1.) INTRODUCTION:
What is a Protocol? What is this stuff? Well, a Protocol is a set of rules, which is used for connecting some computers in a network. As for example a man goes to some different land and want to find his destination. Then there should be some standard pattern for such people to talk to each other or to communicate. These standard patterns are some set of rules with which you need to send your data to this distant land and talk to the person. Thus there is standard set of Protocols without which our communication is impossible for the Network Of Networks or INTERNET. These Protocols are thus called INTERNET PROTOCOLS.
At the end of 2002, an international team from
The present version of the Protocol we are using is the Internet Protocol version 4, which is successful for many of the applications on the Internet. But with the latest trends in the technology we are about to get yet another version of the World Favorite Protocol which is the version 6. Yes, with the help of science and technology we have got a new solution to Ipv4 and probably its successor in the near future called INTERNET PROTOCOL Version 6 which is the topic of discussion below. It will change the entire meaning of Internet connecting itself with the upcoming technologies such are Internet2 and Quality Of Service (QoS). Let’s see about this version in detail now.
1.1.) WHAT’S IPV6?
IPv6 is short for "Internet Protocol Version 6". IPv6 is the "next generation" protocol designed by the IETF to replace the current version Internet Protocol, IP Version 4 ("IPv4").
Most of today's Internet uses IPv4, which is now nearly twenty years old. IPv4 has been remarkably resilient in spite of its age, but it is beginning to have problems. Most importantly, there is a growing shortage of IPv4 addresses, which are needed by all new machines added to the Internet.
IPv6 fixes a number of problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as routing and network auto configuration. IPv6 is expected to gradually replace IPv4, with the two coexisting for a number of years during a transition period.
Some introductory information about the protocol can be found in our IPv6 FAQ. For those interested in the technical details, we have a list of IPv6 related specifications.
1.2.) WHY IPV6?
It is a problem that these features are optional for IPv4, and it is very important to include features of IPv6 into the basic spec. If you don't see why, imagine the following story: You are very novice user of the Internet, who can hardly do if config or routing setup. You carry along your laptop, and visited some university for presentation. Just after you connected your laptop to the local network, the chairman said that there is no DHCP server available in the university, and administrator took a day-off.
1.3.) WHY DO I NEED IPV6?
It is not a matter of if, but when, IPv4 address space will run out. Address re-use is a short-term solution that restricts facilities. Scarcity of IP addresses will lead to rationing, either by arbitrary control, or by price. With IP Version 6 (IPv6) [also sometimes referred to as Ipng] there will be no scarcity of addresses.
Address re-use mechanisms work for people who just use e-mail and the Web, but it is not viable for servers, which need dedicated IP addresses.
Today, customers of ISPs cannot change service providers without changing IP addresses. The ISP can't change its backbone connections without changing the customers' addresses. Avoiding address-change disruption causes "lock-in" for customer and provider alike.
2.) A LITTLE HISTORY OF IPV6:
Around 1992, the IETF became aware of a global shortage of IPv4 addresses, and technical obstacles in deploying new protocols due to limitations imposed by IPv4. An IPng (IP next generation) effort was started to solve these issues. The discussion is outlined in a bunch of RFCs, starting from RFC1550. After a large amount of discussion, around 1995, IPv6 (IP version 6) was picked as the final IPng proposal. The IPv6 base specification is specified in RFC2460.
3.) KEY FEATURES
In a single sentence, IPv6 is a re-engineering effort against IP technology. Key features are listed below:
3.1.) LARGER IP ADDRESS SPACE:
IPv4 uses only 32 bits for IP address space, which allows only 4 billion nodes to be identified on the Internet. 4 billion may look like a large number; however, it is less than the human population on the earth! IPv6 allows 128 bits for IP address space, allowing 340282366920938463463374607431768211456 (three hundred forty undecillion) nodes to be uniquely identified on the Internet. A larger address space allows true end-to-end communication, without NAT or other short-term workarounds against the IPv4 address shortage. (These days NAT is a headache for new protocol deployment and has scalability issues; we really need to decommission NAT networks for the Internet to grow further).
3.2.) DEPLOY MORE RECENT TECHNOLOGIES:
After IPv4 was specified 20 years ago, we saw many technical improvements in networking. IPv6 includes a number of those improvements in its base specification, allowing people to assume these features are available everywhere, anytime. "Recent technologies" include, but are not limited to, the following:
3.2.1.) AUTO CONFIGURATION:
With IPv4, DHCP exists but is optional. A novice user can get into trouble if they visit another site without a DHCP server. With IPv6, a "stateless host auto configuration" mechanism is mandatory. This is much simpler to use and manage than IPv4 DHCP. RFC2462 has the specification for it.
3.2.2.) SECURITY:
With IPv4, IPsec is optional and you need to ask the peer if it supports IPsec. With IPv6, IPsec support is mandatory. By mandating IPsec, we can assume that you can secure your IP communication whenever you talk to IPv6 devices.
3.2.3.) FRIENDLY TO TRAFFIC ENGINEERING TECHNOLOGIES:
IPv6 was designed to allow better support for traffic engineering like diffserv or intserv (RSVP). We do not have a single standard for traffic engineering yet, so the IPv6 base specification reserves a 24-bit space in the header field for those technologies and is able to adapt to coming standards better than IPv4.
3.2.4.) MULTICAST:
Multicast is mandatory in IPv6, which was optional in IPv4. The IPv6 base specifications themselves extensively use multicast.
3.2.5.) BETTER SUPPORT FOR AD-HOC NETWORKING:
Scoped addresses allow better support for ad-hoc (or "zeroconf") networking. IPv6 supports anycast addresses, which can also contribute to service discoveries.
