Network Design - Chapter 1: Introduction - University of Pittsburgh

Nội dung text: Network Design - Chapter 1: Introduction - University of Pittsburgh

1. Network Design David Tipper Associate Professor Department of Information Science and Telecommunications University of Pittsburgh tipper@tele.pitt.edu Slides 1 Course Outline • Introduction (Ch 1) – Class Organization, overview of network design issues • Requirements and Planning (Ch 2, 4, notes) – Business and Technical Goals and Constraints – Economics and Technology Choices – Traffic Demand Modeling and capacity requirements • Network Design Modelling and Algorithms (Ch 5, notes) – Relevant Results from Graph Theory – Relevant Results from Optimization Theory – Heuristics – CAD Tools Telcom 2110 Spring 2006 2 1
2. Course Outline • Access Network Design (Chapter 6) – Topology algorithms, physical design – WLAN design • Wide Area Packet Network Design (Ch 7,8) – Design Algorithms – Virtual network design (Ch 9) – Fault Tolerance/Survivability • Transport/Circuit Switched Network Design – Optical Backbone Design – Metro Network Design • Cellular Network Design • Case Studies (handouts) Telcom 2110 Spring 2006 3 Network Design • A “Network” can be thought as – Electronic communication devices • PCs, phones, PDAs, laptops, etc. – Network Devices • (hubs, routers, cross-connects, base stations, etc ) – Communication links • (Coax cable, 10base T, T1, T3, OC1, etc.) – Services • Phone calls, video, web, etc. • Network Design – Determines the location and type of network devices, the types and size of communication links to provide services to the electronic communication devices. Telcom 2110 Spring 2006 4 2
3. Types of Network Design • Can classify network design problems several ways 1. Greenfield Network Design • build a new network from scratch 2. Incremental Network design • Re-engineering a network – Upgrade/change technology – increase capacity – Improve fault tolerance, performance, etc. • Network expansion design – Add users/facilities to a network 3. Virtual Network Design – Build an overlay network on top of an existing infrastructure Telcom 2110 Spring 2006 5 Greenfield Example Base BS5 BS3 stations BS4 BS4 IBM locations BS3 BS3 BS2 BS4 determined BS2 MSC BS1 by radio BS1 BS7 BS7 BS5 coverage BS1 BS3 BS6 BS3 BS2 BS4 BS4 BS1 BS2 BS1 BS7 BS5 BS5 BS6 BS7 BS6 SD SD SD SD BayNet works Centillion1400 BayNet works Centillion1400 BayNet works Centillion 1400 B ay Net works Ce n tillion 1400 ETHERLINK RS 232C INS ACT ALM ETHERLINK RS 232C INS ACT ALM P* 8x50 RST P* 8x50 RST O O130 O O130 AO N AO N ETHERLINK RS 232C INS ACT ALM ETHERLINK RS 322C INS ACT ALM P* 8x50 P* 8x50 6 6 RST RST O O130 O O130 AO N A O N PCCARD PCCARD 6 6 PC CARD PC CARD ALM ALM PWR ALM FAN0 FAN1 PWR0 PW R1 PWR ALM FAN0 FAN1 PWR0 PW R1 ALM ALM PWR ALM FAN0 FAN1 PWR0 PW R1 PWR ALM FAN0 FAN1 PWR0 PW R1 30 BS, 4 BSC BSC BSC BSC BSC Telcom 2110 Spring 2006 6 3
4. Example Minimum-cost network design BS5 BS3 BS4 BS4 IBM BS3 BS3 SD BS2 BayNet works Ce n tillion1400 BS4 ETHERLINK RS 232C INS ACT ALM P* 8x50 RST O O130 AO N 6 PCCARD ALM PWR ALM FAN0 FAN1 PWR0 PW R1 BS2 BSC MSC SD BayNet works Ce n tillion1400 ETHERLINK RS 232C INS ACT ALM P* 8x50 RST O O130 AO N BS1 6 PCCARD ALM PWR ALM BS1FAN0 FAN1 PWR0 PW R1 BS7 BSC SD BS7 BayNet works Ce n tillion1400 BS5 ETHERLINK RS 232C INS ACT ALM P* 8x50 RST O O130 AO N 6 PCCARD BS1 ALM PWR ALM FAN0 FAN1 PWR0 PW R1 BS3 BSC BS6 BS3 BS2 BS4 SD BayNet works Ce n tillion1400 ETHERLINK RS 232C INS ACT ALM P* 8x50 RST O O130 AO N 6 PCCARD BS4 ALM PWR ALM FAN0 FAN1 PWR0 PW R1 BS1 BSC BS2 BS1 BS7 BS5 BS5 BS6 BS7 BS6 30 BS, 4 BSC Telcom 2110 Spring 2006 7 Incremental Design Example Given Topology how do I make it single link BS5 BS3 fault tolerant BS4 BS4 Mesh-restoration IBM BS3 BS3 SD BS2 BayNet works Centillion1400 BS4 ETHERLINK RS 232C INS ACT ALM P* 8x50 RST O O130 AO N 6 PCCARD ALM PWR ALM network design FAN0 FAN1 PWR0 PW R1 BS2 BSC MSC SD BayNet works Centillion1400 P* 8x50 ETHERLINK RS 232C INS ACT ALM RST O O130 AO N BS1 6 PCCARD ALM PWR ALMBS1 FAN0 FAN1 PWR0 PW R1 BS7 BSC SD BS7 BayNet works Ce n tillion1400 BS5 P* 8x50 ETHERLINK RS 232C INS ACT ALM RST O O130 AO N 6 PCCARD BS1 ALM PWR ALM FAN0 FAN1 PWR0 PW R1 BS3 BSC BS6 BS3 BS2 BS4 SD BayNet works Ce n tillion1400 P* 8x50 ETHERLINK RS 232C INS ACT ALM RST O O130 AO N 6 PCCARD BS4 ALM PWR ALM FAN0 FAN1 PWR0 PW R1 BS1 BSC BS2 BS1 BS7 BS5 BS5 BS6 BS7 BS6 30 BS, 4 BSC Backup link Telcom 2110 Spring 2006 8 4
