Tutorial: How do IP packets and MAC Frames go together?

It is important to understand how packets and frames are related, and in particular, IP packets vs. Ethernet or MAC frames.

Simple network example. Routers move packets from one circuit to another.

Packets are for networks. A packet is a block of user data, such as a piece of an e-mail message, with a network address on the front. The network address is the final destination. The standard for network addresses is IP.

Network equipment like routers receive an IP packet on an incoming circuit, examine the indicated destination IP address, use it to make a route decision, then implement the decision by forwarding the packet to the next router, on a different circuit.

A frame is a lower-level idea. Frames are used to communicate between stations on the same circuit. The circuit may have multiple stations physically connected onto it, like a wireless LAN, a few stations connected by a LAN switch, or only two stations like a point-to-point LAN cable. Each station has a Media Access Control (MAC) address, sometimes called a hardware address, link address or Layer 2 address.

A frame has framing to mark the beginning and end, sender and receiver MAC addresses to indicate the stations on the circuit, control information, a payload and an error detection mechanism.

The frame is transmitted on the circuit, and all stations on the circuit receive it. If an error is detected at a receiving station, the frame is discarded and might have to be retransmitted somehow.

If no errors are detected, the receiver compares the destination MAC address on the received frame to its own MAC address, and if they are the same, processes the frame, extracting the data payload and passing it to higher level software on the receiver.

If the MAC addresses are not the same, the receiver ignores it and waits for the next one.

The end result is that the payload in the frame is communicated to the correct station on the same circuit, with no errors.

Packet with its IP address vs. frame and its MAC address

The main purpose of packets is to append an IP address to your data. The IP address is used by network equipment to make route decisions: to relay the packet from one circuit to a different circuit. This is accomplished by receiving the packet then transmitting it to a different machine, usually the next router in the chain.

To actually transmit a packet to another router, the packet is inserted as the payload in a frame, then the frame is broadcast on the circuit that connects to the next router.

Notice that there are two addresses: the IP network address and the MAC address.

The IP address on the packet is the final destination, and so does not change. The MAC address on the frame indicates the destination on the current circuit, and so is changed as the data is forwarded from one circuit to another.


This and related topics are covered in:

• CTNS Certification Package

• CIPTS Certification Package

• Instructor-Led Course 101
Telecom, Datacom and Networking for Non-Engineering Professionals

• DVD-Video V3 Fundamentals of Datacom and Networking

• Telecom 101 Textbook

Telecom 101 – Fourth Edition, 2016 released and on sale!

Telecom 101 Textbook – Fourth Edition 2016 is out
– and on sale for a limited time!

9781894887038_frontcoverHigh-Quality Reference Book and Study Guide Covering All Major Topics, Up To Date To 2016… in Plain English.

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Telecom 101 covers the core knowledge set required in the telecom business today: the technologies, the players, the products and services, jargon and buzzwords, and most importantly, the underlying ideas… and how it all fits together.

The course materials for Teracom’s famous Course 101 Telecom, Datacom and Networking for Non-Engineers, augmented with additional topics and bound in this one volume bring you consistency, completeness and unbeatable value.

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Telecom 101
7″ x 9″ softcover textbook • 488 pages
4th edition • Published March 2016
print ISBN 9781894887038
eBook ISBN 9781894887786
Print quantities are limited. Order now to avoid disappointment.


Your Go-To Telecom Resource

Covering all major topics, we begin with the Public Switched Telephone Network (PSTN), then

• progress in a logical order, building one concept on top of another,
• from voice and data fundamentals to digital, packets, IP and Ethernet, VoIP,
• fiber and wireless, DSL and cable, routers and networks, MPLS, ISPs and CDNs,
• and finish with the Brave New World of IP Telecom, where voice, data and video are the same thing.

• An invaluable day-to-day reference handbook

• Learn and retain more reading a hard copy, professionally printed and bound

• Up-to-date: published 2016

• Allows you to study and review topics before attending a course

• An economical and convenient way to self-study
… these are the materials to an instructor-led course that costs $1395 to attend.

