exploration switching and wireless chapter 1

8/6/2019 Exploration Switching and Wireless Chapter 1

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2007 Cisco Systems, Inc. All rights reserved. Cisco PublicITE PC v4.0Chapter 1 1

LAN Design

LAN Switching and Wireless Chapter 1


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ITE PC v4.0Chapter 1 2 2007 Cisco Systems, Inc. All rights reserved. Cisco Public

Objectives Describe how a hierarchical network supports the voice, video,and data needs of a small- or medium-sized business.

Describe the functions of each of the three levels of thehierarchical network design model, the principles of hierarchicalnetwork design (aggregate connectivity, network diameter, andredundancy), and the concept of a converged network.

Provide examples of how voice and video over IP affect networkdesign.

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.


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Switched LAN architectureThe Hierarchical Network Model

Is easier to manage and expand

Problems are solved more quickly Dividing networks into three discrete layers

Function of three layers

Modular Facilitates scalability

Facilitates performance

Which three layers? Access layer

Distribution layer Core layer


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Switched LAN architectureThe Hierarchical Network Model Access layer

Interfaces with end-devices Provides access to the network

Controlling which devices are allowed to communicate om

the network


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Switched LAN architectureThe Hierarchical Network Model Distribution layer

Aggregates data from access layer before it is transmittedto the core layer

Controls flow of network traffic using policies

Delineates broadcast domains using routing functionsbetween VLANs


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Core layer

High-speed backbone of the internetwork Connectivity between distribution layers

Must be highly available and redundant

Must be capable of forwarding large amounts of dataquickly


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Logical representation


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Installed in a business

Physical layout


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Switched LAN architectureBenefits of a Hierarchical Network Model

Scalability Can be easily expanded

Redundancy At the core and distribution layer ensures path availability

Performance Link aggregation between levels and high-performance core and

distribution level switches allow for near wire-speed throughout

the network

Security Port security at the access level and policies at the distribution

level make the network more secure Manageability

Consistency between switches at each level makes management

simpler

Maintainability The modularity of hierarchical design allow for the network to

scale without becoming overly complicated


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Switched LAN architecturePrinciples of Hierarchical Network Design

Hierarchical Network Design Principles Network Diameter

The number of devices crossed to the destination

Keep it low to ensure low and predictable latency


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Hierarchical Network Design Principles Bandwidth aggregation

The practice of considering the specific bandwidthrequirements for each part of the hierarchy

Links between switches can be aggregated to achieve higher

throughput


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Redundancy

for creating highly available networks

Redundantlinks in thedistribution

and corelayer


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Start at the access layer

Equipment (PC, servers,) selection at the access layer Determine amount of access layer switches

Continue with distribution layer

Amount of access layer switches and estimated trafficdetermines the distribution layer switches to achieve

performance and redundancy

End with core layer Identify the amount of core layer switches required for

performance


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Server placementTo maximize available LAN bandwidthand performance, the following LANdesign considerations must beaddressed:- The function and placement ofservers- Collision detection issues

- Segmentation issues- Broadcast domain issuesServers can be categorized into twodistinct classes:- enterprise servers: supports aservice that everyone in anorganization would need , such as e-mail or Domain Name System (DNS).(placed in the main distribution facility

(MDF)- workgroup serversupports aspecific set of users, offering servicessuch as word processing and filesharing.(placed in the intermediatedistribution facilities (IDFs)


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Microsegmentation

Micro-segmentation

reduces the collisiondomains


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Layer 2 switching

Access switches provide

connectivity to thenetwork


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Extended Star technologiy

Star topology

Theoretically 100mcatchment area, in

real live 60 to 75m


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Logical diagram


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Cut sheet


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Switched LAN architectureWhat is a converged network?

Legacy equipment

Combining voice and video on the same data-network Needs high requirements and a complex management

Needs QoS (Quality of Service)

Advanced technology Convergence is easier to implement and manage and less

expensive Moving to a converged network

can be difficult if the businessalready invested in separate

voice, video and data-networks


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New options

Video-conference PC-based IP phone applications

Advanced IP phones


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Separate Voice, Video and Data Networks

Voice

network

Video

network

Datanetwork


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Matching switches to specific LAN functionsConsiderations for Hierarchical Network Switches

Traffic flow analysis 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 improvementdecisions

is done using traffic flow analysis software.

Analysis tools


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User communities Analysis the process of identifying various groupings of users and their

impact on network performance

The way users are grouped affects issues related to portdensity and traffic flow, which, in turn, influences the selection

of network switches

Future growth A solid network plan includes the rate of personnel growth

over the past five years to be able to anticipate the futuregrowth


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Data stores and Data Servers Analysis 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 arestored.

Client-servercommunications

Server-servercommunications


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Topology diagrams a graphical representation of a network infrastructure


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Switch features Switch form factors

Fixed configuration fixed in their configuration

you cannot add features or options to the switch beyondthose that originally came with the switch

Modular switches flexibility in their configuration

come with different sized chassis that allow for theinstallation of different numbers of modular line cards

Stackable switches

can be interconnected using a special backplane cablethat provides high-bandwidth throughput between theswitches


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Switch features Performance

Port density number of ports available on a single switch

Fixed ports (24 or 48) Modular (up to 1000 plus ports)

Forwarding rates define the processing capabilities of a switch by rating how

much data the switch can process per second Link Aggregation

you should determine if there are enough ports on a switch

to aggregate to support the required bandwidth


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Switch features PoE (Power over Ethernet)

allows the switch to deliver power to a device over theexisting Ethernet cabling.


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Switch features Layer 3 functionality


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Switch features in a hierarchical Network Access layer switches

Connect to end node devices need to support port security, VLANs, Fast/Gigabit Ethernet,

PoE and link aggregation

The following Cisco switches are commonly used at theaccess layer:

Catalyst 1900 series



Catalyst 4000 series (modular)

Catalyst 5000 series (modular)

Catalist 4000series


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Switch features in a hierarchical Network

Distribution layer switch featuresCollect data from all the access layer switches

Forward data to the core layer switchesNeed to support inter-VLAN routing and Layer 3

functionS

Need to support Security PoliciesAccess Control Lists

Need to support QoSNeed to support redundancy for adequate availability

Need to support multiple, hot swappable power

supplies

need to support link aggregation

Cisco distribution layer switches

Catalyst 2926G

Catalyst 5000 (family)

Catalyst 6000 (familyr)


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Switch features in a hierarchical Network Core layer switches

Need to handle very high forwarding

rates

needs to support link aggregation to

ensure adequate bandwidth

The availability of the core layer is alsocritical, so you should build in as much

redundancy as you can

Need to support hot-swappable

hardware

Need to support QoS

The following Cisco switches aresuitable for the core layer:



IGX 8400 series

Lightstream 1010


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Switches for Small and Medium SizedBusiness (SMB) Catalyst Express 500 Catalyst 2960

Catalyst 3560

Catalyst 3750

Catalyst 4500 Catalyst 4900

Catalyst 6500

Catalyst 6500


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Summary

Switched LAN architecture Matching switches to specific LAN functions

Switch features

Switch features in a hierarchical Network

Switches for Small and Medium Sized Business (SMB)

exploration switching and wireless chapter 1

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