Chapter 13Chapter 13

IPV6

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

ObjectivesObjectives

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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

• 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