LAN Design : LAN Design LAN Switching and Wireless – Chapter 1 Modified by Tony Chen, College of DuPage
Objectives : Objectives Hierarchical network support for voice, video, and data needs of a small- or medium-sized business Functions of the three level hierarchical network design model How voice and video over IP affect network design Select appropriate devices to operate at each level of the hierarchy, including voice and video components Match the appropriate Cisco switch to each layer in the hierarchical network design model
Hierarchical Network Model : Hierarchical Network Model When building a LAN that satisfies the needs of a small- or medium-sized business, your plan is more likely to be successful if a hierarchical design model is used. Hierarchical network design involves dividing the network into discrete layers. Each layer provides specific functions that define its role within the overall network. By separating the various functions that exist on a network, the network design becomes modular, which facilitates scalability and performance. The typical hierarchical design model is broken up in to three layers: access distribution core
Hierarchical Network Model : Hierarchical Network Model 3 layers Hierarchical Model: Access The access layer interfaces with end devices to provide access to the rest of the network. The access layer can include routers, switches, bridges, hubs, and wireless access points. The main purpose of the access layer is to provide a means of connecting devices to the network and controlling which devices are allowed to communicate on the network. VLAN’s defined here
Hierarchical Network Model : Hierarchical Network Model 3 layers Hierarchical Model: Distribution Aggregates the data received from the access layer The distribution layer controls the flow of network traffic using policies (access lists) Separates broadcast domains Routes between virtual LANs (VLANs) defined at the access layer. VLANs allow you to segment the traffic on a switch into separate subnetworks. For example, in a university you might separate traffic according to faculty, students, and guests. Higher-performance devices that have high availability and redundancy
Hierarchical Network Model : Hierarchical Network Model 3 layers Hierarchical Model: Core High-speed backbone of the internetwork. Highly available and redundant. No policies enforced here (minimal packet inspection) Aggregates the traffic from all the distribution layer devices The core area can also connect to Internet resources. Can all these layers be supported in a small network??
Hierarchical Network Model : Hierarchical Network Model Logical Layout The access, distribution, and core layers are separated into a well-defined hierarchy. This logical representation makes it easy to see which switches perform which function. It is much harder to see these hierarchical layers when the network is installed in a business. Physical Layout Diagram shows two floors of a building. User computers and network devices that need network access are on one floor. The resources, such as e-mail servers and database servers, are located on another floor. Access and distribution switches are located in equipment room (wiring closet) The access layer switch and distribution layer switch are stacked one on top of each other in the wiring closet.
Benefits of a Hierarchical Network : Benefits of a Hierarchical Network Scalability Design elements can be replicated Modular approach to network design Redundancy Increased availability of network through redundant elements Distribution and Core should have redundant elements (not possible at Access layer) Performance Aggregated links provide more throughput from Access layer Distribution device provides high speed switching across and to the Core layer Security Port security introduces more stringent controls at the Access layer Access Control Lists or policies control data flow between subnetworks Manageability Deployment of new equipment is simpler Configuration changes are more universal based on layers Maintainability Modular, scaled networks are simpler to support Different layers provide for cost savings through different price points
Principles of Hierarchical Network Design : Principles of Hierarchical Network Design Network Diameter Number of devices that a packet has to cross before it reaches its destination Bandwidth Aggregation Bandwidth aggregation is the practice of considering the specific bandwidth requirements of each part of the hierarchy. Bandwidth needs are met using multiple links or “link aggregation” Link aggregation allows multiple switch port links to be combined for higher throughput Cisco uses the term EtherChannel when describing aggregated switch ports Redundancy Redundancy is one part of creating a highly available network Can include duplicate hardware components or duplicate pathways i.e., redundant power supplies
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What is a Converged Network? : What is a Converged Network? Convergence is the process of combining voice and video communications on a data network. Legacy Equipment Converged networks have existed for a while now, but were only feasible in large enterprise organizations Most telephone companies today have made the transition to digital-based switches. However, there are many offices that still use analog phones Advanced Technology Converging voice, video, and data networks has become more popular recently in the small to medium-sized business market because of advancements in technology. Moving to a converged network can be a difficult decision if the business already invested in separate voice, video, and data networks. One benefit of a converged network is that there is just one network to manage (staff, expertise, infrastructure) High-end VoIP phone and switch combination suitable for a medium-sized business of 250-400 employees
Considerations for Hierarchical Network Switches : Considerations for Hierarchical Network Switches Traffic Flow Analysis Measuring the bandwidth usage on a network Analyzing the data for the purpose of performance tuning, capacity planning, and hardware improvement decisions. Analysis Tools Many traffic flow analysis tools that automatically record traffic flow data to a database and perform a trend analysis are available. Cisco devices support collection of NetFlow data Solarwinds Orion - commercial analyzer Plixer and Caidia - freeware analyzers PRTG Traffic Grapher http://www.paessler.com/prtg/
User Communities Analysis : User Communities Analysis User community analysis is the process of identifying various groupings of users and their impact on network performance. In a typical office building, end users are grouped according to their job function, because they require similar access to resources and applications. The location of the user communities influences where data stores and server farms are located. A solid network plan includes the rate of personnel growth over the past five years to be able to anticipate the future growth.
