IPv6 Deployment

IPv6 deployment introduces IPv6 addressing and connectivity while maintaining access to services that still use IPv4.

IPv4 Address Conservation

Address conservation delays exhaustion without increasing the IPv4 address space.

• NAT with private addresses
  Multiple hosts share public IPv4 addresses, requiring translation state and complicating incoming connections.
• Proxy servers
  Private hosts access external services through an intermediary.
• Name-based virtual hosting
  Multiple websites share an IP address, with the requested hostname selecting the site.
• Address reclamation
  Renumbering networks can release unused portions of earlier allocations.

Deployment Planning

• Define an organizational rollout schedule and coexistence strategy.
• Agree on prefix allocation and IPv6 service levels with the ISP.
• Check vendor support across routers, operating systems, applications, and monitoring tools.
• Coordinate DNS, routing, firewall policies, and application testing.
• Train network administrators, software teams, and support staff.

IPv6 support does not automatically encrypt traffic. IPsec requires configuration and key management. RFC 8504 recommends IPsec support rather than requiring its use for every packet.

Readiness Checks

Linux commands for checking individual parts of IPv6 connectivity:

An AAAA record alone does not establish working IPv6 connectivity. Test the application service as well as its address and route.

Worked Example

The lecture allocates 2401:df0:17::/48 in consecutive /56 blocks. Treat the prefix as the exercise input.

1. Count the available /56 blocks. The extra 8 prefix bits give $2^8 = 256$ blocks.
2. Each /56 contains $2^8 = 256$ /64 subnets.
3. Assign 2 blocks to the backbone and the next 2 to servers.
4. Assign the next 124 blocks to Engineering and the next 64 to Architecture.
5. Assign the remaining $256 - 2 - 2 - 124 - 64 = 64$ blocks to IT.

The first 3 hexadecimal groups remain 2401:df0:17. The high byte of the 4th group selects the /56 block. Consecutive block prefixes advance by hexadecimal 0100 in that group.

For example, Engineering’s first block contains /64 subnets from 2401:df0:17:0400::/64 through 2401:df0:17:04ff::/64.

Contiguous allocations can be summarized where their size and alignment permit:

Engineering needs 5 aggregate prefixes because 124 is not a power of 2. The allocations cover all 256 /56 blocks without overlap.