Foolish: The Internet Protocol, IP, does not provide any guarantees. There is no guarantee that a packet will be transmitted, when that might happen, how often that might happen, or how long it will take to reach its destination. Nothing. Nada. Zip. Bupkes. In IP, there is even no way for a device to which a packet is proposed to be transmitted to report back whether it got the packet, sent it onward or what. Nothing. This is called a connectionless, unreliable network service. 
 
Here’s the foolish part: if we are to use an IP network for real-time, delay- and loss-sensitive applications like phone calls and watching television, implementing Quality of Service (QoS) mechanisms to guarantee transmission characteristics is essential… otherwise, there is no way to guarantee quality of the reconstructed signal at the destination. Television pictures would freeze, then jump forward, sometimes have block distortion effects and other artifacts. Clicks, pops, muting, breaking up and similar effects would be heard on phone calls. Saying that we should not take measures to prevent this is foolish. All phone calls and television will happen over IP in the future. 
 
Guaranteeing transmission characteristics is easy if there is no traffic on the network. The difficulty happens when there is contention, either for the use of an outgoing circuit at a network device, or contention for the use of the processor in a network device… and this contention is going to have to be resolved in favor of real-time, delay- and loss-sensitive applications like phone calls and watching television to the detriment of applications that are less sensitive to delay and packet loss like web page downloads, email and file transfers. 
 
Here’s the ignorant part: IP network service providers are not operating IP networks as such. They are operating MPLS networks. MPLS is the IP world’s implementation of virtual circuits, where we define classes of traffic and pre-determine routes and relative priorities for the classes. A class of traffic is a flow of packets going from the same place to the same place and should experience the same transmission characteristics. We establish multiple classes going from the same place, to the same place but each with a different specified transmission characteristic. This way, the class is a number to look up in a table in the LSR that will yield the address of the next-hop device and the priority level of the packet. My favorite priority level is “discard eligible”.
 
At the entrance to the MPLS network, the first MPLS router analyzes the packet to determine what (among other things) application is being carried in the packet (voice, video, music, email, web page, etc.) to determine class it belongs to, and when it decides, pastes a label on the front of the IP packet with a number indicating the class. Intermediate Label Switching Routers in the network do not examine the IP address, they use the number in the label to lookup the routing decision and the priority level of the packet. This is how Quality of Service is implemented on packet networks.

It’s ignorant for these supposedly-well-informed net-neutrality advocates to talk about “IP” networks when they are actually MPLS networks, and one of the main reasons for the network operator having implemented MPLS was to be able to prioritize packets based on the application being carried inside them, to be able to guarantee transmission characteristics for phone calls and watching television.  It’s already done.  Too late.
 
“Disingenuous” is usually defined as being not straightforward or candid; giving a false appearance of frankness; being insincere. Here’s the disingenuous part: the application that is being “throttled” or traffic that is being “shaped” or “slowed” (the correct term is “policed”) is piracy. Theft. In most places, illegal activity. Downloading illegal copies of copyrighted material. Stealing. 
 
The category of application being policed is peer-to-peer file sharing. Examples of this kind of application include bittorrent and limewire. These applications are used 99.999% of the time to download illegally-made copies of Hollywood movies, music of all kinds from Beethoven to Eminem, training videos, software, ebooks, audio books and other copyrighted works without paying the author or publisher. Take a look at one of the bittorrent sites like piratebay dot org and click “browse torrents” to see for yourself. Yes, the advocates can describe how bittorrent was designed for the legitimate delivery of software, and trot out one example of a legitimate use… but this is definitely a case where the exception proves the rule. 99.999% of the use is theft. 
 
In English common law there is a maxim: you can’t come to court with dirty hands; in other words, you can’t ask for justice if you yourself are obviously breaking the rules. The people whose traffic is being policed have filthy dirty hands. Methinks the lady doth protest too much. 
 
– EC
 
The technical topics in this article are covered in:

Course 101 Telecom, Datacom and Networking for Non-Engineers,
  Chapter 3-3 “Bandwidth-On-Demand: Packet Network Services” and following

the most comprehensive discussion of this topic is in this course:
Course 110 Understanding IP Telecom: IP, VoIP and MPLS for Non-Engineers, (special: 2-for-1 in June)
  Chapter 14. Quality of Service in the IP World:  NET NON -NEUTRALITY

Video Course DVD-4 “Understanding Networking 1″
  Part 3 WANs - Bandwidth On Demand: Packet Network Services (special: get a free copy with Course 150 in June)

Telecom 101 Textbook
 Chapter 18 Bandwidth on Demand 

  
 
Course 110 - Understanding IP Telecom: IP, VoIP and MPLS for Non-Engineers covers virtually all aspects of IP networks, Voice over IP, VPNs, MPLS, IP security, carrier interconnect, service levels and more. Designed for non-engineers, this training course will give you the solid, vendor-independent foundation knowledge necessary to deal with IP telecom network projects and IP voice and data applications with confidence.
  
