ITEC 275 Computer Networks – Switching, Routing, and WANs Week 2 Robert D’Andrea Winter 2016

Agenda Review Chapter #1 and 2 Analyzing Technical Goals Chapter #2 Business Goals Business Constraints Analyzing Technical Goals Chapter #2 Technical Goals Technical Constraints Introduce homework problems Lab Meetings

Typical Business Goals Increase revenue Increase profits Reduce costs Improve communications Shorten product development cycle Expand into worldwide markets Build partnerships with other companies Offer better customer support or new customer services

Typical Business Goals Improve in house training for employees Use a JIT manufacturing approach Avoid material shortages Improve security Modernize technologies Improve data center operations Monitor and reduce network traffic

Network Design and Implementation Cycle Analyze requirements Monitor and optimize network performance Develop logical design Develop physical design Implement and test network Test, optimize, and document design

Network Design Steps Phase 1 – Analyze Requirements Analyze business goals and constraints Analyze technical goals and tradeoffs Characterize the existing network Characterize network traffic

Network Design Steps Phase 2 – Logical Network Design Design a network topology Design models for addressing and naming Select switching and routing protocols Develop network security strategies Develop network management strategies

Network Design Steps Phase 3 – Physical Network Design Select technologies and devices for campus networks Select technologies and devices for enterprise networks

Network Design Steps Phase 4 – Testing, Optimizing, and Documenting the Network Design Test the network design Optimize the network design Document the network design

Top-Down Software Design Steps

The PDIOO Network Life Cycle Plan Design Retire Optimize Implement Operate

Software Life Cycle

Software Life Cycle Costs

Recent Business Priorities Mobility Security Resiliency (fault tolerance/robustness) Business continuity after a disaster Network projects must be prioritized based on fiscal goals Networks must offer the low delay required for real-time applications such as VoIP and video

Business Constraints Budget Staffing Schedule Politics and policies

Cisco Enterprise 3 Layer Design Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Core Layer: Core of the network Responsible for transporting large amounts of traffic reliably and quickly. Switch traffic as fast as possible If there is a failure at the core layer, every single user can be affected. Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Distribution Layer: Communication point between the Core and Access Layer Provide routine Provide filtering WAN access Determine how packets can access the core Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Access Layer: Controls user and workgroup access to internetwork resources Sometimes referred to as the desktop layer Resources usually are accessible locally Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Cisco Enterprise 3 Layer Design Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Network Technical Goals Scalability Availability Performance Security Manageability Usability Adaptability Affordability Scalability: How much growth a network design must support. Availability: The amount of time a network is available to users, often expressed as a percent uptime, or as a mean time between failure (MTBF) and mean time to repair (MTTR). Availability goals can also document any monetary cost associated with network downtime. Security: Goals for protecting the organization's ability to conduct business without interference from intruders inappropriately accessing or damaging equipment, data, or operations. Specific security risks should be documented. Manageability: Goals for fault, configuration, accounting, performance, and security (FCAPS) management Usability: Goals regarding the ease with which network users can access the network and its services, including goals for simplifying user tasks related to network addressing, naming, and resource discovery. Adaptability: The ease with which a network design and implementation can adapt to network faults, changing traffic patterns, additional business or technical requirements, new business practices, and other changes. Affordability: The importance of containing the costs associated with purchasing and operating network equipment and services.

Scalability Scalability refers to the ability to grow a network with existing hardware and software. How much growth is anticipated within the next 5 years? To ask a company to predict it’s growth for the next 5 years is a difficult prediction. Large companies expand more rapidly (users, applications, external networks, and new sites) than smaller ones. Expanding Access to Data 1970 - 1980 data stored on mainframes 1980 – 1990 data stored on servers 1990 – present data stored on centralized mainframes and servers 2010 – present data stored on cloud

Scalability 80/20 Rule Is based on 80 percent local in-house usage and 20 percent external Internet use. At the present time, the 80/20 Rule is moving to the other side of the scale. There is more external Internet access by employees in companies on a daily basis (20/80) than allowed or tolerated in the past. Some companies allow access with other companies, resellers, suppliers, and strategic customers. Introduction of the extranet. The extranet is used to describe an internal internetwork that is accessible by outside users.

