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What is IPv4 and IPv6?

A local area network (LAN) is a computer network within a small geographical area such as a home, school, computer laboratory, office building or group of buildings.

A LAN is composed of inter-connected workstations and personal computers which are each capable of accessing and sharing data and devices, such as printers, scanners and data storage devices, anywhere on the LAN. LANs are characterized by higher communication and data transfer rates and the lack of any need for leased communication lines.


More Technical on LAN
In the 1960s, large colleges and universities had the first local area networks (LAN). In the mid-1970s, Ethernet was developed by Xerox PARC (Xerox Palo Alto Research Center) and deployed in 1976. Chase Manhattan Bank in New York had the first commercial use of a LAN in December 1977. In the late 1970s and early 1980s, it was common to have dozens or hundreds of individual computers located in the same site. Many users and administrators were attracted to the concept of multiple computers sharing expensive disk space and laser printers.

From the mid-1980s to through the 1990s, Novell's Netware dominated the LAN software market. Over time, competitors such as Microsoft released comparable products to the point where nowadays, local networking is considered base functionality for any operating system.

A wide area network (WAN) is a network that exists over a large-scale geographical area. A WAN connects different smaller networks, including local area networks (LANs) and metro area networks (MANs). This ensures that computers and users in one location can communicate with computers and users in other locations. WAN implementation can be done either with the help of the public transmission system or a private network.


More Technical on WAN
A WAN connects more than one LAN and is used for larger geographical areas. WANs are similar to a banking system, where hundreds of branches in different cities are connected with each other in order to share their official data.

A WAN works in a similar fashion to a LAN, just on a larger scale. Typically, TCP/IP is the protocol used for a WAN in combination with devices such as routers, switches, firewalls and modems.

Transmission Control Protocol/Internet Protocol (TCP/IP) is the language a computer uses to access the internet. It consists of a suite of protocols designed to establish a network of networks to provide a host with access to the internet.

TCP/IP is responsible for full-fledged data connectivity and transmitting the data end to end by providing other functions, including addressing, mapping and acknowledgment. TCP/IP contains four layers, which differ slightly from the OSI model. The technology is so common that one would rarely use the full name. In other words, in common usage the acronym is now the term itself.


More Technical on TCP/IP
Nearly all computers today support TCP/IP. TCP/IP is not a single networking protocol – it is a suite of protocols named after the two most important protocols or layers within it – TCP and IP.

As with any form of communication, two things are needed: a message to transmit and the means to reliably transmit the message. The TCP layer handles the message part. The message is broken down into smaller units, called packets, which are then transmitted over the network. The packets are received by the corresponding TCP layer in the receiver and reassembled into the original message.

The IP layer is primarily concerned with the transmission portion. This is done by means of a unique IP address assigned to each and every active recipient on the network.

TCP/IP is considered a stateless protocol suite because each client connection is newly made without regard to whether a previous connection had been established.

An Internet Protocol address (IP address) is a logical numeric address that is assigned to every single computer, printer, switch, router or any other device that is part of a TCP/IP-based network.

The IP address is the core component on which the networking architecture is built; no network exists without it. An IP address is a logical address that is used to uniquely identify every node in the network. Because IP addresses are logical, they can change. They are similar to addresses in a town or city because the IP address gives the network node an address so that it can communicate with other nodes or networks, just like mail is sent to friends and relatives.

The numerals in an IP address are divided into 2 parts:
The network part specifies which networks this address belongs to and
The host part further pinpoints the exact location.


More Technical on IP Address
An IP address is the most significant and important component in the networking phenomena that binds the World Wide Web together. The IP address is a numeric address assigned to every unique instance that is connected to any computer communication network using the TCP/IP communication protocols.

Network nodes are assigned IP addresses by the Dynamic Host Configuration Protocol server as soon as the nodes connect to a network. DHCP assigns IP addresses using a pool of available addresses which are part of the whole addressing scheme. Though DHCP only provides addresses that are not static, many machines reserve static IP addresses that are assigned to that entity forever and cannot be used again.

Classfull IP addressing is a legacy scheme which divides the whole IP address pools into 5 distinct classes—A, B, C, D and E. Classless IP addressing has an arbitrary length of the prefixes.

