Net Neutrality II: If the power company allowed this, your electrical bill would double.

Following up on a previous discussion, a demand for “net neutrality” usually means a demand that the network must not discriminate between applications being carried in IP packets; that identical transmission characteristics (throughput, delay, number of errors, etc.) are to be provided for all packets regardless of what is being carried in them.

But a demand for “net neutrality” is usually also wrapped together with a demand by these same people for no metering, no usage charges. This would mean that users who are continuously transmitting and receiving packets would pay the same flat rate as someone who is paying only for a typical traffic profile.

If this principle were applied to electricity, it would be like having no electricity meter. Everyone pays the same, regardless how much power they use. The problem: if you’re one of the 99% of normal users, you would have to pay DOUBLE what you normally would, to cover the costs of the 1% of users constantly drawing 200 amps 24 hours a day, 7 days a week, 365 days a year.

Here’s how that would work:
Continue reading Net Neutrality II: If the power company allowed this, your electrical bill would double.

Digitally-Signed Email: Authentication and Digital Signatures

E-mail was one of the first “killer apps” on the Internet, and has been a major contributor to increases in productivity over the past ten years. Of course, along with email came the scourge of spam. Criminals infect computers with trojan horse programs, creating collections of machines they control remotely to send millions of unsolicited offers for fake watches, pirated software, phony medications and ecard invitations to infect your computer.

As spam reaches 30, 40 or even 100 unwanted messages per day on a targeted account, it is becoming essential to automatically separate legitimate messages from spam. One tool available to senders of legitimate emails to aid the recipient in this process is to digitally sign their messages, allowing the recipient to establish a level of comfort that the message actually came from the indicated sender.

Continue reading Digitally-Signed Email: Authentication and Digital Signatures

Offshored tech support from the phone company… so bad it's funny + $240 per year for an email address ?!

We usually feature articles on technical fundamentals in the newsletter – but this related topic might lighten up your day… a “help” desk so bad, it’s almost funny.

Recently, a relative asked me to help them sort out an issue with their ISP. They were paying for two internet access services, one old dial-up plan and one DSL plan. They wanted to go to a new 802.16 WiMax broadband wireless plan from the same ISP. They question they were trying to sort out was whether they could move their email addresses from the two existing services to the new one… or if they would lose those email addresses.

So I agreed to contact the ISP’s email “help” desk to find out the answer. One would think that the question: “Can I migrate my email address from one service provided by your company to another?” would be a frequently-asked question at an ISP email help desk, and could be answered “yes” or “no” in a few seconds.

However, it turned out that the ISP, a subsidiary of Bell Canada, has outsourced most of its customer service, and what could have been answered in a few seconds turned into a 20-minute waste of time. Here’s a transcript of the online chat session:

Continue reading Offshored tech support from the phone company… so bad it's funny + $240 per year for an email address ?!

The IP-PSTN

The Packet-Switched Telecommunications Network

Over the past fifty years, several attempts have been made to develop converged networks: networks with “dial tone” that supports all communications: speech, music, text, graphics, images and video. For a number of reasons, convergence strategies employing ISDN and ATM were unsuccessful and did not gain critical mass. This time, it appears that packet-switched network service using IP will gain enough momentum to become the new kind of plain ordinary telecommunications service.

Continue reading The IP-PSTN

TCP/IP over MPLS

Following is a section from the new third edition of the Telecom 101 textbook, tracing the flow of information from server to client over a TCP/IP/MPLS protocol stack.

18.8 TCP/IP Over MPLS

MPLS is deployed for managing traffic on IP networks, and in conjunction with other technologies like VPNs covered in Chapter 19, will end up replacing all other services, including dedicated T1s, Frame Relay, ATM and ISDN.

Since MPLS is a virtual circuit technology, the packet flow from server to client over an MPLS network is similar to the Frame Relay flow examined earlier.

Starting with the server on the right, which is downloading a file to the client on the left, we take a chunk of the file and give it to the TCP software running on the server. That puts a sequence number, error check and application port number on the chunk of the file, passes this to the IP software on the server and starts a timer. The IP software adds the source and destination IP addresses to form an IP packet, which is put in an 802.3 LAN frame (that uses the 802.2 logical link layer protocol), with the MAC address of the premise router on the right pasted on the frame. The frame is then broadcast onto the Gigabit Ethernet over copper (1000BASE-T) LAN on the right and directed to the premise router by the LAN switch.