Scalability The business goal of making data available to more departments, employees, and off site offices often results in a technical goal of using the mainframe as a powerful database server.

Scalability Some technologies are more scalable than others. Flat network designs at Layer 2 ( switch), do not scale well. Top-down network design offers more flexibility in accommodating changes such as hardware, software, and support staff. Top-down network design is an iterative process. Scalability goals and solutions are re-evaluated on a regular basis throughout the phases of the network design process.

Scalability Constraints Constraints often affect scalability inherent in network technologies. Selecting technologies that meet the customers scalability goals initially is a difficult process, especially if it is done without some planning. If there is a radical departure made in the design from the initial plan, the cost factor for enhancing the network could be significant.

Scalability During the initial design phase, extract information from the customer about their site. A network designer needs information about current and future network activity. - Number of sites to be added in the next 5 years - What functionality will be needed at each of these sites? - How many users will be added in the next 5 years? - How many more servers and mainframes will be added to a server farm or individual departments?

Availability Availability is the amount of time a network is operational – that is, how long it is transferring data or other transactions. Availability can be expressed as a percent of uptime per year, month, week, day, or hour, compared to the total time in that period. For example: 24/7 operation Network is up for 165 hours in the 168-hour week Availability is 98.21%

Availability Different applications and areas of a network may require different levels of availability. Availability could be considered a critical goal for a network design customer if indicated by the customer. Some enterprises may want 99.999% or “Five Nines” availability

Availability From a customers perspective, they want to know how much time the network will be operational. Availability is linked to reliability. Reliability addresses a list of issues, which include accuracy, error rates, stability, and the time between failures.

Availability Redundancy is a solution to a goal of high availability. In this manner, redundancy means adding duplicate links or devices to a network configuration to avoid network outages. Disaster Recovery Natural disaster – floods, fires, hurricanes, and earth quakes. Satellite outages – meteorite storms, collisions in space, solar flares, and system failures

Availability Unnatural disaster – bombs, terrorist attacks, riots, or hostage situation. Resiliency is the amount of stress a network can handle over time and how quickly the network can rebound or spring back from security breaches, natural and unnatural disasters, human error, and catastrophic software or hardware failures.

Availability Note: Bank check clearing process after 9/11. A main goal in the planning process would be to recognize which parts of the network are more critical than others. The disaster recovery plan should include keeping data backed up in one or more places that are unlikely to be affected by the disaster. Secondly, the technologies affected by the disaster should be resumed by another site with similar technologies. Note: Canada’s underground facility.

Availability Personnel must be considered an important resource when planning for a disaster recovery. Eyes on the ground are essential. Consider using Virtual Private Network (VPN) to access the corporate office when disaster recovery occurs. Providing VPN service to mission critical staff to work from home or a remote location. VPN service in the case of a disaster would allow this staff to begin building the damaged system without being involved at the site where there may be disease and contamination.

Availability Why Do People Use VPNs? Virtual Private Network is used to secure your connection and increase the privacy there of. In addition to the use cases we highlighted above (securely accessing a remote network as if you were connected to the network as a local user) there are also some very valuable use cases that are more outwardly focused. Why would someone want to, as we mentioned above, use their computer in Sydney, Australia but appear (to all the websites and services they use) as if they were in the United States?

Availability Why Do People Use VPNs? Many services are geographically blocked. If you’re a reader outside the US who has visited a popular YouTube video only to be informed “This video is not available in your country,” or some variant thereof, you’ve experienced geo-blocking. You’ve also experienced it if you’ve attempted to watch Netflix in a country not currently supported by Netflix.

Availability Why Do People Use VPNs? Even when you can access a service like Netflix in your country there are often incongruences between what is available in the primary market (typically the US) and the market you’re in. In addition to absent videos many people (we’re looking at you, Australians) have to deal with insanely high import taxes on software that see them paying twice (or more) what US consumers pay for the same products.

