Advantages And Disadvantages Of IPv6, IPv6 Address Types

Let us discuss about Internet Protocol version 6, IPv6 Address Types, Advantages And Disadvantages Of IPv6.

IPv6

IPv6, or Internet Protocol version 6, is the most recent iteration of the Internet Protocol (IP), the system that is used to locate and identify machines on the Internet. To address the issue of IPv4 exhaustion, the Internet Engineering Task Force (IETF) created IPv6. With an address space of 2128, IPv6 is a 128-bit address that is significantly larger than IPv4. The Hexa-Decimal format used by IPv6 is separated by a colon (:).

Key Characteristics of IPv6 Addressing

Extended Address Space

• Compared to IPv4 addresses, which are 32 bits long, IPv6 addresses are four times longer at 128 bits.
• This enormous area offers over 3.4 x 10^38 addresses, or 340 trillion trillion trillion, guaranteeing an almost limitless supply for expansion in the future. To put that in perspective, this is more than 10^28 times IPv4 addresses.
• It does away with the essential requirement for Network Address Translation (NAT/PAT), a temporary fix for IPv4 depletion. NAT64 continues to be important for IPv4 backward compatibility.

Address Format and Representation

• The hexadecimal format used to write IPv6 addresses consists of 32 hexadecimal digits.
• Eight hextets, or quartets, of four hexadecimal digits are formed from these 32 digits, and they are separated by colons. Fourteen bits are represented by each quartet.
• Abbreviation Rules: The purpose of abbreviation rules is to make writing and typing IPv6 addresses easier.
  • A quartet’s leading zeros might be eliminated (for example, 0001 becomes 1).ng zeros within a quartet can be omitted (e.g., 0001 becomes 1).
  • One can substitute a double colon (::) for a single, continuous string of one or more all-zero quartets. This is a one-time use in an address.

Prefix Length

• IPv6 defines the network portion of the address using a prefix length (e.g., /64), just like IPv4 subnet masks do. It is represented by a / and a decimal value ranging from 0 to 128. For IPv6, there is no dotted-decimal equivalent mask.

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IPv6 Address Types

While broadcast addresses are also used in IPv4, IPv6 employs unicast, multicast, and anycast addresses. In IPv6, broadcast addresses are removed since they are inefficient, and multicast mostly takes their place.

Unicast Addresses

There is just one interface to which packets sent to a unicast address are delivered.

Global Unicast Address (GUA):

• They are publicly routable on the Internet and globally unique, much like public IPv4 addresses.
• They usually begin with two or three (the original range was 2000::/3).
• The structure is made up of a 64-bit interface ID, a 16-bit subnet ID, and a 48-bit global routing prefix that is assigned by an ISP.
• An interface can have more than one global unicast address set up.

Unique Local Unicast Address (ULA):

• ULAs can be routed within an organization but are not routed on the Internet, much as IPv4’s private (RFC 1918) addresses.
• IANA reserves FC00::/7, but ULAs set the eighth bit to 1, thus they start with FD00::/8.
• Locally generated ULAs are frequently prefixed with /48.

Link-Local Address (LLA):

• It is not possible to route these addresses beyond the single local link (network segment) on which they are utilized.
• Their initials are FE80::/10.
• When IPv6 is enabled, LLAs are automatically given to every interface. Despite changes in the global IPv6 prefix, they remain unchanged.

Multicast Addresses

Utilized for one-to-many communication, in which packets are sent to every interface that belongs to a particular multicast group.

• Every multicast address starts with FF (FF00::/8).
• The Address Resolution Protocol (ARP) and IPv4 broadcasts are replaced by them.
• Solicited-Node Multicast Addresses: Every interface’s unicast and anycast addresses have them enabled by default. Part of the Neighbour Discovery Protocol (NDP), they are utilised by hosts and routers to find the data link (MAC) addresses of nearby devices. The prefix FF02::1:FF00:0000/104, along with the low-order 24 bits of a unicast or anycast address, define them.

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Anycast Addresses

If a packet is sent to an anycast address, it is sent to the nearest device in terms of routing distance (also known as “one-to-nearest”). These addresses specify various interfaces on multiple devices.

• Routers, not hosts, are usually where anycast addresses are set up.
• They come from the unicast address range and are frequently set up with a /128 prefix to establish a host route. An anycast address can never be a source address.

Special Addresses

Unspecified Address (::): Shows that there isn’t an IPv6 address and represents all zeros. Only for DHCP or Duplicate Address Detection (DAD) can it be used as a source address, usually before a host has learnt a unicast address.

Loopback Address (::1): Comparable to 127.0.0.1 with IPv4. In order to test network software, a device uses it to transmit packets to itself. It cannot be altered and is assigned automatically when IPv6 is enabled.