3.2.6.) A CURE TO ROUTING TABLE GROWTH:
The IPv4 backbone routing table size has been a big headache to ISPs and backbone operators. The IPv6 addressing specification restricts the number of backbone routing entries by advocating route aggregation. With the current IPv6 addressing specification, we will see only 8192 routes on the default-free zone.
3.2.7.) SIMPLIFIED HEADER STRUCTURES:
IPv6 has simpler packet header structures than IPv4. It will allow future vendors to implement hardware acceleration for IPv6 routers easier.
3.2.8.) ALLOWS FLEXIBLE PROTOCOL EXTENSIONS:
IPv6 allows more flexible protocol extensions than IPv4 does, by introducing a protocol header chain. Even though IPv6 allows flexible protocol extensions, IPv6 does not impose overhead to intermediate routers. It is achieved by splitting headers into two flavors: the headers intermediate routers need to examine, and the headers the end nodes will examine. This also eases hardware acceleration for IPv6 routers.
3.2.9.) SMOOTH TRANSITION FROM IPV4:
There were number of transition considerations made during the IPv6 discussions. Also, there are large numbers of transition mechanisms available. You can pick the most suitable one for your site.
3.2.10.) FOLLOWS THE KEY DESIGN PRINCIPLES OF IPV4:
IPv4 was a very successful design, as proven by the ultra large-scale global deployment. IPv6 is "new version of IP", and it follows many of the design features that made IPv4 very successful. This will also allow smooth transition from IPv4 to IPv6.
4.) INTERNET-6 OBJECTIVES:
§ Continue to promote IPv6 as an enabling technology
§ Focus on mobility and related key technologies such as mobile IPv6, IPv6 networking, QoS, etc.
§ Develop, test and validate IPv6 advanced technologies and set up trial networks enabling early involvement, operational experience, and R&D initiatives
§ Seek cooperation with operator partner(s) to pave the way towards all-IP networks and future Mobile Internet
5.) IPV6 ADDRESSING :
The most dramatic change from IPv4 to IPv6 is the length of network addresses. IPv6 addresses, as defined by RFC 2373 and RFC 2374, are 128 bits long; this corresponds to 32 hexadecimal digits, which are normally used when writing IPv6 addresses, as described in the following section.
The number of possible addresses in IPv6 is 2128 ≈ 3.4 x 1038. The number of IPv6 addresses can also be thought of as 1632 as each of the 32 hexadecimal digits can take 16 values (see combinatorics).
In some situations, IPv6 addresses are composed of two logical parts: a 64-bit network prefix, and a 64-bit host-addressing part, which is often automatically generated from the interface MAC address.
(6.) NOTATION FOR IPV6 ADDRESSES:
IPv6 addresses are 128 bits long but are normally written as eight groups of 4 hexadecimal digits each. For example,
3ffe:6a88:85a3:08d3:1319:8a2e:0370:7344
is a valid IPv6 address.
If a 4 digit group is 0000, it may be omitted. For example,
3ffe:6a88:85a3:0000:1319:8a2e:0370:7344
is the same IPv6 address as
3ffe:6a88:85a3::1319:8a2e:0370:7344
Following this rule, if more than two consecutive colons result from this omission, they may be reduced to two colons, as long as there is only one group of more than two consecutive colons. Thus
2001:2353:0000:0000:0000:0000:1428:57ab
2001:2353:0000:0000:0000::1428:57ab
2001:2353:0:0:0:0:1428:57ab
2001:2353:0::0:1428:57ab
2001:2353::1428:57ab
are all valid and mean the same thing, but
2001::25de::cade
is invalid.
Also leading zeros in all groups can be omitted, thus
2001:2353:02de::0e13
is the same thing as
2001:2353:2de::e13
If the address is an IPv4 address in disguise, the last 32 bits may be written in decimal; thus
::ffff:192.168.89.9 is the same as
::ffff:c0a8:5909, but not the same as
::192.168.89.9 or
::c0a8:5909.
The ::ffff:1.2.3.4 format is called an IPv4-mapped address, and is deprecated. The ::1.2.3.4 format is an IPv4-compatible address.
IPv4 addresses are easily convertible to IPv6 format. For instance, if the IPv4 address was 135.75.43.52, it could be converted to
0000:0000:0000:0000:0000:0000:874B:2B34 or ::874B:2B34.
Then again, one could use the hybrid notation (IPv4 mapped addresses), in which case the address would be ::135.75.43.52
7.) IPV6 HEADER:
The most important and the only working part of any protocol is its HEADER. Without a Header any Protocol is useless. And thus its description and explanation is mandatory. The figure shown below is the IPV6 Header, which is much more simplified than its previous one.
Version: 4-bit Internet Protocol version number = 6.
Traffic Class: 8-bit traffic class field. Flow Label: 20-bit flow label.
Payload Length: 16-bit unsigned integer. Length of the IPv6 payload, i.e., the rest
of the packet following this IPv6 header is in octets. (Note that any extension headers present are considered part of the payload, i.e., included in the length count.) Next Header: 8-bit selector. Identifies the type of header immediately following the IPv6 header. Uses the same values as the IPv4 Protocol field Hop Limit: 8-bit unsigned integer. Decremented by 1 by each node that forwards the packet. The packet is discarded if Hop Limit is decremented to zero. Source Address: 128-bit address of the originator of the packet.
Destination Address: 128-bit address of the intended recipient of the packet (possibly not the ultimate recipient, if a Routing header is present). 8.) IPV6 AND IPV4 HEADER:
This article, will explain the IPv6 header from the basics. In the next article, we will look at advanced features of IPv6 and try to understand them through our knowledge of the IPv6 header.