Availability Why Do People Use VPNs? On a more serious note, an unfortunately large number of people live in countries with high levels of overt censorship and monitoring (like China) and countries with more convert monitoring (like the US); one of the best ways to get around censorship and monitoring is to use a secure tunnel to appear as if you’re from somewhere else altogether.

Availability Why Do People Use VPNs? In addition to hiding your online activity from a snooping government it’s also useful for hiding your activity from a snooping Internet Service Provider (ISP). If your ISP likes to throttle your connection based on content (tanking your file downloads and/or streaming video speeds in the process) a VPN completely eliminates that problem as all your traffic is traveling to a single point through the encrypted tunnel and your ISP remains ignorant of what kind of traffic it is.

Availability Why Do People Use VPNs? In short a VPN is useful anytime you want to either hide your traffic from people on your local network (like the person who controls the free Wi-Fi at the shop you’re working at), your ISP, or your government and it’s also incredibly useful to trick services into thinking you’re right next door when you’re an ocean away.

Availability

Availability

Availability A virtual private network (VPN) extends a private network across a public network, such as the Internet. It enables a computer or network-enabled device to send and receive data across shared or public networks as if it were directly connected to the private network, while benefiting from the functionality, security and management policies of the private network. A VPN is created by establishing a virtual point-to-point connection through the use of dedicated connections, virtual tunneling protocols, or traffic encryptions. Major implementations of VPNs include OpenVPN and IPsec.

Availability

Availability Testing It is important to require employees to be part of drills in the event of a disaster. This includes visiting remote sites, and utilizing the available equipment. Keeping the remote equipment hardware and software at release levels similar to the main operations center. Availability Requirements Uptime 99.95 % - network is down 5 minutes per week

Availability Uptime Five Nines(99.999) - hard to achieve. Involves staff, equipment redundancy, and software. 24/7 equals 8760 hours - Hot swappable boards - No maintenance window - In-service updates - Triple Redundancy One active One active standby One standby or maintenance

Availability Cost of Downtime Each critical application should be documented. How much money the company loses per minute/hour of downtime. Third party network management

Availability MTBF is mean time before failure 4000 hours goal MTTR is mean time to repair One hour goal MTBF and MTTR are used to calculate available goals when the customers wants to specify explicit periods of uptime and downtime, rather than a simple percent uptime value. Availability = (MTBF / (MTBF + MTTR))

Availability A typical MTBF equals 4000hours. A typical MTTR is 1 hour Availability = MTBF / (MTBF + MTTR) Availability = 4000 / (40000 + 1) Goal 99.98 percent Mean times might be different in different parts of the network. The goal of a Cisco core layer in an enterprise network are more stringent than those goals for a switch.

Availability Vendors provide MTBF and MTTR estimates for their products. It is advisable to research independent lab results for MTBF and MTTR estimates before making a final conclusion about a product.

Network Performance Network performance refers to measures of service quality of component(s) as seen by the customer. The performance of a circuit-switched network would involve the number of rejected calls as a measure of how well the network is performing under heavy traffic loads. Other types of performance measure might include noise, and echo. The ATM network performance can be a measure by line rate, QoS, data throughput, connect time, stability, technology, modulation technique.

Network Performance Performance of a network also includes accuracy, efficiency, delay, and response time. Common performance factors include Bandwidth (capacity) Throughput Bandwidth utilization Offered load Accuracy Efficiency Delay (latency) and delay variation Response time

Network Performance Utilization is normally specified as a percent of capacity. Optimum average network utilization is approximately 70 percent. This means that peaks in the network traffic can probably be handled without noticeable performance degradation. Normally, WANs have less capacity than LANs. When setting up the utilization estimate for a WAN links, more consideration is required regarding the bandwidths. WAN links are designed with bandwidths that offer little, if any extra capacity for incidental traffic because WAN links are expensive. LANs are overbuilt with full-duplex Giga-bit Ethernet links to servers and 100-Mbps Giga-bit Ethernet links to clients.

Network Performance Point-To-Point transmission is a full duplex link that connects a switch to a server or some other switch. It is possible to consume all the bandwidth, depending on the traffic load or behavior. At times, network traffic is appears in bursts.