IPv4-mapped IPv6 Address

IPv4 tunnels are used as transition mechanisms to send IPv6 packets across IPv4 networks. The IPv4 address is embedded with 16 all-1 bits and padding in the low-order 32 bits of the IPv6 address. In contrast to the outdated NAT-PT, NAT64 is a contemporary functionality for backward compatibility.

IPv6 Subnetting

Because IPv6 has a much larger address space than IPv4, subnetting is typically easier.

• In IPv6, there are no address classes.
• All deployed subnets should use a /64 prefix length, according to the majority of IPv6 RFCs. Subnetting is made as simple as employing a /24 mask for all IPv4 subnets with this.
• An ISP can create 2^16 (65,536) distinct subnets with 64-bit interface IDs by giving a client a /48 prefix, which leaves 16 bits for the subnet ID.
• The IPv6 subnet prefix, also known as the subnet ID, can be found by copying the first P bits, where P is the prefix length, and setting the remaining bits to 0. Hexadecimal manipulation can be used to do this for prefix lengths that are multiples of 4.

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IPv6 Address Assignment and Configuration

Both static and dynamic techniques are available for IPv6 hosts and routers to receive addresses.

Static Configuration: Includes manually setting up an interface’s complete 128-bit IPv6 address and prefix length using commands like ipv6 address ipv6-address/prefix-length.

Dynamic Configuration:

• Stateless Address Autoconfiguration (SLAAC): As part of the Neighbour Discovery Protocol (NDP), a router’s Router Advertisement (RA) message enables a host to dynamically discover the /64 prefix. The host can then compute its own unique 64-bit Interface ID (IID). Frequently, the Modified EUI-64 format is used for this.
  • EUI-64 (Extended Unique Identifier): By flipping the seventh bit of the first byte of the MAC address and adding the hexadecimal value FFFE in the middle, a 48-bit MAC address can be changed into a 64-bit interface ID.
  • The interface command for SLAAC is ipv6 address autoconfig.
• Stateful DHCPv6: The entire IPv6 address and other network parameters are assigned by a DHCPv6 server using a dynamic approach akin to DHCPv4. In DHCPv6, SARR (Solicit, Advertise, Request, and Reply) packets are used. Solicit messages are sent by clients to the link-local scope multicast address FF02::1:2.
  • The interface command for DHCPv6 is ipv6 address dhcp.
• For complete settings, SLAAC can also be used in conjunction with RA-based DNS server configuration or Stateless DHCP.
• The ipv6 enable interface command is helpful for WAN lines that do not require a routable GUA or ULA because it may be used to activate IPv6 processing and automatically assign a Link-Local Address.

Verification Commands (on Cisco routers):

• show ipv6 interface brief: Provides IPv6 address information for interfaces (but not prefix length details).
• show ipv6 interface: Provides detailed IPv6 interface settings.
• show ipv6 route: Displays the IPv6 routing table.

IPv6 Transition Technologies

Several transition methods are incorporated into IPv6 to enable coexistence with current IPv4 networks and ease the move from IPv4:

Dual-Stack: Devices select the proper protocol stack depending on DNS replies and are set up to run both IPv4 and IPv6 concurrently.

Tunneling: To communicate between IPv6-enabled sites via an IPv4 backbone, IPv6 traffic is encapsulated within IPv4 packets and sent across IPv4 networks. Examples are Teredo and 6to4.

Translation (Address Family Translation – AFT): Translates IPv6 addresses to IPv4 addresses, mostly so that IPv6 hosts can access IPv4 content. Both stateless and stateful options are possible, and NAT64 is a more recent backward compatibility capability.

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IPv6 Routing

Conceptually, IPv6 routing works similarly to IPv4 routing, except it makes use of IPv6 addresses and routing tables. A Cisco router has to have the global configuration command ipv6 unicast-routing in order to enable IPv6 routing.

Advantages of IPv6

• Faster Speeds: Multicast is supported via IPv6 instead of IPv4 broadcast. This feature makes it possible to send bandwidth-intensive packet flows such as multimedia streams to several locations simultaneously.
• Stronger Security: Data integrity and confidentiality are provided by IPSecurity, which is built into IPv6.
• Routing efficiency
• Reliability
• Most importantly it’s the final solution for growing nodes in Global-network.
• The device allocates addresses on its own.
• Internet protocol security is used to support security.
• Enable simple aggregation of prefixes allocated to IP networks; this saves bandwidth by enabling the simultaneous transmission of large data packages.

Disadvantages of IPv6

• Conversion: The current extensive use of IPv4 means that a full transition to IPv6 will take a long time.
• Communication: There is no direct communication between IPv4 and IPv6 machines.
• Not Going Backward Compatibility: Computers with IPv4 capabilities cannot run IPv6 since IPv4 systems do not support it.
• Conversion Time: One major problem with IPv6 is that it cannot uniquely identify every device on the network, which makes switching to IPv4 very time-consuming.
• Communication between IPv4 and IPv6 is prohibited since they cannot communicate with one another.

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