IPv6 is an improved version of the current Internet Protocol, IPv4. However, it is still an Internet Protocol. A protocol is a set of procedures for communications. In Internet Protocol, information such as IP addresses of the sender and the receiver of the data packet is placed in front of the data. This information is called “header”. This is similar to specifying the addresses of the sender and the recipient when you send a package by mail.
Let’s first compare the header of IPv4 and IPv6. Figure 1 shows IPv4 header, and IPv6 header is shown in Figure 2.
However, if you compare Figures 1 and 2 again, you will realize that although IPv6 uses four times more digits to express the addresses of the source and the destination, length of the header has not increased much from that of IPv4. This is because header format has been simplified in IPv6. You can see that among many elements (called “field”) shown in Figure 1, those shown in red do not exist in Figure 2.
One of the important changes is that there is no Options field in Figure 2. In IPv4, Options field can be used to add information about various optional services. For example, information related to encryption can be added here. Because of this, the length of the IPv4 header changes according to the situations. Due to this difference in length, routers that control communications according to the information in the IP header can’t judge the length of the header just by looking at the beginning of the packet. This makes it difficult to speed up packet processing with hardware assist.
On the other hand, IPv6 moves information related to additional services to a section called extension header. The part shown in Figure 2 is called basic header. Therefore, for plain packets, IP header length is fixed to 40 bytes. In terms of making it easier to process packets with hardware, you can say that IPv6 can be accelerated much easier than IPv4.
Another field that exists in Figure 1 but is absent from Figure 2 is the Header Checksum field. A Header Checksum is a number used to check for errors in header information, and is calculated using the numbers in the header. However, problem with this approach is that header contains a number called TTL (Time To Live), which changes every time the packet goes through a router. Because of this, Header Checksum must be recalculated every time the packet goes through a router. If we can free up routers from this type of calculations, we could reduce the delay. Actually, TCP layer that resides above IP layer checks errors of various information including sender address and destination address. Since performing same calculations at the IP layer is redundant and unnecessary, Header Checksum is removed from IPv6.
Figure 1 contains 8bit field called “Service Type”. This field is used to represent the priority of the packet, for example whether it should be delivered express or with normal speed, and allows communication devices to handle the packet accordingly. Service Type field is composed of TOS (Type of Service) field and Precedence field. TOS field specifies the type of service and contains cost, reliability, throughput, delay, or security. Precedence field specifies the level of priority using eight levels from 0 to 7. IPv6 provides the same function with a field called Traffic Class.
Flow Label field has a 20 bits length, and is a field newly established for IPv6. By using this field, packet’s sender or intermediate devices can specify a series of packets, such as Voice over IP, as a flow, and request particular service for this flow. Even in the world of IPv4, some communication devices are equipped with the ability to recognize traffic flow and assign particular priority to each flow. However, these devices not only need to check the IP layer information such as address of the sender and the destination, but also need to check the port number which is an information that belongs to a higher layer. Flow Label field attempts to put together all these necessary information and provide them at the IP layer. However, specifics on how to use it are still undecided.
As we have seen in this article, IPv6 aims to provide intelligent transmission framework that is easy to handle for intermediate devices by keeping the basic header simple and fixed length.
9.) IPV6 EXTENSION HEADERS: In IPv6, optional internet-layer information is encoded in separate headers that may be placed between the IPv6 header and the upper-layer header in a packet. There are a small number of such extension headers, each identified by a distinct Next Header value. As illustrated in these examples, an IPv6 packet may carry zero, one, or more extension headers, each identified by the Next Header field of the preceding header: With one exception, extension headers are not examined or processed by any node along a packet's delivery path, until the packet reaches the node (or each of the set of nodes, in the case of multicast) identified in the Destination Address field of the IPv6 header. There, normal demultiplexing on the Next Header field of the IPv6 header invokes the module to process the first extension header, or the upper-layer header if no extension header is present. The contents and semantics of each extension header determine whether or not to proceed to the next header. Therefore, extension headers must be processed strictly in the order they appear in the packet; a receiver must not, for example, scan through a packet looking for a particular kind of extension header and process that header prior to processing all preceding ones. The exception referred to in the preceding paragraph is the Hop-by-Hop Options header, which carries information that must be examined and processed by every node along a packet's delivery path, including the source and destination nodes. The Hop-by-Hop Options header, when present, must immediately follow the IPv6 header. Its presence is indicated by the value zero in the Next Header field of the IPv6 header. If, as a result of processing a header, a node is required to proceed to the next header but the Next Header value in the current header is unrecognized by the node, it should discard the packet and send an ICMP Parameter Problem message to the source of the packet, with an ICMP Code value of 1 ("unrecognized Next Header type encountered") and the ICMP Pointer field containing the offset of the unrecognized value within the original packet. The same action should be taken if a node encounters a Next Header value of zero in any header other than an IPv6 header. Each extension header is an integer multiple of 8 octets long, in order to retain 8-octet alignment for subsequent headers. Multi-octet fields within each extension header are aligned on their natural boundaries, i.e., fields of width n octets are placed at an integer multiple of n octets from the start of the header, for n = 1, 2, 4, or 8. A full implementation of IPv6 includes implementation of the following extension headers: Ø Hop-by-Hop Options
Ø Routing (Type 0)
Ø Fragment
Ø Destination Options
Ø Authentication
Ø Encapsulating Security Payload
10.) SECURITY IN IPV6 Key fingerprint = AF19 FA27 2F94 998D FDB5 DE3D F8B5 06E4 A169 4E46
10.1.) Authentication Header (AH):
The Authentication Header (AH) provides data integrity and data authentication for the entire IPv6 packet. Anti-replay protection is also provided by the AH. Data authentication refers to the fact that if a given computer receives an IP packet with a given source address in the IP header, it can be assured that the IP packet did indeed come from that IP address. Data integrity refers to the fact that if a given computer receives an IP packet, it can be assured that the contents have not been modified along the path from the source node to the destination node. Anti-replay protection means that if a computer has already received a particular IP packet, another packet with modified data won’t also be accepted as valid data. Next, the Authentication Header fields will be examined to determine how these security features are provided. Refer to Figure for the format of the Authentication Header.