• The Certification Study Guide for the prestigious Telecommunications Certification Organization (TCO) Certified Telecommunications Analyst (CTA) telecommunications certification.


Value Pricing

Written by our top instructor, Eric Coll, M.Eng., Telecom 101 contain 35 years of knowledge and learning distilled and organized into an invaluable study guide and practical day-to-day reference for non-engineers.

Looking through the chapter list and detailed outline below, you’ll see that many chapters of Telecom 101 are like self-contained reference books on specific topics, like the PSTN, IP, LANs, MPLS and cellular.

You can get all of these topics bound in one volume for one low price.

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Tutorial: Packetized Voice

This is Section 2.9.1 of the new Telecom 101, 4th edition
print and ebook available January 2016



Brought to you by BOOT CAMP
January 25-29 2016 – Silicon Valley


– – –

This diagram provides a very high-level block diagram view of the processes involved in communicating speech in IP packets from one person to another:

Voice in IP Packets
Voice in IP Packets End-to-End

Starting on the left, commands from the speaker’s brain cause combinations of lungs, diaphragm, vocal cords, tongue, jaw and lips to form sounds.

A microphone is positioned in front of the mouth and acts as a transducer, creating a fluctuating voltage which is an analog or representation of the sound pressure waves coming out of the speaker’s throat.

This is fed into a codec, which digitizes the voltage analog by taking samples of it 8,000 times per second and coding the value of sample into binary 1s and 0s. Typically, the value of each sample is represented with a byte, meaning 64 kb/s to be transmitted.

Approximately 20 ms worth of coded speech is taken as a segment and placed or encapsulated in an IP packet.

The IP packet begins with a header, which is control information, the most interesting part being the IP address of the source telephone and IP address of the destination telephone.

IP packets are moved from the source to the destination over a sequence of links.

The links are connected with routers, which relay the packets from one link to the next.

Lower level functions such as framing and link addressing are usually performed following the IEEE Ethernet and MAC standards.

At the lowest level, the links are physcially implemented with Category 6 LAN cables, DSL modems, Cable modems, fiber optics and radio systems.

At the destination, the bits are extracted from the IP packet and fed into a codec, which re-creates the analog voltage.

This voltage drives a speaker, which re-creates the sound pressure waves, which travel down the ear canal to the inner ear, causing hairs on the cochlea to vibrate, triggering neural impulses to the brain, making the listener think they are hearing something.

– – –

It’s important to note that the voice packets are communicated directly from one telephone to the other over the IP network.
The packets do not pass through a CO telephone switch, for example.

– – –

For a full explanation of all of the technologies mentioned in this tutorial, register for BOOT CAMP in Sunny Silicon Valley in January!


is Core Training Course 101 Telecom, Datacom and Networking for Non-Engineering Professionals
and VoIP Course 130 Understanding Voice over IP
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Development #4: A Worldwide Standard for Mobile Wireless

A closer look at the fourth item in our list of eight major recent developments and trends in telecom.

Telecommunications technology is constantly changing and improving – seemingly faster and faster every year – and at Teracom, we keep our training courses up to date to reflect these changes. In a previous post, we identified eight major developments and trends in telecommunications incorporated in our training.

In this post, we take a closer look at the fourth development:
a worldwide standard for mobile wireless has finally been achieved with 4G LTE.

Mobility means it is possible to start communicating with a particular radio base station, then when moving physically away, be handed off to another base station down the road to continue communications uninterrupted. In a non-mobile system (like WiFi), communication ceases if you move too far away.

The first generation (1G) of mobile radio was characterized by analog FM on frequency channels. Numerous incompatible systems were deployed: AMPS in North America, TACS in the UK, NMT in Finland and others.

The second generation (2G) was digital, which means modems communicating 1s and 0s between the handset and base station. Again, several incompatible systems were deployed, and two warring factions emerged, which could be called the “GSM/TDMA faction”, and the “CDMA faction”.

By far, the most popular 2G system was GSM, a European technology where a number of users time-share a single radio channel. Another system was IS-136, called “TDMA” in North America, deployed by the company currently known as AT&T Wireless in the US and Rogers in Canada.

