3. ipv6_addressing scheme
TRANSCRIPT
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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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ALTTC/DX/SC/IPADDRESSING 20
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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ALTTC/DX/SC/IPADDRESSING 21
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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ALTTC/DX/SC/IPADDRESSING 22
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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ALTTC/DX/SC/IPADDRESSING 23
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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ALTTC/DX/SC/IPADDRESSING 24
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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ALTTC/DX/SC/IPADDRESSING 25
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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