3. Ipv6_addressing Scheme

8/22/2019 3. Ipv6_addressing Scheme

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IPv6 Addressing


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Agenda

OSI & TCP/IP Model

IPv4 Addressing

IPv6 Addressing


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TCP/IP and OSI

OSI is made of seven layers. TCP/IP protocol is made of five layers.

PHYSICAL

DATA LINK

NETWORK

TRANSPORT

APPLICATION

PHYSICAL

DATA LINK

NETWORK

TRANSPORT

SESSION

PRESENTATION

APPLICATION

OSI Model TCP/IP Model


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Frame Head Trailer

Frame

Data Encapsulation

Data

Data

Data

TCP Header

TCP Segment

UDP Header

UDP Message

TCP-UDP DataIP Header

IP Datagram

IP Header TCP-UDP Data

Application

TPT Layer

NW Layer

Data Link


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D

P

N

T

A

TCP/IPv4 Protocol Suite..

ICMP IGMPRARPARP

FTPSMTP

TELNETHTTP

TFTPNFS

SNMPDNS

TCP UDP

IP

Protocols defined by the underlying networks


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IP Header..

HEADER CHECKSUMPROTOCOLTIME TO LIVE

DESTINATION ADDRESS OF HOST

SOURCE ADDRESS OF HOST

PADDINGOPTIONS

76543210765432107654321076543210

FRAGMENT OFFSETM

F

D

FIDENTIFICATION

TOTAL LENGTHTOSHLENVER

Octet +3Octet +2Octet +1Octet +0


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ARP Operation

Request

Ignored

Request

IgnoredARP

Response

Accepted

Give me MAC address of 129.1.1.4

Thats

Me

Here is my MAC address

129.1.1.1 129.1.1.4

129.1.1.2 129.1.1.3

08-00-39-00-2F-C3

08-00-10-99-AC-54

08-00-5A-21-A7-2208-00-39-00-2F-AB


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RARP Operation

Give me my IP address RARP Response

Diskless

work

station RARP

Server

08-00-39-00-2F-C3 08-00-10-99-AC-54

08-00-5A-21-A7-22

223.1.2.1

223.1.2.2

223.1.2.3

08-00-39-00-2F-AB


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IPv4 Header

Version(4)

Destination IP Address (32)

HeaderLength (4)

Priority & Type

of Service (8)Total Length (16)

Identification (16)Flags

(3) Fragment offset (13)

Time to live (8) Protocol (8) Header checksum (16)

Source IP Address (32)

20

Bytes

Removed Changed


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IPv6 Header

Version(4)

Destination IP Address (128)

Traffic Class(8) Flow Label(20)

Payload Length(16) Next Header(8) Hop Limit(8)

Source IP Address (128) 40Bytes

New


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Extension Header

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IPv6 Header

Next Header

= TCP

TCP Header

+ Data

IPv6 Header

Next Header

= Routing

Routing Header

Next Header

= TCP

TCP Header

+ Data

TCP Header

+ Data

IPv6 Header

Next Header

= Routing

Routing Header

Next Header

= ESP

ESP Header

Next Header

= TCP

New way of doing options

Added after the basic IPv6 header

Daisy chained


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Summary

Comparison of IPv4 and IPv6 headers shows a longer

header, but less number of fields

Header processing is simpler

Options are handled by extension headers Routing header for source routing changes the destination

address in the IP header

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ALTTC/DX/SC/IPADDRESSING 19

IPv4 Addressing

8 Bits8 Bits 8 Bits 8 Bits

Network Host

32 Bits

172 . 16 . 122 . 204


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IPv4 Address Scheme

Two types of addressing schemes for IPv4

Classful

Classless

Classful Original style of addressing based on first few

bits of the address.

Generally used in customer sites.

Classless A new type of addressing that disregards theclass bit of an address and applies a variableprefix (mask) to determine the network number.


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IPv4 Address classes

H H HNClass-A:

H HN NClass-B:

HN N NClass-C:

Class-D: For Multicast

Class-E: For Research

N=Network number assigned by IR.

H=Host number assigned by network administrator.


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Identifying a class of address

Address Identifier Network Address Host Address

0 7 bits Network Address 24 bits Host AddressA

10 14 bits Network Address 16 bits Host AddressB

110 21 bits Network Address 8 bits Host AddressC

1110 Multicast address (224.0.0.0-239.255.255.255)D

1111 Reserved for future useE


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IP Address Bit Patterns

8 Bits8 Bits 8 Bits 8 Bits

Class-A:

Class-B:

Class-C:

Class-D:

Class-E:

0-127

128-191

192-223

224-239

240-255

0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0

1 1 0 0 0 0 0 0

1 1 1 0 0 0 0 0

1 1 1 1 0 0 0 0

0 1 1 1 1 1 1 1

1 0 1 1 1 1 1 1

1 1 0 1 1 1 1 1

1 1 1 0 1 1 1 1

1 1 1 1 1 1 1 1


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Networks Vs Hosts

In Classless environment we can have

232=4294967296 Hosts

Class Networks Hosts/Network

A 126 16777214

B 16384 65354

C 2097152 254


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Private Address Space

IANA has reserved the following three blocks of

the IP address space for private internets (RFC

1918):

10.0.0.0 - 10.255.255.255 (10.0.0.0/8 prefix) 24-bit block

Complete class-A network number

172.16.0.0 - 172.31.255.255 (172.16.0.0/12 prefix)