The premise router on the right brings in the LAN frame, extracts the packet and passes it to the routing software on the premise router, which makes a routing decision, puts the packet in a LAN frame, changes the MAC address, recalculates the error check and sends it over the Gigabit Ethernet over fiber (1000BASE-LX) access circuit to the service provider’s MPLS network.

diagram of TCP/IP/MPLS protocol stack

FIGURE 153  TCP/IP OVER MPLS

The service provider receives this packet with an ingress Label Switching Router (LSR). That device examines the IP address on the packet and along with other factors, decides what Forwarding Equivalence Class the packet belongs to, and implements its decision by labelling the packet with a 20-bit label identifying the FEC. It then does a table lookup to determine what network device packets with this label are forwarded to, and transmits the labelled packet in a frame on the appropriate circuit.

Each LSR in the middle of the network (not shown) brings in the frame, extracts the packet then only looks at the label and performs a table lookup to determine where to forward it and what priority to give it.

Eventually the labelled packet is delivered to the network’s egress LSR on the left. This device removes the label from the packet and uses conventional IP routing to send the packet in an Ethernet frame to the customer’s premise router on the left. 

The premise router on the left brings in the packet, and looks in a table to find out what MAC address (what LAN card) is currently assigned that IP address. If it does not find an entry, it broadcasts an address resolution request on the LAN at the left using the Address Resolution Protocol (ARP), asking “who owns this IP address?” The client responds with its MAC address. The premise router puts the packet in a LAN frame with that MAC address on the front, and broadcasts the frame onto the LAN at the left. The LAN switch on the left directs the frame to the client on the left. 

The client pulls in the frame, extracts the packet and gives it to the IP software on the client. Seeing that the destination IP address on the packet is the same as its address, the client’s IP software extracts the data out of the packet and gives it to the TCP software on the client. This checks the error check, and if it fails, discards the data. 

Shortly after, the TCP timer on the server times out, so the TCP software on the right retransmits the data. Let’s say the second time, it passes the error check at the client, so the client TCP software sends an acknowledgement to the server, then extracts the data from the TCP protocol data unit and parks it in a memory space for the application identified by the port number on the TCP header… the file transfer application, which picks up the data shortly after.

Meanwhile, we’re sending the next one.

 

Want more ?
There is, of course, much more to the story than this brief tutorial.

This discussion is actually the final discussion in a whole chapter that leads up to it, starting with bandwidth on demand and packet network fundamentals, ideas like virtual circuits and jargon like connectionless network services, then going through the technologies: X.25, Frame Relay, TCP/IP over Frame Relay, understanding what is needed for voice over packet networks, how Frame Relay doesn’t do it, but ATM was supposed to, then MPLS and how QoS is implemented with MPLS and finally the discussion above.

This topic is covered in more detail in Teracom instructor-led courses, DVD video Computer-Based Training courses, and textbooks.
Telecom 101 textbook, 3rd edition: Chapter 18 (26 pages)

Course 101 Telecom, Datacom and Networking for Non-Engineers
: Chapter 15
Course 110 Understanding IP Telecom: IP, VoIP and MPLS for Non-Engineers: Chapters 5, 8 and 13
DVD 4 Understanding Networking 1: Part 3

 



GSM vs. UMTS… and the CDMA tipping point finally reached

Recently, we’ve noticed there is confusion regarding GSM cellular technology, and how it relates to CDMA. Not a big surprise given the wealth of jargon, buzzwords and semi-informed “analysts” in this area, but worth straightening out.

First generation: analog
In the beginning was analog cellular mobile radio. This was the first generation (1G) of cellular, an improvement on the previous Mobile Phone System (MPS) that provided better coverage, more capacity and allowed mobility: the possibility of the user moving, and being handed off from one base station [antenna] to another without dropping the call.

Various flavors were deployed by operators in different countries, including AMPS in North America, TACS in England and NMT in Scandanavian countries. These 1G systems are Frequency-Division Multiple Access (FDMA), meaning that the spectrum [radio band] allocated to the operator is divided into smaller bands called channels, and channels are allocated to users.

Second generation: digital and the warring factions
Problems with capacity and data communication led us to second generation (2G) cellular. Two warring factions emerged, with radically different views on sharing spectrum amongst users: the TDMA faction and the CDMA faction.