Considerations for Hierarchical Network Switches : Considerations for Hierarchical Network Switches Data Stores and Data Servers Analysis When analyzing traffic on a network, consider where the data stores and servers are located so that you can determine the impact of traffic on the network. Data stores can be servers, storage area networks (SANs), network-attached storage (NAS), tape backup units, or any other device or component where large quantities of data are stored. When considering the traffic for data stores and servers, consider both client-server traffic and server-server traffic. Client-server traffic is the traffic generated when a client device accesses data from data stores or servers. Server-server traffic is the traffic generated between data storage devices on the network.
Topology Diagrams : Topology Diagrams A topology diagram is a graphical representation of a network infrastructure. Shows how all switches are interconnected Graphically displays any redundant paths or aggregated ports Dhows where and how many switches are in use on your network, as well as identifies their configuration. Can also contain information about device densities and user communities. Allows you to visually identify potential bottlenecks in network traffic A network topology can be very difficult to piece together after the fact if you were not part of the design process. Network cables become spaghetti in wiring closets Hard to identify uplinks between Access and Distribution switches Many hours involved in re-documenting the network
Switch Features : Switch Features Switch Form Factors When you are selecting a switch, you need to decide between Fixed configuration Modular configuration Stackable Non-stackable . Another consideration is the thickness of the switch expressed in number of rack units . For example, the Fixed Configuration Switches shown in the figure are all 1U .
Feature: Switched vs. Modular : Feature: Switched vs. Modular Fixed Configuration Switches Fixed configuration switches means is that you cannot add features or options to the switch beyond those that originally came with the switch. For example, if you purchase a 24-port gigabit fixed switch, you cannot add additional ports when you need them. Modular Switches Modular switches typically come with different sized chassis that allow for the installation of different numbers of modular line cards. The line cards actually contain the ports. The line card fits into the switch chassis like expansion cards fit into a PC Catalyst 6500 chassis can support up to 1,000 ports!
Feature: Stackable : Feature: Stackable Stackable switches can be interconnected using a special backplane cable that provides high-bandwidth throughput between the switches. Cisco introduced StackWise technology. Connected in daisy chain fashion. The stacked switches effectively operate as a single larger switch. Stackable switches are desirable where fault tolerance and bandwidth availability are critical and a modular switch is too costly to implement. Using cross-connected connections, the network can recover quickly if a single switch fails. Stackable switches use a special port for interconnections and do not use line ports for inter-switch connections. The speeds are also typically faster than using line ports for connection switches.
Feature: Performance : Feature: Performance When selecting a switch for the access, distribution, or core layers , consider the ability of the switch to support the port density, forwarding rates bandwidth aggregation Port Density Port density is the number of ports available on a single switch. Fixed configuration switches typically support up to 48 ports on a single switch. Modular switches can support very high port densities through the addition of multiple switch port line cards, as shown in the figure. Large enterprise networks that support many thousands of network devices require high density, modular switches to make the best use of space and power. You must also address the issue of uplink bottlenecks. A series of fixed configuration switches may consume many additional ports for bandwidth aggregation between switches for the purpose of achieving target performance. With a single modular switch, bandwidth aggregation is less of an issue because the backplane of the chassis can provide the necessary bandwidth to accommodate the devices connected to the switch port line cards.
