INTRODUCTION OF IPV6

Ravikumar Naik

21/11/2011

Outline

• Why we need a new version of the IP protocol?

• IPv6 Basics

• IPv6 Addressing

Contemporary studies indicated that it may be depleted within the next ten years – around 2005!

Why we need a new version of the IP protocol?

Two possible approaches were at hand

• Minimal: Keep the protocol intact, just increase the address length. This was the easier way promising less pain in the deployment phase.

• Maximal: Develop an entirely new version of the protocol. Taking this approach would enable incorporating new features and enhancements in IP.

Minimal possible approach.

• The most important of these was Classless Inter-Domain Routing (CIDR).

• network address translation (NAT)

New version of the protocol-IPv6

IPv6 Datagram Header

IPv6 Datagram Header

Version Protocol version identification. It contains value 6 to identify IPv6. Traffic Class Intended for the Quality of Service (QoS). It may distinguish various classes or priorities of traffic (in combination with other header fields, e.g. source/destination addresses). Flow Label Identifies a flow which is a “group of related datagrams”. Payload Length Length of the datagram payload, i.e. all the contents following the basic header (including extension headers). It is in Bytes, so the maximum possible payload size is 64 KB. Next Header The protocol header which follows. It identifies the type of following data - it may be some extension header or upper layer protocol (TCP, UDP) data. Hop Limit Datagram lifetime restriction. Source Address Sender identification. It contains the IPv6 address of the node who sent this datagram. Destination Address Receiver identification. This is the target - the datagram should be delivered to this IPv6 address.

IPv4 and IPv6 Header Comparison

• Basic datagram size fixed to 40 bytes 1

• Fragmentation moved to extension header 2

• CRC has been abandoned 3

• Extension headers. 4

Key Developments

Extension Headers (Header Chaining)

• Appended after the basic datagram header.

• Next Header field has two duties: it determines the following extension header or identifies the upper-layer protocol to which the datagram content should be passed.

• IPv6 specifies a particular order of extension headers.

Extension Headers (Header Chaining) Value

(decimal) Extension Header

0 Hop-by-hop option

43 Routing

44 Fragment

50 Encapsulating Security Payload (ESP)

51 Authentication Header (AH)

59 No next Header

60 Destination Option

62 Mobility Header

Protocols 6 TCP

8 EGP

9 IGP

17 UDP

46 RSVP

47 GRE

58 ICMP

Examples of Header Chaining

IPV6 ADDRESSING

Address Space

• The IPv6 address is 128 bits, 16 bytes

• Addresses are written using 32 hexadecimal digits.

• The digits are arranged into 8 groups to improve readability.

– 2001:0718:1c01:0016:020d:56ff:fe77:52a3

The following rules can be applied to address representations:

(a) Letters are case-insensitive.

(b) Leading zeros in a field are optional. For example, ‘00c1’ equals ‘c1’.

(c) Successive fields of ‘0’ are represented as ‘::’, but only once in an address.

For example,

2001:0000:1234:0000:0000:C1C0:ABCD:0876

can be represented, using rule a), by:

2001:0000:1234:0000:0000:c1c0:abcd:0876

which can be compressed using rule b) to:

2001:0:1234:0:0:c1c0:abcd:876

which can be further compressed using rule c) to:

2001 : 0 : 1234 :: c1c0 : abcd : 876

IPv6 Address Types

Unicast (individual) address identifies one single network interface (typically a computer or similar device). The packet is delivered to this individual interface. Multicast (group) address identifies group of interfaces. Data must be delivered to all group members. Anycast (selective) address also identifies a group of network interfaces. But this time the packet is delivered just to one single member of the group (to the nearest one).

Unicast Address

Global routing prefix is the network address in IPv4 parlance. This address prefix identifies uniquely the network connected to the Internet. Subnet ID is the identifier of a subnet. Interface ID holds the identifier of single network interface. Interface identifiers are unique inside the same subnet only, there may be devices holding the same interface ID in different subnets. Internet standards request the modified EUI-64 to play the role of interface ID.

Global Unicast Address

Global addresses are used for communications between nodes on the Internet. They are the normal addresses that every node uses. These addresses, called global unicast addresses [RFC 3513], are currently assigned as 001 as the 3 leftmost bits in the 128 bit address. This corresponds to addresses from 2000:: to 3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff, or 2000::/3.

Interface Identifier – Modified EUI-64

Link-Local and Site-Local Addresses

RFC 3513 actually defines two scoping levels: link-local (prefix fe80::/10) and site-local (fec0::/10) addresses. But due to a long-term lack of consensus on the definition of “site” RFC 3879 [RFC3879] deprecated the usage of site-local addresses and prohibits new IPv6 implementations to handle the fec0::/10 prefix. RFC 3879 states that the given prefix is reserved for potential future usage.

Consequently, unicast addresses have just two scope levels: link-local (starting with fe80::/10) or global (all the others).

Anycast Addresses

The essential idea behind anycast is that there is a group of IPv6 nodes providing the same service. If you use an anycast address to identify this group, the request will be delivered to its nearest member using standard network mechanisms.

An anycast address is hard to distinguish. There is no separate part of the address space dedicated for these addresses, they are living in the unicast space. The local configuration is responsible for identification of anycast addresses.

In summary: anycast addresses represent an experimental area where many aspects are still researched.

Multicast Addresses There is a separate part of the IPv6 address space dedicated to multicast. It is identified by the prefix ff00::/8. So every multicast address starts with “ff” which makes them easy to distinguish.

Scope bits in a multicast address Value of S (4 bits binary) Value of S (4 bits hex) Scope description 0001 1 Interface 0010 2 Link 0100 4 Admin 0101 5 Site 1000 8 Organization 1110 E Global All others Unassigned/reserved

Real-World Addresses

::0/128 Unspecified address ::1/128 Loopback address ff00::/8 Multicast addresses fe80::/10 Link-local addresses fec0::/10 Deprecated (former site-local addresses) other Global unicast addresses

IPv6 Address Allocation

Global Unicast Address Prefixes in Use

2001::/16 Regular IPv6 addresses 2002::/16 6to4 addresses 3ffe::/16 6Bone addresses (to be deprecated 6 June 2006)

QUESTIONS?