1 Switch Features – Hierarchical Network • Core Layer Switch Features: Layer 3 Support Link Aggregation Very High Forwarding Rate Gigabit/10 Gigabit Redundant Components Quality of Service (QoS) CCNA3-42 Chapter 1 14 .

23-04-2012 Switches – Small and Medium Business (SMB) • Cisco has seven switch product lines. • Hierarchical Design Model is composed of 3 layers: • Access • Distribution • Core • Switches selected for each layer must meet the needs of each hierarchical layer as well as the needs of the business. CCNA3-45 Chapter 1 15 . scalability. maintainability & manageability issues. Each product line offers different characteristics and features. • • • • • • • CCNA3-43 Catalyst Express 500 Catalyst 2960 Catalyst 3560 Catalyst 3750 Catalyst 4500 Catalyst 4900 Catalyst 6500 Chapter 1 Summary • Hierarchical Design model addresses performance. allowing you to find the right switch to meet the functional requirements of your network. • Traffic Analysis is used to monitor network performance. Please refer to the text or online curriculum for details on • The Cisco switch product lines are: each model.