Introduction to IPv6 - I Basics of IPv6 Alvaro Vives | 26 June 2017 - - PowerPoint PPT Presentation

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Introduction to IPv6 - I Basics of IPv6 Alvaro Vives | 26 June 2017 - - PowerPoint PPT Presentation

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Introduction to IPv6 - I Basics of IPv6 Alvaro Vives | 26 June 2017 | Workshop on Open Source Solutions for the IoT Contents Digital Data Transmission Packet-Switched Networks Layered Model IPv4 and IPv6 basics - IPv4 Header -

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Alvaro Vives | 26 June 2017 | Workshop on Open Source Solutions for the IoT

Basics of IPv6

Introduction to IPv6 - I

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Alvaro Vives | Workshop on Open Source Solutions for the IoT | 26 June 2017

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Contents

  • Digital Data Transmission
  • Packet-Switched Networks
  • Layered Model
  • IPv4 and IPv6 basics
  • IPv4 Header
  • IPv6 Header
  • Differences
  • IPv6 addresses
  • Types of IPv6 addresses
  • IPv6 Notation
  • Interface Identifier (IID)
  • IPv6 Addresses Exercise
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Alvaro Vives | Workshop on Open Source Solutions for the IoT | 26 June 2017

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Digital Data Transmission (1)

  • Objective: send information from one place/device to

another

  • Different type of info, through different transport

networks

  • Need to codify the info -> digitally
  • Three symbols: using 1 transmitted unit of information you

could represent 3 different codes (A,B or C)(3^1)

  • If you transmit 2 units of information: 9 codes (3^2)
  • Binary codification -> uses two characters: 0 / 1
  • Bit (0 or 1) minimal unit of information
  • Byte = 8 bits -> used by ASCII characters => 256

(2^8)

A B C

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Alvaro Vives | Workshop on Open Source Solutions for the IoT | 26 June 2017

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Digital Data Transmission (2)

  • If you want to transmit “hi”:
  • h ->
  • i ->
  • This codification is defined by ASCII
  • There could be other ones
  • Could codify hexadecimal (16 from 0 to F) numbers

using 4 bits (2^4 = 16)

  • 0 = -> Represented as 0x0
  • 1 = -> Represented as 0x1
  • 2 = -> Represented as 0x2
  • . . .
  • A = -> Represented as 0xA

0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 1 0 1 0 1 1 1 1 1 1 1

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Alvaro Vives | Workshop on Open Source Solutions for the IoT | 26 June 2017

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Packet-Switched Networks (1)

  • Digital pieces of information put in packets
  • Packets sent over packet-switched networks:
  • Paths can vary
  • Shared resources (best effort)
  • Communication can start at any moment

(example: postal mail, Internet)

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Packet-Switched Networks (2)

Basic elements on a switched network:

  • Sender: Generates the info to be sent to a receiver.

Should codify the message.

  • Receiver: Is the destination of the information sent

by the sender. Should decode the message.

  • Forwarder: Nor the origin or the destination of the
  • information. Just receive and forward the

information in its path to the destination

  • Identification: Each element in the switched

network should be uniquely identified

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Packet-Switched Networks (3)

Senders Forwarders Receivers

F1 F2 F3 F4 F5 F6 F7 F8 S1 S2 R1 R2

SRC: S2 | DST: R1 SRC: S2 | DST: R1

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Layered Model (1)

Let’s define things:

  • Layered model: physical, link, network, etc. each
  • ne is in charge of different things/services
  • Network elements: Node, host, router, server
  • Addresses: link layer, network layer
  • Protocol: definition of the format and order of

messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or reception of a message or other event

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Layered Model (2)

  • TCP/IP layered model -> Used in Internet

Layer 5 Layer 4 Layer 3 Layer 2 Layer 1 Layer 2 Layer 1 Layer 3 Layer 2 Layer 1 Layer 5 Layer 4 Layer 3 Layer 2 Layer 1 Application Transport Network Link Physical Host Switch Router Host

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Layered Model (3)

  • PDU: Protocol Data Unit
  • Layer 3 Header includes Source and destination Network

Address (IP Address)

  • Layer 3 is the only common layer in Internet: IP

Layer 5 Layer 4 Layer 3 Layer 2 Layer 1 Message Segment Datagram Frame I-PDU Send

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IPv4 and IPv6 basics (1)

