IPv6 Tarik Cicic University of Oslo December 2001 Overview New - - PDF document

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IPv6

Tarik Cicic University of Oslo December 2001

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Overview

• New generation IP protocol (IPv6):

– why do we need it – support for new Internet services

• discussion

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Internet technology

• Idea: exchange of

information between remote systems

• all users, with their

individual needs, using different applications, on different systems and various network interconnects, must be able to communicate! Users e-mail Web voice IP ATM Ethernet TCP UDP Functionality

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Internet today: Problem list

• Address space insufficient
• traffic congestion implies waiting for all
• network configuration and reconfiguration
• lack of Quality of Service support
• no built-in security mechanisms

The best solution to these problems is provided through improving IP itself.

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Internet 2 terminology

• IP or IPv4: internet protocol in use today
• IPv6: new generation internet protocol

(formerly called IPng), experimentally deployed today

• Internet 2: experimental IP network.

Originally an American research project, now also research project in Norway.

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IPv6: improvements

• The Internet (with IPv4) is a tremendous success
• IPv6 should inherit good features from IPv4, solve the

problems and add functionality:

– huge address room, autoconfiguration – Quality of Service attributes – mobility through improved routing – security support – simplicity – extensibility

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IPv6 packets

Header Extension headers Payload

• Addresses: 128 bit instead of 32
• IPv6 header is simpler than IPv4
• Quality of Service through priority field

and flow label

• optional parameters in “extension headers”

Fixed size Variable size Optional

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IPv6 vs. IPv4 header

Version Hlen

TOS Length Ident Flags Offset

Protocol

TTL Checksum Source address Destination address Options (variable) Pad (variable)

VersionTraffic Class

Flow label Payload length Source address

Next header Hop limit

Destination address 4 x 32 = 128 bit 4 x 32 = 128 bit

IPv4 IPv6

32 bit

Header has got a fixed length

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Addressing

• 128 bits give 3.4 1038 addresses (couple of

thousands per square meter of the Earth)

• this

– covers traditional needs ☺ – opens for new services

• geographical addressing
• hierarchical multicast etc.
• autoconfiguration of networking equipment
• anycast addresses

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Extension headers

• All non-essential information is moved from the

IP header to the extension headers:

– hop-by-hop header (per-hop processing) – destination options header – routing header (e.g. explicit route) – fragment header (if payload is larger than the MTU) – authentication header – encapsulating security payload header

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Quality of Service

• QoS-friendliness achieved through the traffic

class and flow label fields

• traffic class sample:

0 urgent network maintenance 2 CBR real-time service 3 VBR service …. 8 telnet 10 www 15 e-mail

• IPv6 is not a resource reservation protocol!
• flow label can be used in QoS routing

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Mobile computing

• Destination address change is a challenge for

mobile computing based on IPv4

• routing extension header adds new functionality
• explicit routing:

– incoming packets with an explicit route should be answered to with the inverse explicit route – can move from net to net without breaking TCP connections!

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Security

• Built-in authentication and privacy

mechanisms (by special headers)

• in IPv4, the security was left to higher level

protocols (applications, SSL)

• now every packet (even the addresses) can

be encrypted

• one cannot present himself as another user
• lower overhead, higher security than today.

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Transition mechanisms

• Smooth transition:

– dual protocol stack – tunneling – name resolution (DNS) – Network Address Translation

• these mechanisms are in place today.

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… but when will it come?

• IPv6 is still not widely used:

– 4 billion addresses we have today is sufficient? – new host and router software costs? – no substantial improvements compared to IPv4?

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IPv4/v6 comparison

Tiny difference No support + No support – Quality of Service Mobility, security Header and routing complexity Address space There services can be added to IPv4 Supported No support Routers are getting faster, unclear Fixed, simple Variable size, much to compute CIDR and NAT can extend IPv4 life Huge Big, poorly utilized

Conclusion IPv6 IPv4