IPv6

    Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet.IPv6 provides other technical benefits in addition to a larger addressing space. In particular, it permits hierarchical address allocation methods that facilitate route aggregation across the Internet, and thus limit the expansion of routing tables. The use of multicast addressing is expanded and simplified, and provides additional optimization for the delivery of services. Device mobility, security, and configuration aspects have been considered in the design of the protocol. IPv6 addresses are represented as eight groups, separated by colons, of four hexadecimal digits. The full representation may be shortened for example, 2001:0db8:0000:0000:0000:8a2e:0370:7334 becomes 2001:db8::8a2e:370:7334.

Introduction

Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Internet.IPv6 was developed by the Internet Engineering Task Force (IETF) to deal with the long-anticipated problem of IPv4 address exhaustion. In December 1998, IPv6 became a Draft Standard for the IETF, who subsequently ratified it as an Internet Standard on 14 July 2017.There is some serious limitations of the current IP protocol, or IPv4 to be precise. IP version 6 or IPv6 provides 128-bit addressing. And compatibility with Ipv4 addresses, security and authentication, quality of service(reserving bandwidth), plug-and-play for network device configuration, hierarchically structured routing and an ability to seamlessly integrate with the current IP during the transition stages.

 

Block diagram 

Version (4-bits): It represents the version of Internet Protocol, i.e. 0110.

Traffic Class (8-bits): These 8 bits are divided into two parts. The most significant 6 bits are used for Type of Service to let the Router Known what services should be provided to this packet. The least significant 2 bits are used for Explicit Congestion Notification (ECN).

Flow Label (20-bits): This label is used to maintain the sequential flow of the packets belonging to a communication. The source labels the sequence to help the router identify that a particular packet belongs to a specific flow of information. This field helps avoid re-ordering of data packets. It is designed for streaming/real-time media.

Payload Length (16-bits): This field is used to tell the routers how much information a particular packet contains in its payload. Payload is composed of Extension Headers and Upper Layer data. With 16 bits, up to 65535 bytes can be indicated; but if the Extension Headers contain Hop-by-Hop Extension Header, then the payload may exceed 65535 bytes and this field is set to 0.

Next Header (8-bits): This field is used to indicate either the type of Extension Header, or if the Extension Header is not present then it indicates the Upper Layer PDU. The values for the type of Upper Layer PDU are same as IPv4’s.

Hop Limit (8-bits): This field is used to stop packet to loop in the network infinitely. This is same as TTL in IPv4. The value of Hop Limit field is decremented by 1 as it passes a link (router/hop). When the field reaches 0 the packet is discarded.

Source Address (128-bits): This field indicates the address of originator of the packet.

Destination Address (128-bits): This field provides the address of intended recipient of the packet.

Data :  This is the payload portion of the IPv6 packet.  When the packet reaches its destination, the payload will be removed from the IP packet and passed on to the protocol specified in the next header field.

IPv6 Features 

·      Larger Address Space

In contrast to IPv4, IPv6 uses 4 times more bits to address a device on the Internet. This much of extra bits can provide approximately 3.4×10³⁸ different combinations of addresses. This address can accumulate the aggressive requirement of address allotment for almost everything in this world. According to an estimate, 1564 addresses can be allocated to every square meter of this earth.

·      Simplified Header

IPv6’s header has been simplified by moving all unnecessary information and options (which are present in IPv4 header) to the end of the IPv6 header. IPv6 header is only twice as bigger than IPv4 provided the fact that IPv6 address is four times longer.

·      End-to-end Connectivity

Every system now has unique IP address and can traverse through the Internet without using NAT or other translating components. After IPv6 is fully implemented, every host can directly reach other hosts on the Internet, with some limitations involved like Firewall, organization policies, etc.

·      Auto-configuration

IPv6 supports both stateful and stateless auto configuration mode of its host devices. This way, absence of a DHCP server does not put a halt on inter segment communication.

·      Faster Forwarding/Routing

Simplified header puts all unnecessary information at the end of the header. The information contained in the first part of the header is adequate for a Router to take routing decisions, thus making routing decision as quickly as looking at the mandatory header.

·      IPSec

Initially it was decided that IPv6 must have IPSec security, making it more secure than IPv4. This feature has now been made optional.

·      No Broadcast

Though Ethernet/Token Ring are considered as broadcast network because they support Broadcasting, IPv6 does not have any broadcast support any more. It uses multicast to communicate with multiple hosts.

·      Any-cast Support

This is another characteristic of IPv6. IPv6 has introduced Anycast mode of packet routing. In this mode, multiple interfaces over the Internet are assigned same Anycast IP address. Routers, while routing, send the packet to the nearest destination.

·      Mobility

IPv6 was designed keeping mobility in mind. This feature enables hosts (such as mobile phone) to roam around in different geographical area and remain connected with the same IP address. The mobility feature of IPv6 takes advantage of auto IP configuration and Extension headers.

