IPv6 was developed to replace IPv4 due to IPv4's limited 32-bit address space and inefficient use of addresses. IPv6 supports 2128 addresses, improves security with IPSec, and uses more efficient routing through address aggregation. IPv6 addresses are 128-bit and written in hexadecimal, with groups of zeros represented by double colons. IPv6 implements subnet masks as CIDR prefixes between /48 and /64. It uses DNS clusters, global unicast addresses, and DHCPv6 to assign addresses and DNS servers to clients.

1. IPV6
Chapter 13

2. Objectives
• Discuss the fundamental concepts of IPv6
• Describe the IPv6 practices
• Implement IPv6 in a TCP/IP network

3. • Internet Protocol version 4 (IPv4) limits
– 32-bit address space supports only about 4
billion addresses
– Used inefficiently with classful addressing
– Wasteful method of passing out addresses
– Running out of addresses

4. • Internet Protocol version 6 (IPv6)
– Developed by Internet Engineering Task Force
(IETF)
– Slowly replacing IPv4
– IPv6 supports 2128 (or ~3.4x1038) IP addresses
– Improved security with IPSec out-of-the-box
– More efficient routing scheme via aggregation

5. • IPv6 Address Notation
– 128 bits written in hexadecimal
– Every four hex characters separated by a colon.
– Example:
2001:0000:0000:3210:0800:200C:00CF:1234
– Leading zeroes dropped
– Pair of colons (::) used to represent a string of
consecutive groups of zeroes
– Example: 2001::3210:800:200C:CF:1234

6. • IPv6 Subnet Masks
– Function like IPv4 subnets
– Represented with /X CIDR naming
– 3. Example: FEDC::CF:0:BA98:1234/64 (64-bit
subnet mask)
• Two Rules
– No subnet greater than /64
– IANA gives /32 subnets to bit ISPs and others needing large
allotments; ISPs and other pass out /48 and /64 subnets. Vast
majority of IPv6 subnets are between /48 and /64

7. • Used in DNS
– Makes a bunch of clusters all over the world act
as a single server
– Give a number of computers (of clusters) the
same IP address
– Routers can determine which of the servers is
closest

8. • Global Address
– Called a global unicast address
– Required for Internet access
– Given to host by its IPv6-capable default gateway
router
– Router must be configured to pass out global
IPv6 addresses

9. • Aggregation
1. Current problem with tier-one routers
– No default routes
– Therefore, huge routing table (30,000-50,000 routes)
2. Aggregation solution
– A router hierarchy in which every router underneath a
higher router always uses a subnet of that router’s
existing routes.
– Reduces the size and complexity of routing tables

10. • DHCP in IPv6
– DHCPv6
– Works differently than in IPv4
– IP address and subnet received from gateway
router advertisements
– Need DHCPv6 for other IP information
• DNS server IP

11. • DNS in IPv6
– Trivial
– Most present DNS servers support IPv6
addresses
– DNS servers supporting IPv6 use AAAA records
– DNSv6 details not finalized
– For now, manually add DNS server information
to IPv6 clients