Feature: Forwarding Rates : Feature: Forwarding Rates Forwarding rates define 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, it cannot accommodate full wire-speed communication across all of its switch ports. For example, a 48-port gigabit switch operating at full wire speed generates 48 Gb/s of traffic. If the switch only supports a forwarding rate of 32 Gb/s, it cannot run at full wire speed across all ports simultaneously. Fortunately, 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. Save money at the Access layer; spend at the Distribution and Core layer where line speed and large backplane is needed.
Feature: Link Aggregation : Feature: Link Aggregation As part of bandwidth aggregation, you should determine if there are enough ports on a switch to aggregate to support the required bandwidth. For example, consider a Gigabit Ethernet port, which carries up to 1 Gb/s of traffic. If you have a 24-port switch, with all ports capable of running at gigabit speeds, you could generate up to 24 Gb/s of network traffic. If the switch is connected to the rest of the network by a single network cable, it can only forward 1 Gb/s of the data to the rest of the network. Result:1/24th wire speed for each device Link aggregation helps to reduce these bottlenecks of traffic by allowing up to 8 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 EtherChannel when describing aggregated switch ports.
Feature: POE and L3 : Feature: POE and L3 Power over Ethernet Power over Ethernet (PoE) allows the switch to deliver power to a device over the existing Ethernet cabling. PoE allows you more flexibility when installing wireless access points and IP phones because you can install them anywhere you can run an Ethernet cable. You do not need to consider how to run ordinary power to the device. You should only select a switch that supports PoE if you are actually going to take advantage of the feature, because it adds considerable cost to the switch. Layer 3 Functions Layer 3 switches offer advanced functionality that will route traffic in layer 3 IP address. Layer 3 switches are also known as multilayer switches. Typically, switches operate at Layer 2 of the OSI reference
Switch Features in a Hierarchical Network : Switch Features in a Hierarchical Network Access Layer Switch Features Access layer switches facilitate the connection of end node devices to the network. They need to support features such as: Port security: allows the switch to decide how many or what specific devices are allowed to connect to the switch. It is an important first line of defense for a network. VLANs: Access layer switches allow you to set the VLANs for the end node devices on your network. Voice traffic is typically given a separate VLAN. In this way, voice traffic can be supported with more bandwidth, more redundant connections, and improved security. Port speed: Fast Ethernet allows up to 100 Mb/s of traffic per switch port. Gigabit Ethernet allows up to 1000 Mb/s of traffic per switch port. Fast Ethernet is adequate for IP telephony and data traffic on most business networks. Gigabit Ethernet allows allows for much more efficient data transfers, enabling users to be more productive. PoE: It should only be considered when voice convergence is required or wireless access points are being implemented, and power is difficult or expensive to run to the desired location . Link aggregation: Access layer switches take advantage of link aggregation when aggregating bandwidth up to distribution layer. QoS : In a converged network supporting voice, video and data network traffic, access layer switches need to support QoS to maintain the prioritization of traffic. Cisco IP phones are types of equipment that are found at the access layer. QoS needs to be enabled on access layer switches so that voice traffic the IP phone has priority over, for example, data traffic.
Switch Features in a Hierarchical Network : Switch Features in a Hierarchical Network Distribution Layer Switch Features Distribution layer switches collect the data from all the access layer switches and forward it to the core layer switches. They need to support features such as Support Layer 3 functions: Distribution layer switches provides the inter-VLAN routing functions so that one VLAN can communicate with another on the network. Security Policies: Access lists are used to control how traffic flows through the network. This inspection is performed at the distribution layer, because the switches at this layer typically have the processing capability to handle the additional load, and it also simplifies the use of ACLs. Quality of Service: The distribution layer switches need to support QoS to maintain the prioritization of traffic coming from the access layer switches that have implemented QoS. Priority policies ensure that audio and video communications are guaranteed adequate bandwidth to maintain an acceptable quality of service. Redundancy: It is important that distribution switches support redundancy for adequate availability. Loss of a distribution layer switch could have significant impact on the rest of the network because all access layer traffic passes through the distribution layer switches. Link aggregation : Typically, access layer switches use multiple links to connect to a distribution layer switch to ensure adequate bandwidth to accommodate the traffic generated on the access layer, and provide fault tolerance in case a link is lost. Because distribution layer switches accept incoming traffic from multiple access layer switches, they need to be able to forward all of that traffic as fast as possible to the core layer switches.
