IPv6 SpecificationIPv6 SpecificationRFC - 2460RFC - 2460

By Nyi Nyi TheinBy Nyi Nyi Thein

CS-556 Telecom Network IICS-556 Telecom Network II

Instructor: Dr. Kim, YeongkwunInstructor: Dr. Kim, Yeongkwun

1111thth Sept, 2003 Sept, 2003

DefinitionDefinition

• IPv6 (Internet Protocol Version 6) is the latest level

of the Internet Protocol and is now included as part

of IP support in many products including the major

computer operating systems. has also been called

"IPng" (IP Next Generation), designed as the

successor to IP version 4 (IPv4) [RFC-791].

IPv6 ( Introduction )IPv6 ( Introduction )

• 32-bit address space means all possible addresses will be completely allocated by sometime between 2008 and 2018.

• Although there is a lot of time left until the current address space is exhausted, it will take considerable time to deploy a new technology on such an extensive scale so it is important to start now.

IETF IPv6There are 90 RFCs that describe aspects of IPv6,

including:

• RFC2460: Internet Protocol, Version 6 (IPv6) Specification [December 1998]

• RFC2373: IP Version 6 Addressing Architecture [July 1998]

• RFC3177: IAB/IESG Recommendations on IPv6 Address [September 2001]

And many more that reference application to IPv6

IPv6( expanded addressing capability )IPv6( expanded addressing capability )

• IPv6 increase the size of the IP address from 32 bit to

128 bit.

• This is enough to allow every grain of sand its own IP

address. ( Yes! That is a VERY Big number !!! )

• Smaller number of header fields

• Altered support for header extensions

• Addition of a flow label header field

IPv6 Strengths• Larger Addresses: Allows billions of devices to be interconnected

• Larger Address pool means no forced Network Address Translators in many future deployment scenarios

• Eliminate NAT architectures as a means of address scaling

• Allow coherent end-to-end packet delivery

• Improve the potential for use of end-to-end security tools for encryption and authentication

• Allow for widespread deployment peer-to-peer applications

• Users and service providers can update to IPv6 independently without having to coordinate with each other.

IPv6 (Additional motivation)IPv6 (Additional motivation)

• header format helps speed pocessing /

forwarding

• Introduce new “anycast ” address: allows a

datagram addressed to an anycast address to

be delivered to any one of a group hosts.

IPv6 ( What has not change )IPv6 ( What has not change )

• IPv6 is a connectionless datagram delivery

service, using end-to-end address identifiers and

end-to-end signaling, with TCP and UDP

transport services.

IPv4 vs IPv6( datagram format)IPv4 vs IPv6( datagram format)

ver length

data (variable length,typically a TCP or UDP segment)

16-bit identifier

Internet checksum

time tolive

32 bit source IP address

head.len

type ofservice

flgsfragment

offsetupper layer

32 bit destination IP address

Options (if any)

• Version: 4-bit Internet Protocol version number = 6.

• Traffic Class: 8-bit traffic class field.

• Flow Label: 20-bit flow label.

• Payload Length: 16-bit unsigned integer. Length of the IPv6 payload, i.e., the rest of the packet following this IPv6 header, in octets.

Fields defined in IPv6 Fields defined in IPv6

• Next Header: this 8-bit selector. Identifies the type of header immediately

following the IPv6 header. Uses the same values as the IPv4 Protocol field

• Hop Limit: 8-bit unsigned integer. Decremented by 1 by each node

that forwards the packet. The packet is discarded if

Hop Limit is decremented to zero.

Fields defined in IPv6 Fields defined in IPv6

• Source Address: 128-bit address of the originator of the

packet

• Destination Address: 128-bit address of the intended

recipient of the packet

Fields defined in IPv6 Fields defined in IPv6

IPv6 HeaderIPv6 Header

• A closer look at some of the fields:

• Priority: identify priority among datagrams in flow

• Flow Label: identify datagrams in same “flow.” (concept of“flow”

not well defined).• Next header: identify upper layer protocol

for data

IPv6 HeaderIPv6 Header

• Traffic Class: Similar idea to the type of service field in IPv4

• Checksum: Does not exist in IPv6! It was removed entirely to reduce

processing time at each hop• Options: allowed, but outside of

header, indicated by “Next Header” field

IPv6 datagram format:IPv6 datagram format:

• fixed-length 40 byte header: allows for faster processing of the IP datagram. A new encoding of options allows for more flexible options processing

• no fragmentation/reassembly allowed at intermediate router. The operations can be performed only by the source and destination.

New ICMP for IPv6 New ICMP for IPv6 (ICMPv6)(ICMPv6) • used by IP nodes to report error conditions and

provide limited information

• added new types and codes required by the new IPv6 functionality. (e.g. “Packet Too Big” type and “unrecognized IPv6 options” error code.

• Used to managed a host’s joining and leaving: so called multicast group management functions

Terminology Terminology

• node - a device that implements IPv6.

• router - a node that forwards IPv6 packets not explicitly addressed to itself.

• host - any node that is not a router.

• upper layer - a protocol layer immediately above IPv6.

• link - a communication facility or medium over which nodes can communicate at the link layer, i.e., the layer immediately below IPv6.

• neighbors - nodes attached to the same link. • interface - a node's attachment to a link.

• address - an IPv6-layer identifier for an interface or a set of interfaces.

• packet - an IPv6 header plus payload.