  • IPv6 is an evolution of IPv4

LEGEND Field’s name kept from IPv4 to IPv6 Field not kept in IPv6 Name and position changed in IPv6 Version IHL Type of Service Total Length Identification Flags Fragment Offset Time to Live Protocol Header Checksum Source Address Destination Address Options Padding

IPv4 Header

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IPv4 and IPv6 basics (2)

  • Simplified, fixed-length, 64 bits aligned ->

complexity from core to border

LEGEND Field’s name kept from IPv4 to IPv6 Name and position changed in IPv6 New field in IPv6 Source Address Destination Address Version Traffic Class Flow Label Payload Length Next Header Hop Limit

IPv6 Header

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IPv4 and IPv6 basics (3)

  • New IPv6 basic header has advantages:
  • Simplified, fixed length, and aligned to 64 bits -> routers

can process it faster --> Scalable

  • Redundant or not needed features are eliminated:

checksum, header length (IHL)

  • New QoS field (IntServ): Flow Label
  • Much more addresses
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IPv4 and IPv6 basics (4)

  • Fixed: Types and order
  • Flexible use
  • Processed only at endpoints
  • Exceptions: Hop-by-hop (and Routing)
  • Only appear once
  • Exception: Destination Options

* Options for IPs in routing header ** Options for destination IP

Basic IPv6 Header Hop-by-hop Options Destination Options* Routing Fragmentation IPSec: AH IPSec: ESP Destination Options** Upper Layer

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IPv4 and IPv6 basics (5)

  • Basic IPv6 header is processed in all hops
  • Extension headers processed at destination (exception Hop-by-hop)

R1 S R2 R3 D

IPv6 EHs DATA IPv6 EHs DATA IPv6 EHs DATA IPv6 EHs DATA IPv6 IPv6 EHs IPv6 IPv6

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Types of IPv6 Addresses

  • Unicast (one-to-one)
  • Link-local
  • Unique Local (ULA)
  • IPv4-mapped
  • Global (GUA)
  • Site-local (deprecated)
  • IPv4-compatible (deprecated)
  • Multicast (one-to-many)
  • Anycast (one-to-nearest) (taken from unicast space)
  • Reserved (Trans. Mechs, documentation, loopback, etc.)
  • There are no BROADCAST addresses -> well-known

multicast

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IPv6 addresses: Notation (1)

Group 1 16 bits

:

Group 2 16 bits

:

Group 3 16 bits

:

Group 4 16 bits

:

Group 5 16 bits

:

Group 6 16 bits

:

Group 7 16 bits Nibble 1 4 bits Nibble 2 4 bits Nibble 3 4 bits Nibble 4 4 bits Binary 0000 0001 0010 0011 … 1111 Hexadecimal 1 2 3 … F

:

Group 8 16 bits

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IPv6 addresses: Notation (2)

  • IPv6 address notation rules:
  • 8 Groups of 16 bits separated by “:”
  • Hexadecimal notation of each nibble (4 bits) ->
  • No case sensitive
  • Compression rules:
  • Leftmost zeroes within each group could be eliminated
  • One or more consecutive groups of all zeroes could be

changed by “::”. Only once!

Binary 0000 0001 0010 0011 … 1111 Hexadecimal 1 2 3 … F

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IPv6 addresses: Notation (3)

  • Use “[]” to specify port -> http://[2001:db8::10]:8080
  • Examples:
  • 2001:0db8:0102:0DA0:0000:0000:0000:1000 ->

2001:db8:102:DA0::1000

  • 2001:db8:0000:0000:0020:0000:0000:0abc -> ?
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IPv6 addresses: Notation (4)

  • Network prefixes follow CIDR notation
  • Compression rules could be applied
  • Examples:
  • 2001:db8::/32 -> 2001:0db8:0000:0000:0000:0000:0000:0000
  • 2001:db8:1200::/40 -> 2001:0db8:1200:0000:0000:0000:0000:0000
  • Non-prefix bits (rightmost) used for subneting
  • Example: I’ll take the first two /52 prefixes out of 2001:db8:abcd::/48
  • 2001:db8:abcd::/48 -> 2001:0db8:abcd:0000:0000:0000:0000:0000
  • 2001:0db8:abcd:0000:0000:0000:0000:0000 -> 2001:db8:abcd:0000::/52
  • 2001:0db8:abcd:1000:0000:0000:0000:0000 -> 2001:db8:abcd:1000::/52
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IPv6 addresses: IID (1)

