Chap 1 LAN Design Learning Objectives Describe how

Chap 1 – LAN Design Learning Objectives • • Describe how a hierarchical network supports the voice, video and data needs of a small and mediumsized business. Match the appropriate Cisco switch to each layer in the hierarchical network design model. 1 Chapter 1

Hierarchical Design Model The use of a hierarchical design model will make it easier to make changes to the network as the organization grows. Cisco currently recognize the following layers: • Access layer provides users in workgroups access to the network. • Distribution layer provides policy-based connectivity. • Core layer provides optimal transport between sites the backbone. 2 Chapter 1

Hierarchical Design Model 3 Chapter 1

Hierarchical Design Model – Access Layer • Shared Bandwidth • Switched Bandwidth • MAC Layer filtering • Micro-segmentation The access layer is the entry point for user workstations and servers to the network – typical devices being switches or hubs. 4 Chapter 1

Hierarchical Design Model – Distribution Layer • Aggregation of the wiringcloset connections • Broadcast/multicast domain definition • VLAN routing • Any media transitions that need to occur (copper to FO) • Security (ACLs) • The purpose of this layer is to provide a boundary definition in which packet manipulation can take place. 5 Chapter 1

Hierarchical Design Model – Core Layer • Doesn’t perform any packet manipulation - would slow down the switching of packets. • Provide redundant alternate paths. • Can be designed to use Layer 2 or Layer 3 switching - ATM or Ethernet. The core layer is a high-speed switching backbone. 6 Chapter 1

LAN Design Goals • Scalability - Hierarchical networks scale very well, as the modularity of the design allows the replication of design elements as the network grows. • Redundancy - As a network grows, availability becomes more important. Availability can be increased through easy redundant implementations with hierarchical networks. • Performance - enhanced by avoiding the transmission of data through lowperforming, intermediary switches. • Security - Access layer switches can be configured with various port security options that provide control over which devices are allowed to connect to the network. • Manageability - Each layer of the hierarchical design performs specific functions that are consistent throughout that layer – easy to manage. • Maintainability - Because hierarchical networks are modular in nature and scale very easily, they are easy to maintain. 7 Chapter 1

Switched LAN Design Principles • Links between specific switches can be aggregated, which is called link aggregation. Link aggregation allows multiple switch port links to be combined so as to achieve higher throughput between switches. • Redundancy is one part of creating a highly available network. Redundancy can be provided by doubling up the network connections between devices, or doublinge the devices themselves. • Network diameter - number of devices that a packet has to cross before it reaches its destination – a low number ensures low and predictable latency between devices. 8 Chapter 1

Converged Networks • • Many separate communications networks have evolved to support various different types of communication. Traditionally, data and voice networks remained separate. Circuit Switch Aggregate Link Traditional Phones/Video To PSTN DCE 9 Link IP Network Chapter 1

Converged Networks Convergence is the process of combining voice and video communications on a data network. Traditional Phones/Video • It is less expensive to implement a single network infrastructure than multiple network infrastructures. DCE 10 Link IP Network Chapter 1

Considerations for Hierarchical Network Switches • Traffic Flow Analysis - Traffic flow analysis is the process of measuring the bandwidth usage on a network and analyzing the data for the purpose of performance tuning, capacity planning, and making hardware improvement decisions. Analysing the various traffic sources and their impact on the network, allows more accurate tuning and upgrading of the network to achieve the best possible performance. 11 Chapter 1

Considerations for Hierarchical Network Switches User community analysis - the process of identifying various groupings of users and their impact on network performance. The way users are grouped affects issues related to port density and traffic flow, which, in turn, influences the selection of network switches • Future Growth - 24 port switch has only 4 spare ports, so future growth of the department is not considered. • A stackable or modular switches that can scale would probably be a better initial solution. 12 Chapter 1

Considerations for Hierarchical Network Switches Server Placement Servers can be categorized as either enterprise servers or workgroup servers: • Enterprise servers support all the users on the network as it offers services, such as e-mail or Domain Name System (DNS). • Workgroup servers support a specific set of users and offers services such as word processing and file sharing. 13 Chapter 1

Considerations for Hierarchical Network Switches Server Placement 14 Chapter 1

Considerations for Hierarchical Network Switches LAN Design Goals - Documentation Topology Diagram Cut Sheet Addressing Map 15 Chapter 1

Switch Features – Form Factors • Fixed configuration - can’t add features or options to the switch. • Modular switches – chassis allows for the installation of different numbers of modular line cards containing switch ports. • Stackable switches - interconnected using a special backplane cable that provides high -bandwidth throughput between switches. 16 Chapter 1

Switch Features – Port Density • Port density is the number of ports available on a single switch. • Modular switches can support very high port densities through the addition of multiple switch port line cards - Catalyst 6500 switch can support in excess of 1, 000 switch ports on a single device. • Without using a high-density modular switch, the network would need many fixed configuration switches to accommodate the number of devices that need network access. This approach can consume many power outlets and a lot of closet space. • Fixed configuration switches may consume many additional ports for bandwidth aggregation between switches. Less of an issue with modular switches because the backplane of the chassis can provide the necessary bandwidth. 17 Chapter 1

Switch Features – Port Forwarding • Forwarding rates define the processing capabilities of a switch by rating how much data the switch can process per second. Switch 24 x 100 Mbps Switch Ports • Wire speed is the data rate that each port on the switch is capable of attaining • If the forwarding rate is not equal to or greater than the sum of the port speed, ports can not run at wire speed 18 Chapter 1

Switch Features – Link Aggregation • Link aggregation helps to reduce bottlenecks of traffic by allowing up to eight switch ports to be bound together for data communications, providing up to 8 Gb/s of data throughput when Gigabit Ethernet ports are used. • Cisco uses the term Ether. Channel when describing aggregated switch ports. 19 Chapter 1

Access Layer Switch Features • Port Security • VLANs • Fast Ethernet/Gigabit Ethernet • Power over Ethernet (Po. E – 802. 3 af) • Link Aggregation • Quality of Service (Qo. S) 20 Chapter 1

Distribution Layer Switch Features • Layer 3 Support • High Forwarding Rate • Gigabit Ethernet / 10 Gigabit Ethernet • Redundant Components • Security Policies / Access Control Lists • Link Aggregation • Quality of Service (Qo. S) 21 Chapter 1

Core Layer Switch Features • Layer 3 Support • Very High Forwarding Rate • Gigabit Ethernet / 10 Gigabit Ethernet • Redundant Components • Link Aggregation • Quality of Service (Qo. S) 22 Chapter 1

Typical Network Switches Access Distribution • Catalyst 2960 series • Catalyst 3560 series • Catalyst 4000 series • Catalyst 5000 series 23 • Catalyst 5000 family • Catalyst 6000 family Core • Catalyst 6500 series • Catalyst 8500 series • IGX 8400 series • Lightstream 1010 Chapter 1

Chap 1 – LAN Design Learning Objectives • • Describe how a hierarchical network supports the voice, video and data needs of a small and mediumsized business. Match the appropriate Cisco switch to each layer in the hierarchical network design model. 24 Chapter 1

Any Questions? 25 Chapter 1