• The limits of IPv4 – IPv6 Highlights

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IPv6

Next Generation Internet Protocol

• The limits of IPv4 – IPv6 Highlights

• Addressing

• IPv6 Packet formats

• QoS

• Further aspects

• Migration scenarios

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The Limits of IPv4

• Basic design over 25 years old - Packet format, ... outdated

- Hardware development of networks overran IP algorithms

• Address space exhausted

- ‚Regular‘ Internet growth runs out of addresses

- New kinds of Internet devices (mobile telephones, intelligent devices,...) need new quantities of addresses

- Caused by address bottle-neck: NAT-ALGs

• Support of new services tedious to implement

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IP Routing: CIDR

• Static subnet masks in IPv4 (classes) lead to two main problems:

Class B exhaustion & explosion of R-T

• Internet backbone routers need methods for aggregation, to limit routing tables:

– Classless Interdomain Routing (CIDR) – Variable Length Subnet Masks (VLSM)

• Approach:

– Allocation of coherent blocks of net addresses – Aggregation through ‚Supernetting‘ addresses

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Route Aggregation via VLSM

11.0.0.0/8

11.2.0.0/16 11.3.0.0/16 .

. .

11.252.0.0/16 11.254.0.0/16

Router A

11.1.0.0/16

11.1.1.0/24 11.1.2.0/24 .

. .

11.1.252.0/24 11.1.254.0/24

Router B

11.253.32.0/19 11.253.64.0/19 .

. .

11.253.160.0/19 11.253.192.0/19

11.1.253.0/24

11.1.253.32/27 11.1.253.64/27 11.1.253.96/27 11.1.253.128/27 11.1.253.160/27 11.1.253.192/27

Router D

11.253.0.0/16 Router C

Internet

Bekanntgegebener Weg zu Subnetzen durch Aggregation

11.253.0.0/16 Router C

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IPng History

• IETF WG IPng began to work in the early 90er

• Winter 1992: 7 proposals for development of IP

– CNAT, IP Encaps, Nimrod, Simple CLNP, PIP, SIP, TP/IX

• Autum 1993: several mergers lead to

– ‚Simple Internet Protocol Plus‘ (SIPP) and ‚Common Architecture for the Internet‘

CATNIP

• July 1994: IPng Area Director recommend roadmap (RFC 1752) on basis of SIPP (Steve Deering)

• Dec. 1995: S. Deering, R. Hinden, „Internet Protocol,

Version 6 (IPv6) Specification“ (RFC 1883, now RFC 2460)

• Sub-TLAs available (RIPE-NCC, APNIC, ARIN) since 1999

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IPv6 Innovations

•

- Elimination of address bottle-neck: 128 Bit addresses - Address hierarchy can simplify backbone routing

- Several addresses per interface

• Simple administration

- Autoconfiguration of interfaces without DHCPv6 - Floating net masks, renumbering via prefix change

• Security: IPSec

– Security header extension for authentication, integrity and encryption

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IPv6 Innovations(2)

• Protocol configuration

– Slim header for fast processing – Optional extension headers – Fixed format for all headers – No header checksum

– No fragmentation in routers

• Improved multicast, anycast, QoS and mobile services

• Transition and coexistence concept IPv4 ↔ IPv6

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Addressing

• IPv6 addresses are 128-bit long and variably built

• Address architecture: RFC 3513 (April ´03, Hinden & Deering)

• Automatic address configuration

• Global address hierarchy from top level allocation to the interface-ID designated

• Aggregation-based allocation to simplify the global routing (possible)

• 3 Bit format prefix (FP) initially used for identification of address type

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Notation of IPv6 Addresses

• Standard Form: 8 x 16 bit Hexadecimal

Example: 1080:0:FF:0:8:800:200C:417A

• Short form: sequences of nulls replaced by ::

Example: FF01:0:0:0:0:0:0:43 → FF01::43

• IPv4 compatible addresses:

Example: 0:0:0:0:0:0:13.1.68.3 → ::13.1.68.3

• CIDR notation for prefixes:

Example: 1080:645:FF::/48

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Address Types

Type Binary Prefix

• Unicast (one-to-one)

– global all not specified elsewhere

– site-local 1111 1110 11 (FEC0::/10)

– link-local 1111 1110 10 (FE80::/10)

– compatible (IPv4, a.a.) 0000...0 (96 zero bits)

– Loop back 0000..1 ::1/128

• Multicast (one-to-many) 1111 1111 (FF00::/8)

• Anycast (one-to-nearest) of Unicast Prefixes

• No broadcast addresses (only multicast)!