A less popular 2G system employed CDMA, using technology patented by American company Qualcomm, and deployed by Verizon, Sprint and Canadian telephone companies.

These 2G systems were totally incompatible. A basic phone from a carrier could not work on another carrier unless they both used exactly the same system.

To try to avoid a repeat of the incompatibility for the third generation, the International Telecommunications Union (ITU) struck a standards committee in year 2000 called IMT-2000, its mission to define a world standard for 3G.

They failed. IMT-2000 instead published a 3G “standard” with five incompatible variations. The two serious variations were both CDMA – but differed on the width of the radio bands, the control infrastructure and synchronization method among other things.

The GSM/TDMA faction favored the deployment of CDMA in a 5 MHz wide band. This was called IMT-DS, Direct Spread, Wideband CDMA and Universal Mobile Telephone Service (UMTS). Its data-optimized version was called HSPA.

The CDMA faction favored a strategy that was a basically a software upgrade from 2G, employing existing 1.25 MHz radio carriers. This is called IMT-MC, CDMA multi-carrier, CDMA2000 and 1X. Its data-optimized version was called 1XEV-DO.

Again, these 3G systems were completely incompatible. A basic UMTS phone could not work on a 1X network.

Market forces finally pushed the two camps together.

The fact that there were far more users in the GSM/TDMA faction meant that their phones were less expensive, had better features and appeared on the market first. This put the carriers in the CDMA/1X faction at a disadvantage. This trend was continuing into 3G, where UMTS phones would have the same advantage over 1X phones.

Then, Steve Jobs invented the world’s most popular consumer electronic product, the iPhone – but only permitted carriers in the GSM/TDMA/UMTS faction to have it. This severely tilted the playing field.

In the face of this, the CDMA/1X faction threw in the towel, and decided to go with the GSM/TDMA/UMTS faction’s proposal for the fourth generation (4G), called LTE, to level the playing field.

And once this was agreed, Steve Jobs allowed the iPhone on all networks. One of the legacies of Steve Jobs will not just be the iPhone, but ending the standards wars by pushing the industry to agree on LTE as a single worldwide standard for mobile communications as of the fourth generation, using the leverage of his iPhone.

I hope you’ve found this article useful!

If you like, you can watch a video segment of our instructor explaining why LTE became a worldwide standard on youTube

Additional explanation of cellular concepts, TDMA, CDMA and LTE is available in:
Teracom online tutorials
Course 101: Telecom, Datacom and Networking
for Non-Engineering Professionals

Textbook T4210
Telecom, Datacom and Networking
for Non-Engineer

Online Course 2206 Wireless Telecommunications
(part of the CTNS certification coursework)
Online Course 2232 Mobile Communications
(part of the CWA certification coursework), and
DVD Course V6 “Wireless”

Tutorial: Bluetooth

This tutorial on Bluetooth is Lesson 2: Bluetooth, from Course 2233 “Fixed Wireless”.  Watch the lesson by clicking the picture below.
You can also watch the video on YouTube.
The text is from the Course book / CWA certification study guide.


Young man illustrating Bluetooth channel as frequency-hopping pattern using a pogo stick. Click the image to watch the full lesson. The text that follows is from the course book.
Young man illustrating Bluetooth channel as frequency-hopping pattern using a pogo stick.
Click the image to watch the full lesson. The text that follows is from the course book.

Bluetooth is a set of standards for short-range digital radio communication published by a consortium of companies called the Special Interest Group. It was originally developed as a wireless link to replace cables connecting computers and communications equipment.

Bluetooth connections are called piconets and Personal Area Networks since (in theory) up to eight devices can communicate on a channel within a range of 1 to 100 meters depending on the power.

In reality, Bluetooth is mostly used point-to-point with ten meters range.

The first data rate for Bluetooth was 0.7 Mb/s, followed by an enhancement to “3” Mb/s (2.1 Mb/s in practice). A High Speed variation employs collocated Wi-Fi for short high-bitrate transmissions at 24 Mb/s. The Smart or Low Energy variation allows coin-sized batteries on devices like heart-rate monitors.