Switch Features in a Hierarchical Network : Switch Features in a Hierarchical Network Core Layer Switch Features The core layer of a hierarchical topology is the high-speed backbone of the network and requires switches that can handle very high forwarding rates. They need to support features such as Link Aggregation: The core layer also needs to ensure adequate bandwidth coming into the core from the distribution layer switches. Core layer switches should have support for aggregated 10GbE connections, which is currently the fastest available Ethernet connectivity option. Redundancy: Layer 3 redundancy typically has a faster convergence than Layer 2 redundancy in the event of hardware failure. You want to ensure that your core layer switches support Layer 3 functions. Also, look for core layer switches that support additional hardware redundancy features like redundant power supplies that can be swapped while the switch continues to operate. QoS: An important services provided by core layer switches. At the core and network edge, mission-critical and time-sensitive traffic such as voice should receive higher QoS guarantees than less time-sensitive traffic such as file transfers or e-mail.
For Small and Medium Sized Business (SMB) : For Small and Medium Sized Business (SMB) Cisco has seven switch product lines. Each product line offers different characteristics and features, allowing you to find the right switch to meet the functional requirements of your network. The Cisco switch product lines are: Catalyst Express 500 Catalyst 2960 Catalyst 3560 Catalyst 3750 Catalyst 4500 Catalyst 4900 Catalyst 6500
Catalyst Express 500 : Catalyst Express 500 The Catalyst Express 500 is Cisco's entry-layer switch. It offers: Forwarding rates from 8.8 Gb/s to 24 Gb/s Layer 2 port security Web-based management Converged data/IP communications support This switch series is appropriate for access layer implementations where high port density is not required. The Cisco Catalyst Express 500 series switches are scaled for small business environments ranging from 20 to 250 employees. The Catalyst Express 500 series switches are available in different fixed configurations: Fast Ethernet and Gigabit Ethernet connectivity Up to 24 10/100 ports with optional PoE or 12 10/100/1000 ports Catalyst Express 500 series switches do not allow management through the Cisco IOS CLI . They are managed using a built-in web management interface, the Cisco Network Assistant or the new Cisco Configuration Manager developed specifically for the Catalyst Express 500 series switches. The Catalyst Express does not support console access. To learn more about the Cisco Express 500 series of switches, go to http://www.cisco.com/en/US/products/ps6545/index.html.
Catalyst 2960 : Catalyst 2960 The Catalyst 2960 series switches enable entry-layer enterprise, medium-sized, and branch office networks to provide enhanced LAN services. The Catalyst 2960 series switches are appropriate for access layer implementations where access to power and space is limited. The CCNA Exploration 3 LAN Switching and Wireless labs are based on the features of the Cisco 2960 switch. The Catalyst 2960 series switches offers the following: Forwarding rates from 16 Gb/s to 32 Gb/s Multilayered switching QoS features to support IP communications Access control lists (ACLs) Fast Ethernet and Gigabit Ethernet connectivity Up to 48 10/100 ports or 10/100/1000 ports with additional dual purpose gigabit uplinks The Catalyst 2960 series of switches do not support PoE. The Catalyst 2960 series supports the Cisco IOS CLI, integrated web management interface, and Cisco Network Assistant. This switch series supports console and auxiliary access to the switch. To learn more about the Catalyst 2960 series of switches, visit http://www.cisco.com/en/US/products/ps6406/index.html.
Catalyst 3560 : Catalyst 3560 The Cisco Catalyst 3560 series is a line of enterprise-class switches that include support for PoE, QoS, and advanced security features such as ACLs. These switches are ideal access layer switches for small enterprise LAN access or branch-office converged network environments. The Cisco Catalyst 3560 Series supports forwarding rates of 32 Gb/s to 128 Gb/s (Catalyst 3560-E switch series). The Catalyst 3560 series switches are available in different fixed configurations: Fast Ethernet and Gigabit Ethernet connectivity Up to 48 10/100/1000 ports, plus four small form-factor pluggable (SFP) ports Optional 10 Gigabit Ethernet connectivity in the Catalyst 3560-E models Optional Integrated PoE (Cisco pre-standard and IEEE 802.3af); up to 24 ports with 15.4 watts or 48 ports with 7.3 watts To learn more about the Catalyst 3560 series of switches, visit http://www.cisco.com/en/US/products/hw/switches/ps5528/index.html.