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Global Unicast Addresses (RFC 3513)

n bits m bits 128–m–n bits Subnet

ID Interface Identifier Global Routing

Prefix

• All fields have variable length and are not ‚self-explanatory ‘ (as of CIDR)

• All global unicast addresses, which do not begin with 000 (binary), carry a 64 bit interface ID, this means m + n = 64

• Mechanisms of automatic prefix exchange provided

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Local Unicast Addresses

• Link-local addresses for use during auto-configuration and in nets without routers:

1111111010 0 Interface ID

• Site-local addresses independent of TLA/NLA:

1111111011 0 SLA Interface ID

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Example: FHTW IPv6 Net

• 2001:: /16 - Pre-set prefix

• 2001:0600:: /23 - Regional registry Europa (RIPE)

• 2001:0638:: /29 - DFN prefix

• 2001:0638:0801:: /48 - FHTW net address

• 2001:0638:0801:0001:: /64 - First FHTW subnet

• 2001:0638:0801:0001:0000:0000:0000:0001 /128 - First IPv6 computer address at FHTW

☺

Addressing of Sub-TLAs (Ripe) according to RFC 2450

Internet Control Message Protocol (ICMPv6)

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• RFC 2463 (Conta, Deering)

• Defines two (expandable) message classes:

Informational Messages

• Echo Request (128)

• Echo Reply (129)

Error Messages

• Destination Unreachable (1)

• Packet Too Big (2)

• Time Exceeded (3)

• Parameter Problem (4)

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Stateless Auto-Configuration

1. Interface assigns a link-local address on activation (e.g. built from a hardware address).

2. Interface sends router solicitation, to omit waiting for router advertisements.

3. Router sends router advertisement (prefix, default gateway, …).

4. The interface creates its global address from prefix and link-local address.

5. For verification of uniqueness a ICMP neighbour solicitation will be sent (Duplicate Address Detection).

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IPv6 Packet Format: Basic Header

16

0 4 12 24 31

V E R S IO N T R A FF IC C LA S S F LO W LA BE L

PA Y LO A D LE N G T H N E X T H E A D ER H O P LI M IT

S O U RC E A D D R E S S

D ES T IN A T IO N A D D R E S S

V E R S I O N 4 B i t I n t e r n e t P r o t o c o l V e r s i o n n u m b e r = 6 T R A F F I C C L A S S 8 B i t T y p e - o f - S e r v i c e s

F L O W L A B E L 2 0 B i t

P A Y L O A D L E N G H T 1 6 B i t O k t e t t a n z a h l d e s P a k e t e s o h n e I P v 6 - H e a d e r N E X T H E A D E R 8 B i t T y p e d e s " e n c a p s u l a t e d p r o t o c o l "

H O P L I M I T 8 B i t T T L - Z ä h l e r w i r d d e k r e m e n t i e r t j e R o u t e r S O U R C E A D D R E S S 1 2 8 B i t A d r e s s e d e s A u s g a n g s k n o t e n ( 1 2 8 B i t s )

D E S T I N A T I O N A D R E S S 1 2 8 B i t A d r e s s e d e s A u s g a n g s k n o t e n ( 1 2 8 B i t s ) Q o s - I n f o r m a t i o n e n f ü r R o u t e r v e r a r b e i t u n g

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1 4 8 16 19 24 32

Version Servicetypen Paketlänge

Identifikation D F

M

F Fragmenabstand Lebenszeit Transport Kopfprüfsumme

Senderadresse Empfängeradresse

Füllzeichen Optionen

IP-Protocolkopf

Länge

IPv4 Header

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IPv6 Packet Format: Option Headers

• Extended option mechanisms: Each header references a possible successive header or data, e.g.:

I P v 6 h e a d e r N H : r o u t i n g

I P v 6 h e a d e r N H : r o u t i n g

f r a g m e n t h e a d e r N H : T C P

T C P h e a d e r d a t a r o u t i n g h e a d e r

N H : f r a g m e n t

• Option headers have no length limit (IPv4:

40 Octets), Padding to 8 Octets

• Option headers will be processed only by hosts, not by routers.

