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Chapter 6Chapter 6

IP Version6IP Version6

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Internet Protocol (IP)Internet Protocol (IP)

IP connectionless network-layer protocol. IP is based on datagram routing. IP is unreliable !! Routing in IP is a mixture of hierarchical, distance vector and

link state routing algorithms.

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DatagramDatagram

Packets in IP layer are called datagram.Packets in IP layer are called datagram.

Datagram has two parts namely headerDatagram has two parts namely header

and data.and data.The header is 20 to 60 bytes in length.The header is 20 to 60 bytes in length.

It contains the information essential forIt contains the information essential for

routing and delivery.routing and delivery.

It also contain variable length data.It also contain variable length data.

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IP AddressesIP Addresses

Every host or router on the internet has aEvery host or router on the internet has a

unique IP address.unique IP address.

It is 32 bits long.It is 32 bits long.

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IP AddressesIP Addresses

192.168.0.140

(11000000.10101000.00000000.10001100)

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Class AClass A

a.0 in the first field indicates type A.

b. The host number range from 0.0.0.0 to

127.255.255.255

c.There are 126 types of networks and 17 million

host.

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Class BClass B

a.10 in the first field indicates type B.

b.First two fields identify the network, and the

number in the first field must be in the range 128

191. (10000000 - 10111111).

c. Class B network are large.

d.The host number range from 0.0 to 255.255 i.e.65,534.

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Class CClass C

a.110 in the first field indicates type C.

b. 21 bits are reserved for network.

c.8 bits Host.

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Class DClass D

a.1110 in the first field indicates type D.

b. 2 million networks with up to 254 host.

c.Class D format allows multicast in which adatagram is directed to multiple host.

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Class EClass E

a.11110 in the first field indicates type E.

b. These addresses are reserved for future use.

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IPv4 Datagram HeaderIPv4 Datagram Header

VERS HLEN TOS TOTAL LENGTH

IDENTIFICATION FLAG FRAGMENT OFFSET

TTL PROTOCOL CHECKSUM

SOURCE ADDRESS

DESTINATION ADDRESS

OPTIONS (if any) + PADDING

0 4 8 16 19 31

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Problems with IPv4: LimitedProblems with IPv4: Limited

Address SpaceAddress Space

IPv4 has 32 bit addresses.IPv4 has 32 bit addresses.

Flat addressing (only netid + hostid withFlat addressing (only netid + hostid with

fixed boundaries)fixed boundaries) Results in inefficient use of address space.Results in inefficient use of address space.

Class B addresses are almost over.Class B addresses are almost over.

Addresses will exhaust in the next 5 years.Addresses will exhaust in the next 5 years. IPv4 is victim of its own success.IPv4 is victim of its own success.

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Advantages of IPv6:Advantages of IPv6:

Large address spaceLarge address space

Better Header formatBetter Header format

New optionsNew optionsAllows extensionAllows extension

Support for resource allocationSupport for resource allocation

Support for more securitySupport for more security

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IPv6 AddressesIPv6 Addresses

128-bit addresses128-bit addresses

Multiple addresses can be assigned toMultiple addresses can be assigned to

an interfacean interface

Provider-based hierarchy to be used inProvider-based hierarchy to be used in

the beginningthe beginning

Addresses should have 64-bit interfaceAddresses should have 64-bit interface

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IPv6 Addresses:IPv6 Addresses:

HEX in blocks of 16 bitsHEX in blocks of 16 bits

BC84 : 25C2 : 0000 : 0000 : 0000 : 55AB :BC84 : 25C2 : 0000 : 0000 : 0000 : 55AB :

5521 : 00185521 : 0018

leading zero suppressionleading zero suppression

BC84 : 25C2 : 0 : 0 :55AB : 5521 : 18BC84 : 25C2 : 0 : 0 :55AB : 5521 : 18

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Compressed format removes stringsCompressed format removes stringsofof00ss

BC84 : 25C2 :: 55AB : 5521 : 18BC84 : 25C2 :: 55AB : 5521 : 18

:::: can appear only once in an address.can appear only once in an address.

can also be used to compress leading orcan also be used to compress leading ortrailingtrailing 00ss

Mixed NotationMixed Notation (X:X:X:X:X:X:d.d.d.d)(X:X:X:X:X:X:d.d.d.d)

e.g.,e.g., ::144.16.162.21::144.16.162.21

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IPv6 Header FormatIPv6 Header Format

Priority Flow LabelVers

Payload Length Next Header Hop Limit

Source Address

Destination Address

0 4 12 16 24 31

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IPv6 Header FieldsIPv6 Header Fields

Version number (4-bit field)Version number (4-bit field)The value is always 6.The value is always 6.

Priority (4 bit field) : specifies priorityPriority (4 bit field) : specifies priority

Flow label (24-bit field or 3 bytes)Flow label (24-bit field or 3 bytes)Used to label packets requesting specialUsed to label packets requesting specialhandling by routers.handling by routers.

Payload length (16-bit field)Payload length (16-bit field)Length of the packet following the IPv6Length of the packet following the IPv6header, in octets.header, in octets.

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Next header (8-bit field)Next header (8-bit field)

The type of header immediately followingThe type of header immediately following

the IPv6 header.the IPv6 header.

Hop limit (8-bit field)Hop limit (8-bit field)

Decremented by 1 by each node thatDecremented by 1 by each node that

forwards the packet.forwards the packet.Packet discarded if hop limit isPacket discarded if hop limit is

decremented to zero.decremented to zero.

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IPv6 Header FieldsIPv6 Header Fields

Source Address (128-bit field)Source Address (128-bit field)An address of the initial sender of theAn address of the initial sender of the

packet.packet.

Destination Address (128-bit field)Destination Address (128-bit field)An address of the intended recipient ofAn address of the intended recipient of

the packet. May not be the ultimatethe packet. May not be the ultimate

recipient, if Routing Header is present.recipient, if Routing Header is present.

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Header Changes from IPv4Header Changes from IPv4

Longer address - 32 bitsLonger address - 32 bits 128 bits128 bits Fragmentation field moved to separate headerFragmentation field moved to separate header

Header checksum removedHeader checksum removed

Header length removed (fixed length header)Header length removed (fixed length header) Length field excludes IPv6 headerLength field excludes IPv6 header

Time to liveTime to live Hop limitHop limit

ProtocolProtocol Next headerNext header 64-bit field alignment64-bit field alignment

TOS replaced by flow label, traffic classTOS replaced by flow label, traffic class

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