IPv4 and IPv6 Communication

IPv6 Migration

• IPv4 and IPv6 are not compatible, and a transition from IPv4 to IPv6 is necessary.
• Three methods are used to migrate from IPv4 to IPv6: Dual Stack, Tunneling, and Translation.

Dual Stack Method

• Allows IPv4 and IPv6 to coexist in the same device and network.
• Devices like PCs, switches, routers, and ADSL modems are configured with both IPv4 and IPv6 drivers.
• Enables gradual transition from IPv4 to IPv6.

Tunneling

• Allows IPv6 hosts to communicate over IPv4 infrastructure.
• Encapsulates IPv6 traffic within IPv4 packets.
• Enables isolated IPv6 end systems and routers to communicate without upgrading IPv4 infrastructure.
• Three tunneling configurations exist: Router-to-Router, Host-to-Router, and Host-to-Host.

Translation (SIIT and NAT64)

• Involves configuring devices with IPv6 addresses only, and gateways with SIIT and NAT64 protocols and DNS-64.
• Enables communication between IPv4-only and IPv6-only end stations.
• The translator translates IPv6 packets into IPv4 packets by performing address and port translation.

IPv6 Addressing Scheme

• 128-bit IPv6 address is represented as 32 hexadecimal numbers arranged in 8 quartets of 4 hexadecimal digits, separated by a colon (:).
• Not case sensitive for A, B, C, D, E, and F.
• Omission of zeros is allowed.
• Leading zero in any quartet can be omitted.
• Four successive zeros in a quartet can be substituted by one zero.
• Replacing successive fields of zeros with "::" is allowed.
• Multiple quartets with zero can be represented as :: but only once in an address.

IPv6 Features

• Provides sufficient address space for the near future.
• Offers enhanced security with built-in IPSec.
• Has a simpler header than IPv4, which is not protected by a checksum.
• Does not require NAT since every device has a globally unique IPv6 address.
• Supports stateless address auto-configuration, allowing IPv6 hosts to automatically configure themselves with an IPv6 address without a DHCP server.

Private Addressing Scheme

• Private addresses are used in data networks of Indian Railways.
• IPv4 private addresses allotted by the Railway Board are 10.0.0.0/8.
• The 10.0.0.0/8 network address is further subnetted to 10.X.0.0/16 network by the Railway Board and allocated to Zonal Railways, divisions, RDSO, PSUs, and Training Institutes.

Private IP Addresses

• Are free and do not require permission for use.
• Must be unique within the same local network and cannot be repeated.
• Cannot communicate in the public domain and are not able to use Internet services.
• Can be used via NAT at the Intranet gateway level, where private IP addresses are logically hidden and public IP addresses represent the Intranet traffic.

Internet Service Provider (ISP)

• Provides Internet access to organizations and home users.
• Is responsible for making sure users can access the Internet, routing Internet traffic, resolving domain names, and maintaining the network infrastructure.

IPv6 Migration

• IPv4 and IPv6 are not compatible, and a transition from IPv4 to IPv6 is necessary.
• Three methods are used to migrate from IPv4 to IPv6: Dual Stack, Tunneling, and Translation.

Dual Stack Method

• Allows IPv4 and IPv6 to coexist in the same device and network.
• Devices like PCs, switches, routers, and ADSL modems are configured with both IPv4 and IPv6 drivers.
• Enables gradual transition from IPv4 to IPv6.

Tunneling

• Allows IPv6 hosts to communicate over IPv4 infrastructure.
• Encapsulates IPv6 traffic within IPv4 packets.
• Enables isolated IPv6 end systems and routers to communicate without upgrading IPv4 infrastructure.
• Three tunneling configurations exist: Router-to-Router, Host-to-Router, and Host-to-Host.

Translation (SIIT and NAT64)

• Involves configuring devices with IPv6 addresses only, and gateways with SIIT and NAT64 protocols and DNS-64.
• Enables communication between IPv4-only and IPv6-only end stations.
• The translator translates IPv6 packets into IPv4 packets by performing address and port translation.

IPv6 Addressing Scheme

• 128-bit IPv6 address is represented as 32 hexadecimal numbers arranged in 8 quartets of 4 hexadecimal digits, separated by a colon (:).
• Not case sensitive for A, B, C, D, E, and F.
• Omission of zeros is allowed.
• Leading zero in any quartet can be omitted.
• Four successive zeros in a quartet can be substituted by one zero.
• Replacing successive fields of zeros with "::" is allowed.
• Multiple quartets with zero can be represented as :: but only once in an address.

IPv6 Features

• Provides sufficient address space for the near future.
• Offers enhanced security with built-in IPSec.
• Has a simpler header than IPv4, which is not protected by a checksum.
• Does not require NAT since every device has a globally unique IPv6 address.
• Supports stateless address auto-configuration, allowing IPv6 hosts to automatically configure themselves with an IPv6 address without a DHCP server.

Private Addressing Scheme

• Private addresses are used in data networks of Indian Railways.
• IPv4 private addresses allotted by the Railway Board are 10.0.0.0/8.
• The 10.0.0.0/8 network address is further subnetted to 10.X.0.0/16 network by the Railway Board and allocated to Zonal Railways, divisions, RDSO, PSUs, and Training Institutes.

Private IP Addresses

• Are free and do not require permission for use.
• Must be unique within the same local network and cannot be repeated.
• Cannot communicate in the public domain and are not able to use Internet services.
• Can be used via NAT at the Intranet gateway level, where private IP addresses are logically hidden and public IP addresses represent the Intranet traffic.

Internet Service Provider (ISP)

• Provides Internet access to organizations and home users.
• Is responsible for making sure users can access the Internet, routing Internet traffic, resolving domain names, and maintaining the network infrastructure.