Exeption: Hop-by-Hop Option Header

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Basic Option Headers

•

Advanced routing information (source routing)

• Fragmentation

Fragmentation / defragmentation information

• Authentication

Security information: authentication and integrity

• Encapsulation

‚Tunnelling‘, i.g. for confidential data

• Hop-by-Hop Option

Dedicated options to be processed by every router

• Destination Option

Information for the destination host (header extension)

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IPv6 & QoS

Priority: Traffic Class Feld (8 Bit) break down in two classes:

• Flow controlled traffic (0 - 7)

0 Not specified 4 Bulk (i.g. ftp, http) 1 ‚Feeder‘ (i.g. netnews) 5 (Reserved)

2 Unnoticed (i.g. email) 6 Interactive (i.g. telnet, X11) 3 (Reserved) 7 Internet control (i.g. rip)

• Traffic without flow control (Realtime, Constant Bitrate, ...)

Priority from 8 to 15 (ascending)

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Flow Labels

24-bit Flow Labels can be uses by senders to mark associated packets.

• At present still experimental

• Goal: accelerated, uniform handling of packet streams through routers

• Flow label: Random per Flow

• Header information consistent per flow (router caching)

• Defines router states: 120 s lifecycle

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More to IPv6

•

– A-Record → AAAA - Record versus

– A-Record → [A6 - Record (storage of address parts)]

• SNMP: in review, SNMP(v4) can manage IPv6 interfaces

• IPsec is mandatory part of IPv6

• Secure Neighbour Discovery (Send)

• IPv6 over 3GPP

• Mobile IPv6

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Packet Tunnelling of IPv6

• RFC 2473 (Conta, Deering)

• Mainly used for explicit routing path control

• Defines (statefull) ‚ends‘:

- Tunnel Entry-Point - Tunnel Exit-Point

• State variables contain MTU, Traffic Class, Flow Label

• Fragmentation may be necessary at tunnel entry point

New Header Ext. Hds. Original Packet (incl. Header)

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IPv4 → IPv6 Porting

• Source and binary code compatibility for existent application: ‘all goes on’

• Address data structure:

New for IPv6

• Name-to-address translation:

New functions to support IPv6 and IPv4

• Address converting functions:

New functions to support IPv6 and IPv4

• DNS resolver:

Gives IPv6 or IPv4 address or both back

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IPv4 → IPv6 Migration

Many techniques for migration are designed and implemented according to the following approach:

– Dual-Stack techniques, which allow the coexistence of IPv4 and IPv6 for the same devices and nets

– Tunnel, which connect IPv6 regions over IPv4 regions

– Protocol translator, which let IPv6 devices with IPv4 devices speak

During migration the combined use of all this methods likely.

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IPv4 IPv6 IPv4 IPv6

TCP/UDP

Dual Stack

• On activation of IPv6 the IPv4 can continously being used (multi protocol approach)

• Devices can keep their addresses (IPv4 in IPv6)

• Application / libraries choose the IP version:

– On approach in dependency of DNS answer

– On answering in dependency from received packets

• The Dual stack operation can continue without limits, it allows the step by step porting of applications

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Information

• Christian Huitema: IPv6, die neue Generation Addison Wesley, 2000

• Herbert Wiese: Das neue Internetprotokoll IPv6, Hanser 2002

• www.ip6forum.com

• www.6net.org

• playground.sun.com/ipng

• www.cisco.com/ipv6

• www.6bone.net

• www.ietf.org/html.charters/ipngwg-charter.html