TDMA, Time-Division Multiple Access, means sharing one radio channel amongst a number of users by taking turns, one after another, in time. In North America, systems conforming to the IS-136 standard implement eight time slots on 30 kHz channels, allowing three users (one time slot for each direction for each user, plus time slots for control information). In the Rest Of The World, systems conforming to the Global System for Mobile Communications (GSM) standard implement sixteen time slots on 200 kHz channels, allowing seven users. Modems transmit 1s and 0s that are digitized speech (or digitized silence), or data (or idle patterns) at 9.6 kb/s between the phones and the base station over the radio channel.

CDMA, Code-Division Multiple Access, means not dividing spectrum into narrow channels, and not implementing time-sharing on those channels, but instead having all users transmit in the same carrier [wide frequency band], all at the same time. However, instead of transmitting 1s and 0s directly, the users transmit codes to represent 1s or 0s, and only transmit when they have something to say. Codes are binary numbers – strings of 1s and 0s – chosen so that if some users transmit and some do not, the base station can determine which transmitted. In North America and in limited places in the Rest of The World, a solution from Qualcomm Incorporated called CDMAOne and standardized as IS-95 was deployed. Qualcomm has patents on several functions necessary for cellular CDMA.

GSM/TDMA is the most popular today
GSM/TDMA became far more popular than IS-95, and so the market for selling phones and collecting money from GSM users is currently the largest. But, GSM/TDMA assigns 9.6 kb/s time slots to users, and even with band-aids and add-ons like GPRS and HSCSD, bandwidth like that is not useful for data communication (email, text messaging, Internet browsing, Google maps and location-based advertising, video) in any meaningful way. Further, GSM/TDMA reserves bandwidth for users whether they have anything to transmit or not – a very wasteful and inefficient use of scarce radio spectrum.

Third generation broadband: the factions continue to disagree
So we needed a third generation (3G). Because of the 2G schism, it was desired to have a global standard for 3G mobile radio. A group called International Mobile Telecommunications 2000 (IMT-2000) was formed to come up with a single world standard – and failed. They produced a document that had five incompatible variations. The two serious variations both were CDMA, since it is the most flexible and most efficient way of sharing the radio spectrum.

The warring factions did not make peace, they just changed what they were arguing about.

The 2G CDMA faction supported the variation called IMT-Multi Carrier, known as CDMA2000, basically a software upgrade from IS-95. A version called 1X using 1.25 MHz carriers was immediately deployed. 1X Evolution – Data Optimized (1XEV-DO) allows high-bitrate data communications.

The GSM/TDMA faction supported the variation called IMT-Direct Spread, known as Wideband CDMA and now marketed as Universal Mobile Telecommunications System (UMTS), which uses 5 MHz carriers and allows high-bitrate data communications using technologies like High-Speed Packet Access (HSPA).

The CDMA tipping point in the GSM/UMTS faction
After numerous false starts, the tipping point between 2G and 3G in the GSM/UMTS camp was finally reached in the summer of 2007, when more new activations on GSM/UMTS carriers’ networks were UMTS (3G CDMA) instead of GSM (2G TDMA).

What to take away from this discussion

  • The 2G TDMA technology GSM at present has far more users, but like 1G analog, GSM will eventually disappear.
  • Two incompatible competing 3G CDMA-based technologies: IMT-MC (CMDA2000 1X) and IMT-DS (UMTS) will go forward.
  • Qualcomm sells a chip or gets a patent license royalty for every handset and base station sold, for both 1X and UMTS.
  • Many users, salespeople and semi-informed analysts and reporters will erroneously refer to IMT-DS (UMTS) as “GSM”.
  • Want more ?
    There is, of course, more to the story than this brief tutorial. This topic is covered in more detail in Teracom instructor-led courses, DVD video Computer-Based Training courses, and textbooks:
    Course 101 Telecom, Datacom and Networking for Non-Engineers: Chapter 6
    Course 120 Understanding Wireless: Chapters 8, 9 and 10
    DVD 6 Understanding Wireless 1: Parts 2, 3 and 4
    Telecom 101 textbook, 3rd edition: Sections 8.2 – 8.7 (21 pages)

    What is "Web 2.0"?

    Teaching a class, a student asked me, “What is ‘Web 2.0′”? 

    Having briefly scanned some online articles about it, I answered “It doesn’t mean anything. Just hot air”. 

    Later, I did a bit more digging on “Web 2.0” and confirmed my initial take: hot air. 

    In fact, I re-defined “Web 2.0” it in my mental storage system as: “Been there, done that.”

    The term “Web 2.0” appears to have been coined during a “brainstorming session” between Tim O’Reilly of O’Reilly Media and MediaLive International. Presumably, the purpose of this brainstorming session was to create themes for a new commercial tradeshow. 