The Authentication Header contains a Next Header field, which identifies the next Extension Header or transport type (e.g. TCP). The Payload Length field contains the length of the Authentication Header. The Security Parameters Index (SPI) field contains the Security Parameters Index to be used in identifying the Security Association.
The Sequence Number field is a counter field. The sequence number is set to 0 when the communication phase between the sender and receiver is established. It is subsequently incremented by 1 when either the sender or receiver transmits data.
The variable length Authentication Data contains the Integrity Check Value (ICV), which provides the authentication and data integrity. The SA specifies the authentication algorithm used to compute the ICV.
The use of the Authentication Header prevents IP Spoofing Attacks, one of the network attack methods in use today. In IP Spoofing, the hacker creates IP packets, via various hacker utilities; with a different IP address then the host computer. This can be used for various malicious reasons. The hacker can act as one side of a trust relationship to gain access to a trusting host.
10.2.) ENCAPSULATING SECURITY PAYLOAD (ESP) HEADER:
The Encapsulating Security Payload header provides confidentiality and/or authentication and data integrity to the encapsulated payload. The ESP header also provides anti-replay protection. Note: During authentication in the ESP Header, the authentication algorithm is only applied to the data being encrypted. Therefore, the authentication algorithm does not protect the IP header fields unless those fields are encapsulated in “tunnel mode”.
In the ESP header, both the confidentiality and authentication services are optional, however, at least one of these services must be selected
The Encapsulating Security Payload Header also contains an SPI field containing the Security Parameters Index that is used to identify the Security Association. The Sequence Number field is used to provide anti-replay protection as described in the section on the Authentication Header. The encrypted data is placed in the “Payload Data” field, as seen in Figure
ENCAPSULATING SECURITY PAYLOAD HEADER
The Padding field contains any padding bytes that may be needed by the encryption algorithm. The Pad Length field contains the number of bytes in the Padding field. The Next Header Field describes the type of data contained in the Payload Data field.
The use of the ESP header, with the confidentiality service enabled, prevents use of a technique called “sniffing”. “Sniffing” is a process of getting network transmission either for the data itself or for providing valuable information, which may be used later in attacking other computers. Sniffers are one of the most common tools used by hackers.
11.) MOBILE IP:
Mobile IP is the IETF proposed standard solution for handling terminal mobility among IP subnets and was designed to allow a host to change its point of attachment transparently to an IP network. Mobile IP works at the network layer (layer 3), influencing the routing of datagrams, and can easily handle mobility among different media (LAN, WLAN, dial-up links, wireless channels, etc.).
The generic problem with IP mobility is that when an IP node moves to a new subnet, it either has to change its IP address to reflect the new point of attachment, or the routers must have host specific routes for the mobile node. Both these alternatives have their drawbacks. Host-specific routes in general cannot be scaled up for Internet-wide use. Changing the IP address seen by the transport and the application layers every time a MN (Mobile Node) moves to a new network may be a solution to infrequent roaming, but not to mobility in general. This is because the transport layer (e.g. TCP) uses the IP address as an identifier, correlating IP packets to transport sessions. If this IP address is changed, then the correlation is lost and the sessions need to be restarted.
Mobile IP solves the mobility problem by managing the correlation between a changing IP address (care-of address) and the static home address. The transport and application layers keep using the home address, allowing them to remain ignorant of any mobility-taking place. The home address is naturally routed to the Home Agent (HA), which maintains the mapping (“binding”) from the home address to the current (primary) care-of address (CoA). The HA will tunnel packets to the MN at its current point of attachment via the CoA. In Mobile IPv4 the care-of address can be either hosted by a Foreign Agent (FA in Figure 1) or co-located with the mobile node itself. The visited network always assigns the CoA, so that the routing of the packets to the mobile node will remain transparent to the routers in transit. The packets from the MN to the correspondent node (CN) will be routed naturally without going through the home agent. As the MN moves from one subnet to another, and its CoA changes, it will inform the HA of the new binding.
Mobile IP was originally defined for IPv4 (IETF RFC 2002). This definition has suffered from the fact that mobility support for IPv4 is an add-on, and the vast majority of IPv4 nodes do not support Mobile IP. For IPv6, the mobility support has been on the list of required features from the beginning. The Mobile IPv6 specification is on its way to becoming a standard, so it is expected that virtually all IPv6 deployments will include at least the minimal mobile IP support (i.e. the correspondent node functions).
11.1.) MOBILE IPV4
Mobile IP was originally defined for IP version 4, before IPv6 existed. The base protocol is defined in RFC 2002. Many enhancements have been proposed to Mobile IPv4 to counter some of the identified problems, which include:
Ø Triangular routing as shown in Figure 1. All packets sent to the mobile node are routed through its home agent, causing increased load on the home network and higher latency. This problem could be solved with route optimization extension, but the required update may not be practical.