  • IID could be created in many different ways
  • Automatically from MAC addresses (EUI-64)
  • Automatically using some kind of algorithm (randomly)
  • Manually
  • DHCPv6
  • /64 prefix for a LAN
  • IIDs generated locally in the host (except DHCP)

Interface ID Link Prefix 64 bits 64 bits

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IPv6 addresses: IID (2)

  • EUI-64: IID generated from MAC address

48 bits - MAC Address FF FE 24 bits 24 bits

Interface ID

64 bits u bit

1

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IPv6 addresses: Link-local

  • Valid only in a link
  • Always present in IPv6-enabled interface
  • Prefix fe80::/10 (In practice fe80::/64)
  • IID generated locally in the host: based on

MAC, randomly or anyhow

Interface ID fe80:: 64 bits 64 bits

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IPv6 addresses: ULA

  • ULA addresses: FC00::/7 Prefix
  • L = 1 prefix is locally assigned
  • L = 0 may be defined in the future (defined for

centrally assigned prefixes)

  • Global ID: pseudo-randomly generated
  • You’ll create a /48 prefix, starting with FD00::/8

Interface ID fc00::/7 16 bits 64 bits L Global ID Subnet ID 40 bits 7 bits 1 bit ULA Prefix = 48 bits

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IPv6 addresses: Multicast (1)

  • Multicast addresses: Prefix FF00::/8
  • Flags: used for multicast routing and services
  • Scope: part of network where address is valid
  • 1 - Interface-Local
  • 2 - link-local
  • 4 - admin-local
  • 5 - site-local
  • 8 - organization-local
  • E - global
  • Group ID: Identifies the multicast group

Group ID 4 bits 112 bits FF Flags 8 bits 4 bits Scope

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IPv6 addresses: Multicast (2)

  • Substitute of IPv4 Broadcast addresses
  • Well-known IPv6 multicast addresses:
  • FF02::1 (all nodes)
  • FF02::2 (all routers)
  • FF02::1:2 (all DHCP-agents)
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IPv6 addresses: Types and Prefixes

  • Unicast (one-to-one)
  • Link-local (FE80::/10)
  • Unique Local (ULA) (FC00::/7)
  • IPv4-mapped (::FFFF:IPv4/128)
  • Global (GUA) (2000::/3) (binary: 0010)
  • Site-local (deprecated) (FEC0::/10)
  • IPv4-compatible (deprecated) (::IPv4/128)
  • Multicast (one-to-many) (FF00::/8)
  • Anycast (one-to-nearest) (taken from unicast space)
  • Reserved (Trans. Mechs, documentation (2001:db8::/32),

loopback (::1/128), unspecified (::/128), etc.)

  • No BROADCAST addresses -> well-known multicast

(FF02::1, FF02::2)

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IPv6 addresses: Scope

  • Where the address is valid

GLOBAL SITE LINK INTERFACE

fe80::A:b:100 ff01::2 ff02::1 FD00:A:B::100 FF05::1:3 2001:67c:2e:1::c1

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IPv6 addresses: Exercise (1)

  • Short Exercise with IPv6 Addresses:
  • Your IPv6 prefix 2001:0db8:1002:AB00::/56
  • Take three /64 prefixes from it to assign to three different

LANs: LAN1, LAN 2 and LAN3

  • Give IPv6 address to hosts: H1, H2, H3, and H4

IPv6 Internet

R1 R2 R3 H1 H2 H3 H4

LAN1 LAN2 LAN3 2001:db8:1002:AB00::/56

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IPv6 addresses: Exercise (2)

  • Complete the table:

Description Prefix / Address LAN 1 /64 LAN 2 /64 LAN 3 /64 H1 H2 H3 H4

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IPv6 addresses: Exercise (3)

  • Start with /56 prefix -> you have to divide into /64s

2001:0db8:1002:AB00:0000:0000:0000:0000

  • In total 28 = 256 /64 prefixes:

2001:db8:1002:ab00::/64, 2001:db8:1002:ab01::/64, … 2001:db8:1002:abFF::/64

: 1010 1011 0000 0000 : (binary) : 1010 1011 0000 0001 : (binary) . . . : 1010 1011 1111 1111 : (binary) :AB00: (hex.) :AB01: (hex.) … :ABFF: (hex.)

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Questions

avives@ripe.net @TrainingRIPENCC