Network Performance Throughput is the quantity of error-free data that is transmitted per unit of time. The assessment of the amount of data that can be transmitted per unit of time. Throughput is typically the same as capacity. Customers specify throughput goals in terms of number Packets Per Second (PPS). Vendor use either PPS or Cells Per Second (CPS) from their independent tests conducted on their product(s). Many internetwork devices can forward packets a theoretical maximum, which is called wire speed.

Network Performance Bandwidth means capacity and is normally fixed. A measure of the width of a range of frequencies. Example: PVC pipe with water running through it. Capacity depends on the physical IOS layer. The capacity of a network should be adequate to handle bursts of data.

Network Performance Goodput is the number of useful bits of information at the application layer considered throughput. This information is delivered by the network to a certain destination, per unit of time. This is related to the amount of time from the first bit of the first packet is sent until the last bit of the last packet is delivered. Goodput is a measure of good and relevant application layer data transmitted per unit of time.

Network Performance Application Layer Throughput Vendors refer to the application layer throughput as goodput. Being called goodput, heightens the fact that it is a measure of good and relevant application layer data transmitted per unit of time. Throughput means bytes per second (BPS). Applications using throughput as goodput would file transfers and data base applications.

Network Performance Factors that constrain the application layer throughput. End-to-end error rates Protocol functionality, handshaking, windows, and acknowledgements Protocol parameters, frame size and retransmission timers Packets Per Second (pps) and Cells Per Second (cps) rate of internetworking devices Lost packets or cells at the internetworking devices Workstation and server performance factors

Network Performance Accuracy is paramount when sending and receiving data. The data sent over the wire is expected to be identical to the data received at the destination. Typical causes of data errors. - Power surges or spikes - Impedance mismatches - Poor physical connections - Failing devices - Noise from electrical devices - Some specific software bugs

Network Performance WANs links accuracy is based on bit error rate (BER). WAN links are on a serial interface, and collision errors should never occur. Analog links BER threshold 1 in 105 (100,000) Copper links BER threshold 1 in 106 (1,000,000) Fiber optic links BER threshold 1 in 1011 Digital BER threshold is considerably lower than analog links

Network Performance LANs links accuracy is based on frames and not bits. A good threshold is 1 in 106

Network Performance Ethernet errors usually result from collisions. The error is termed, Cyclic Redundancy Check (CRC). Errors can occur at the preamble, past the preamble, and beyond the 64 bytes after the preamble.

Not registered - First eight byte preamble of a frame Network Performance Not registered - First eight byte preamble of a frame Registered – First sixty four bytes of a data frame (considered a runt frame) Illegal (late) – after the first 64 bytes Collisions should never occur when using full-duplex Ethernet WAN collisions should never occur.

Network Performance Accuracy refers to the number of error-free frames transmitted relative to the total number of frames transmitted. Efficiency is a measurement of how effective an operation is in comparison to the cost in effort, energy, time, and money. Note: Large and small frame sizes. Large frame make better use of bandwidth and improve application throughput. Bigger frames introduce more bit errors and a need for an elaborate recovery procedure. Response delays are expected to be minimal. Variations in delay, called jitter

Network Performance - Jitter causes disruptions in voice and video streams. - Telnet protocol - Customer perspective on running any delay-sensitive applications Delays in voice and video streams will be a major consideration to be discussed with the customer.

Network Performance Serialization delay is the time to put digital data on a transmission line. Using too large of data frame can cause delays if the shared transmission line includes time sensitive data (like voice or video).

Network Performance Propagation delay  is the amount of time it takes for the head of the signal to travel from the sender to the receiver (186,000 miles per second) Serial delay is the time to put digital data onto a transmission line. Packet-switching delay is the latency accrued when switches and routers forward data. DRAM SRAM

Dynamic Random Access Memory Dynamic random-access memory (DRAM) is a type of random-access memory that stores each bit of data in a separate capacitor within an integrated circuit. The capacitor can be either charged or discharged; these two states are taken to represent the two values of a bit, conventionally called 0 and 1. Since capacitors leak charge, the information eventually fades unless the capacitor charge is refreshed periodically. Because of this refresh requirement, it is a dynamic memory as opposed to SRAM and other static memory.

