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IP: Next GenerationA Tutorial Bruce A. Mah bmah@{CS.Berkeley.EDU,research.ATT.COM} University of California at Berkeley International Computer Science Institute AT&T Bell Laboratories 29 August 1994 Y O T I F S R C A

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IP: Next Generation—A Tutorial

Bruce A. Mah bmah@{CS.Berkeley.EDU,research.ATT.COM} University of California at Berkeley International Computer Science Institute AT&T Bell Laboratories 29 August 1994

H E

N I V E R S I T Y

A L I F O R N I A

8 6 8

E T T H E R E B E L I G H T

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Disclaimer

I am not an IPng researcher. I don’t even play one on TV.

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Outline

Introduction IPng features

Better header 128-bit address space Better options support Routing QOS support (sort of) IPv4 interoperability (Simple SIPP Transition)

Current hot topics

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Problems with the Internet Protocol

IP address space exhaustion Routing table explosion Inefficient headers for high-speed networks Some features (e.g. source routing) not well supported New features needed (e.g. security) No QOS support

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IP: Next Generation

Replace IP with a new internetwork layer Retain the same basic philosophy, but try to solve IP’s problems Avoid changing other protocols (i.e. TCP, UDP) or applications (i.e. telnet) where possible Need a transition plan Proposals

SIPP (Simple Internet Protocol Plus) TUBA (TCP and UDP with Bigger Addresses)

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Terminology

IPv4 Internet Protocol, Version 4 SIP Simple Internet Protocol SIPP Simple Internet Protocol Plus

SIPP-8 Original version, 64-bit addresses SIPP-16 Revised version, 128-bit addresses

IPng IP: Next Generation IPv6 Internet Protocol, Version 6

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The IPv6 Header

Version Flow Label Payload Length Next Header Hop Limit Source Address Destination Address

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Changes from IPv4 Header

Fixed size header (no need for header length) Precedence/TOS handled with QOS and Flow Label TTL now a Hop Limit Fragmentation now an option Header protected by transport layer pseudo-header and checksums

Version Hdr Ln Prec TOS Total Length ID Flags Fragment Offset TTL Protocol Header Checksum Source Address Destination Address

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Addressing

Each address identifies an interface, possibly multiple addresses per interface Types of addresses distinguished by prefix Unicast Addresses

IPv4 Provider-Based Geographic-Based (sort of, space reserved) NSAP IPX Local Use

Cluster Addresses Multicast Addresses

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IPv4 Compatable Addresses

IPv4 IPv4 with IPv6 Support Examples

0:0:0:0:0:FFFF:8020:C941 0:0:0:0:0:FFFF:128.32.201.65 ::FFFF:8020:C941 ::FFFF:128.32.201.65 0000........................................................................0000 IP Address 0000.......................................................................FFFF IP Address

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Provider-Based Unicast Addresses

Globally unique No fi xed fi eld boundaries Open issues

How to easily reconfi gur e when switching providers? How to handle multi-homed hosts with multiple providers? 01 Provider ID Subscriber ID Subnet Node

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Local-Use Addresses

Address scope limited to a single subscriber site Subnet ID used for routing Node ID can be an IEEE 802 address (for example) Applications

Private internetworks (i.e. not attached to the Internet) Autoconfi guration and bootstrapping 11111110 000......................00 Subnet ID Node ID

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Cluster Addresses

“Nearest” boundary router in a cluster of nodes Intended for use in source routing

Cluster Prefi x 0000..............................................0000

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Multicast Addresses

Flags: Transient/Permanent Scope: Control extent of propagation

Analagous to use of TTL for IPv4 multicast

Group ID: Identifi es multicast gr oup

Similar to IPv4 multicast groups

No broadcast addresses, pre-defi ned gr oups used

All Nodes All Hosts All Routers 11111111 Flg Scp Group ID (112 Bits)

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DNS Modifi cations

New ASEQ records contain IPv6 addresses (or sequences of addresses for source routed addreses) New sipp-addr.arpa domain for reverse name translation A records continue to hold IP addresses for IPv4-compatable hosts

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IPv6 Options

Options (usually) only examined at destination specifi ed in IPv6 header

IPv6 Header (Next Header= Opt1) Opt1 Header (Next Header= Opt2) Opt2 Header (Next Header= TCP) TCP Header TCP Payload

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IPv6 Options

Hop-by-hop options (TLV format) Routing Fragmentation Authentication End-to-end (TLV format)

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Routing Option

Routing option processing off fast path Cluster addresses can be used to force routing through a given service provider or network SRDP has a similar routing option with Routing Type = 1

Next Header Routing Type=0

Num. Addrs.

Next Addr Reserved Address [0] ....

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Fragmentation Option

M bit: 1 = More Fragments Same functionality as IPv4 (datagram ID is bigger) Not a part of common-case processing but easy to detect at receiver Path MTU discovery algorithms mandatory

ICMP messages now return next-hop MTU Next Header Reserved Fragment Offset Res.M Datagram ID

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Security Options

SIPP Authentication Header

Authentication and Integrity Assurance MD5 (128-bit key) recommended, other algorithms optional Want an exportable (outside USA) algorithm

SIPP Security Encapsulation Protocol

Authentication, Integrity, and Confi dentiality DES CBC proposed, other algorithms optional

Open Issues

Key Management?

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Routing

Very similar to IPv4 CIDR Routing lookup based on longest prefi x matches Relies on reasonable assignment of addresses for routing aggregation Common-case routing code only examines destination address in IPv6 header, regardless of routing headers

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Source Routing

Version Flow Label Payload Length Next = Routing Hop Limit Source Address = my:provider:my.net.subnet.host Destination Address = her:provider:0:0 Next = TCP Type = 0 Num Addrs = 2 Next Addr = 0 Reserved Address[0] = his:provider:0:0 Address[1] = your:provider:your.net.subnet.host

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QOS Support

Flow is defi ned by Flow ID (24 bits) and sour ce IPv6 address TClass = Traffi c Class

Flow controlled vs. non-flow controlled “Priority” within flow controlled or non-flow controlled traffi c types

Open issues:

Resource model? Signalling to set up flows? TClass Flow ID

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Simple SIPP Transition Goals

Support IPv6 over IPv4 infrastructure Interoperability between IPv4 hosts and IPv6 hosts, where possible Operational requirements

No “fl ag days” Gradual transition Uneven rates of IPv6 deployment Some hosts may never transition

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SST Addressing

Special IPv6 addresses for IPv4 compatability

0:0:0:0:0:0:128.32.201.65 (IPv4 only) 0:0:0:0:0:FFFF:128.32.201.65 (IPv4 and IPv6)

A and ASEQ records in DNS servers Some interfaces may have multiple addresses

IPv4 compatable, local to an IPv4 area IPv4 incompatable, presumed globally unique

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SST Mechanisms

Dual protocol stacks in hosts and routers Tunnelling via IPv4 encapsulation Header Translation

IPv6 IPv6 IPv4 Only Cloud IPv4 Only Cloud IPv6 Only Cloud Router

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SST Routing

IPv4 to anything

Route using normal IPv4 routing

IPv6 to IPv6

If possible to send directly (same subnet) do so Else if there is an on-subnet IPv6 router, route via it Else if there is an off-subnet IPv6 router, tunnel to it Else tunnel to the destination

IPv6 to IPv4

If a dual-stack machine, send as IPv4 Else, compute IPv6 address and send as to an IPv6 host

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Topics Flambé

Should the IPv6 address space be expanded to 20+ bytes to accomodate OSI NSAP addresses? Provider based addressing? Autoreconfi guration

Is it necessary? How to make it work?

Authentication and source routing?

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