ECEN4533 Design Problem #2 80 points Due???

Transcription

1 ECEN4533 Design Problem #2 80 points Due??? You are a Staff Engineer, Networking, for MegaMoron Communications Inc., the world's premier communications design company. You have been tasked with the design of an advanced WAN backbone for RedNeckNet, a regional Internet Service Provider (ISP). A year has passed since RedNeckNet installed a MegaMoron designed IP backbone network, with Points of Presence (POP's) in Stillwater, Oklahoma; Joplin, Missouri; Lubbock and Dallas, Texas; Little Rock, Arkansas; and Salina, Kansas. Some recent well publicized link failures have led to a loss of customers and emphasized the importance of a more survivable network. In an attempt to reverse sinking profits, the company president has decided to upgrade RedNeckNet's offerings to include integrated data and real time video services. RedNeckNet has decided to continue to purchase leased line bandwidth from U.S. Sprawl and install either upgraded Routers or ATM switches at their six POP's. Your goal is to design a least cost network that will meet average one-way end-to-end delay specifications for a mixed traffic (video & data) environment. This will involve specifying the number and type of Leased Line connections to obtain from U.S. Sprawl, and specifying the type of ACME switching gear to purchase and install at the six RedNeckNet POP's. After some discussion, you have decided that designing the network for the peak halfhour will be a good compromise between price and performance. Investigation has revealed the following: Propagation Delays between sites are as follows: Stillwater - Lubbock: 5.2 msec Stillwater - Salina: 3.1 msec Stillwater - Joplin: 2.5 msec Stillwater - Dallas: 3.7 msec Stillwater - Little Rock: 4.6 msec Salina - Lubbock: 7.0 msec Salina - Joplin: 3.3 msec Salina - Dallas: 6.8 msec Salina - Little Rock: 6.6 msec Lubbock - Joplin: 7.7 msec Lubbock - Dallas: 4.8 msec Lubbock - Little Rock: 8.9 msec Dallas - Little Rock: 4.7 msec Dallas - Joplin: 5.2 msec Joplin - Little Rock: 3.3 msec Router/Switch Options: RedNeckNet wishes to use one of the following three techniques for connectivity. Hence all POP's must have the same type of switch installed. (1) Commodity Internet: Map all traffic to IP packets. StatMux the composite traffic flow over current generation IP Routers, which will not differentiate between traffic types and will treat all the traffic identically. (2) QoS Enabled Internet: Map all traffic to IP packets. StatMux the composite traffic flow over more expensive Differential Services (DiffServ) routers, which are capable of

2 prioritizing traffic and hence can give preferential treatment to real time video. (3) ATM using VBR Video and UBR Data: Map all traffic to ATM cells. With this option, the composite traffic flow is also StatMuxed by switches which are capable of prioritizing the traffic. Data Traffic: The average packet size of data that will travel this network during the peak half-hour is 430 bytes. *An average packet therefore contains 7 bytes of PPP, 20 bytes of IPv4, and 20 bytes of TCP overhead, leaving 383 bytes of application traffic (89.07% traffic). *If the packet is moved over ATM, an average of nine cells are required to move each packet (383 bytes of application traffic divided by 9(53) bytes = 80.29% application traffic). Video Traffic: Analysis and testing has shown that the average packet size generated by the video coders expected to be used on the network is 760 bytes. * If you go with either Router option, each packet will therefore require 7 bytes of PPP, 20 bytes of IPv4, 8 bytes of User Datagram Protocol (UDP), and 12 bytes of RTP (Real Time Transport Protocol) overhead to move 713 bytes of application video traffic (93.82% traffic). * If you go with the ATM VBR Video option, sixteen cells (848 B) will be required to move the 713 application bytes of the average sized video packets (84.08% traffic). Average Packet Size & Traffic Ratios: IP Options: Offered application traffic loads are expected to be 84% video and 16% data. Hence for each Mbps of offered application traffic there will be 840 Kbps of video and 160 Kbps of data, on average. The video will require (840 Kbps)/[(713 video bytes/packet)(8 bits/byte)] = packets/second to move (per Mbps of offered application traffic), and the data will require (160 Kbps)/[(383 data bytes/packet)(8 bits/byte)] = packets/second (per Mbps of offered application traffic) % of the packets will therefore be carrying video and 26.17% will be carrying data. The average packet size is therefore seen to be (760) (430) = bytes = 5,389 bits. ATM using VBR video and UBR data: Offered application traffic loads are expected to be 84% data video and 16% voice data. As just noted above, for each Mbps of offered application traffic there will be 840 Kbps of video and 160 Kbps of data. The video will generate (840 Kbps)/[(713 video bytes/16 cells)(8bits/byte)] = 2,356 cells/second (per Mbps of offered application traffic). The data will require (160 Kbps)/[(383 data bytes/ 9 cell)(8 bits/byte)] = cells/second (per Mbps of offered application traffic) % of the cells will therefore be carrying video and 16.63% will be carrying voice data. All ATM cells are 53 bytes = 424 bits. End-to-End Delays: Based on the delays OSI Layer 7 Applications and the end users will tolerate, the target average one-way end-to-end delivery delays during the peak half-hour must be less than or equal to 68 msec for the real time video, and less than or equal to 437 msec for data. Different switching choices allow these values to be analyzed differently. (1) Current Internet: If this option is chosen, to meet the required average end-to-end delivery delays for video, you will have to deliver all the traffic end-to-end within the video