Catalyst 3750 : Catalyst 3750 The Cisco Catalyst 3750 series of switches are ideal for access layer switches in midsize organizations and enterprise branch offices. This series offers forwarding rates from 32 Gb/s to 128 Gb/s (Catalyst 3750-E switch series). The Catalyst 3750 series supports Cisco StackWise technology. StackWise technology allows you to interconnect up to nine physical Catalyst 3750 switches into one logical switch using a high-performance (32 Gb/s), redundant, backplane connection. The Catalyst 3750 series switches are available in different stackable fixed configurations: Fast Ethernet and Gigabit Ethernet connectivity Up to 48 10/100/1000 ports, plus four SFP ports Optional 10 Gigabit Ethernet connectivity in the Catalyst 3750-E models Optional Integrated PoE (Cisco pre-standard and IEEE 802.3af); up to 24 ports with 15.4 watts or 48 ports with 7.3 watts To learn more about the Catalyst 3750 series of switches, visit http://www.cisco.com/en/US/products/hw/switches/ps5023/index.html.
Catalyst 4500 : Catalyst 4500 The Catalyst 4500 is the first midrange modular switching platform offering multilayer switching for enterprises, small- to medium-sized businesses, and service providers. With forwarding rates up to 136 Gb/s, the Catalyst 4500 series is capable of managing traffic at the distribution layer. The modular capability of the Catalyst 4500 series allows for very high port densities through the addition of switch port line cards to its modular chassis. The Catalyst 4500 series offers multilayer QoS and sophisticated routing functions. The Catalyst 4500 series switches are available in different modular configurations: Modular 3, 6, 7, and 10 slot chassis offering different layers of scalability High port density: up to 384 Fast Ethernet or Gigabit Ethernet ports available in copper or fiber with 10 Gigabit uplinks PoE (Cisco pre-standard and IEEE 802.3af) Dual, hot-swappable internal AC or DC power supplies Advanced hardware-assisted IP routing capabilities To learn more about the Catalyst 4500 series of switches, visit http://www.cisco.com/en/US/products/hw/switches/ps4324/index.html.
Catalyst 4900 : Catalyst 4900 The Catalyst 4900 series switches are designed and optimized for server switching by allowing very high forwarding rates. The Cisco Catalyst 4900 is not a typical access layer switch. It is a specialty access layer switch designed for data center deployments where many servers may exist in close proximity. This switch series supports dual, redundant power supplies and fans that can be swapped out while the switch is still running. This allows the switches to achieve higher availability, which is critical in data center deployments. The Catalyst 4900 series switches support advanced QoS features, making them ideal candidates for the back-end IP telephony hardware. Catalyst 4900 series switches do not support the StackWise feature of the Catalyst 3750 series nor do they support PoE. The Catalyst 4900 series switches are available in different fixed configurations: Up to 48 10/100/1000 ports with four SFP ports or 48 10/100/1000 ports with two 10GbE ports Dual, hot-swappable internal AC or DC power supplies Hot-swappable fan trays To learn more about the Catalyst 4900 series of switches, visit http://www.cisco.com/en/US/products/ps6021/index.html.
Catalyst 6500 : Catalyst 6500 The Catalyst 6500 series modular switch is optimized for secure, converged voice, video, and data networks. The Catalyst 6500 is capable of managing traffic at the distribution and core layers. The Catalyst 6500 series is the highest performing Cisco switch, supporting forwarding rates up to 720 Gb/s. The Catalyst 6500 is ideal for very large network environments found in enterprises, medium-sized businesses, and service providers. The Catalyst 6500 series switches are available in different modular configurations: Modular 3, 4, 6, 9, and 13 slot chassis LAN/WAN service modules PoE up to 420 IEEE 802.3af Class 3 (15.4W) PoE devices Up to 1152 10/100 ports, 577 10/100/1000 ports, 410 SFP Gigabit Ethernet ports, or 64 10 Gigabit Ethernet ports Dual, hot-swappable internal AC or DC power supplies Advanced hardware-assisted IP routing capabilities To learn more about the Catalyst 6500 series of switches, visit http://www.cisco.com/en/US/products/hw/switches/ps708/index.html
Product Videos From Cisco : Product Videos From Cisco 500 Series http://www.youtube.com/watch?v=Iiw6GL8DPtM 3500 and 3700 Series http://www.youtube.com/watch?v=ake-nsGcwd8&feature=related 4500 Series http://www.youtube.com/watch?v=QkYD7rMul14&feature=related
Chapter Lab : Chapter Lab Lab 1.2.4 Build a Hierarchical Topology