In three days, you’ll get up to speed, demystify jargon and buzzwords, fill the gaps, understand the technologies, the underlying ideas and how it all fits together… knowledge you can’t get reading trade magazines or talking to salespeople.
 
This investment will be repaid many times over, eliminating frustration at buzzword-filled meetings and increasing your accuracy and efficiency. Understanding IP Telecom is an essential knowledge set going forward in telecommunications. Get this career-enhancing knowledge today!
 
Key Course Features
 • Solid coverage of IP telephony and VoIP systems
 • Solid coverage of IP networking and its components
 • MPLS, Service Levels and Traffic Shaping
 • IP Security
 • Practical Mainstream Solutions and Products 

Course 150 - Understanding IP Contact Center Technology covers virtually all aspects of IP in the call center with a complete, unbiased picture and a thorough understanding of IP contact center technologies, benefits, issues, options for solutions, migration and integration strategies and vendor offerings, complete with practical templates and checklists you can put to immediate use. 
 
Impossible to find in one place anywhere else, this incredibly comprehensive and up-to-date course will save you hundreds of hours trying to research these topics yourself. Numerous detailed checklists and templates will ensure you’re not missing any critical items… or alternatives vendors might “forget” to mention.

This investment will be repaid many times over, eliminating frustration at buzzword-filled meetings and increasing your efficiency, and helping to ensure you make the right choices. Understanding IP Contact Center Technology is essential for going forward in the contact center business.
 
Key Course Features
 • Get Up to Speed on IP in the Contact Center
 • Build on a Solid Base
 • IP-Based Technologies and Capabilities
 • Mainstream Practical Choices and Solutions
 • Business Case examples
 • Implementation, Vendors and Project Management
 • Formulating an RFP – and dealing with vendors

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.

This email is digitally signed. Your mail client may indicate that it has verified the signature; for example, yahoo mail displays a key icon and gmail states “signed by” below the the to: and from: information. This verification can be used to raises the confidence level at your end that the message is legitimate.

Digital signatures are implemented with asymmetric encryption. Asymmetric means that there are two keys (binary numbers). What is encrypted using one key can be decrypted with the other… and vice-versa. The most popular method of generating key pairs and using them for encryption and decryption was devised by three fellows named Rivest, Shamir and Adelman and is called RSA.

A standard strategy is to generate a key pair, then make one of the keys visible to the public and keep the other key private.

Digitally signing a message means the sender using their private key to encrypt selected text and attaching that to the message.

To authenticate the message, that is, verify the digital signature, the recipient can get a copy of the purported sender’s public key and use that to try to decrypt the selected text attached to the message.

If the decryption using the sender’s public key is successful, then the recipient knows that the message was indeed “signed” by the sender (or by someone who stole the sender’s private key).

This process is called authentication.

Yahoo developed the Domainkeys strategy, which is implemented for Teracom’s email newsletters.

At the sender, the Secure Hash Algorithm 1 (SHA-1) is used to generate a “hash” or unique binary number representing the email message body and headers such as Message-ID, Received header, the X-Mailer header, Date header, From:, To:, MIME-Version: and Content-Type headers. This hash is then encrypted with the sender’s private key using RSA, and the encrypted hash is added as another message header.

At the receiver, it is necessary to get the sender’s public key… so how does the receiver get that? The Domain Name System (DNS) is used. Normally, DNS records relate domain names to IP addresses; but it turns out that a DNS record type that allowed free text for comments or domain info was implemented, and this is used to store the domain’s public key.

So the receiver examines the domain name of the purported sender, does a DNS lookup to get the domainkeys public key for that domain, and uses it to decrypt the hash contained in the email header. The receiver also computes the hash of the received message and compares the two.

If they are not the same, then the message was not sent by that domain (the From: field is false, for example), or the message was altered, and the receiver would generally put the message in the garbage where it belongs.

If the hash of the message and the hash in the header are the same, then we have a high confidence that domain sent the message. This knowledge might be combined with other knowledge, for example the reputation of the sending domain, and used to decide to place the message in the inbox.

