IPv4 :

IPv4 Data gram

Pack in IPv4 are called data gram.

These are the data following fields in a Data gram

1. Ver:

4 bit field defined the varsion of IPv4 protocol and here it is 4.

2. Header length ( HLEN)

This 4 bit field defines the total length of the data gram header.

3. Services:

Defines this 8 bit field defines priority of data gram in issues such as conjuction.

4. Total length:

16 bit field that defines total length ( Header + data) of IPv4 data gram

•°• length of data = Total length _ header length ( HELN)

5. Identification: 

16 bit used for fragmentation. 

6. Flags:

3 bits used for fragmentation 

7. Fragment off set :

13 bits used for fragment

8.Time to live:

A data gram had a limited life time .In its travel through internet . This field was orginally designed to hold a time stamp, which was decremented by each visted router.

9. Protocol:

8bit field defines the higher level protocol that uses the services IPv4 layer such as TCP/ UDP/ ICMP and IGMP

10. Header check:

16 bit field user for error detection. 

11.Source IP address: 

32 bit field defines address of the source. 

12. Destination IP address:

32 bit field defines address of destination. 

 IPv6 Addresses 

☆Indian Registry for Internet  Names and Numbers (IRINN) has started issuing next version of internet addresses 'IPv6',which would make it easy for security agencies to identify  each Intrest user.

☆The Internet  addresses under the present version IPv4 ( Internet Protocol Version 4), are limited and service providers often assign single IP address to many users, making it difficult to identify the end user.

☆APNIC, which is one of the five authorished bodies for issuing  Intrest addresses, has recognised Indian Registry for Internet Names and Numbers ( IRINN) for issuing IP addresses in india.

☆ The new addresses will be multiple  times cheaper for companies that IPv4 addresses.

IPv6 packet format

IPv6 is 128 bits i.e it consists of 2¹²⁸ IP address. 
The packet format is as follows:


It is 6 in this case ( 4 bits) field


8 bit field used to distinguish between packets whose source can be flow control and those which cannot be flow control 

● value 0 to 7 used for used for transmission that are capable for slowing down in the event of conjuction.
● Value 8 to 15 are used for real time traffic.

3 Flow label:

The flow label field is 20 bits and is used to provide special handling for a particular flow of data.

4. Pay load field:

16 bit defines the length of IP data gram excluding the header .
Length of header in IPv6 is fixed i.e 40 bytes.

5. Nex header:

8 bytes field defines the types of first extension header ( if present) or the type of data that follows the base header.

6. HOp limit:

8 bytes field and is same as time to live.

Source and destination address 

16 byte that is 128 bit internet address that defines the source and destination. 

Comparision between IPv4 & IPv6.

1. The IPv4 is 32 bits in length while as IPv6 is 128 bits ie.a huge increase in address space.

2 IPv6 uses a new header format in which options are separated from the basis header. Header length field is eliminated in IPv6 because the length of header is fixed in IPv6.

3. The Service type fields is eliminated in IPv6. The priority  and flow level field together in IPv6 take over the function service types field.

4. Total length field is eliminated in IPv6 and replaced by payload length field.

5 The time to live is called HOp limit in IPv6.

6. Protocol field is replaced by next header field in IPv6.

7. The header check some fields is eliminated in IPv6 because the check some is provided by upper layer protocol. 

8. The options fields in IPv4 are implemented as extension header in IPv6.

Advantage of IPv6 over IPv4

● IPv6 solves the IPv4 public address depletion problem by providing an address space to last well. The business benefit of moving to IPv6 is that mobile cell phones, personal data assistants ( PADs), automobiles,  appliances, and even people can be assigned multiple globally reachable addresses.
● Connectivity between disjoint networks requires intermediate devices such as NATs or proxy servers.With IPv6, both homes and enterprises will be assigned global address prefixes and can seamlessly connect,  subject to security restrictions such as firewalls filtering and authenticated communication. 

● With IPv6, public address prefixes are assigned to regional Internet registries, which, in turn, assign address prefixes to other ISPs and organizations based on justified need. This new address allocation practice ensures that address prefixes will be distributed globally based on regional connectivity needs, rather than by historical origin.

● With IPv6, NATs are no longer necessary to conserve public address space, and the problems associated with mapping addresses and ports disappear for developers of applications  and gateways.

● Unlike IPv4 addresses, IPv6 addresses have a scope, or a defined area of the network over which they are unique and relevant.

● IPv6 is a streamlined  version of IPv4. Excluding prioritized delivery  traffic, Ipv6 has fewer fields to process and fewer decisions to make in forwarding an IPv6  packet.

● The result of designing IPv6  with security and mobility in mind is an implementation  that is a defined started, has fewer limitations, and is more robust and scalable to handle the current and future communication  needs of the users of the Internet.


Internet Service provider ( ISP) 

● An Internet service provider ( ISP) is a business or organization that offers users access to the Internet and related services. 

● Many but not all ISPs are telephone companies or other telecommunication providers.

● They provide services such as Internet access, Internet transit, domain in name registration and hosting, dial _ up access,  leased line access and colocation.

● Internet service providers may be organized in various forms, such as commercial, community _ owned, non_ profit, or otherwise privately owned. 

National Internet Exchange of India ( NIXI)( IT)

● The National Internet Exchange of India is the neutral meeting point of the ISPs in india.
● Its main purpose is to facilitate exchange of domestic Intrest ttaffic between the peering ISP members.
● This enables more efficient use of international bandwidth,  saving foreign exchange.
● It also improves the Quality of services for the customers of member  ISPs, by avoiding  multiple international hopes and thus reducing latency. 

Indian Registry for Internet Names and Numbers ( IRINN) (IT)

● Indian Government has launched the National internet Registry which will manage IP address allocations  and other internet  resources.
● NIR has been named Indian Registry for Internet Names and Numbers (IRINN) which is a division in National Internet Exchange of India (NIXI) .
● NIR functions under Regional Internet Registry ( RIR) which is Asia Pacific Network Information Centre in Brisbane, Australia.  APNIC manage IP address allocation and other intrest resources for the Asia Pacific region.
● Eariler IP address had to be bought directly from APNIC which proved out to be time consuming  and quite expensive. With NIR, buying IP address will become up to 70% cheap and will also help the country in cyber crime investigations. INDIAN SPACE POLICY


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