172.0001/0000.0.0-172.0001/1111.255.255

20-bit block

Set of 16 contiguous class-B network numbers

192.168.0.0 - 192.168.255.255 (192.168.0.0/16 prefix)

16-bit block

Set of 256 contiguous class-C network numbers


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IPv6 Addressing

IPv6 addresses

Format

Unicast

Multicast Anycast

Required Node Addresses

Address Selection

Addressing Architecture

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Addresses

IPv4 = 32 bits

IPv6 = 128 bits

This is not 4 times the number of addresses

This is 4 times the number of bits

~3,4 * 1038 possible addressable nodes

1030 addresses per person on the planet

Well, as with any numbering scheme, we will be using only a

portion of the full address space

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Address Format

x:x:x:x:x:x:x:x

Where x is a 16 bits hexadecimal field

2001:0000:1234:0000:0000:C1C0:ABCD:0876

Case insensitive 2001:0000:1234:0000:0000:c1c0:abcd:0876

Leading zeros in a field are optional:

2001:0:1234:0:0:C1C0:ABCD:876

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Address format

Successive fields of 0 are represented as ::, but only once

in an address:

2001:0:1234::C1C0:ABCD:876

Not valid: 2001::1234::C1C0:ABCD:876

Other examples:

FF02:0:0:0:0:0:0:1 => FF02::1

0:0:0:0:0:0:0:1 => ::1

0:0:0:0:0:0:0:0 => ::

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Addresses in URL

In a URL, it is enclosed in brackets

http://[2001:1:4F3A::206:AE14]:8080/index.html

URL parsers have to be modified

Cumbersome for users

Mostly for diagnostic purposes

Should use Fully Qualified Domain Names (FQDN)

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Address Types

Unicast

Unspecified

Loopback

Scoped addresses:

Link-local

Site-local (Deprecated now)

Unique-Local

Aggregatable Global:

Multicast

Broadcast: none in IPv6

Anycast

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Unspecified

Used as a placeholder when no address available

Initial DHCP request

Duplicate Address Detection (DAD)

Like 0.0.0.0 in IPv4

0:0:0:0:0:0:0:0 or ::

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Loopback

Identifies self

Localhost

Like 127.0.0.1 in IPv4

0:0:0:0:0:0:0:1 or ::1 To find if your IPv6 stack works:

Ping6 ::1

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Link-Local

Scoped address (new in IPv6)

Scope = local link (i.e. VLAN, subnet)

Can only be used between nodes of the same link

Cannot be routed

Automatically configured on each interface

Uses the interface identifier (based on MAC address)

Format:

FE80:0:0:0:

Gives every node an IPv6 address to start communications

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Site-Local( now ULA)

Scoped address

Scope = site (a network of links)

Can only be used between nodes of the same site

Cannot be routed outside the site (i.e. the Internet)

Very similar to IPv4 private addresses

Not configured by default

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Unique local address

ULA is an IPv6 address in the block

fc00::/7 defined in RFC 4193.

To be used for systems that are not

connected to the Internet.

Divided into two /8 address groups

assigned and random

valid /48 prefixes are derived

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Aggregatable Global

Generic use. Globally reachable.

Allocated by IANA

To Regional Registries

Then to Tier-1 Providers

Called Top-level Aggregator (TLA)

Then to Intermediate Providers

Called Next-level Aggregator (NLA)

Then to sites

Then to subnets

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Aggregatable Global

Structure:

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TLA RES NLAs SLA Interface ID

48 bits 16 bits 64 bits

128 bits as the total

48 bits prefix to the site

16 bits for the subnets in the site 64 bits for host part


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Aggregatable Global

Consists of the following (left to right):

3 bits: 001 (10% of the total address space reserved)

13 bits for the TLA

213 TLAs ~ 8K TLAs

8 bits reserved 24 bits for the NLAs

224 NLAs per TLA ~ 16M NLAs per TLA

16 bits for the site subnets

216 subnets per site = 65536 subnets

64 bits for the interface identifier

Total = 128 bits.

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Multicast

Multicast = one-to-many

No broadcast in IPv6. Multicast is used instead, mostly

on local links

Scoped addresses:

Node, link, site, organisation, global

No TTL as in IPv4

Format:

FF::

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Multicast assigned Addresses

Some reserved multicast addresses:

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Address Scope Use

FF01::1 Interface-local All Nodes

FF01::2 Interface-local All RoutersFF02::1 Link-local All Nodes

FF02::2 Link-local All Routers

FF05::2 Site-local All Routers

FF02::1:FFxx:xxxx Link-local Solicited-Node


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Anycast

One-to-nearest: great for discovery functions

Anycast addresses are indistinguishable from unicast

addresses

Allocated from the unicast addresses space

Some anycast addresses are reserved for specific uses

Few uses:

Router-subnet

MobileIPv6 home-agent discovery

discussions for DNS discovery

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Required Node Addresses

Any IPv6 node should recognize the following addresses

as identifying itself:

Link-local address for each interface

Assigned (manually or automatically) unicast/anycast addresses

Loopback address

All-nodes multicast address

Solicited-node multicast address for each of its assigned unicast

and anycast address

Multicast address of all other groups to which the host belongs

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Thanks

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3. Ipv6_addressing Scheme

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