Ø Deployment problem: Mobile IPv4 typically requires each potential foreign network to have foreign agent(s). If foreign agents were not used, every mobile node would need a globally routable IPv4 address from the foreign network.
Ø Ingress filtering: In an ISP (Internet Service Provider), any border router may discard packets that contain a source IP address that is not topologically correct. In Mobile IPv4, the Mobile nodes that are away from home, i.e., in a foreign ISP, use their home address as the source IP address, resulting in the likelihood of dropping of packets by ingress filtering.
Ø Authentication and Authorization: Mechanisms specific to Mobile IPv4 are used for authentication of Mobile IPv4 registrations. Mobile IPv4 has only a small percentage (a few million nodes) of the overall IPv4 deployment. A shortage of globally routable IPv4 addresses and use of private IPv4 addresses with Network Address Translators hampers its deployment in many cases.
11.2.) Mobile IPv6
Mobile IPv4 and Mobile IPv6 protocols share similar ideas, but their implementations are somewhat different. Figure 2 shows the basic elements of Mobile IPv6. Mobility signaling and security features (IPsec) are integrated in the IPv6 protocol as header extensions, whereas Mobile IPv4 uses a separate UDP (User Datagram Protocol) based protocol for registrations. These registrations apply special mobility security associations. In IPv6 stateless address auto configuration, addresses can be generated easily by combining the network prefix of a visited network and an interface identifier of the MN. In addition, address exhaustion is not a problem. Therefore, an IPv6 Care-of Address (CoA) is always co-located at the MN, and the concept of the foreign agent has been eliminated. Also, route optimization is built into Mobile IPv6. If route optimization is used, user privacy may be violated, because it will reveal the true location of the mobile node. If the MN needs to discover it’s HA dynamically, it can make the enquiry using IPv6 anycast. This is more efficient and reliable than IPv4 directed multicast, which may return several replies. Several ICMPv6 (Internet Control Message Protocol for IPv6) mechanisms provide support for mobility management. These include:
Ø Router Advertisement
Ø Router Solicitation
Ø Address Auto-configuration
(Stateful and stateless)
Ø Neighbor Discovery
Some of these have been extended in Mobile IPv6 to better support its needs. These changes include a new home agent bit to the router advertisement, a new bit to the prefix information option format, allowing the router to efficiently advertise its global IPv6 address instead of the link local address. Also, the timing rules for router advertisements and solicitations have been refined and a new Advertisement Interval Option has been defined for Router Advertisements.
12.) MOBILE IPV6 IN GPRS/WCDMA TECHNOLOGY:
This section describes the benefits of the introduction of Mobile IPv6 as a service in GPRS and WCDMA mobile networks. The use of Mobile IPv6 as a complementing mobility method and a method for multi-access mobility is discussed. The following section shows how Mobile IPv6 can be used to provide static IPv6 addresses for GPRS/ WCDMA terminals. Finally, the benefits of Mobile IPv6 are summarized.
12.1.)MOBILE IPV6 FOR INTER-PLMN MOBILITY
Consider the situation that a GPRS subscriber of an operator in Finland is roaming in the U.S. and accessing a local service there. If the link layer mobility were used, the user’s IP packets would first be tunnelled to Finland, and then routed back to the U.S. In this scenario a round trip time from the mobile terminal to a server and back could be unacceptable to many services. As a solution to this problem, the roaming GPRS subscriber should use the services of a local GGSN in the visited network, allowing IP packets to be routed as soon as possible, without crossing over to the home network. As the IP address is now being assigned from the visited network, the mobile node would not be accessible via a network layer identity of the home network. For some applications this may not be a problem, but in general it would be desirable if the mobile node could be reached with an IP address being assigned from the home network as well. A natural solution to this problem is to use Mobile IP to register the visited network address with the home network, allowing packets sent to the home address to be delivered to the mobile node.
12.2.) THE BASIC OPERATION OF MOBILE IPV6 IN GPRS/WCDMA NETWORK
When the mobile terminal is roaming in a foreign network, it is addressable by a care-of address, in addition to its home address. The IPv6 address prefix in the mobile terminal’s care-of address is the prefix of the foreign link. The care-of address is acquired by the addressing mechanism provided by the visited network. While roaming in the foreign network, the mobile terminal registers one of its care-of addresses with the home agent and sends a “Binding Update” to the home agent. The home agent replies with “Binding Acknowledgement.” Any IPv6 packets containing Binding Update or Binding Acknowledgement destination options must be authenticated using IP Security AH (Authentication Header). After the binding, this care-of address becomes the mobile terminal’s primary care-of address.
The home agent intercepts all IPv6 packets from a correspondent node (for example a WWW server that is communicating with the mobile terminal) addressed to the mobile terminal’s home address. The home agent encapsulates each intercepted packet using IPv6 encapsulation, with the outer header addressed to the mobile terminal’s primary care-of address. After the mobile terminal has received the first encapsulated packet from the home agent, it sends a Binding Update to the correspondent node informing it of its care-of address: the correspondent node then replies with a Binding Acknowledgement. After this, sending IP packets between the correspondent node and the mobile terminal is straightforward and routing via a home agent is not needed. For packets sent by a mobile terminal while away from home, the mobile terminal’s care-of address is typically used as the source address in the packet’s IPv6 header. The Home Address option can be used to inform the packet recipient of the mobile node’s home address.
The correspondent node can then substitute the mobile node’s home address for this care-of address making the use of the care-of address transparent to the correspondent node. The upper protocol layers (e.g. TCP) thus only see the home address.