Bluetooth applications
Bluetooth applications

Applications include wireless keyboard, mouse and modem connections… though today, 2 Mb/s Bluetooth is likely slower than the modem.

Bluetooth is used to replace wires connecting a phone to an earpiece, or to an automobile sound system for hands-free phone calls while driving. In this case, both two-way audio and two-way control messages are transmitted.

Bluetooth is also used to stream music from a smartphone to a receiver connected to an amplifier and speakers in an automobile or in a living room.

In the future, wireless collection of readings from devices like heart-rate monitors will be widespread.

Each of these types of applications corresponds to a Bluetooth profile, which is a specified set of capabilities and protocols the devices must support.

Bluetooth implements frequency-hopping, where the devices communicate at one of 79 carriers spaced at 1 MHz in the 2.4 GHz unlicensed band for 625 microseconds (µs), then hop to a different carrier for 625 µs, then to another, in a repeating pattern known to both devices. A particular hop sequence is called a channel, and is identified by an access code.

This is called Frequency-Hopping Spread Spectrum (FHSS), since hopping between 79 carriers spreads energy across spectrum 79 times wider than one carrier. It has the advantage of reduced sensitivity to noise or fading at any particular carrier.

If different pairs of devices are using different hop sequences, they can communicate at the same time in the same place without interfering. There are security advantages if the hop sequence can not be determined by a third party.

The initiator of communications is called the master. It determines the frequency hopping pattern, when the pattern begins, when a packet begins and when a bit begins. The packet and bit timing is based on the master’s clock, which ticks every 312.5 microseconds. Two ticks make a slot. A slot corresponds to a hop. The master transmits and the slave listens in even-numbered slots; vice-versa in odd-numbered slots.

To establish the channel, the master derives a channel access code from its Bluetooth address, and indicates the code to the slave at the beginning of every packet. Both master and slave use this to determine the actual frequency-hopping sequence.

Data is organized into Bluetooth packets for transmission. Packets can be 1, 3 or 5 slots long. A bit rate of 2 Mb/s would mean Bluetooth packets are about 150, 450 or 750 bytes long.

Discovering other devices means sending requests in packets on pre-defined channels called inquiry scan channels. Making a device discoverable means it listens on the inquiry channels, and responds to inquiries with information like its Bluetooth address, name and capabilities. This results in a list of Bluetooth devices displayed on the discovering device, such as a smartphone.

Connecting to a device means paging the device on its paging channel, a channel with access code derived from the target’s Bluetooth address. Devices listen on their paging channel, and respond to pages to establish a session. Once the session setup protocol is completed on the paging channel, the devices begin communicating on the channel defined by the master.

The frequency hopping pattern can be adapted to skip carriers where the signal to noise ratio is permanently low, to improve overall performance.

I hope you’ve enjoyed this tutorial!

This discussion is covered in the following Teracom training courses:
• DVD-Video Course V6: Understanding Wireless

• Online Course 2233 Fixed Wireless

CWA course books released – and the first one is FREE!

The course books for the three Certified Wireless Analyst courses are now available on Google Play Books!

Course 2231: Wireless Fundamentals Course Book  – FREE
Course 2232: Mobile Communications Course Book – US$9.99
Course 2233: Fixed Wireless Course Book – US$5

We’re using Google Play Books because it allows you to read the book on any device: desktop, laptop, tablet, phone, PC, Mac, iPad, android… which is way more flexible than iTunes or other platforms.

The books are formatted the same way as Teracom instructor-led course and DVD course books, with detailed text notes on the left page and the corresponding graphics / bullets page on the right in two-page view.

To get you started, the course book for Course 2231: Wireless Fundamentals is free, downloadable and printable!

To download and print the the course book for Course 2231: Wireless Fundamentals, first add the book to your library (it’s FREE), then on the My Books page, click the three dots and choose “Download PDF” as shown in the screenshot below.

If you print the PDF two-sided then put it in a 3-ring binder, the result will be almost identical to the course books supplied with Teracom instructor-led and DVD courses!