Internet Protocol Version 4 (IPv4) is the fourth revision of the Internet Protocol and a widely used protocol in data communication over different kinds of networks. IPv4 is a connectionless protocol used in packet-switched layer networks, such as Ethernet. It provides the logical connection between network devices by providing identification for each device. There are many ways to configure IPv4 with all kinds of devices – including manual and automatic configurations – depending on the network type.

IPv4 is based on the best-effort model. This model guarantees neither delivery nor avoidance of duplicate delivery; these aspects are handled by the upper layer transport.


More Technical IPv4
IPv4 is defined and specified in IETF publication RFC 791. It is used in the packet-switched link layer in the OSI model. IPv4 uses 32-bit addresses for Ethernet communication in five classes: A, B, C, D and E. Classes A, B and C have a different bit length for addressing the network host. Class D addresses are reserved for multicasting, while class E addresses are reserved for future use.

Class A has subnet mask 255.0.0.0 or /8, B has subnet mask 255.255.0.0 or /16 and class C has subnet mask 255.255.255.0 or /24. For example, with a /16 subnet mask, the network 192.168.0.0 may use the address range of 192.168.0.0 to 192.168.255.255. Network hosts can take any address from this range; however, address 192.168.255.255 is reserved for broadcast within the network. The maximum number of host addresses IPv4 can assign to end users is 232.

IPv6 presents a standardized solution to overcome IPv4's limitations. Because of its 128-bit address length, it can define up to 2,128 addresses.

Internet Protocol Version 6 (IPv6) is an Internet Protocol (IP) used for carrying data in packets from a source to a destination over various networks. IPv6 is the enhanced version of IPv4 and can support very large numbers of nodes as compared to IPv4. It allows for 2128 possible node, or address, combinations. IPv6 is also known as Internet Protocol Next Generation (IPng).


More Technical on IPv6
Released June 6, 2012, IPv6 was developed in hexadecimal format and contains 8 octets to provide large scalability. Like IPv4, IPv6 deals with address broadcasting without containing broadcast addresses in any class.

An IP address is binary numbers but can be stored as text for human readers. For example, a 32-bit numeric address (IPv4) is written in decimal as four numbers separated by periods. Each number can be zero to 255. For example, 1.160.10.240 could be an IP address. In this IP version, addresses are defined by using a decimal and 32-bit format that looks like this: x.x.x.x. Each “x” represents a potential number between 0 and 255. In this case, this is a standard address example: 1.2.3.4.


IPv6 addresses are 128-bit IP address written in hexadecimal and separated by colons. An example IPv6 address could be written like this: 3ffe:1900:4545:3:200:f8ff:fe21:67cf. The most noteworthy difference is the address representation. IPv4 has a more easy-to-comprehend address format as opposed to IPv6 (y:y:y:y:y:y:y:y or y:y:y:y:y:y:x.x.x.x).

IPv6 addresses are 128 bits long, which gives a total of 2128 ≈ 3.4 × 1038 possible addresses in the address space. This is ≈79 septillions times greater than all the address space defined by IPv4 protocol. If we compare this figure with the number of visible stars in our Universe (which is estimated at about 1024 stars), then to each star can be granted roughly a little more than 340 trillion addresses. It is so large that we can talk that IPv6 once and forever solve the problem of Internet addresses exhausting. In other words, the IPv6 address space is theoretically as big that it is able to meet the needs of IP-addresses for the whole Universe.

IPv6 address 128 bits length:

-------------------------------------------------------
| Prefix Provider | Network | Interface ID |
|     48 bits      |     16 bits      |    64 bits    |
-------------------------------------------------------
| Subnet prefix |
-----------------------------
| Global prefix |
-------------------

Methods for allocation of IPv6 addresses from the global address space are determined precisely the address structure. The first 48 bits of the address represent global prefix and these blocks are usually allocated to providers and various organizations. Those, in turn, are able to use the next 16 bits of address for the organization of their subnets. The remaining 64 bits are the interface ID of the user's device. As we can see, in theory, it allows you to connect to the same subnet 264 ≈ 1.8 × 10 19 different devices. That although seems redundant, but it is done so in order to simplify the auto-configuration of the connection for these devices.

