Objectives
In this lab, students will examine the following objectives.
· Calculate the VoIP traffic load in access trunks to the packet network.
· Calculate the number of IP PBX access channels to the packet network.
· Calculate the number of backup access channels to PSTN.
Scenario
ABC Inc. is planning to retire an analog PBX serving its location, and to deploy an IP PBX to integrate telephone services into the TCP/IP network using VoIP technologies. It plans to use primarily the packet network (Internet) to make and receive phone calls. To meet its phone service objectives, ABC Inc. must size access links to the Internet and determine the number of SIP trunk connections that are needed. In addition, the company wants to have a backup connection (i.e., a subscription to a few analog lines) to the PSTN through a trunk gateway in case of failure in the packet network.
Your task is to calculate the following traffic engineering parameters to correctly size access connections to WAN.
1) Calculate VoIP traffic load in access trunks to the Internet.
2) Calculate the access bandwidth required and the number of SIP trunks needed for VoIP calls to the Internet.
3) Calculate the number of backup access channels to PSTN.
Topology
The figure below shows the IP PBX network at the company’s location.
Note: Text in red indicates required iLab questions.
Task 1— Calculate the VoIP traffic load in access trunks to the Internet
In this exercise, you will calculate the phone service traffic load in Erlangs on the access links connecting the company’s location with the Internet through the ISP. The following assumptions are given.
1. The PSTN connection is only used as a backup. No phone calls will go to the PSTN trunk, which is only used in case of packet network WAN failure.
2. There are 510 phones at the company’s location, including IP phones, soft phones, and analog phones.
3. Sixty percent of the phones generate simultaneous call attempts in the busy hour, with an average duration of 7 minutes per call.
Q1 What is the number of call attempts during the busy hour at the company’s location?
Roughly 307.2
Q2. What is the traffic load in Erlangs during the busy hour? Show calculation and units.
Q3. What is the dimension of traffic measurement unit Erlang?
Task 2—Calculate the number of SIP trunks and access link bandwidth required for VoIP calls to the Internet
In this exercise, you will calculate the access bandwidth and the number of SIP trunks required to meet the company’s objective. Use the busy-hour traffic load to the Internet that was calculated in Task 1. The following assumptions are given.
1. The call-blocking probability during busy hour should not exceed 1% (i.e., 0.01).
2. Use the G.711 codec with a 20-millisecond payload duration per packet.
3. Use the Erlang-to-VoIP bandwidth calculator at http://www.erlang.com/calculator/eipb/.
Q4. What is the difference between a completed call and a call attempt?
Q5. What is the number of SIP trunks (lines from the online calulcator) required to meet company’s needs?
Q6. What access link bandwidth (Kbps from the online calculator) is required to connect the company’s location to the Internet?
Q7. If T1 bandwidth is 1.544 Mbps, T3 bandwidth is 44.736 Mbps, and there are 28 T1 in a T3, what access connection(s) does the company need to lease in terms of T1 and/or T3? Show the calculation.
Q8. Include a screenshot below showing the results from the Erlang-to-VoIP bandwidth calculator.
Task 3—Calculate the number of backup access channels to the PSTN
ABC Inc. is concerned with performance degradation and service interruptions due to the Internet availability. It decides to have a backup connection to the PSTN in case of any disruptions of phone services through the packet network.
You will calculate the number of analog lines the company needs to lease from a telephone service provider (TSP) as a backup in case of packet network failures. The following assumptions are given.
1. Use the same busy-hour traffic load as in Task 1.
2. The call blocking should not exceed 10% (i.e., 0.01).
3. Use the Erlang B calculator at http://www.erlang.com/calculator/erlb/.
Q9. How many analog lines does the company need to subscribe from a TSP? Include a screenshot below that shows the calculator results.
Q10. Assume that each analog line can carry 1 Erlang of voice traffic. What is the utilization of the PSTN trunks if an Internet failure occurs during the busy hour? Show the calculation.
Try it now!
How it works?
Follow these simple steps to get your paper done
Place your order
Fill in the order form and provide all details of your assignment.
Proceed with the payment
Choose the payment system that suits you most.
Receive the final file
Once your paper is ready, we will email it to you.
Our Services
Custom Writings Help is a Quality-Oriented Company in Online Writing as a result of hiring exceptional professionals to execute clients' tasks.
Essays
At Custom Writings Help,We understand the struggle of research paper writing, and that is why at Custom WritingS Help, we are all out to help you. We pride ourselves on having a team of clinical writers. The stringent and rigorous vetting process ensures that only the 'BEST' Writers are chosen for the job. We have highly qualified Ph.D. and MA writers working with us; we equally offer these experienced writers specific bonuses and incentives to make them deliver highly original, unique, and informative content at reasonably low prices.
Admissions
Thesis Writing Service
Worlwide, Many Masters Students are struggling with Thesis Completion. A thesis is likely to be the longest and most challenging piece of work a student has ever completed. However, unlike essays and other assignments, a student can pick a particular interest topic and work on their initiative. Fortunately, we are there for you. At Custom Writings Help, you are assured of an authentic, imaginative, informative, linguistically great, and advantageous thesis that adheres to all your needs. So, why continue considering different writers when you have discovered the best in the field?
Editing
Custom Papers
Not a single student can avoid writing custom papers. However, a total lack of experience, skills, and time makes it very hard to produce a superb writing piece. Therefore, if you are seeking professional help, turn to us. Our specialized and experienced writers compose a variety of model papers, including custom essays, college term papers, research papers, book reports, MBA essays, executive summaries, dissertations, Ph.D. theses, admission essays, and research proposals for college and university students at any level.
Coursework
Essay Writing
Most of the students disregard the critical principles of essay writing and compose papers below sensible guidelines. Therefore, with Custom Writings Help, one should not worry about his/her essay. Our Writers compose informative and engaging content on all complexities and topics. We write meaningful and smart essays while prioritizing all aspects that bring about a good grade, such as impeccable grammar, proper structure, zero-plagiarism, and conformance to guidelines.
Coursework
Coourse Work Writing
Don't let the seemingly never-ending onslaught of writing assignments get you down. If you are looking where to get course work assistance online, the writers at Custom Writings Help are here to assist you with all of your writing needs. We undertake to unique delivery of papers that meet the professor's requirements. The content is proofread, edited, and checked plagiarism before submission to customers. No matter how big or small your work is, we will deliver on time. Try US Now! !
Coursework
Dissertation Writing Service
High-Quality Dissertation Writing Services are rare. They require Ph.D. academicians – not easily found. However, are an exception. The years, time, and resources we have invested in the dissertation world has given us a competitive advantage over others. Choose to come to Custom Writings Help; You will find perfect Ph.D. consultants who have written hundreds of dissertations theses ready to help you. Let our dissertation-writing services help you craft your dissertation, for you are assured we will give you the results.