3 requirement of 68 msec (on the average), as the system is unable to discriminate between the various types of traffic. I.E. use 68 msec as your target end-to-end delay specification. (2) QoS Enabled Internet: This system can prioritize the real time video traffic, moving it in a more timely manner than the data. If this option is chosen, to meet the required average endto-end delays for voice video and data you will need to design the system to meet a weighted average end-to-end delay of.7383(437 msec) (68 msec) = msec (68 msec) (437 msec) = msec. I.E. use msec as your target end-to-end delay specification. (3) ATM using VBR Video and UBR Data: This system can also give preferential treatment to the voice video traffic. If this option is chosen, to meet the required average end-toend delays for voice video and data you will need to design the system to meet an average endto-end delay of.8337(437 msec) (68 msec) = msec (68 msec) (437 msec) = msec. I.E. use msec as your target end-to-end delay specification. Self-Similarity: Lab tests show that the data traffic has an H parameter of 0.97 and that compressed variable rate video traffic has an H parameter of Assume that combined traffic has an H parameter equal to the weighted average of the traffic mix moving over the link. *Internet Options: Use an H parameter of.7383(.59) (.97) = *ATM using VBR Voice Video and UBR data: Use an H parameter of.8337(.59) (.97) = Application Traffic Matrix: The following layer 7 application traffic matrix shows the expected peak rate average layer 7 application traffic flows (in Kbps) between sites for the three options above. Important!! Note that the matrix below does not include OSI Layer 2-6 overhead. You need to add this overhead in when calculating the trunk loads. From \ To Salina Little Rock Lubbock Stillwater Dallas Joplin Salina Little Rock Lubbock Stillwater Dallas Joplin For example, the amount of application traffic that will need to be moved from Dallas to Joplin during the peak half hour is expected to be 2,140 Kbps, on average. All traffic originating from and terminating at a specific city pair must be routed over the same path. Traffic being moved in the reverse direction does not necessary have to be routed over the path traffic moving in the forward direction is using. For example, you cannot route

