Transcript IPV6 ADDRESSING Scheme

IPv6 Addressing
Agenda
• OSI & TCP/IP Model
• IPv4 Addressing
• IPv6 Addressing
TCP/IP and OSI
• OSI is made of seven layers.
• TCP/IP protocol is made of five layers.
APPLICATION
PRESENTATION
APPLICATION
SESSION
OSI Model
TRANSPORT
TRANSPORT
NETWORK
NETWORK
DATA LINK
DATA LINK
PHYSICAL
PHYSICAL
TCP/IP Model
Data Encapsulation
Application
Data
TCP Header
TPT Layer
Data
TCP Segment
UDP Header
Data
UDP Message
NW Layer
IP Header
TCP-UDP
Data
IP Datagram
Data Link
Frame Head
IP Header
TCP-UDP
Frame
Data
Trailer
TCP/IPv4 Protocol Suite..
A
FTP
SMTP
TELNET
HTTP
T
N
TFTP
NFS
SNMP
DNS
TCP
ICMP
IGMP
UDP
IP
ARP
D
Protocols defined by the underlying networks
P
RARP
IP Header..
Octet +0
Octet +1
Octet +2
Octet +3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
VER
HLEN
TOS
IDENTIFICATION
TIME TO LIVE
PROTOCOL
TOTAL LENGTH
DM
F F
FRAGMENT OFFSET
HEADER CHECKSUM
SOURCE ADDRESS OF HOST
DESTINATION ADDRESS OF HOST
OPTIONS
PADDING
ARP Operation
Give me MAC address of 129.1.1.4
Here is my MAC address
129.1.1.1
ARP
Response
Accepted
129.1.1.4
Request
Ignored
129.1.1.2
08-00-39-00-2F-AB
08-00-39-00-2F-C3
Request
Ignored
129.1.1.3
08-00-5A-21-A7-22
That’s
Me
08-00-10-99-AC-54
RARP Operation
Give me my IP address
RARP Response
Diskless
work
station
RARP
Server
08-00-39-00-2F-AB
223.1.2.1
08-00-39-00-2F-C3 223.1.2.2
223.1.2.3
08-00-10-99-AC-54
08-00-5A-21-A7-22
IPv4 Header
Version
(4)
Header
Length (4)
Priority & Type
of Service (8)
Flags
(3)
Identification (16)
Time to live (8)
Total Length (16)
Protocol (8)
Fragment offset (13)
Header checksum (16)
Source IP Address (32)
Destination IP Address (32)
Removed
Changed
20
Bytes
IPv6 Header
Version
(4)
Traffic Class(8)
Payload Length(16)
Flow Label(20)
Next Header(8)
Source IP Address (128)
Hop Limit(8)
40
Bytes
Destination IP Address (128)
New
Extension Header
• New way of doing options
• Added after the basic IPv6 header
• Daisy chained
IPv6 Header
Next Header
= TCP
TCP Header
+ Data
IPv6 Header
Next Header
= Routing
Routing Header
Next Header
= TCP
IPv6 Header
Next Header
= Routing
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Routing Header
Next Header
= ESP
TCP Header
+ Data
ESP Header
Next Header
= TCP
TCP Header
+ Data
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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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IPv4 Addressing
32 Bits
Network
8 Bits
172
.
Host
8 Bits
16
8 Bits
8 Bits
. 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 the
class bit of an address and applies a variable
prefix (mask) to determine the network number.
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IPv4 Address classes
Class-A:
N
H
H
H
Class-B:
N
N
H
H
Class-C:
N
N
N
H
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
A
0 7 bits Network Address
B
10
C
110
D
1110
E
1111
Host Address
24 bits Host Address
14 bits Network Address
16 bits Host Address
21 bits Network Address
8 bits Host Address
Multicast address (224.0.0.0-239.255.255.255)
Reserved for future use
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IP Address Bit Patterns
8 Bits
8 Bits
8 Bits
8 Bits
Class-A:
00000000
01111111
0-127
Class-B:
10000000
10111111
128-191
Class-C:
11000000
11011111
192-223
Class-D:
11100000
11101111
224-239
Class-E:
11110000
11111111
240-255
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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:<interface identifier>
• 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:
TLA
RES
48 bits
•
•
•
•
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NLAs SLA
Interface ID
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<flags><scope>::<multicast group>
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Multicast assigned Addresses
• Some reserved multicast addresses:
Address
Scope
Use
FF01::1
Interface-local
All Nodes
FF01::2
Interface-local
All Routers
FF02::1
Link-local
All Nodes
FF02::2
Link-local
All Routers
FF05::2
Site-local
All Routers
FF02::1:FFxx:xxxx Link-local
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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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