Printable course book

Printable course book

New TCO Certification Package: Certified Wireless Analyst (CWA)

The Certified Wireless Analyst (CWA) Certification Package is released!

CWA includes three training courses covering the full range of wireless technologies, giving you the broad knowledge base required of an analyst in the wireless business — plus certification to prove it.

Learn the fundamentals, jargon and buzzwords, principles of operation and ideas behind today’s wireless.

You get three high-quality courses with our entertaining instructor, graphics and bullets, plus your certification:

Course 2231: Wireless Fundamentals
• Radio fundamentals. Radio spectrum.
• Digital radio: modems and modulation

Course 2232: Mobile Communications
• Cellular principles. Mobility and handoffs.
• Digital voice. Mobile Internet Access.
• The generations: 1G, 2G, 3G, 4G
• The technologies: FDMA, TDMA, CDMA and OFDM
• The systems: GSM, 1X, UMTS, HSPA and LTE

Course 2233: Fixed Wireless
• Wireless LANs, 802.11 standards, WiFi, security
• Bluetooth, WiMAX, point-to-point and satellites

Upgrade your skills – and your résumé – with this training and certification today.

Guaranteed To Pass with the Unlimited Plan!


Quality You Can Trust
Benefit from decades of knowledge, insight and experience distilled into clear lessons, logically organized to build one concept on another… in plain English.

Join our thousands of satisfied customers including:
AT&T, Verizon, Bell Canada, Intel, Microsoft, Cisco, Qualcomm, NSA, CIA, FAA, US Army, Navy, Marines and Air Force, Coast Guard, CIA, IRS, CRA, CRTC, RCMP, banks, power companies, police forces, manufacturers, government, local and regional telcos, broadband and fiber carriers and thousands of individuals.

gsa contract holder - assurance of quality
Teracom is a supplier of this training to the US Government under GSA contract GS-02F-0053X. Obtaining this Federal Supply Schedule contract involved a two-year-long process of evaluation including a customer quality rating where we scored 97%!

money-back guarantee
30-day, 100%, no questions asked money back guarantee.
If for any reason you change your mind during the 30 days after purchase, you can get your money back.
You have nothing to lose – and a marketable knowledge skill to gain! Get started now!


telecommunications certification organization (TCO)

About TCO Certification
Teracom is a Gold Training Partner of the Telecommunications Certification Organization, authorized to administer exams for TCO certifications on the myTeracom Learning Management System and award TCO certifications.

TCO certification is proof of your knowledge of telecom, datacom and networking fundamentals, jargon, buzzwords, technologies and solutions.

It’s backed up with a Certificate suitable for framing, plus – a Teracom exclusive – a personalized Letter of Reference / Letter of Introduction detailing the knowledge your certification represents and inviting the recipient to contact us for verification.

You may list Teracom Training Institute as a reference on your résumé if desired.

Benefits of Certification for Individuals
TCO Certification differentiates you from the rest of the crowd when applying for a job or angling for a promotion.

The knowledge you gain taking these high-quality courses, confirmed with TCO Certification, is foundational knowledge in radio and wireless: fundamental concepts, mainstream technologies, jargon, buzzwords, the underlying ideas – and how it all fits together.

This type of knowledge and preparation makes you an ideal candidate to hire or promote to a task, as you will be able to build on your knowledge base to quickly get up to speed and work on a particular project – then have the versatility to work on subsequent projects.

TCO Certification will help demonstrate you have this skill… a desirable thought to have in your potential manager’s mind.

Benefits of Certification for Employers
Take advantage of these courses for individual learning, a team, or for an entire organization. The scalable myTeracom Learning Management System can register and manage all of your people through their courses, lessons and exams, and generates reports showing progress and scores.

For larger organizations, the courses and exams can also be licensed and deployed on an organization’s internal LMS.

Teracom certification packages are an extremely cost-effective way of implementing consistent, comprehensive telecommunications and networking technology fundamentals training, ensuring that existing resources and new hires are all up to the same speed, with a common vocabulary, framework and knowledge base.

Get started today with this invaluable addition to your knowledge and skills!