5. Virtual Private Network Design Provider Edge (PE) Router Provider Core Router C Label Switch Path (LSP) Overlay A VPN Network B 1 2 Service Provider Core Network 3 5 4 6 Telcom 2110 Spring 2006 9 Types of Network Design • Can classify network design problems - size 1. Access Networks • LAN, Campus, Metro access networks, cellular networks, etc • Historically informal design procedures – becoming more mathematical based 2. Metro Networks • Interconnection central offices , POPs, corporate locations • Higher bandwidth, may include leased lines 3. Wide Area Networks • Backbone networks (UUNET, Verizon) • Corporate VPN • Mathematical Optimization based design procedures Telcom 2110 Spring 2006 10 5
6. Network Infrastructure Components Network have varying technology, components, protocols and applications Long haul - WAN Building 3 (inter exchange network) Building 4 City D Metro (LEC inter- Building 1 City C City E City A office network) Building 2 Central office 1 Access Enterprise 2 Central office 2 City B Central office 3 Cross connects, routers, etc. Sonet, Fiber, MPLS, FR, etc Enterprise 1 DWDM, ATM, MPLS, IP, etc. SS7, SIP, BGP, etc, Access: Twisted pair, T1, DSL, Cable Modem, etc. Telcom 2110 Spring 2006 11 Transmission Rates POTS Line <64 Kbps T1 1.5 Mbps T3 44.736 Mbps OC-1 51 Mbps OC-3 155 Mbps OC-12 622 Mbps Rates increase OC-48 2.5 Gbps from edge to core OC-192 10 Gbps OC-768 40 Gbps DWDM 1.6Tbps Next Gen 10 Tbps Microwave 45 Mbps Laser <1Gbps Cable 3-10 Mbps POTS = "Plain Old Telephone Service" DWDM= Dense Wavelength Division Multiplexing, OC= Optical Carrier Telcom 2110 Spring 2006 12 6
7. Types of Network Design • Can classify network design problems on technology – Wired vs. Wireless – Circuit switched vs. packet switched – Hierarchical facility vs. flat – ATM vs. IP –Etc. Vs. Telcom 2110 Spring 2006 13 LAN vs. WLAN Design -80 dBm • LAN selection of technology and cabling • AP Placement Minimize path loss – Maximum signal to most users – Transmitter placement problem – Take measurement to get Signal -80 dBm quality map Telcom 2110 Spring 2006 14 7
8. Main Network Design Issues • How many $ are needed to get a usable network? • What sort of network performance can we get with Y additional $? • What should our network look like? Telcom 2110 Spring 2006 15 Network Design Tools • Computer Aided Design Tools available – Aimed at Metro and Backbone network Design – User provides set of traffic demands, geographic locations, performance requirements – Use some optimization based formulation with heuristic solution to minimize $ Telcom 2110 Spring 2006 16 8
9. Network Design Tools • Variety of tools available – WANDL, VPISystems, OPNET, RSOFT, etc. – trend to link them to simulation packages – can verify design Telcom 2110 Spring 2006 17 Top Down Network Design Approach • Regardless of network design problem can follow a top down network design approach A top down network design project approach should follow three phases: – Conceptual Model • Objectives, Requirements, Constraints – Logical Model • Technology, network graph, node location, link size, etc. (where algorithms are used to minimize cost) – Physical Model • Specific hardware/software implementations • (e.g., wiring diagram, repeater locations, etc.) Telcom 2110 Spring 2006 18 9
10. Conceptual Model Design • Determining Objectives – Try to understand the customer’s business • industry, market, suppliers, product, the competition they face, etc. – Try to understand the organizational structure of the business, their separate departments, lines of business, remote offices, etc. • Identify Business Objectives of the project – Through surveys/questionnaires, meetings Telcom 2110 Spring 2006 19 Business Goals • Identify overall business goal of network – What will the network be used for? Mission critical uses? – How does the customer think the new network will improve their business practices? – What is the criteria to be used to judge the network success/failure? • Typical business goals (may not be realistic!) – Increase revenue and profit – Shorten product development cycles/improve corporate communications – Provide new services/Modernize out-dated technologies – Reduce network costs – Make more data available to more people – Improve network security and reliability Telcom 2110 Spring 2006 20 10