13.) MOBILITY OF IPV6 IN 2G AND 3G NETWORKS
Implementation of Mobile IPv6 in 2G and 3G mobile networks primarily requires user plane (application layer) IPv6 support from the network, installing a home agent (HA) router in the home network, using mobile terminals supporting Mobile IPv6 and implementing IP Security infrastructure, because Mobile IPv6 uses IPsec for all its security requirements.
The home agent can be located in the network operator’s network or some other network (e.g. company intranet, home network, etc.). In both cases, the GGSN elements do not necessarily need to be involved with the Mobile IPv6 protocol. A feasible place to install the home agent could be near the operator’s network edge router.
14.) MIGRATION FROM 6TO4 NETWORK:
Combined ISATAP and 6to4 tunneling mechanisms allow to easily interconnecting IPv6 and IPv4 nodes over an existing IPv4 architecture. As such, it could largely be used as a first step deployment towards IPv6.
Ø A key advantage of the 6to4 mechanism is that a customer can use IPv6 without the need of any global IPv6 prefix allocated by an ISP or any other service provider. Only a valid, globally unique 32-bit IPv4 address is necessary. Moreover, 6to4 requires fewer configurations than configured tunnels.
Ø ISATAP hosts do not require any manual configuration and create ISATAP addresses using standard address auto configuration mechanisms. ISATAP can be used for communication between IPv6/IPv4 nodes on an IPv4 network.
The combination of these two mechanisms brings a transition mechanism that is powerful and easy to configure.
Using 6to4 enables 6to4 hosts (meaning that at least one 6to4 address has been configured) to communicate with other 6to4 hosts located on the same site, and also with 6to4 hosts located in other sites on the IPv4 Internet thanks to 6to4 routers. It also enables the communication with IPv6 native hosts connected for instance to the 6bone thanks to a 6to4 relay router. To do so, 6to4 uses a public IPv4 address to create the 64-bit identifier portion of an IPv6 address. The full address of a 6to4 node is:
2002:WWXX:YYZZ:[SLA ID]:[Interface ID]
where 2002 is the TLA ID reserved to 6to4 addresses, and WWZZ:YYZZ corresponds to the colon-hexadecimal representation of an IPv4 address.
Local routers advertise the 6to4 prefixes and hosts use them to build an auto-configured 6to4 address. Additionally, a 2002::/16 route is used to tunnel the IPv6 traffic to other 6to4 hosts outside the local network. This traffic is forwarded to the 6to4 router located at the border of the IPv6 site. The 6to4 router then encapsulates the traffic in an IPv4 header and sends it to the destination IPv4 address that is embedded in the right portion of the 6to4 address. At the other side, the IPv6 packet is decapsulated and forwarded to the appropriate node.
ISATAP can also be used for communication between IPv4/IPv6 nodes through an IPv4 network. The full format of an ISATAP identifier is:
::0:5EFE:w.x.y.z
where 0:5EFE is the combination of a reserved OUI (Organizationally Unique Identifier) and a type indicating an embedded IPv4 address ; and where w.x.y.z. is a unicast public or private IPv4 address in decimal.
The ISATAP interface identifier can be combined with any 64 bits prefix including 6to4 prefixes to build an IPv6 address.
15.) IPV6 TUNNELLING OVER IPV4
Tunneling allows early IPv6 implementations to take advantage of existing IPv4 infrastructure without any change to IPv4 components. A dual-stack router or host on the “edge” of the IPv6 topology simply appends an IPv4 header to each IPv6 packet and sends it as native IPv4 traffic through existing links. IPv4 routers forward this traffic without knowledge that IPv6 is involved. On the other side of the tunnel, another dualstack router or host de-encapsulates the IPv6 packet and routes it to the ultimate destination using standard IPv6 protocols. To accommodate different administrative needs, IPv6 transition mechanisms include two types of tunneling: automatic and configured. To build configured tunnels, administrators manually define IPv6-to-IPv4
address mappings at tunnel endpoints. On either side of the tunnel, traffic is forwarded with full 128-bit addresses. At the tunnel entry point, a router table entry is defined manually to dictate which IPv4 address is used to traverse the tunnel. This requires a certain amount of manual administration at the tunnel endpoints, but traffic is routed through the IPv4 topology dynamically, without the knowledge of IPv4 routers. The 128-bit addresses do not have to align with 32-bit addresses in any way.
16.) AUTOMATIC TUNNELLING
Automatic tunnels use “IPv4-compatible” addresses, which are hybrid IPv4/IPv6 addresses. Adding leading zeros to the 32-bit IPv4 address to pad them out to 128 bits creates compatible addresses.
When traffic is forwarded with compatible addresses, the device at the tunnel entry point can automatically address encapsulated traffic by simply converting the IPv4-compatible 128-bit address to a 32-bit IPv4 address. On the other side of the tunnel, the IPv4 header is removed to reveal the original IPv6 address. Automatic tunneling allows IPv6 hosts to dynamically exploit IPv4 networks, but it does require the use of IPv4-compatible addresses, which do not bring the benefits of the128-bit address space.
17.) IPV6 IN MOBILE PACKET NETWORKS
Packet switched IP networks offer several specific advantages over circuit switching implementations.Automatic fault tolerance is one of the common denominator of these advantages.Packet switched networks automatically configures themselves so each router knows the topology of its surroundings.
Information about a failure situation in network nodes or links connecting the network nodes is propagated to the nearby nodes and after a short period the network is able to rereout the packet around the failure point. Even Ipv4 is capable of this rerouting functionality through routing protocols. Ipv6 adds the ability to automatically configure and learn about new network nodes. Ipv4 is weaker in this respect evne though both are fault tolerant systems.