While increasing the pool of addresses is one of the most often-talked about benefit of IPv6, there are other important technological changes in IPv6 that will improve the IP protocol:

No more NAT (Network Address Translation)
Auto-configuration
No more private address collisions
Better multicast routing
Simpler header format
Simplified, more efficient routing
True quality of service (QoS), also called "flow labelling"
Built-in authentication and privacy support
Flexible options and extensions
Easier administration (say good-bye to DHCP)

IPv6 can run end-to-end encryption. While this technology was retrofitted into IPv4, it remains an optional extra that isn’t universally used. The encryption and integrity-checking used in current VPNs is a standard component in IPv6, available for all connections and supported by all compatible devices and systems. Widespread adoption of IPv6 will therefore make man-in-the-middle attacks significantly more difficult.

IPv6 also supports more-secure name resolution. The Secure Neighbor Discovery (SEND) protocol is capable of enabling cryptographic confirmation that a host is who it claims to be at connection time. This renders Address Resolution Protocol (ARP) poisoning and other naming-based attacks more difficult. And while not a replacement for application- or service-layer verification, it still offers an improved level of trust in connections. With IPv4 it’s fairly easy for an attacker to redirect traffic between two legitimate hosts and manipulate the conversation or at least observe it. IPv6 makes this very hard.

This added security depends entirely on proper design and implementation, and the more complex and flexible infrastructure of IPv6 makes for more work. Nevertheless, properly configured, IPv6 networking will be significantly more secure than its predecessor.

1. More Efficient Routing
IPv6 reduces the size of routing tables and makes routing more efficient and hierarchical.IPv6 allows ISPs to aggregate the prefixes of their customers' networks into a single prefix and announce this one prefix to the IPv6 Internet.

2. More Efficient Packet Processing
IPv6's simplified packet header makes packet processing more efficient. Compared with IPv4, IPv6 contains no IP-level checksum, so the checksum does not need to be recalculated at every router hop. Getting rid of the IP-level checksum was possible because most link-layer technologies already contain checksum and error-control capabilities. In addition, most transport layers, which handle end-to-end connectivity, have a checksum that enables error detection.

3. Directed Data Flows
IPv6 supports multicast rather than broadcast. Multicast allows bandwidth-intensive packet flows (like multimedia streams) to be sent to multiple destinations simultaneously, saving network bandwidth. Disinterested hosts no longer must process broadcast packets. In addition, the IPv6 header has a new field, named Flow Label that can identify packets belonging to the same flow.

4. Simplified Network Configuration
Address auto-configuration (address assignment) is built in to IPv6. A router will send the prefix of the local link in its router advertisements. A host can generate its own IP address by appending its link-layer (MAC) address, converted into Extended Universal Identifier (EUI) 64-bit format, to the 64 bits of the local link prefix.

5. Support For New Services
By eliminating Network Address Translation (NAT), true end-to-end connectivity at the IP layer is restored, enabling new and valuable services. Peer-to-peer networks are easier to create and maintain, and services such as VoIP and Quality of Service (QoS) become more robust.

6. Security
IPSec, which provides confidentiality, authentication and data integrity, is baked into in IPv6. Because of their potential to carry malware, IPv4 ICMP packets are often blocked by corporate firewalls, but ICMPv6, the implementation of the Internet Control Message Protocol for IPv6, may be permitted because IPSec can be applied to the ICMPv6 packets.

When IPv6 first launched, it required companies to encrypt internet traffic with IPSec, a fairly common (but not nearly as common as SSL) encryption standard. Encryption scrambles the content of internet traffic so anyone who intercepts it cannot read it.

But in order to get more companies on board, that requirement transformed into more of a strong suggestion. Encrypting and decrypting data requires computing resources, which requires more money. IPSec can also be implemented on IPv4, which in theory means IPv6 is equally as safe as IPv4. We’ll likely see an increase in IPSec use overall as we transition, but it’s not required of everyone.

While we’re in the transition phase, some experts argue IPv6 users are actually more at risk than those who stick to IPv4. Some ISPs use transition technologies–IPv6 tunnels, in particular–that make users more vulnerable to attack. A tunnel broker is normally used by ISPs to give users on their IPv4 networks access to IPv6 content. Hackers can target IPv6 tunnel users with packet injection and reflection attacks. Note that some tunnel brokers offer better security than others.

The transition is expected to take several more years before it’s complete, so these transition methods will remain in place for some time.

