Communication and Internet Technology: Mobile IP with IPv6 (Part 6 of 6)

By Prof. Chandan Tilak Bhunia

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Mobile IPv6 is a protocol developed as a sub-set of Internet Protocol version 6 (IPv6) to support mobile connections. It allows mobile devices to move from one network to another and still maintain existing connections.

Mobile Internet Protocol (IP) provides mobility support on the existing IP infrastructure. It is needed without any modifications for existing routers, applications or fixed end-hosts. How can then mobile IP change with IPv6?Mobile IPv6 allows an IPv6 node to be mobile like an IPv4 node. Mobile IPv6, unlike mobile IPv4, supports additional support for mobility, route optimisation and security. IPv6 allows Internet nodes to associate a mobile node’s (MN’s) home address with its care of address (COA) and send packets directly to COA (and not via home address).

MN obtains COA, eliminating the need for foreign agents. Mobile IPv6 uses route optimisation by which MN sends its current COA to the correspondent node. When it knows about MN’s current COA, a correspondent node can deliver packets directly to MN’s home address without any assistance from home agent.

Since mobile IPv6 does not make use of foreign agents, it uses correspondent node and binding. Binding refers to an association of home address with COA of MN.

Correspondent node is a peer node with which MN communicates. It may either be mobile or stationary. Its functional operation is given below.

  • MN gets registration to foreign network (FN) and gets COA as in mobile IPv4.
  • MN sends binding update to home agent.
  • Home agent uses proxy neighbour discovery to record MN in home network (HN).
  • IP datagram addressed to MN is encapsulated in IPv6 to IPv6 tunnel. Then, the encapsulated packet is sent to COA of MN.
  • IP datagram from MN makes use of the same tunnel in reverse.
  • IP datagram from MN is sent to correspondent node directly.
  • MN sends binding update to correspondent node.
  • Mobility support in IPv6 retains the ideas of HN, home agent and use of encapsulation to deliver packets from HN to MN’s current point of attachment, like in IPv4.
  • Foreign agents are not required to support mobility in IPv6. IPv6 improves routing efficiency, enhances mobility support and simplifies procedures.

IP telephony and VoIP

The Internet was established primarily for transporting traditional data. Traditional data differs from other communication services, namely, voice and video, in many respects. From customers’ point of view, a single network for all services (voice, video and data) sounds appealing.

Single infrastructure, single access is always affordable and convenient.The natural question that arose then was, “Why not use the Internet to carry all services of voice, video and data?”

Solutions for this came in the forms of Internet Protocol telephony (IP telephony)/Voice over Internet Protocol (VoIP) and Internet Protocol TV (IPTV). These solutions address the technical challenges of carrying real-time and jitter-free voice and video over the Internet.

There are several advantages for transmitting VoIP, including:

  1. Long-distance calls at low cost but, maybe, of low quality
  2. Cheaper two-in-one service
  3. Use of PC as a true multimedia terminal
  4. One connection for all services
  5. Local exchanges to support telephone with the Internet as backbone and without high investment in expensive backbone infrastructure
  6. Use of packetised voice allows voice compression, which, in turn, decreases transmission time and cost. Earlier, telecommunication traffic or telephony connections outnumbered data traffic.

In the future, there will be explosion in data traffic. The need to deploy the Internet for real-time services like voice and video has necessitated redesigning of some features of the Internet. The two important features related to this emerging issue are:

  • Redesigning of IP datagram format
  • Using real-time data transfer protocol (RTP) and IP for carrying voice over conventional IP datagram and the Internet

Internet telephony refers to communications services—voice, facsimile and/or voice-messaging applications—that are transported via the Internet, rather than public switched telephone network (PSTN).

IP telephony is a general term used for technologies that use IP’s packet switched connections to exchange voice, fax and other forms of information that have traditionally been carried over dedicated circuit-switched connections of PSTN.

Using the Internet, calls travel as packets of data on shared lines, avoiding tolls of PSTN. The challenge in IP telephony is to deliver voice, fax or video packets in a dependable flow to the user. Much of IP telephony focuses on this challenge. VoIP is an organised effort to standardise IP telephony.

IP telephony is an important part of the integration of computers, telephones and TVs in a single, integrated information environment. It has become a reliable communication option with a well-established standardised communication protocol.

VoIP is simply transmission of voice traffic over IP-based networks. PSTN based on circuit switching provides voice service with guaranteed quality of service (QoS). This is not the case with voice service provided by the Internet that acts on packet switching.

There are many technical challenges that a voice packet faces while in transition over packet switching network like the Internet. These include packet loss, packet transfer delay and jittering delay.

Voice communication involves human interaction. As such, loss of some voice packets can be tolerated due to human intelligence and perception involved in recovery. However, excessive loss of voice packets may seriously degrade voice quality. Moreover, PSTN is a reliable voice service provider, whereas the Internet is not, because it is datagram-based.

