IPv6

IPv6 advantages

• Address assignment features
• Aggregation
• No need for NAT/PAT
• IPsec
• Header improvements
• Transition tools

IPv6 is assigned by ICANN

ICANN > Regional Internet Registry (RIR) > ISP

Representing IPv6 Addresses

• If quartet consists of all zeros, you can leave only one zero
• Represent 1 or more consecutive quartets of all hex 0s with a double colon (::), but only for one such occurrence in a given address
• The last/third major part is the host part of the address, called the interface ID in IPv6, and is meant to uniquely identify a host inside a subnet.

Prefix types

• Registry prefix: By ICANN to an RIR
• ISP prefix: By an RIR to an ISP
• Site prefix: By an ISP to a customer (site)
• Subnet prefix: By an enterprise engineer for each individual link

Addresses assignment

• 2000::/3 - unicast global addresses
• FF00::/8 - multicast
• FF02::2 - All routers on this link - multicast for router solicitation (RS) messages
• FF02::1 - All IPv6 nodes on this link - multicast for router advertisment(RA) messages
• FD00::/8 - unique local unicast addresses
• FE80::/10 - link local addresses. IPv6 uses these addresses when sending packets over the local subnet; routers never forward packets destined for link local addresses to other subnets. The host uses its link local address as the source IP address in the RS message. This address is calculated by host: first ten bits is 1111111010, next 54 bits is 0, and the last 64 bits is EUI. Interestingly, routers normally use link local addresses as the next-hop IP address in IPv6 routes, rather than the neighboring router’s global unicast or unique local unicast address.
• ::1 (127 binary 0s and a 1) - loopback
• :: - inknown address

Address configuration

• Stateful DHCP - the same as IPv4 DHCP, but instead of broadcast, multicast is used, FF02::1:2 - has been reserved in IPv6 to be used by hosts to send packets to an unknown DHCP server, with the routers working to forward these packets to the appropriate DHCP server
• EUI-64 - configuration of ip address based on mac address. Splits MAC into two 3 byte halfs and inserts between them FFFE. Also 7th bit in the first byte of MAC is set to 1
• Stateless DHCP - is most useful in conjunction with stateless autoconfiguration. It can supply DNS server ip address. It can't supply host IP address. It doesn't remember state information.
• Stateless autoconfiguration - a host dynamically learns the /64 prefix used on the subnet, and then calculates the rest of its address by using an EUI-64 interface ID based on its network interface card (NIC) MAC address. IPv6 Neighbor Discovery Protocol (NDP) is used to discover the prefix used on the LAN. Stateless autoconfiguration uses two NDP messages, namely router solicitation (RS) and router advertisement (RA) messages, to discover the IPv6 prefix used on a LAN
• Static assignment - full address or EUI-64(this is when last 64 bit of IPv6 address are filled with MAC address of the interface. MAC address is splitted into 2 3-byte parts and FFFE is inserted between them. Seventh bit in first byte of MAC must be 1)

Configuration

ipv6 unicast-routing global command

ipv6 router rip name global configuration command

ipv6 address address/prefix-length [eui-64] interface command

ipv6 rip name enable interface subcommand

Transition

• Dual stack
• Tunneling (if both end hosts support IPv6): IPv6 packet sent by a host is encapsulated into an IPv4 packet
• Manually configured tunnels (MCT) - creates staticly with hands.Dynamic 6to4 tunnels - created dynamicly, based on the destination IPv6 address
• Intra-site Automatic Tunnel Addressing Protocol (ISATAP) - Another dynamic tunneling method, typically used inside an enterprise. Unlike 6to4 tunnels, ISATAP tunnels do not work if IPv4 NAT is used between the tunnel endpoints
• Teredo tunneling - tunnel between host, directly
• NAT-PT (Network Address Translation–Protocol Translation) - communication between IPv4 only and IPv6 only hosts. Router configured with NAT-PT must know what IPv6 address to translate to which IPv4 address and vice versa. And like traditional NAT, NAT-PT allows static definition, dynamic NAT, and dynamic PAT, which can be used to conserve IPv4 addresses configured