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IS516 Computer Communication and Networks การสื่อสารคอมพิวเตอร์และเครือข่าย. Asst.Dr.Surasak Mungsing Sripatum University. Lecture 07 Network Design. Design Activities.

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Sripatum university


Computer Communication and Networks


Asst.Dr.Surasak Mungsing

Sripatum University

Lecture 07 network design

Lecture 07Network Design

Design activities
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

Lan design goals
LAN Design Goals

  • Functionality – network must work at reasonable speed and reliability

  • Scalability – network must be scalable without sigรดรฟะ 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

Design methodology
Design Methodology

  • Analyze requirements

  • Develop LAN structure (topology)

  • Set up addressing (and naming conventions) and routing

Analyze network and user requirements
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)

Analyze network load requirements
Analyze Network Load Requirements

  • Client/Server

  • Host/terminal

  • Routing protocols

  • backup

  • worst-case trafficload

Develop lan topology
Develop LAN Topology

  • Use LAN topology that fulfils requirements

  • Topology

    • Star Topology

    • Extended Star Topology

Ethernet technology
Ethernet Technology

  • Segmentation

    Bridge andswitch use for segmentation

    • Make more collision domains

    • Is stillsingle 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

  • Network design
    Network Design

    Three types of topology design according to OSI model

    • Layer 1 - Physical LayerRelated to type of transmission lines such as CAT5 UTP andfiber-opticcable 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 switchesfor connecting layer-1 devices to LAN segment. Layer-2 layer devices define collision and broadcast domains.

    • Layer 3 - Network LayerRelated to selection of layer-3 devices, e.g. routers that create unique LAN segments and communicate using layer 3 address such IP address

    Design goals
    Design Goals

    • Physical Layer

      • Creates communication layer focus on speed and performmance

    • Data Link Layer

      • Build MDFs or IDFs such that end hosts are groupin Layer 1 to create physical LAN segment

      • Install LAN switches usingmicrosegmentation 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

      • separatecollisions among segments.

      • Filter layer-4 services among segments

    Cable types and wiring configurations
    Cable Types and Wiring Configurations

    • Copper

      • Coaxial

      • Twisted pair

    • Fiber-optic

      • Multimode

      • Single-mode

    • Wiring configurations

      • Star/Extended Star

      • Distance limitations

    Extended star topology
    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.

    Layer 2 lan switching
    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, thereforeit 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

    Mdf main distribution facility
    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 switchconnects 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

    Use switches to reduce congestion
    Use Switches to reduce congestion

    • Use microsegmentation to limit collision domains

    • Cascade switches and hubs

    • Reassign use of resources to appropriate needs


    • Divide network into small segments to improve overall bandwidth of network

    • Installation of LAN switching atMDF 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

    Collision domains
    Collision Domains

    • In the operational environment of only switch in network, size of collision domain is just the two hosts, whena hub is usedthe 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

    Layer 3 routing
    Layer 3 - Routing

    • Using Layer-3 devices such asrouters can createsegmentation 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

    Documenting your network
    Documenting Your Network

    • Physical Network Maps (cutsheet)

    • Logical Network Map (IP addressing scheme)

    • Addressing Maps (snapshot view of network)

    Reasons to document
    Reasons to Document

    • Reducing a lot of time for problem solving

    • Least document networks have the most problems

    • Good documenting helps reduce amount of problemsvery much

    • The more documents the better network(maintenance)

    Summary of network design
    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


    • บริษัท ABC เป็นบริษัทที่ตั้งขึ้นใหม่ มีสำนักงานใหญ่และฝ่ายขายตั้งอยู่ในเมืองใหญ่ซึ่งมีโครงสร้างพื้นฐาน (Infrastructure) ด้านการติดต่อสื่อสารเพรียบพร้อม

    • บริษัทฯได้ลงทุนสร้างโรงงานผลิตในเขตชนบทเพื่อให้ได้สิทธพิเศษด้านการลงทุนและภาษี แต่ที่ตั้งโรงงานเป็นท้องถิ่นที่ขาดแคลนระบบโทรศัพท์พื้นฐานและการติดต่อสื่อสารทางสาย

    • การดำเนินการของธุรกิจจะต้องมีการค้นหาข้อมูลเพื่อการจัดซื้อซื้อวัตถุดิบจากต่างประเทศมาป้อนให้กับโรงงานผลิตอย่างสม่ำเสมอและการหาตลาดต่างประเทศ เพื่อการจำหน่ายสินค้า บริษัทฯมีนโยบายให้โรงงานผลิตส่งรายงานการผลิตด้วยเอกสารอิเลกทรอนิกส์ทุกวัน

    • จงออกแบบระบบเครือข่ายคอมพิวเตอร์เพื่อรองรับการดำเนินธุรกิจของบริษัท ABC โดยพิจารณาให้ครอบคลุมถึงการใช้งานภายในสำนักงาน การติดต่อสื่อสารระหว่างหน่วยงานของบริษัทฯที่อยู่ห่างไกลกันตลอดจนการติดต่อสื่อสารกับต่างประเทศ ในการออกแบบ ให้อธิบายเหตุผลและวาดภาพประกอบการออกแบบและตั้งสมมติฐานได้คามที่เห็นสมควร

    Sripatum university

    Next Lecture:

    Network Performance