This sending-domain authentication using digital signatures is one tool in the fight against spam. Teracom has implemented it to help ensure that our newsletter goes into your inbox, particularly if you use Yahoo mail. Note that if you want to be absolutely sure these messages go in your inbox, also add “newsletter@teracomtraining.com” to your whitelist / trusted senders / address book… this is the “reputation” part of the previous paragraph.

The Yahoo Domainkeys strategy is being improved and standardized in RFC 4871.

Asymmetric encryption, digital signatures and authentication are covered in:
  Teracom DVD-Video Course V5, “Understanding Networking 2″, and in
  Teracom instructor-led Course 110, “IP Telecommunications”.

DNS is covered in
  Teracom DVD-Video Course V5, “Understanding Networking 2″, and in
  Teracom instructor-led Course 101 Telecom, Datacom and Networking for Non-Engineers”

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:

This is so bad, it’s almost funny.
What’s not so funny is the wasted 20 minutes of my life.

Calling the toll-free number, I spoke to a person who sounded like they lived on the same continent I do, and after putting me on hold for 30 seconds while they looked up the question online, gave me the answer: one of the services could be upgraded to WiMax and so the email address would be preserved. What about the other? Sorry. Email addresses can not be transferred from one service to another.

So, to keep both email addresses, it would be necessary to continue paying for the $20 per month dial-up plan in addition to the $65 per month WiMax… $240 per year plus tax for an email address, with online customer support on the cheap.
Sounds like a good business to get into!

This is a favorite trick of ISPs, locking you into paying for their service by tying you to an email address they control.
Solution: don’t use an email address furnished by your ISP. Use an ISP-independent email address you can keep for the rest of your life.

Google’s gmail may be a good choice as it is a) free, b) provides very good spam filtering, c) supports both browser and POP (e.g. Outlook) access and d) includes gigabytes of free email and file archiving. Yahoo, MSN and others might also be good choices.

Ideally, you would forward your ISP mail accounts to your new gmail for a few months while you notify everyone of your new email address then kill the ISP email accounts.

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.

Beginning with grunts and gestures, progressing to verbal messages, signal fires, written messages, postal services, telegraphy, radio, telephone, television and computer networks, each advance in technology has meant communication of more information, faster and to more people – but often with the need to adapt the information to suit the communication technology being used. Realization of a converged network will be another step in the evolution of the way humans communicate, in that communication mechanisms best suited to the information will be used, rather than the other way around.

The abbreviation “PSTN” has been a familiar part of the telecom lexicon for perhaps 100 years. Now its meaning is going to change. For the past hundred years, PSTN has meant Public Switched Telephone Network:
- Public: Accessible to anyone who pays.
- Switched: Circuit-switched service, a trunk reserved and switched onto the access lines at each end, for the duration of the call, then released.
- Telephone: Speaking at a distance.
- Network: Many interconnected nodes.

Now, “PSTN” will mean Packet-Switched Telecommunications Network:
- Packet-Switched: Communications segmented and encapsulated in packets that are routed using IP or switched using MPLS to the far end.
- Telecommunications: Transferring any kind of information across distance.
- Network: Many interconnected nodes.

It may be necessary to use IP-PSTN or IPSTN for a transitional period, until circuit-switching falls into the same dustbin of history as step-by-step switches.

FIGURE 1.02  THE IP-PSTN

This new PSTN will provide broadband IP dial tone: high bit-rate access circuits plus the possibility of communicating IP packets to any point on the network. “Businesses” (including government, educational institutions and the like) will use Ethernet over fiber at Gigabit speeds for access. Residences will use modems over copper wires – either DSL or cable for access for quite some time to come.

Many different kinds of value-added services will be available in addition to basic IP packet communication service, some of them provided by the same company that provides the “dial tone”, others provided by third parties.

The lowest level of value-added services includes service level agreements and network and information security services. An unending list of higher-level services will be available for use on the network; some free, many not. Telephone service, television, web surfing, radio, videophones, desktop sharing, and integrated email/voicemail messaging are easy examples.

DMS-100 and 5ESS switches will be replaced with softswitches – software on servers on the IP network. Media servers will support voicemail and video programming. Internet access service will become simply a few ancillary services such as a Domain Name Server and an outgoing email server; the capability to communicate with web servers will be part of the dial tone.

This is the biggest change in telecommunications since the invention of the telephone switch… certainly more important than the change from analog to digital transmission in the 1980s, and it will have a profound impact on the way people communicate.

This is the first page of Course 110 Understanding IP Telecom: IP, VoIP and MPLS for Non-Engineers… a big-picture view to get things started.

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.

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