Dynamic Random Access Memory The advantage of DRAM is its structural simplicity; only one transistor and a capacitor are required per bit, compared to four or six transistors in SRAM.

Static Random Access Memory Static Random Access Memory (Static RAM or SRAM) is a type of RAM that holds data in a static form, that is, as long as the memory has power. Unlike dynamic RAM, it does not need to be refreshed. SRAM stores a bit of data on four transistors using two cross-coupled inverters. The two stable states characterize 0 and 1. During read and write operations another two access transistors are used to manage the availability to a memory cell.

Static Random Access Memory To store one memory bit it requires six metal-oxide-semiconductorfield-effect transistors (MOFSET). MOFSET is one of the two types of SRAM chips; the other is the bipolar junction transistor. The bipolar junction transistor is very fast but consumes a lot of energy. MOFSET is a popular SRAM type. The term is prononuced "S-RAM", not "sram."

Network Performance Queuing delay  is the time a job waits in a queue until it can be executed. A good rule is to inform the customer that they should experience less than delay 1 or 2 percent Response time is the network performance goal that users are interested in. Users begin to get frustrated if the response is longer then 1/10th (100 ms) of a second.

Security Focus on requirements first (MD5 / AES combined) Detailed security planning later (Chapter 8) Identify network assets Including their value and the expected cost associated with losing them due to a security problem. Analyze security risks Hackers compromise a network device, such as a switch, router, server, firewall, or IDS.

Network Assets Hardware Software Applications Data Intellectual property Trade secrets Company’s reputation

Security Risks Hacked network devices Data can be intercepted, analyzed, altered, or deleted User passwords can be compromised Device configurations can be changed Reconnaissance attacks Denial-of-service attacks Security should not disrupt the company’s business. Note: BOTNETS and high capacity servers.

Manageability Some customer goals are specific. They want to visualize problems occurring on the network. They use SNMP to capture the number of bytes each router receives and sends. Fault management – detecting, isolating, and correcting problems. Configuration management – controlling, operating, identifying, and collecting data Accounting management – accounting of network usage to allocate costs to network users and/or plan for changes in capacity requirements. Performance management – analyze traffic and application behavior to optimize a network, meet service-level agreements, and plan for expansion. Security management- Monitoring and testing security and protection policies, maintaining passwords, encryption keys, and auditing adherence to security policies.

Usability Usability: the ease of use with which network users can access the network and services. VPN might be a consideration for flexible access. Networks should make users’ jobs easier Some design decisions will have a negative affect on usability: Strict security, for example financial institutions and government offices

Adaptability Avoid incorporating any design elements that would make it hard to implement new technologies in the future. Change can come in the form of new protocols, new business practices, new fiscal goals, new legislation. A flexible design can adapt to changing traffic patterns and Quality of Service (QoS) requirements.

Affordability A network should carry the maximum amount of traffic possible for a given financial cost. Affordability is especially important in campus network designs. WANs are expected to cost more, but costs can be reduced with the proper use of technology Quiet routing protocols, for example

Making Tradeoffs Scalability 20 Availability 30 Network performance 15 Security 5 Manageability 5 Usability 5 Adaptability 5 Affordability 15 Total (must add up to 100) 100

Making Tradeoffs Mimic Lab Assignments Lab #1: Due date: February 7, 2016 Lab #2: Due date: March 13, 2016 Lab #3: Due date: April 10, 2016 Midterm Exam February 22 - 27, 2016 Final Exam April 11 – 16, 2016

This Week’s Outcomes Business Goals Business Constraints Technical Goals Technical Constraints Cisco’s Three Tier Network Design Network Performance

Due this week 1-3 – Concept questions 1

Next week Read Chapters 3 and 4 in Top-Down Network Design 2-1 – Concept questions 2

Q & A Questions, comments, concerns?

Q & A

Q & A