Information Science Institute of Sripatum University

IS516 Computer Communication and Networks การสื่อสารคอมพิวเตอร์และเครือข่าย Asst.Dr.Surasak Mungsing

[email protected] [email protected]

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

Sripatum University

1 SPU

Lecture 07

Network 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 3 SPU

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LAN Design Goals



Functionality

– network must work at reasonable speed and reliability 

Scalability

รดรฟะ – network must be scalable without sig 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 4 SPU

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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) 6 SPU

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Analyze Network Load Requirements

     Client/Server Host/terminal Routing protocols backup worst-case traffic load 7 SPU

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Develop LAN Topology

  Use LAN topology that fulfils requirements Topology • Star Topology • Extended Star Topology 8 SPU

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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 9 SPU

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Network Design

Three types of topology design according to OSI model 

Layer 1 - Physical Layer

Related 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 Layer

Related 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 10 SPU

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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 packets • Separate ARP protocol • separate collisions among segments. • Filter layer-4 services among segments to filter flow of data 11 SPU

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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 12 SPU

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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 facility (MDF) that includes patch panels. main distribution horizontal cross connect (HCC) HCC patch cables used to connect Layer 1 (Layer 1) to LAN switch ports (Layer 2) 'horizontal cabling' uplink port of LAN switch connects to Ethernet port of router (Layer 3 ) using to router port ‘ patch cable' . At this point, end host connects Quality of horizontal cable and number of ports of HCC patch panels will be defined by user requirements 19 SPU

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Use Switches to reduce congestion



Use microsegmentation to limit domains collision



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 24 SPU

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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 25 SPU

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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 (WANS) e.g. Internet

wide area networks

 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) 31 SPU

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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 32 SPU

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Exercise

 บริษัท ABC เป็นบริษัทที่ตั้งขึ้นใหม่ มีส ำนักงำนใหญ่และฝ่ำยขำยตั้งอยู่ใน เมืองใหญ่ซึ่งมีโครงสร ้ำงพื้นฐำน (Infrastructure) ด ้ำนกำรติดต่อสื่อสำร เพรียบพร ้อม  บริษัทฯได ้ลงทุนสร ้ำงโรงงำนผลิตในเขตชนบทเพื่อให ้ได ้สิทธพิเศษด ้ำนกำร ลงทุนและภำษี แต่ที่ตั้งโรงงำนเป็นท ้องถิ่นที่ขำดแคลนระบบโทรศัพท์พื้นฐำน และกำรติดต่อสื่อสำรทำงสำย  กำรด ำเนินกำรของธุรกิจจะต ้องมีกำรค ้นหำข ้อมูลเพื่อกำรจัดซื้อซื้อวัตถุดิบ จำกต่ำงประเทศมำป้อนให ้กับโรงงำนผลิตอย่ำงสม ่ำเสมอและกำรหำตลำด ต่ำงประเทศ เพื่อกำรจ ำหน่ำยสินค ้ำ บริษัทฯมีนโยบำยให ้โรงงำนผลิตส่ง รำยงำนกำรผลิตด ้วยเอกสำรอิเลกทรอนิกส์ทุกวัน  จงออกแบบระบบเครือข่ำยคอมพิวเตอร์เพื่อรองรับกำรด ำเนินธุรกิจของบริษัท ABC โดยพิจำรณำให ้ครอบคลุมถึงกำรใช ้งำนภำยในส ำนักงำน กำร ติดต่อสื่อสำรระหว่ำงหน่วยงำนของบริษัทฯที่อยู่ห่ำงไกลกันตลอดจนกำร ติดต่อสื่อสำรกับต่ำงประเทศ ในกำรออกแบบ ให ้อธิบำยเหตุผลและวำด ภำพประกอบกำรออกแบบและตั้งสมมติฐำนได ้คำมที่เห็นสมควร 33 SPU

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Next Lecture: Network Performance

34 SPU