You are on page 1of 15


Chapter 1 LAN Design


Chapter 1

• 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


Chapter 1

LAN Design

Switched LAN Architecture


Chapter 1


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

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

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 .

CCNA3-17 Chapter 1 Principles of Hierarchical Network Design More on • Network Diameter: this in • For PC1 to Chapter 5 communicate with PC3. • Redundancy: • The practice of providing multiple paths to a destination or multiple instances of a device. links between specific switches can be aggregated or combined to provide higher bandwidth. • Bandwidth Aggregation: • After the bandwidth requirements of the network are known. Chapter 1 Principles of Hierarchical Network Design • Just because a network is hierarchical. • In a hierarchical network. the data must traverse 6 intermediate switches. • Each switch introduces some latency.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. it doesn’t mean it’s well designed. • In this case. network diameter is always going to be a predictable number of hops between the source and destination devices. CCNA3-18 Chapter 1 6 . the network diameter is 6. • Network Diameter: • The number of devices that a packet has to cross before it reaches its destination.

CCNA3-19 Chapter 1 Principles of Hierarchical Network Design • Redundancy: • Redundancy is one part of creating a highly available network. CCNA3-21 Chapter 1 7 . • The determining factor is using link aggregation is the requirements of the user applications. • Legacy Equipment: • Until now. mainly feasible on large enterprise networks.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. • 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. 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. • It is feasible at the distribution and core layers.

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 . 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. • Add a webcam and video conference. • Software integrated on a PC eliminates an expensive handset. • Can be a difficult decision considering current investments in technology.23-04-2012 What is a Converged Network? • Advanced Technology: • More popular to medium and small sized businesses. • Benefit: • Only one network to manage.

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

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

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

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. higher performing switches at the distribution and core layers. • More expensive. • Allows the use of: • Less expensive. where the forwarding rate makes a bigger difference. 24 Port 48 Port Very high density.23-04-2012 Switch Performance • Port Density: • Port density is the number of ports available on a single switch. Catalyst 6500 . it cannot accommodate full wire-speed communication across all of its switch ports.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. • A 48 port Gigabit switch is capable of switching 48 Gigabits of traffic.1. lower performing switches at the access layer. CCNA3-36 Chapter 1 12 .

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. CCNA3-39 Chapter 1 13 .23-04-2012 Switch Performance • Link Aggregation: • As part of bandwidth aggregation.1 Gigabit 8 Gigabits. 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. 24 Port Gigabit Up to 8 ports bound together to provide up to Single Port . you should determine if there are enough ports on a switch to aggregate to support the required bandwidth.

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 .

allowing you to find the right switch to meet the functional requirements of your network. • • • • • • • 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. Each product line offers different characteristics and features. • Traffic Analysis is used to monitor network performance.23-04-2012 Switches – Small and Medium Business (SMB) • Cisco has seven switch product lines. scalability. Please refer to the text or online curriculum for details on • The Cisco switch product lines are: each model. • 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 . maintainability & manageability issues.