    According to O’Reilly, they formulated a definition of Web 2.0 by example:

    Web 1.0
      Web 2.0
    DoubleClick
    –>
    Google AdSense
    Ofoto
    –>
    Flickr
    Akamai
    –>
    BitTorrent
    mp3.com
    –>
    Napster
    Britannica Online
    –>
    Wikipedia
    personal websites
    –>
    blogging
    evite
    –>
    upcoming.org and EVDB
    domain name speculation
    –>
    search engine optimization
    page views
    –>
    cost per click
    screen scraping
    –>
    web services
    publishing
    –>
    participation
    content management systems
    –>
    wikis
    directories (taxonomy)
    –>
    tagging (“folksonomy”)
    stickiness
    –>
    syndication

    The main theme: the web as a platform for applications. Second theme: collaborative efforts.

    So Web 1.0 was the development and adoption of the browser, HTTP and HTML. Web 2.0 was the development of applications like Wikipedia that use it. 

    Been there, done that, or what?

    Let’s talk about Web 3.0 and 4.0!

    At Teracom, we’re interested in getting you up to speed on the technology underlying today’s and tomorrow’s telecom products and services. 

    Taking our acclaimed training, you’ll understand the concepts and ideas, mainstream solutions and how it all fits together.

    For example: we’ll cover the idea of virtual circuits, how they are implemented in the IP world with MPLS, and how MPLS can be used to implement Quality of Service guarantees and Service Level Agreements in the IP world. 

    … this is knowledge you can’t get from pundits or trade shows. Career-enhancing knowledge you can leverage going forward.

    So let’s talk about the next two technology steps: 
    call them Web 3.0 and 4.0 – or VoIP and IPTV. 

    Web 3.0: The IP-PSTN 

    Web 3.0 will have happened when the Public Switched Telephone Network and the Internet become the same thing.

    You will know we have reached that point when you read that a telephone company has applied to its regulator to stop being required to provide analog POTS for new service orders. 

    Broadband IP Dial Tone will be the new Plain Ordinary Telephone Service.

    In this future, you won’t have analog telephone service. You’ll only pay for high-speed internet access – from the cable company, the telephone company or maybe some metro wireless or metro fiber outfit.

    They’ll give you a drop wire / entry cable / wireless access plus an adapter which does the functions of Modem / UPS / Gateway / Edge router / Ethernet switch / NAT (a MUGEEN). 

    You can plug this box into an existing phone jack and it will implement POTS on your inside wiring – dial tone, ringing, off-hook detection… 

    The MUGEEN also has Gigabit Ethernet ports. You can plug it onto your LAN and it provides Gigabit Ethernet LAN switching in your house and access to the Internet for anything on the LAN. 

    You can also plug in an Ethernet IP phone to do VoIP over the Internet. If you can set up a phone call by right-clicking on someone’s email address on your computer screen and choosing “Call” or “Talk”, then pick up the phone to use its microphone and speaker, you’ll know you have arrived at Web 3.0. Some people are already there!

    Web 3.0 is covered in: 

    Course 130, Understanding Voice over IP (2 days, for managers) and 

    Course 110, IP Telecom: VoIP and the All-IP Network (3 days, for the more technically-oriented). 

    Web 4.0: IPTV 

    So if VoIP and broadband IP dial tone is Web 3.0, what is Web 4.0? 

    Well, as a picture is worth a thousand words… 
    video is next

    HD video streaming from a video server to your video display over your 20+ Mb/s Internet connection. 

    Subscribe to a package of “channels” or customize your own feeds via a web page. 

    On the web page, search for, then download or stream and initiate the playing of any television show episode, movie, sporting event or other video that has been catalogued. 

    Access this web page on-screen via a wireless keyboard, on your desktop or maybe see it on your wireless palmtop. Or just use a clicker. 

    Much of the existing video will be archived somewhere on the Web. Content that is out of copyright or public license will be free. You’ll have to pay for new episodes of Lost. 

    One milestone will be good-quality streaming of Standard Definition video (DVD quality, 480×720 pixels). You’ll know we are truly there when you can stream HD (1080×1920). 

    You’ll get a good understanding of the network that will support Web 4.0 in Course 110, IP Telecom: VoIP and the All-IP Network. We’ll beef up the IPTV content in that course as the story progresses. 

    Tutorials and articles on telecom, datacom, IP, networking, VoIP, MPLS and wireless from Teracom Training Institute. teracomtraining.com … Best of breed: telecom training – since 1992