sripatum university

SPU

Information Science Institute of Sripatum University

Sripatum University1

IS516

Computer Communication and Networks

การสื่��อสื่ารคอมพิ�วเตอร�และเคร�อข่�าย

Asst.Dr.Surasak Mungsing

[email protected] [email protected]

http://www.spu.ac.th/teacher/surasak.mu

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Lecture 07 Network DesignNetwork Design

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Design Activities

The design activity is truly an in-depth process, which includes:

• collection of requirement and user expectations

• determine type of current and future data traffic based on growth rate of data and additional servers • determine all layer 1, 2 and 3 network devices to be used in the network system

• Create documents for both physical and logical design

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LAN Design Goals

Functionality – network must work at reasonable speed and reliability

Scalability – network must be scalable without sig รดรฟะ change of overall design

Adaptability – network design must take consideration of future technology and must not use components or devices not support by future technology when the time comes

Manageability – design must support network monitoring and management

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Design Methodology

Analyze requirements

Develop LAN structure (topology)

Set up addressing (and naming conventions) and routing

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Analyze Network and User Requirements Business issues

Technology issues

Administrative issues

Gather Data (corporate structure, business information flow, application in use, current topology, etc.)

Business requirements

Technical requirements

Applications or business operations

Availability requirements (throughput, response time, access to resource)

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Analyze Network Load Requirements

Client/Server

Host/terminal

Routing protocols

backup

worst-case traffic load

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Develop LAN Topology

Use LAN topology that fulfils requirements

Topology• Star Topology• Extended Star Topology

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Ethernet Technology Segmentation

Bridge and switch use for segmentation • Make more collision domains • Is still single broadcast domain

Collision domain (bandwidth domain)• Repeaters and hubs broadcast collisions

but not for switches, bridges androuters

Broadcast domain• Group of devices will receive frames from a

device in the group• Broadcast domains scope are limited by

routers because they do rebroadcast frames

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Network DesignThree types of topology design according to OSI

model Layer 1 - Physical LayerRelated to type of transmission lines such as CAT5 UTP and fiber-optic cable and also EIA/TIA 568 standard for line connection Layer 2 - Data Link LayerRelated to selection of layer-2 devices, e.g. bridges or LAN switches for connecting layer-1 devices to LAN segment. Layer-2 layer devices define collision and broadcast domains. Layer 3 - Network Layer Related to selection of layer-3 devices, e.g. routers that create unique LAN segments and communicate using layer 3 address such IP address

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Design Goals Physical Layer

• Creates communication layer focus on speed and performmance

Data Link Layer

Build MDFs or IDFs such that end hosts are group in Layer 1 to

create physical LAN segment Install LAN switches using microsegmentation to reduce size of

collision domain Build signal distribution point in network topology so that users are

group (at Layer 2) as virtual workgroups (VLANs) and unique broadcast domains.

Network Layer• Create communication path among LAN segments to filter flow of

data packets • Separate ARP protocol• separate collisions among segments. • Filter layer-4 services among segments

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Cable Types and Wiring Configurations Copper

• Coaxial• Twisted pair

Fiber-optic• Multimode• Single-mode

Wiring configurations• Star/Extended Star• Distance limitations

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Extended Star Topology Define standard according to EIA/TIA

Build groups of network and connect them with vertical cabling (Catchment areas )

All vertical cabling connect to MDF to build a single LAN segment

Vertical cabling - (Backbone cabling) transmission line that connects wiring closets and POP, and POP of other buildings that are parts of the same LAN

Catchment areas – areas that are serviced by networking device such as hubs

IDF - Intermediate Distribution Facility. Secondary network distribution room in a building for star network topology, a dependence of MDF.

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Layer 2 - LAN Switching

Objective of Layer 2 (Data Link Layer) is to control data flow and correct errors in network. The devices are NIC, Bridges and LAN switches

LAN switches (Layer 2 Switch) are capable to allocate bandwidth to a port, therefore it can assign very high bandwidth to vertical cabling, uplinks and servers

The theoretical maximum bandwidth for a Layer 2 Switch = (No-of-ports * Bandwidth)/2

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MDF-Main Distribution Facility MDF - Main Distribution Facility. A main distribution

room in a building for star topology, which contains patch panels, hub, and router

In a simple star topology, there is only one main distribution facility (MDF) that includes horizontal cross connect (HCC) patch panels.

HCC patch cables used to connect Layer 1 'horizontal cabling' (Layer 1) to LAN switch ports (Layer 2)

uplink port of LAN switch connects to Ethernet port of router (Layer 3 ) using‘ patch cable'. At this point, end host connects to router port

Quality of horizontal cable and number of ports of HCC patch panels will be defined by user requirements

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Use Switches to reduce congestion

Use microsegmentation to limit collision domains

Cascade switches and hubs

Reassign use of resources to appropriate needs

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Microsegmentation

Divide network into small segments to improve overall bandwidth of network

Installation of LAN switching at MDF and IDFs affects size of collision domains and data speed in each of horizontal cable and vertical cable. Vertical cable must handle all data traffic between MDF and IDFs therefore requires higher capacity

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Collision Domains

In the operational environment of only switch in network, size of collision domain is just the two hosts, when a hub is used the size of collision domain increases and bandwidth will be shared

Shared LAN hub is multiport repeater , therefore is collision domain. All hosts connected to shared LAN hub will share collision domain and the bandwidth

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Layer 3 - Routing

Using Layer-3 devices such as routers can create segmentation of LAN as unique networks for both physical and logical.

Routers can be used to connect wide area networks (WANS) e.g. Internet

Routers serve as broadcast firewalls

Routers consolidate for scalable internetworks

Network protocol addressing and routing provides

built-in scaling

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Documenting Your Network

Physical Network Maps (cutsheet) Logical Network Map (IP addressing

scheme) Addressing Maps (snapshot view of

network)

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Reasons to Document

Reducing a lot of time for problem solving Least document networks have the most

problems Good documenting helps reduce amount of

problems very much The more documents the better network

(maintenance)

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Summary of network design Gathering network requirements and using

information

Bandwidth requirements analysis

Define all layer-1, -2, and -3 networking devices (e.g. cable, hub, bridge, switch, router) and network topology

Documenting design such as table of equipments

Draw cable diagram and location of distribution box

Draw connection diagram of networking devices in network

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Exercise

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Next Lecture:Next Lecture:

Network Performance

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