Another potential security issue comes with a new IPv6 feature: autoconfiguration. This allows devices to assign themselves IP addresses without the need for a server. These addresses are generated using a device’s unique MAC address, which every phone, computer, and router has. This creates a unique identifier that third parties could use to track specific users and identify their hardware. Windows, Mac OSX, and iOS devices already have privacy extensions installed and enabled by default, so this won’t be a problem for most people.



IPv6 cannot work on VPN

Unfortunately, almost all VPNs operate solely on IPv4. If you submit a request for a website that defaults to an IPv6 address, it will resolve using an IPv6 DNS server that’s outside of your VPN network. This is called an IPv6 leak, and it can reveal your true location to a geo-locked website or app such as Hulu and Netflix. If the website is set up to detect such leaks, it can block you from viewing content. You can test for IPv6 DNS leaks here (it also tests for IPv4 leaks).

While we encourage users to get on board with IPv6, in this case you would have to disable it on your computer, tablet, or smartphone. This can usually be done somewhere in the internet connection settings, depending on your device.

Very few VPN providers support IPv6 at all due to the extra costs of running an IPv6 DNS server.

Comparing IPv6 against IPv4? IPv4 IPv6
IPv6 has more addresses 4.3 billion addresses 340 trillion trillion trillion addresses
IPv6 networks are easier and cheaper to manage Networks must be configured manually or with DHCP. IPv4 has had many overlays to handle Internet growth, which demand increasing maintenance efforts. IPv6 networks provide autoconfiguration capabilities. They are simpler, flatter and more manageable for large installations.
IPv6 restores end-to-end transparency Widespread use of NAT devices means that a single NAT address can mask thousands of non-routable addresses, making end-to-end integrity unachievable. Direct addressing is possible due to vast address space – the need for network address translation devices is effectively eliminated.
IPv6 has improved security features Security is dependent on applications – IPv4 was not designed with security in mind. IPSEC is built into the IPv6 protocol, usable with a suitable key infrastructure.
IPv6 has improved mobility capabilities Relatively constrained network topologies restrict mobility and interoperability capabilities in the IPv4 Internet. IPv6 provides interoperability and mobility capabilities which are already widely embedded in network devices.
IPv6 encourages innovation IPv4 was designed as a transport and communications medium, and increasingly any work on IPv4 is to find ways around the constraints. Given the numbers of addresses, scalability and flexibility of IPv6, its potential for triggering innovation and assisting collaboration is unbounded.

There are also many differences at the protocols level of IPv4 and IPv6, but for the end Internet-user it is a negligible value. However, for anyone interested, we present a short comparison of the differences in protocols below.

IPv4 IPv6
Addresses are 32 bits (4 bytes) in length Addresses are 128 bits (16 bytes) in length
Address (A) resource records in DNS to map host names to IPv4 addresses Address (AAAA) resource records in DNS to map host names to IPv6 addresses
Pointer (PTR) resource records in the IN-ADDR.ARPA DNS domain to map IPv4 addresses to host names Pointer (PTR) resource records in the IP6.ARPA DNS domain to map IPv6 addresses to host names
IPSec is optional and should be supported externally IPSec support is not optional
Header does not identify packet flow for QoS handling by routers Header contains Traffic Class field, which identifies packet flow priority for QoS handling by router
Both routers and the sending host fragment packets Routers do not support packet fragmentation. Sending host fragments packets
Header includes a checksum Header does not include a checksum
Header includes options Optional data is supported as extension headers
ARP uses broadcast ARP request to resolve IP to MAC/Hardware address Multicast Neighbor Solicitation messages resolve IP addresses to MAC addresses
Internet Group Management Protocol (IGMP) manages membership in local subnet groups Multicast Listener Discovery (MLD) messages manage membership in local subnet groups
Broadcast addresses are used to send traffic to all nodes on a subnet IPv6 uses a link-local scope all-nodes multicast address
Configured either manually or through DHCP Does not require manual configuration or DHCP
Must support a 576-byte packet size (possibly fragmented) Must support a 1280-byte packet size (without fragmentation)
Used TTL (Time to Live) header field for packets TTL renamed to Hop Limit
Header size is 20 bytes Header size is 40 bytes
Max packet size is 65535 bytes (216 - 1) Supporting jumbograms - huge packets up to 4 Gb (4294967295 = 232 - 1)