The ability to use Ipv6 on a global scale adds on furthur security to Ipv6-based networks. If the network of one ISP stops working for example or become sluggish, it is possible for the Ipv6 network to make a binding update to its home agent through another ISP, thus allowing the use of alternative routes an bringing a new level of robustness to the network.
3GPP, a standardization body for mobile networks, has desingned Ipv6 to be used exclusively in the IP Multimedia Core Network (IM CN) domain in 3GPP Release 5. This is the domain that will process all the packet based multimedia in the future 3G networks.
18.) PACKET SIZE ISSUES
IPv6 requires that every link in the Internet have an MTU of 1280 octets or greater. On any link that cannot convey a 1280-octet packet in one piece, link-specific fragmentation and reassembly must be provided at a layer below IPv6. Links that have a configurable MTU (for example, PPP links [RFC- 1661]) must be configured to have an MTU of at least 1280 octets; it is recommended that they be configured with an MTU of 1500 octets or greater, to accommodate possible encapsulations (i.e., tunneling) without incurring IPv6-layer fragmentation. From each link to which a node is directly attached, the node must be able to accept packets as large as that link's MTU. It is strongly recommended that IPv6 nodes implement Path MTU Discovery, in order to discover and take advantage of path MTUs greater than 1280 octets. However, a minimal IPv6 implementation (e.g., in a boot ROM) may simply restrict itself to sending packets no larger than 1280 octets, and omit implementation of Path MTU Discovery. In order to send a packet larger than a path's MTU, a node may use the IPv6 Fragment header to fragment the packet at the source and have it reassembled at the destination(s). However, the use of such fragmentation is discouraged in any application that is able to adjust its packets to fit the measured path MTU (i.e., down to 1280 octets). A node must be able to accept a fragmented packet that, after reassembly, is as large as 1500 octets. A node is permitted to accept fragmented packets that reassemble to more than 1500 octets. An upper-layer protocol or application that depends on IPv6 fragmentation to send packets larger than the MTU of a path should not send packets larger than 1500 octets unless it has assurance that the destination is capable of reassembling packets of that larger size. In response to an IPv6 packet that is sent to an IPv4 destination (i.e., a packet that undergoes translation from IPv6 to IPv4), the originating IPv6 node may receive an ICMP Packet Too Big message reporting a Next-Hop MTU less than 1280. In that case, the IPv6 node is not required to reduce the size of subsequent packets to less than 1280, but must include a Fragment header in those packets so that the IPv6-to-IPv4 translating router can obtain a suitable Identification value to use in resulting IPv4 fragments. Note that this means the payload may have to be reduced to 1232 octets (1280 minus 40 for the IPv6 header and 8 for the Fragment header), and smaller still if additional extension headers are used. 19.) IPV6 ADVANTAGES OVER IPV4:
| Scalability | IPv6 has 128-bit address space, which is 4 times wider in bits in compared to Ipv4's 32-bit address space. |
| Security | IPv6 includes security in the basic spec. It includes encryption of packets (ESP: Encapsulated Security Payload) and authentication of the sender of packets (AH: Authentication Header). |
| Consideration to realtimeness | To implement better support for real-time traffic (such as videoconference), IPv6 includes flow label in the spec. With flow label mechanism, routers can recognize to which end-to-end flow the packets belongs. |
| Plug and play | IPv6 includes plug and play in the standard spec. It therefore must be easier for novice users to connect their machines to the network --- it will be done automatically! |
| Clearer spec and optimization | Ipv6 follows good practices of IPv4, and rejects minor flaws/obsolete item |
20.) DIFFICULTIES AND ERRORS IN IPV6:
20.1.) THE IPV6 MESS, PART ONE: INCOMPATIBILITY
Unfortunately, the straightforward transition plan described above does not work with the current IPv6 specifications. The IPv6 designers made a fundamental conceptual mistake: they designed the IPv6 address space as an alternative to the IPv4 address space, rather than an extension to the IPv4 address space.
In other words: The current IPv6 specifications don't allow public IPv6 addresses to send packets to public IPv4 addresses. They also don't allow public IPv4 addresses to send packets to public IPv6 addresses. Public IPv6 addresses can only exchange packets with each other. The specifications could have defined a functionally equivalent public IPv6 address for each public IPv4 address, embedding the IPv4 address space into the IPv6 address space; but they didn't. (RFC 2893 does some of this, but the IPv6 proponents say that RFC 2893 is a local option, not part of the IPv6 architecture. In particular, they say that an IPv6 client is not supposed to send a packet to an IPv4 address by using the RFC 2893 address.)
This might sound like a very small mistake: after all, once IPv6 is working, we can move everything to IPv6, so who cares about IPv4? The problem is that this mistake has gigantic effects on the cost of making IPv6 work in the first place.
20.2.) INCOHERENCE
It gets worse. The IPv6 designers don't have a transition plan. They've taken some helpful steps, but they typically declare success (``IPv6 support'') when the real problem---making public IPv6 addresses work just as well as public IPv4 addresses---still hasn't been solved.
This doesn't make any sense. Why is it a recommendation, rather than a requirement? Why is it only for mail servers? If we don't have all servers and clients talking to IPv6 addresses, how are we going to reach the magic moment? Answer: We won't!
20.3.) DISTRACTIONS
It gets even worse. The IPv6 designers are putting most of their energy into pointless efforts that (1) won't bring us any closer to the magic moment and (2) won't help after the magic moment.
For example, some people make quite a fuss about replacing IPv4 with IPv6 as a mechanism for computers that aren't on the Internet to talk to the local proxies. Wake up, folks: That isn't the problem we need to solve. We can, and do, use private 10.* IPv4 addresses to talk to proxies. The address crunch involves public IPv4 addresses; to fix it, we need public IPv6 addresses that can talk to all the same sites.
