Information Science Institute of Sripatum University
IS516
Computer Communication and Networks
ื่ สารคอมพิวเตอร์และเครือข่าย
การสอ
Asst.Dr.Surasak Mungsing
surasak.mu@spu.ac.th
mungsing@gmail.com
http://www.spu.ac.th/teacher/surasak.mu
Sripatum University
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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
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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 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 fiberoptic 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
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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

Cascade switches and hubs

Reassign use of resources to appropriate
needs
domains
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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
บริษัท ABC เป็ นบริษัททีต
่ ัง้ ขึน
้ ใหม่ มีสำนั กงำนใหญ่และฝ่ ำยขำยตัง้ อยู่ใน
ื่ สำร
เมืองใหญ่ซงึ่ มีโครงสร ้ำงพืน
้ ฐำน (Infrastructure)
ด ้ำนกำรติด ต่อสอ
เพรียบพร ้อม

ิ ธพิเศษด ้ำนกำร
บริษัทฯได ้ลงทุนสร ้ำงโรงงำนผลิตในเขตชนบทเพือ
่ ให ้ได ้สท
ลงทุนและภำษี แต่ทต
ี่ งั ้ โรงงำนเป็ นท ้องถิน
่ ทีข
่ ำดแคลนระบบโทรศัพท์พน
ื้ ฐำน
ื่ สำรทำงสำย
และกำรติดต่อสอ

ื้ ซอ
ื้ วัต ถุด บ
กำรดำเนินกำรของธุรกิจจะต ้องมีกำรค ้นหำข ้อมูลเพือ
่ กำรจั ดซ อ
ิ
จำกต่ำ งประเทศมำป้ อนให ้กับ โรงงำนผลิต อย่ำ งสม่ ำ เสมอและกำรหำตลำด
ิ ค ้ำ บริษั ทฯมีน โยบำยให ้โรงงำนผลิต ส่ ง
ต่ำ งประเทศ เพื่อ กำรจ ำหน่ ำ ยส น
์ ก
รำยงำนกำรผลิตด ้วยเอกสำรอิเลกทรอนิกสท
ุ วัน

จงออกแบบระบบเครือข่ำยคอมพิวเตอร์เพือ
่ รองรับกำรดำเนินธุรกิจของบริษัท
ABC โ ด ย พิ จ ำ ร ณ ำ ใ ห ค
้ ร อ บ ค ลุ ม ถึ ง ก ำ ร ใ ช ง้ ำ น ภ ำ ย ใ น ส ำ นั ก ง ำ น ก ำ ร
ติด ต่ อ ส ื่อ สำรระหว่ำ งหน่ ว ยงำนของบริษั ทฯที่อ ยู่ ห่ำ งไกลกั น ตลอดจนกำร
ติด ต่ อ ส ื่อ สำรกั บ ต่ ำ งประเทศ ในกำรออกแบบ ให ้อธิบ ำยเหตุ ผ ลและวำด
ภำพประกอบกำรออกแบบและตัง้ สมมติฐำนได ้คำมทีเ่ ห็นสมควร

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Next Lecture:
Network Performance
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