4 70% of the Salina to Dallas traffic over one route, and the other 30% over a different route. All Salina to Dallas traffic must be moved over the same path. Dallas to Salina traffic can use the same path as the Salina to Dallas traffic, or it may use a different path. StatMux End-to-End Delays: Note that as RedNeckNet cannot control the size of the access lines customers purchase, end-to-end here is defined from the input switch of RedNeckNet's backbone to the output switch. Use the following equation to estimate the overall average end-to-end delivery delay over a single hop Leased Line connection: with Average Delay = Average Switch Delay + Propagation Delay, Average Switch Delay = [E[Ts]*(Load) (2H-1)/(2-2H) ]/[(1- Load) H/(1-H) ] where E[Ts] is the average service time, and the average switch delay is "E[T]" in Mir's text. For example, if the amount of traffic routed over a 64 Kbps Leased Line is 34 Kbps for Option (1), the average queuing delay a packet can expect to see is (E[Ts]= 5,389/64,000 = msec, H Parameter = ) (.08220* )/ =.05589/.1860 = msec. * End-to-End average delays associated with multiple hop paths are found by summing the perhop delays. U.S. Sprawl Leased Line Costs: *Leased Lines from U.S. Sprawl are available from 12 Kbps on up in integer multiples of 12 Kbps. *Leased Line pricing is a function of distance and bandwidth. Use the following formula to calculate monthly costs for each Leased Line in place: Monthly Leased Line Costs = $67 + $141(propagation delay in msec) 0.22 [(trunk line speed)/(320 Kbps)] 0.77 Example) An 60 Kbps Leased Line between Dallas and Joplin would cost $67 + $141(5.2) 0.22 [0.1875] 0.77 = $67 + $141(1.437)(.2756) = $ per month These are full duplex lines, so you get the listed bandwidth in both directions. For example, a 60 Kbps leased line between Joplin and Dallas gives you 60 Kbps from Joplin to Dallas and 60 Kbps from Dallas to Joplin. ACME Monthly Router & Switch Costs:

5 Switching devices have costs based on internal bus speed required, memory for handling traffic in queues, and a fixed cost associated with power supplies, internal software, etc. All POP's must have the same type of switching gear installed. *Option 1 requires an Acme Roto-Router at each POP. Monthly cost is $125 + $48(Sum of Leased Line Trunk Speeds in Mbps attached to the router) *Option 2 requires an Acme Roto-Router Pro at each POP. Monthly cost is $134 + $63(Sum of Leased Line Trunk Speeds in Mbps attached to the router). *Option 3 requires an Acme ATM Glitch-Switch at each POP. Monthly cost is $177 + $83(Sum of Leased Line Trunk Speeds in Mbps attached to the router). For example if the Stillwater POP has a Roto-Router with two 1.75 Mbps and one 735 Kbps line installed, the monthly cost associated with this router is $125 + $ = $ Reliability: All POP's must have a minimum of two-connectivity. I.E. all POP's must have a minimum of two trunk lines terminated at two different POP's. Additionally, the loss of a single trunk line should not isolate any portion of the network. Two-connectivity will allow the system to operate in a degraded manner in the event of the loss of any single trunk. Instead of doing a complicated analysis to properly size the protect bandwidth, we will specify that for the purposes of this design problem, each link attached to a POP must have a minimum line speed of 768 Kbps. It is up to the designer as to how traffic will be split over these and other connections. Rules of Engagement: Double-check the math in this document. Derived values, while believed to be correct, are not guaranteed to be correct. You may work in one or two person teams if you so desire. The low bid will be that design with the lowest monthly cost. The low bid designer(s) will receive 20 extra credit points. The 2nd lowest bid designer(s) will receive 15 points, and the 3rd lowest bid designer(s) will receive 10 points. All remaining designs with cost < the average class cost will receive 5 points extra credit. Only working bids will be considered for the above. The instructor reserves the right to modify these rules in the event of a tie, and to deduct points for crappy designs. Make your final report short and sweet. DO NOT GIVE ME A RUNNING COMMENTARY OF YOUR DERIVATION. I will dock you points if you do so. Your final report should be three to four pages and include: (1) a WAN backbone network diagram showing links used, average traffic routed over these links in each direction, and trunk size. (2) a table, with 30 entries, showing how each Traffic Matrix entry is routed, and the expected average one-way end-to-end delays traffic will face moving over this route. (3) a list of costs (links & router/switch) (4) (4) Sample calculations for End to End Propagation Delay. Pick one link and show your calculations for that link. Treat your project as if it were proprietary corporate information, i.e. do not disseminate your design in any manner to the competition. Doing so, and getting caught, will get anyone involved either "demoted" (i.e. a 0 for the project) or "fired" (i.e. an F for the course) depending on the seriousness of the leak.

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