NETW250 Week 5 iLab: VoIP Traffic Engineering

NETW250 Week 5 iLab: VoIP Traffic Engineering

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?

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.

Fill in all the assignment paper details that are required in the order form with the standard information being the page count, deadline, academic level and type of paper. It is advisable to have this information at hand so that you can quickly fill in the necessary information needed in the form for the essay writer to be immediately assigned to your writing project. Make payment for the custom essay order to enable us to assign a suitable writer to your order. Payments are made through Paypal on a secured billing page. Finally, sit back and relax.

About Wridemy

We are a professional paper writing website. If you have searched a question and bumped into our website just know you are in the right place to get help in your coursework. We offer HIGH QUALITY & PLAGIARISM FREE Papers.

How It Works

To make an Order you only need to click on “Place Order” and we will direct you to our Order Page. Fill Our Order Form with all your assignment instructions. Select your deadline and pay for your paper. You will get it few hours before your set deadline.

Are there Discounts?

All new clients are eligible for 20% off in their first Order. Our payment method is safe and secure.

Hire a tutor today CLICK HERE to make your first order