11. Business Goals - Continued • What is the scope of the project? – Greenfield or incremental design • Interoperability? –Network Size • (LAN, Campus net, enterprise WAN, backbone, etc.) • Sites to be connected, distances, etc. – What are current/existing networks and services – Identify applications and services to be provided from surveys and meetings – As a guideline construct a table with the following info Type of New App? Application Application Freq of use Criticality Comments Sales Distributed No/hourly Very Tracking client/server Telcom 2110 Spring 2006 21 Business Constraints • Organizational Politics and Policies – Who will manage/run network – What are the companies policy on suppliers, platforms, vendors etc. – Open vs. proprietary solutions? – Security issues • Budget and Staffing Constraints – Your design must fit the budget – Staff abilities may determine some of your design – Is a business case/life cycle cost analysis needed? • Scheduling – Timeline, milestones Telcom 2110 Spring 2006 22 11
12. Technical Goals & Constraints • From surveys/questionnaires, meetings etc. application data determine technical goals and constraints • Technical goal is to build a network that meets user’s requirements + some they may not know they need. • Technical Goals – Scalability – Availability – Network Performance • Utilization, Throughput, Delay, Delay Jitter, Packet Loss, Call blocking, etc. • Traffic Estimation important –Security – Manageability/Interoperability – Affordability $$ Telcom 2110 Spring 2006 23 Conceptual Level of Network Design œ What do the users want? –Services  What do the users need? ž What don’t they know they need? (e.g., reliability, security) Interviews/questionnaires used to gather data What type of applications (voice, data, email) Application – characteristics Frequency of use Identify Constraints: Budget management capabilities technical requirements, etc. Telcom 2110 Spring 2006 27 12
13. Logical Level Network Design • Translate Conceptual Level Goals and requirements into Logical Level design – what kind of network will meet the conceptual design based on the information gathered – Characterize network traffic and performance requirements – Topological network design (may use an algorithm here!) • Technology selection • Costing • Performance tradeoffs • Need for sub-netting • addressing issues •etc. Telcom 2110 Spring 2006 28 Logical Level Network Design • Typically many alternate logical designs are feasible • Rank based on attributes –Cost – Performance • Delay, throughput,call blocking, availability, etc. – Scalability – Management – Maintenance – Utilization –Etc. • May ask managers to evaluate tradeoffs – One approach is assume 100 point to be distributed among the categories of interest and users must allocate the points among the attributes Telcom 2110 Spring 2006 29 13
14. Physical Level Network Design • Hardware level requirements – Specific Router performance based on bandwidth requirements – Switches, Repeaters, etc • Equipment location requirements – Physical security requirements – Electrical Power • Capacity and Media selection – Bandwidth required, coax, fiber, etc. – Wiring diagrams Telcom 2110 Spring 2006 30 Summary • Network Design is not a precise science. – Many different types of problems • e.g., greenfield vs. incremental, wired vs. wireless – There can be several good answers (many more bad ones!) - usually no one best solution. – It involves trade-offs among cost vs. performance, technical vs. non-technical issues • Top Down Design approach useful as a framework • In large network designs (WAN, Metro) use mathematics to help designers. •Use computer models to solve mathematical formulations when possible Telcom 2110 Spring 2006 31 14