Detailed Course Outlines

Course 2231 Wireless Fundamentals is the first course in the CWA Certification Package. We begin with the fundamentals: what radio is, how it’s organized and how and it’s used to communicate information. Since most systems are digital, we spend time understanding how modems represent 1s and 0s on radio, and explain jargon like QAM and QPSK. We finish with penetration and fading.
A. Radio
B. Wireless Spectrum and Radio Bands
C. Analog Radio
D. Digital Radio: How Modems Work
E. Propagation, Penetration and Fading

Course 2232 Mobile Communications is the second course in the CWA Certification Package. With a good foundation in place, we’ll cover mobile communications from A to Z: cellular principles, digital voice, data over cellular, mobile Internet access, the technologies: FDMA, TDMA, CDMA and OFDM, and the generations: 2G GSM, 3G 1X, UMTS and HSPA and 4G LTE. This is where the money is!
A. Mobile Network Components and Operation
B. Cellular
C. 1G: Analog Frequency-Division Multiple Access
D. Second Generation: Digital Cellular
E. Digital Cellular: Voice Communications
F. Internet Access via Cellular: “Data” Communications
G. 2G TDMA (IS-136): Time-Division Multiple Access
H. 2G TDMA (GSM): Time-Division Multiple Access
I. 2G CDMA: Code-Division Multiple Access
J. Spread Spectrum
K. CDMA Operation and Patents
L. 3G: CDMA 1X and UMTS
M. 4G: LTE
O. Dynamic Assignment of Subcarriers
P. Spectrum-Sharing Roundup: FDMA, TDMA, CDMA, OFDM

Course 2233 Fixed Wireless is the third and final course in the CWA Certification Package. We’ll round out your knowledge with fixed wireless: WiFi, 802.11, WiFi security, Bluetooth, WiMAX, point-to-point microwave and satellites.
A. Infrared
B. Bluetooth
C. WiFi: Wireless LANs
D. WiFi Security and WPA2
E. 802.16 WiMAX
F. Point-to-Point Microwave
G. Satellite

printable brochure

What You Get With The CWA Certification Package

1. High-quality, up-to-date, comprehensive training
You will get a solid foundation of structured knowledge. Understand the fundamentals, technologies, jargon and buzzwords… and how it all fits together

2. The certification exam
Each course in the certification package has an associated exam, typically ten multiple-choice questions.  You get unlimited repeats of the exam – which means guaranteed to pass.
Plus, on achieving a passing grade:

3. Your certificate, suitable for framing
A full-color TCO Certificate suitable for framing is automatically awarded by the Learning Management System on completion of the required exams.
It can be immediately printed on plain or textured paper on any color printer and framed by student as desired, with no shipping charges. It can also be attached to the electronic version of the student’s CV. An original hard copy of your Certificate, signed and sealed, can be sent to you by mail for $25 plus first-class mail cost.

4. A personalized Letter of Reference / Letter of Introduction
You also receive a personalized Letter of Reference / Letter of Introduction explaining the courses you took and the knowledge you have, and inviting anyone you give it to to contact us as a reference… excellent addition to your CV.

5. Right to display the TCO logo
You’ll have the right to display a high-resolution copy of the TCO logo on your rĂ©sumĂ©, business card, LinkedIn profile, web page, blog, or email signature.

6. TCO Certification Designation
Passing the Certified Wireless Analyst, you will be able to state that you:
– “are a Certified Wireless Analyst”,
– “hold a Certified Wireless Analyst certification from the Telecommunications Certification Organization”,
– are “certified as a Wireless Analyst by the Telecommunications Certification Organization”,
– are a “Telecommunications Certification Organization (TCO) Certified Wireless Analyst”,
– are “TCO-certified”,
and may sign your name
– “Richard Smith, CWA,” or “Jane Smith, Certified Wireless Analyst”

7. A 30-day no-questions-asked 100% money-back guarantee.
If for any reason you change your mind, for 30 days after purchase you can get your money back.

You have nothing to lose! – and a marketable skill to gain!

get started now!

Invest in yourself! Upgrade your résumé with this essential core knowledge.