Delay is a more serious issue for real-time interactive services like voice. It is the time difference between the time the sender releases the packet to the network and the time at which the receiver receives the packet from the network. Delay refers to:

  • Total transfer delay of a packet that includes coding/decoding delay, propagation delay, transmission delay, node processing and queue delay, switching and routing delay
  • Jittering delay that refers to phase delay between two successive packets

If total delay exceeds a certain value, users may get irritated with the service. According to a statistic, a delay up to eighty milli-seconds between the caller and callee is acceptable, but beyond that is not.

Total delay is a variable quantity, and it varies from packet to packet.

Jittering delay, on the other hand, is a serious issue. If phase lags between voice packets at source and destination vary, service quality degrades. Phase lags between packets differ from source end to destination end because total transfer delay varies from packet to packet.

Internet Protocol TV

Internet Protocol TV, or IPTV, Internet TV and Video on Demand (VoD) provide excellent opportunities to service providers and customers. IPTV offers unique opportunities to integrate voice, video and data over a broadband network. It is a simple, low-cost system of delivering TV services using IP to transport audio/video signals.

Use of IP for carrying audio, video and image signals is not new. What is new is the use of broadband consumer bandwidth and IP to meet desired performance and QoS for providing TV services. It is a form of commercial broadcasting TV using IPs, including IP, Transmission Control Protocol/User Datagram Protocol (TCP/UDP) and Real-Time Protocol/Real-Time Control Protocol (RTP/RTCP).

The carrier network is provided by service providers. IPTV, simply speaking, is a system of audio and video delivery over an Internet connection. The difference between IPTV and Internet TV is that, IPTV uses a dedicated network for distribution like very high rate digital subscriber line (VDSL) for broadband support, usually 25mbps, whereas Internet TV uses the whole infrastructure or the whole Internet as the transport medium.

IPTV has limited scope for users as it is considered to exist in a closed network. While, Internet TV is available and accessible everywhere, subject to Internet access availability.

Interplanetary Internet

Everywhere (terrestrial and celestial) Internet access and availability is the motto of Interplanetary Internet (IPN). Internet over the years has undergone far-reaching and profound changes while becoming a critical communications infrastructure. It has become a fully-pervasive infrastructure providing anywhere, anytime and any service connectivity.

For the future Internet, the most important challenge is to ensure anywhere, everywhere communication support in the entire solar system. In data communication, anywhere and everywhere IP is the next-generation Internet technology.

IPN is next to IPv6, IPTV, VoIP, compressed header IP, mobile IP and other IPng (IP next generation). It is, in fact, an attempt of human ingenuity to move towards the future integration of space and terrestrial communication that will support the migration of human intelligence throughout the solar system.

IPN’s vision is to provide Internet-like services across the solar system. IPN will look like the Internet on Earth and a similar one on Mars linked by gateways. These gateways are satellites that will relay the information between the Internets. How?

Like terrestrial or classical Internet, IPN will support:

  • Best effort delivery of packets over stateless infrastructure
  • Unique global addressing with dynamic routing
  • End-to-end reliable service and flow control
  • Scalable global domain names decoupled from addressing

IPN will not be like the Internet because of the differences in communication parameters between IPN and classical Internet (see table above). Main differences imply that IPN protocol cannot rely on end-to-end connectivity; here, end-to-end delay is huge and cost of transmission is high.

This implies designing IPN as a network of regional internets spanning dissimilar environments and as a delay-tolerant network is important. In IPN what is needed is to transfer packets end-to-end through disconnected multiple regions that tolerate variable delay.

A protocol of IPN takes care of these requirements using Bundling Protocol Suite, which is believed to provide general-purpose delay tolerant protocol. IPN proposes to interconnect IPN regions by way of common messaging layers called bundles.

Bundling is a new overlay protocol to put together a set of heterogeneous Internets. Bundles (messages) are arbitrarily long messages designed for end-to-end delivery between IPN nodes over distinct or identical transport layers. These are routed by a routing function through a concatenated series of Internets, like how terrestrial IP routes packets through a series of independent sub-networks.

To achieve guaranteed end-to-end delivery, bundles may be retransmitted as in Automatic Repeat Request (ARQ) protocol used in TCP layer of terrestrial Internet. The interplanetary backbone of IPN depends on very fragile wireless links. Besides, hubs on the interplanetary backbone move with respect to each other. This may disturb the line-of-sight communication, which needs some sort of relay communication from time to time. Hence, unlike Earth’s backbone environment of continuous connectivity, IPN transmission may get discontinued.

Bundles are routed, forwarded and custody-transferred with new concepts. In IPN, routing means sending using best efforts to the next IPN hop for the desired destination. Forwarding means sending bundles on demand for non-persistent nodes. Custody transfer is a reliable intra-IPN delivery with storage for persistent nodes. In fact, in custodial transfer, the sender can transmit a file to the receiver over a single link and, on receipt of the entire file, the receiver can notify the sender about any successive forward transmission hops.

IPN nodes are of the following types: agent, relay, gateway and custody transfer.

  • Agent builds and consumes bundles.
  • Relays are agents that forward bundles within or between regions.
  • Gateways are relays that do routing between regions.
  • Custody transfers are optional, and optional versus nodes.

