Chapter 1: LAN Design
Scaling Networks
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Chapter 1 – Sections & Objectives
§ 1.1 Campus Wired LAN Designs
• Explain why it is important to design a scalable hierarchical network.
§ 1.2 Selecting Network Devices
• Select network devices based on feature compatibility and network
requirements.
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1.1 Campus Wired LAN Designs
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Campus Wired LAN Designs
Cisco Validated Designs
§ The Need to Scale the Network
• Allenterprisenetworksmust:supportcriticalapplications,supportconverged network traffic, support diverse business needs, and provide centralized administrative control.
• CampusnetworkdesignsincludesmallnetworksthatuseasingleLANswitch,upto very large networks with thousands of connections.
§ A hierarchical LAN design includes the access, distribution, and core layers:
• The access layer provides endpoints
and users direct access to the
network.
• The distribution layer aggregates
access layers and provides
connectivity to services.
• The core layer provides connectivity
between distribution layers for large LAN environments.
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Campus Wired LAN Designs
Expanding the Network
§ To support a large, medium or small network, the network designer must develop a strategy to enable the network to be available and to scale effectively and easily.
§ One method of implementing redundancy is by installing duplicate equipment and providing failover services for critical devices. Another method of implementing redundancy is redundant paths.
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Campus Wired LAN Designs
Expanding the Network (Cont.)
§ A failure domain is the area of a network that is impacted when a critical device or network service experiences problems. Smaller failure domains reduce the impact of a failure on company productivity.
§ Link aggregation allows an administrator to increase the amount of bandwidth between devices by creating one logical link made up of several physical links. EtherChannel is a form of link aggregation used in switched networks.
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Campus Wired LAN Designs
Expanding the Network (Cont.)
§ To communicate wirelessly, end devices require a wireless NIC that incorporates a radio transmitter/receiver and the required software driver to make it operational. Additionally, a wireless router or a wireless access point (AP) is required for users to connect.
§ Link-state routing protocols, such as Open Shortest Path First (OSPF), works well for larger hierarchical networks where fast convergence is important. OSPF routers establish and maintain neighbor adjacency or adjacencies, with other connected OSPF routers.
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1.2 Selecting Network Devices
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Selecting Network Devices Switch Hardware
§ There are five categories of switches for enterprise networks: Campus LAN, Data Center, Cloud- Managed, Service Provider, and Virtual Networking.
§ The port density of a switch refers to the number of ports available on a single switch. Fixed configuration switches typically support up to 48 ports on a single
device. Modular switches can support very high-port densities through the addition of multiple switch port line cards.
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Selecting Network Devices
Switch Hardware (Cont.)
§ Forwarding rates define the processing capabilities of a switch by rating how much data the switch can process per second.
§ Wire speed is the data rate that each Ethernet port on the switch is capable of attaining. Data rates can be 100 Mb/s, 1 Gb/s, 10 Gb/s, or 100 Gb/s.
§ Less expensive, lower performing switches can be used at the access layer, and more expensive, higher performing switches can be used at the distribution and core layers, where the forwarding rate has a greater impact on network performance.
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Selecting Network Devices
Switch Hardware (Cont.)
§ Power over Ethernet (PoE) allows the switch to deliver power to a device over the existing Ethernet cabling.
§ Multilayer switches are typically deployed in the core and distribution layers of an organization’s switched network. Multilayer switches are characterized by their ability to build a routing table, support a few routing protocols, and forward IP packets at a rate close to that of Layer 2 forwarding.
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Selecting Network Devices
Router Hardware (Cont.)
§ Routers play a critical role in networking by connecting homes and businesses to the Internet, interconnecting multiple sites within an enterprise network, providing redundant paths, and connecting ISPs on the Internet. They also act as a translator between different media types and protocols.
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Selecting Network Devices
Router Hardware (Cont.)
§ There are three categories of routers: Branch, Network Edge, and Service Provider.
§ Routers also come in many form factors. Network administrators in an enterprise environment should be able to support a variety of routers, from a small desktop router to a rack-mounted or blade model.
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Selecting Network Devices Managing Devices
§ IOS refers to the package of routing, switching, security, and other internetworking technologies integrated into a single multitasking operating system.
§ Out-of-band management is used for initial configuration or when a network connection is unavailable.
§ In-band management is used to monitor and make configuration changes to a network device over a network connection.
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Selecting Network Devices
Managing Devices (Cont.)
§ A basic router configuration includes the hostname for identification, passwords for security, assignment of IP addresses to interfaces for connectivity, and basic routing. Verify and save configuration changes using the copy running-config startup- config command. To clear the router configuration, use the erase startup-
config command and then the reload command.
§ Some of the most commonly used IOS commands to display and verify the operational
status of the router and related IPv4 network functionality are
• showipprotocols-Displaysinformationabouttheroutingprotocols configured.
• showiproute-Displaysroutingtableinformation,including:routingcodes,known networks, administrative distance and metrics, how routes were learned, next hop, static routes, and default routes.
• showinterfaces-Displaysinterfaceswithline(protocol)status,bandwidth,delay, reliability, encapsulation, duplex, and I/O statistics.
• showipinterfaces-Displaysinterfaceinformation,including:protocolstatus,the IPv4 address, if a helper address is configured, and whether an ACL is enabled on the interface.
• showipinterfacebrief-DisplaysallinterfaceswithIPv4addressinginformation and interface and line protocols status.
• showprotocols-Displaysinformationabouttheroutedprotocolthatisenabled, and the protocol status of interfaces.
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Selecting Network Devices
Managing Devices (Cont.)
§ A basic router configuration includes the hostname for identification, passwords for security, assignment of IP addresses to interfaces for connectivity, and basic routing.
§ Verify and save configuration changes using the copy running-config startup-config command. To clear the router configuration, use the erase startup-config command and then the reload command.
§ Some of the most commonly used IOS commands to display and verify the operational status of the router and related IPv4 network functionality are:
• showipprotocols
• showiproute
• showinterfaces
• showipinterfaces
• showipinterfacebrief • showprotocols
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Selecting Network Devices
Managing Devices (Cont.)
§ Verify and save the switch configuration using the copy running-config startup-config command. To clear the switch configuration, use the erase startup-config command and then the reload command. Erase any VLAN information using the command delete flash:vlan.dat. When switch configurations are in place, view the configurations using the show running- config command.
§ Switches make use of common IOS commands for configuration, to check for connectivity and to display current switch status:
• show port-security
• show port-security address
• show interfaces
• show mac-address-table
• show cdp neighbors
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