·      Enhanced Priority Support

IPv4 used 6 bits DSCP (Differential Service Code Point) and 2 bits ECN (Explicit Congestion Notification) to provide Quality of Service but it could only be used if the end-to-end devices support it, that is, the source and destination device and underlying network must support it.

In IPv6, Traffic class and Flow label are used to tell the underlying routers how to efficiently process the packet and route it.

·      Smooth Transition

Large IP address scheme in IPv6 enables to allocate devices with globally unique IP addresses. This mechanism saves IP addresses and NAT is not required. So devices can send/receive data among each other, for example, VoIP and/or any streaming media can be used much efficiently.

Other fact is, the header is less loaded, so routers can take forwarding decisions and forward them as quickly as they arrive.

·      Extensibility

One of the major advantages of IPv6 header is that it is extensible to add more information in the option part. IPv4 provides only 40-bytes for options, whereas options in IPv6 can be as much as the size of IPv6 packet itself.

IPv6 Addressing

Internet Protocol version 6 (IPv6), it is basically a 128 bit address. IN IPv6 address, hexadecimal notation is preferred. There are total 8 fields in IPv6 hexadecimal notation and each field consits of 16 bits. Hence, total bits are 8 * 16 =128.

Example-

Rules of compresion :  There are some basic  rules for compression

Rule 1 :-

If two or more segment contains  consecutive zeros, out them all and replace  with double colon sign “::”

IPv6 = FFFF : ABDC : B1CA : 90AC : 0000 : 0000 : FAC0 : 9010

After compression

IPv6 = FFFF : ABDC : B1CA : 90AC : : FAC0 : 9010

Rule 2 :-

 “::” must be used to represent to largest number of 16 bits sets of zero as possible 

IPv6 = FFFF : 0000 : 0000 : 90AC : 0000 : 0000 : 0000 : 9010

 After compression

IPv6 = FFFF : 0000 : 0000 : 90AC : : 9010 

Rule 3 :-

Remove Leading Zeros.

IPv6 = FFFF : ABDC : 0DCA : 00AC : 0000 : 0000 : FAC0 : 9010

 After compression

IPv6 = FFFF : ABDC : 0DCA : 00AC : : FAC0 : 9010

IPv6 = FFFF : ABDC : DCA : AC : : FAC0 : 9010

Rule 4 :-

If there are multiple places where “::” can be used , and the number of zeros are the same, Use “::” on the leftmost

sets of zeros.

IPv6 = FFFF : 0000 : 0000 : 90AC :  FADC : 0000 : 0000 : 9010

 After compression

IPv6 = FFFF : : 90AC : FADC : 0 : 0 : 9010

Rule 5 :-

“ ::” Cannot be used to shorten a single 16 bit set of zeros.

IPv6 =000A: 0000 : 000B : 0000: 0000 : 0000 : 0000 : 0000

 After compression

IPv6 = A : 0 : B :: 

Types of IPv6 Addressing

Unicast :-

Unicast IPv6 addresses are similar to unicast IPv4 addresses. These are meant to configure on one interface so that you can send and receive IPv6 packets. There are a number of different unicast address types that we’ll discuss here.

Ø  Global unicast :- The global unicast IPv6 addresses are similar to IPv4 public addresses. These addresses can be used on the Internet. The big difference with IPv4 however, is that IPv6 has so much address space that we can use global unicast addresses on any device in the network.

Ø Unique Local :- Unique local addresses work like the IPv4 private addresses. You can use these addresses on your own network if you don’t intend to connect to the Internet or if you plan to use IPv6 NAT. The advantage of unique local addresses is that you don’t need to register at an authority to get some address space.

Ø Link-local:- Link-Local addresses are something new in IPv6. As the wording implies, these addresses only work on the local link, we never route these addresses. These addresses are used to send and receive IPv6 packets on a single subnet.

Multicast 

One to many.

Enables more efficient use of the network.

Uses a larger address range.

Anycast 

One-to-nearest { allocated from unicast address space}

Multiple devices share the same address.

All anycast nodes should provide uniform service.

Source devices send packets to reach that destination.

Routers decide on closest device to reach that destination.

Suitable for load balancing and content delivery services.

Industrial Application

Ø The IPv6  protocol makes possible to communicate without NAT in the whole internet. Many embedded  systems can provide server  function more simply.

Ø The big IPv6 address sing space is interesting for sensor network technologies  including wireless sensor  networks.

Ø  To create IPv6–enable sensor network requires appropriate inter-working between the IPv6  layer and the link layer. The IPv6 operation must be  specified for every specific sensor link technology. RFC 4944 specifies Ipv6 operation over IEEE 802.15.4 network.. RFC 6282, which updates RFC 4944.

Ø  Bluetooth devices can also support the Ipv6 protocol.