BASICS OF IPv6 JUBIN AGHARA

Tropics

Its Need IPv6 Size Comparison Header Format IPv6 Addressing Format Prefix Presentation and CIDR Notation IPv6 Addressing types IPv6 Address Allocation Interface ID Subnetting Host Configuration

Need of IPV6

IETF IPv6 working group began in early 90s, to solve addressing growth issues, but CIDR, NAT were developed to fix the shortage of IPv4 address.

IPv4 32 bit address = 4 billion hosts 40% of the IPv4 address space is still unused which is

different from unallocated. The rising of Internet connected device, IoT, IoE and

appliance will eventually deplete the IPv4 address space. IP is everywhere, Data, voice, audio and video integration is

a reality. So, only compelling reason: More IP addresses

IPv6 Addressing

Size?

Header Format

IPv6 Addressing Format

16-bit hexadecimal numbers Numbers are separated by (:) Hex numbers are not case sensitive Abbreviations are possible

Abbreviations are possibleLeading zeros in contiguous block could be represented by (::)Example:

2001:0db8:0000:130F:0000:0000:087C:140B2001:0db8:0:130F::87C:140B

Double colon only appears once in the address

Prefix Presentation

Representation of prefix is just like CIDR In this representation you attach the prefix length Like v4 address: 198.10.0.0/16

V6 address is represented the same way: 2001:db8:12::/48 Only leading zeros are omitted. Trailing zeros are not

omitted

2001:0db8:0012::/48 = 2001:db8:12::/482001:db8:1200:adfc::/64 ≠ 2001:db8:12:adfc::/64

IPv6 Addressing

Link Local Address

A special address used to communicate within the local link of an Interfacei.e. anyone on the link as host or router basically to communicate between IPv6 enabled devices

This address in packet destination that packet would never pass through a router

Example: FE80::/10

Unique Local

Unique Local IPv6 Unicast Address Addresses similar to the RFC 1918 / private address like in

IPv4 but will ensure uniqueness A part of the prefix (40 bits) are generated using a pseudo-

random algorithm and it's improbable that two generated ones are equal

FC00::/7

Global Unicast

IPV6 Global Unicast AddressGlobal Unicast Range: 0010 2000::/3 0011 3FFF:FFFF:…. :/3

All five RIRs are given a /12 from the /3 to further distribute within the RIR region, APNIC 2400:0000::/12 ARIN 2600:0000::/12 AfriNIC 2C00:0000::/12 LACNIC 2800:0000::/12

IPv6 Address Allocation

The allocation process is: The IANA is allocating out of 2000::/3 for initial IPv6 unicast

use Each registry gets a /12 prefix from the IANA Registry allocates a /32 prefix (or larger) to an IPv6 ISP Policy is that an ISP allocates a /48 prefix to each end

customer

64 bits reserved for the interface ID Possibility of 264 hosts on one network LAN Arrangement to accommodate MAC addresses within the IPv6

address

16 bits reserved for the end site Possibility of 216 networks at each end-site 65536 subnets equivalent to a /12 in IPv4 (assuming 16 hosts

per IPv4 subnet)

16 bits reserved for the service provider Possibility of 216 end-sites per service provider 65536 possible

customers: equivalent to each service provider receiving a /8 in IPv4 (assuming a /24 address block per customer)

IPv6 Address Allocation

32 bits reserved for service providers Possibility of 232 service providers i.e. 4 billion discrete

service provider networks. Although some service providers already are justifying more than a /32

Equivalent to the size of the entire IPv4 address space

IPv6 Address Allocation

Subnetting

Provider A has been allocated an IPv6 block 2001:DB8::/32 Provider A will delegate /48 blocks to its customers Find the blocks provided to the first 4 customers

Original block: 2001:0DB8::/32

Rewrite as a /48 block: 2001:0DB8:0000:/48 This is Network Prefix

How many /48 blocks are there in a /32

Subnetting

Interface ID

Lowest order 64-bit field of unicast address may beassigned in several different ways:

A. Auto-configured from a 64-bit EUI-64, or expanded from a 48-bit MAC address (e.g., Ethernet address)

B. Auto-generated pseudo-random number (to address privacy concerns)

C. Assigned via DHCPD. Manually configured

EUI-64

Stateless (RFC2462) Host autonomously configures itsown Link-Local address Router solicitation are sent bybooting nodes to request RAs forconfiguring the interfaces.Stateful DHCPv6 – required by mostenterprisesRenumbering Hosts renumbering is done bymodifying the RA to announce theold prefix with a short lifetime andthe new prefix Router renumbering protocol (RFC2894), to allow domain-interior routers to learn of prefix introduction /withdrawal

IPv6 Auto Configuration

A new host is turned on. Tentative address will be assigned to the new host. Duplicate Address Detection (DAD) is performed. First the host transmit a Neighbor Solicitation (NS) message to the solicited node multicast

address (FF02::1:FF64:1D) corresponding to its to be used address If no Neighbor Advertisement (NA) message comes back then the address

is unique. FE80::310:BAFF:FE64:1D will be assigned to the new host.

IPv6 Auto Configuration

The new host will send Router Solicitation (RS) request to the all-routers multicast group (FF02::2).

The router will reply Routing Advertisement (RA). The new host will learn the network prefix. E.g, 2001:1234:1:1::/64 The new host will assigned a new address Network prefix+Interface ID E.g, 2001:1234:1:1:310:BAFF:FE64:1D

DHCPv6

Updated version of DHCP for IPv4 Supports new addressing Can be used for renumbering DHCP Process is same as in IPv4, but, Client first detect the presence of routers on the link If found, then examines router advertisements to determine if DHCP

can be used If no router found or if DHCP can be used, then DHCP Solicit message

is sent to the All-DHCP-Agents multicast address Using the link-local address as the source address

Types of DHCP

Stateful DHCP Stateful DHCP is centrally managed on a DHCP server; and the DHCP clients

use Stateful DHCP to obtain an IP address and other useful configuration information from the DHCP server.

Stateless DHCP Stateless DHCP on the other hand; means the DHCP server is not required

to store any dynamic state information on the DHCP server about any individual DHCP clients. Instead, the DHCP clients autoconfigure their own IP address based on router advertisements.

So, with Stateless DHCP, the DHCP clients don't use the DHCP server to obtain IP address information, they use the DHCP server to obtain the other useful configuration information like the address of DNS servers.

Stateful DHCPv6 Operation

Stateless DHCPv6 Operation

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