Alternative IPN nodes may be Non-Persistent (NP) node, Persistent (P) node and Exception (E) node. IPN nodes face huge challenges due to instability of backbone and a very long-haul link (long delay and error). An interplanetary backbone is a set of high-capacity, high-availability links between network traffic hubs like terrestrial network backbones. The difference is that hubs and nodes in IPN are, in many cases, hundreds of millions of kilometres apart.

The final journey of the Internet

The Internet is the most amazing gift from the field of information technology (IT). The father of information theory Claude Elwood Shannon defines information from the point of view of communication engineering. In his information theory, more entropy means more information. While in the probabilistic second law of thermodynamics, more entropy means more disorder. Does this mean that more information results in decrease in order? If yes, how?

Entropy of thermodynamics (decrease in order) is a measure of how much a reaction is irreversible. The steam engine produces some waste heat energy. This waste heat energy that causes hot atoms to randomly bounce around is improbable to get back into orderly atoms. Once you get some information, you get so by consuming some energy either by computer processing, network information downloading or other means of communication.

These functions produce some waste heat, which is irreversible. Thus, the durable definition of entropy—a measure of information by Shannon—perfectly matches with entropy of thermodynamics.

An appropriate definition of information in the IT age is by Tom Stonier. Recently, Stonier speculated in his work, titled “Information and Internal Structure of the Universe,” that there is an analogy between mass/matter, energy/heat and information/order of an organisation. He argued that information (I) resident in any organisation is proportional to order (O) of the organisation:

I = C.O

where C is the constant of proportionality

If this relation exists, there may be a possibility of interchangeability of information with energy, which, otherwise speaking, will establish a measurable and quantifiable relation between an industrial-based society and an information-based one.

Stonier established an exchange rate, which is one Joule per degree Kelvin=1023 bits of information. This has raised a lot of criticism and questions, but there is a direction, which, if proven correct in the future, may lead to the conclusion that information is not external to nature but a fundamental unit of nature.

Shannon’s theory demonstrates the inverse relationship between information and entropy in case of communication or information processes. The inverse relationship also holds good for physical or life processes. By the relation between information and knowledge, as demonstrated by several works, it is a reasonably good assumption that knowledge is proportional to information. Hence, entropy and knowledge hold an inverse relationship to each other.

The laws of thermodynamics, particularly the second law, govern physical or life processes. The second law is related to entropy, which is a measure of disorder. An orderly system is associated with entropy minimisation, which means minimisation of energy, space and time for a given amount of effort.

Life is an open system that exchanges energy and information with its surroundings for any effect due to any cause. The second law of thermodynamics confirms that an open or life system can be made more knowledgeable (more orderly or reduced entropy) only by increasing disorder in its surroundings or environment. Thus, knowledge increases order of organisation or, otherwise speaking, minimises organisational consumption of energy, space and time. Therefore justification of Stonier’s theory may hold true.

These developments are the manifestation of the basic law of nature, which says, in this universe if anything remains constant, it is nothing but change. Stonier’s work on information treats information as the fundamental thing of the universe. And so, information must follow the fundamental laws of the universe, like Newton’s laws of motion, mass-energy equivalency, theory of relativity, etc.

Bringing analogy to Newton’s laws of motion, it can be said that laws guide information. Before establishing laws, analogies are defined, as follows:

  1. A bit of information is analogically a mass particle. (Here, bit is a bit of information.)
  2. Network is the universe of bits.
  3. A bit moves with velocity that has the unit of bit/sec, and acceleration with the unit of bit/sec2. (Here, bit is a bit of data.)
  4. Knowledge is analogous to force. Unit of knowledge is proposed as KN such that,

1KN=1bit – bit/sec2

First law of information

All bits continue to stay in their files, unless compelled to move by processing by application of knowledge to add value, and vice-versa.

Second law of information

Acceleration (a) of bits for moving in a network derives from application of knowledge (k) by the rule:

k=(bits of information)×a

Third law of information

Every action created by knowledge has an equal and opposite reaction. Computer viruses/security are reactions to the knowledge application on information.

After natural and electrical communication, what is left is mind communication. Today, one of the main criteria for the development of technological electrical communication is “fast.”

It is said “fast” will be last thing for electrical communication to solve. For example, data transfer rates started with a few bits per second, but have now gone up to kilobits (1000) per second to megabits (1,000,000) per second to gigabits (1,000,000,000) to terabits (1,000,000,000,000) per second.

In Navaratna Sabha, once Akbar asked his Ratanas, “What moves fast?” When eight of nine Ratanas pointed towards the royal horse, Birbal got an edge over others by saying, “Our mind.” It has been established that today’s fiction becomes tomorrow’s reality in science and technology. It will therefore not be unreasonable to state that, in future, technological communication may lead to mind communication, too, which may lead to Mind Internet.

This article is dedicated by the author to Sir J.C. Bose, the greatest engineer India has ever produced


Prof. Chandan Tilak Bhunia is PhD in computer engineering from Jadavpur University. He is also fellow of Institution of Electronics and Telecommunication Engineers, fellow of Institution of Engineers (India) and fellow of Computer Society of India

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