• link MTU - the maximum transmission unit, i.e., maximum packet size in octets, that can be conveyed over a link

• path MTU - the minimum link MTU of all the links in a path between a source node and a destination node.

Terminology Terminology

Transition From IPv4 To IPv6Transition From IPv4 To IPv6

• Not all routers can be upgraded simultaneously

• no “flag days”

• How will the network operate with mixed IPv4 and IPv6 routers?

Transition From IPv4 To IPv6Transition From IPv4 To IPv6

• Two proposed approaches:

• Dual Stack: some routers with dual stack (v6, v4) can “translate” between

formats

• Tunneling: IPv6 carried as payload in IPv4 datagram among IPv4

routers

Dual Stack ApproachDual Stack Approach

• IPv6 nodes have full IPv4 capabilities as well. When operating with an IPv4 node, the IPv6 node uses v4 datagrams. The node will be able to determine the capabilities of the node it is communicating with by looking at the address returned by the DNS.

Dual Stack ApproachDual Stack Approach A B E F

IPv6 IPv6 IPv6 IPv6

C D

IPv4 IPv4

Flow: XSrc: ADest: F

data

Flow: ??Src: ADest: F

data

Src:ADest: F

data

A-to-B:IPv6

Src:ADest: F

data

B-to-C:IPv4

D-to-E:IPv4

E-to-F:IPv6

TunnelingTunneling

Logical View

A B E F

IPv6 IPv6 IPv6 IPv6

tunnel

TunnelingTunnelingPhysical View

B-to-C:IPv6 inside

IPv4

D-to-E:IPv6 inside

IPv4

A B E F

IPv6 IPv6 IPv6 IPv6

C D

IPv4 IPv4

Flow: XSrc: ADest: F

data

Flow: XSrc: ADest: F

data

Flow: XSrc: ADest: F

data

Src:BDest: E

Flow: XSrc: ADest: F

data

Src:BDest: E

A-to-B:IPv6

E-to-F:IPv6

Expanded Addressing Capabilities Expanded Addressing Capabilities

• IPv6 increases the IP address size from 32 bits to 128 bits, to support more levels of addressing hierarchy, a much greater number of addressable nodes, and simpler auto-configuration of addresses. The scalability of multicast routing is improved by adding a "scope" field to multicast addresses. And a new type of address called an "anycast address" is defined, used to send a packet to any one of a group of nodes.

Header Format Simplification Header Format Simplification

• Some IPv4 header fields have been dropped or made optional, to reduce the common-case processing cost of packet handling and to limit the bandwidth cost of the IPv6 header.

IPv6 Extension Headers IPv6 Extension Headers

• In IPv6, optional internet-layer information is encoded in separate headers that may be placed between the IPv6 header and the upper- layer header in a packet. There are a small number of such extension headers, each identified by a distinct Next Header value. As illustrated in these examples, an IPv6 packet may carry zero, one, or more extension headers, each identified by the Next Header field of the preceding header:

Improved Support for Extensions Improved Support for Extensions and Options and Options

• Changes in the way IP header options are encoded allows for more efficient forwarding, less limits on the length of options, and greater flexibility for introducing new options in the future.

Flow Labeling Capability Flow Labeling Capability

• A new capability is added to enable the labeling of packets belonging to particular traffic "flows" for which the sender requests special handling, such as non-default quality of service or "real-time" service.

Authentication and Privacy Authentication and Privacy Capabilities Capabilities

• Extensions to support authentication, data

integrity, and (optional) data confidentiality

are specified for IPv6.

IPv6 Is ReadyIPv6 Is ReadyVolume deployment has begun

• Microsoft XP and Server 2003• Apple MacOS X 10.2• Linux and *BSD• Sun Solaris• IBM• HP• Symbian OS 7• Realtime OS’s available• Cisco, Juniper, Hitachi routers support IPv6• IPv6 is waiting to be turned on!

IPv6 – Transition and Coexistence

• V6 will not take over all data networking requirements in a working future time frame (i.e. V4 is not disappearing anytime soon)

• About the most likely scenario is a dual stack world for some years to come

• Dual stack transitional worlds present many complex issues in terms of referential integrity of identity, reach ability, gateway functionality, security and application functionality

IPv6 (current activities)

• Increasing level of experimentation and trials within the ISP provider sector, and some commercial services are appearing

• BUT still no overwhelming impetus to immediately deploy V6 services in many markets

IPv6 Myths

• IPv6 is “more secure” than V4

Not Really

• IPv6 is no more or less secure than V4. Both IPv6 and IPv4 offer stronger potential security than “IP with header” architectures simply because the original IP source and destination address header fields can be included in the packet authentication space

IPv6 Myths

• Only IPv6 supports mobility

Not Really

• Both V4 and V6 support mobility equally well

• The problem is the overloaded semantic of an IP address which duals as identity and network location

IPv6 Vs IPv4

• There is no compelling “feature” or aspect of V6 that does not have a functional counterpart in V4.

• Any industry adoption of V6 cannot based on superior functionality of V6 over V4 as a protocol platform

• The fundamental difference is the larger address fields used in V6

• But this single difference might well be enough to propel V6 adoption in a ‘smart device’ world

ReferencesReferences

• James F Kurose, Keith W.Ross (Computer Networking, A top down approach featuring the Internet )

• RFC 2460 fount at (http://www.ietf.org/rfc/2460)

• IPv6 Specification found at (http://www.potaroo.net)

Thank You !!!

Internet Protocol Version 6 Specification (IPv6)

RFC - 2460