IPv6 (Internet Protocol Version 6) is the latest level of the Internet Protocol (IP) and is now included as part of IP support in many products including the major computer operating systems. IPv6 has also been called "IPng" (IP Next Generation). Formally, IPv6 is a set of specifications from the Internet Engineering Task Force (IETF). IPv6 was designed as an evolutionary set of improvements to the current IP Version 4. Network hosts and intermediate nodes with either IPv4 or IPv6 can handle packets formatted for either level of the Internet Protocol. Users and service providers can update to IPv6 independently without having to coordinate with each other.
The most obvious improvement in IPv6 over the IPv4 is that IP addresses are lengthened from 32 bits to 128 bits. This extension anticipates considerable future growth of the Internet and provides relief for what was perceived as an impending shortage of network addresses.
IPv6 describes rules for three types of addressing: unicast (one host to one other host), any cast (one host to the nearest of multiple hosts), and multicast (one host to multiple hosts). Additional advantages of IPv6 are:
Options are specified in an extension to the header that is examined only at the destination, thus speeding up overall network performance.
The introduction of an "anycast" address provides the possibility of sending a message to the nearest of several possible gateway hosts with the idea that any one of them can manage the forwarding of the packet to others. Anycast messages can be used to update routing tables along the line.
Packets can be identified as belonging to a particular "flow" so that packets that are part of a multimedia presentation that needs to arrive in "real time" can be provided a higher quality-of-service relative to other customers.
The IPv6 header now includes extensions that allow a packet to specify a mechanism for authenticating its origin, for ensuring data integrity, and for ensuring privacy.
21.) INTERNET2 AND IPV6:
The Internet2 developers are nowadays are about to use the successful version of IPV6 after the commercially unusable version of IPV5. Internet2 is the latest trendsetter in the industry after IPV6 because it will totally generalize the concept of Internet to the commercial level. Also with its large bandwidth facilities this version is going to blast its way out to the competitive market giving the facilities like the one of Tele-emersion, Virtual Schools, Virtual laboratories, Video Conferencing, Distributed Learning module etc. These facilities will be provided to the public all over the world trading off information with each other. Then again unlike the present Internet there will we the Quality Of Service Technology behind this. Owing to this there will be the service quality similar to that of the Satellite Transmission. Thus the connectivity and the number of users are going to increase. But most importantly there will be the need of large bandwidth protocols and hence we can say that we will need a large number of bits transmitted per second due to which we need a larger IP address for a single user. It is thus essential to switch from the present Protocol we are using for the Internet. Hence we will need IPV6 as for larger data to be crossed across the world and provide all the facilities a user needs. Thus the future of these two Technologies is obviously hand-in-hand and without the one the other is yet not feasible to prevail.
22.) QoS AND IPV6:
When we go to any of the Cinema Hall we search for a better place and a better screen because we need a good quality of picture we are seeing as this obliges and pleases all of us. But the same when comes to Internet we are ready to compromise which should not be the case. The next of the friendly hand is the QoS or the Quality Of Service, which is the latest challenge to the Internet Pundits. QoS is concerned with the Quality with which this data is transmitted over the network. This technology is not used in the present system and thus we face the consequences. Sometimes it happens that when you download a file form the Internet many times the download is complete but when you are opening the file the important data at a very crucial time doesn’t open and thus again download the same. With this technology we will get Quality of Data as that is received or transmitted for the Satellite Communication. Thus if you doing web chatting with your family members there will be sound picture and crystal clear sound without any delays in transmission. These include the services as that of the Satellite Communication for data transmission and thus end users are always going to get benefited by this also the thing gets much cheaper for any user.
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23.) ADDITIONAL ADVANTAGES OF IPV6:
IPv6 is version 6 of the Internet Protocol. IPv6 is intended to replace the previous standard, IPv4, which only supports up to about 4 billion (4 × 109) addresses, whereas IPv6 supports up to about 3.4 × 1038 addresses.
IPv6 is the second version of the Internet Protocol to be widely deployed, and is expected (as of 2001) to form the basis for future expansion of the internet. In 2003, Nihon Keizai Shimbun (as cited in CNET Asia Staff, 2003) reported that Japan, China, and South Korea claimed to have made themselves determined to become the leading nations in internet technology, which would partially take the form of jointly developing IPv6, and completely adopting IPv6 starting in 2005.
The compelling reason behind the formation of IPv6 was lack of address space, especially in the heavily populated countries of Asia such as India and China.
24.) CONCLUSION:
IPV6 the latest version of IP series is going to set trends and make waves in the industry as its predecessors. IPV6 is having easy configuration, larger address bits, larger data transmission capacities and also supports a large number of users with its addressing scheme. It is having a simpler header format than IPV4. The Mobile networks are of course benefitted by this Protocol. It will change the meaning of the present Mobile Commnication with the facilitites it provides to the same. This technology aids in one of the major developments in the Industry. It will also make its ways into the Internet world by joining hands with Internet2. The large data exchange which is the biggest requirement of the upcoming World cannot be satisfied by IPV4 and thus the higher data transmissions will lead to switch over IPV6. It will be the biggest boon to the heavily populated countries like the one of ourselves. The researches are being developed for the area and still it requires a large budget,funding and a bit of time to completely come to the common people and other commercial uses. The highly speed networks which were seen at the beginning of the topic can only be setted up by these Protocols only. Thus at last we can say that presently there is no match for these set of rules or Protocols in the industry and this will definitely lead to the new generation of the Internet World and Commercial World.
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