ipv6 - FAKULTI SAINS KOMPUTER DAN TEKNOLOGI MAKLUMAT

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					Next Generation of TCP/IP Protocol
              Suite:


     IPv6 and ICMPv6




             Fahrul Hakim jab. Tek kom dan rangkaian upm
What is IPv6?
  "IPng is a new version of IP which is designed to be an evolutionary step from
  IPv4. It is a natural increment to IPv4. It can be installed as a normal software
  upgrade in Internet devices and is interoperable with the current IPv4. Its
  deployment strategy is designed to not have any flag days or other dependencies.
  IPng is designed to run well on high performance networks (e.g. ATM) and at the
  same time is still efficient for low bandwidth networks (e.g. wireless). In addition,
  it provides a platform for new Internet functionality that will be required in the near
  future."




                                 Fahrul Hakim jab. Tek kom dan rangkaian upm
  Why IPv6 ??

There were several reasons for the development of a new standard in the
face of a current working and widely used system. Most important was
the exhaustion of the 32-bit address space of IPv4.




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What’s wrong with IPv4??
We know that
IPv4 provides the host-to-host communication between systems in
 the internet.
Although IPv4 is well designed, data communication has
 evolved since the inception of IPv4 in the 1970s.
IPv4 has some deficiencies that make it unsuitable for the fast-
 growing Internet, including the following:




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1.   The inefficient of the use of address space in ipv4. (4billion addresses spa)
     e.g. When an organization is granted a class A address, 16 million addresses
     from address space are assigned for the organization’s exclusive use.
     If class C – only 256 addressess are assigned to this organization.
     (not sufficient).
     Also millions of addresses are wasted in classes D and E.
     This method of addressing has depleted the address space of IPv4, and soon
     there will not be any addresses left to assign to any new system that wants to
     be connected to the Internet.
     subnetting/supernetting alleviated some of the addressing problems, but make
     routing more complicated.




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Part of the effort of defining a new standard included an attempt to
identify the future size of the Internet, assuming that growth would
continue, not only in the number of individuals using it, but also in the
number of computers per individual (many Americans already have
multiple computers at home and at work, and integration of chips
into other devices, such as automobiles and home appliances, has
become widespread in the US). The working assumption of a
hundred computers per human being was given a safety margin, and
the final estimate to be used in developing an addressing
specification was 1 quadrillion (1015) computers connected by 1
trillion (1012) networks. The designers took into account the
inefficiencies in address assignment and came to the conclusion that new
addresses should be somewhere between 57 and 68 bits in size.


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The IPv6 address space is truly vast; 2128 is nearly 1039, a number so big
we don't really have a convenient name for it-call it a million quadrillion
quadrillion. This is many more than the number of nanoseconds since the
universe began (somewhere around 1026), or the number of inches to the
farthest quasar (about 1027); it 's about the number of protons in 100
million metric tons (one quadrillion liters-enough for several hundred
thousand Zeppelins) of hydrogen. Even if addressing assignments are
truly inefficient, it seems unlikely that the IPv6 address space will be
exhausted in the near future. With so much space to work with, the
designers have been able to partition the address space in a number of
ways to provide services and address assignments that were not available
previously



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2. The Internet must accommodate real-time audio and video
  transmission. This type of transmission requires minimum delay
  strategies and reservation of resources not provided in the IPv4
  design.




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3. IPv4 lack of security. No encryption and authentication is
   provided by IPv4.
  In order to upgrade the security, The Internet must
  accommodate encryption and authentication of data for some
  application.




                         Fahrul Hakim jab. Tek kom dan rangkaian upm
  What’s the different between IPv4 and IPv6 in
     order to overcome these deficiencies?

• The format and the length of the IP addresses were
  changed along with the packet format.
• Related protocols, such as ICMP, were also modified.
• Other protocols in the network layer, such as ARP, RARP,
  and IGMP, were either deleted or included in the ICMP
  protocol.




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IPv6 packet datagram

 VER     PRI                                                        Flow Label


         payload length                                  Next header             Hop limit



                          Source address




                          Destination address


                          Payload extension headers
                                    +
                          Data packet from the upper layer




                      Fahrul Hakim jab. Tek kom dan rangkaian upm
IPv4 packet datagram




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The advantages of IPv6 over IPv4 can be summarized as
follows:
• Larger address space. 4 times
• Better header format. IPv6 uses a new header format in
  which options are separated from the base header and
  inserted, when needed, between the base header and the
  upper-layer data. This simplifies and speeds up the routing
  process because most of the options do not need to be
  checked by routers.
• New options. IPv6 has new options to allow for additional
  functionalities (see diff between packet e.g. priority, ICMPv6)
• Allowance for extension. IPv6 is designed to allow the
  extension of the protocol if required by new technologies
  or applications.


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                                 Cont’d

• Support for resource allocation. In IPv6, the type-of-
  service field has been removed, but a mechanism (called
  flow label) has been added to enable the source to request
  special handling of the packet. This mechanism can be
  used to support traffic such as real-time audio and video.
• Support for more security. The encryption and
  authentication options in IPv6 provide confidentiality and
  integrity of the packet.




                       Fahrul Hakim jab. Tek kom dan rangkaian upm
     security

In the present design of the Internet, security considerations have been
relegated to upper-level protocols and applications. The original design
of IP did not contemplate methods for providing secure communication.
(It may be noted that the ISO OSI definition originally placed security
at the presentation layer, which is well above the network/transport
layers where the functions of IP reside, remembering that IP does not
precisely fit into the OSI model. Later developments led to security
propagating to many other layers of OSI implementations, often because
individual manufacturers simply provided it there.) One goal of the IPv6
design team was to provide additional security mechanisms at the IP
level of communication.



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There are two mechanisms introduced in IPv6 to provide security: the
Authentication Header and the Encapsulating Security Header. Both of
these are extension headers beyond the basic packet header. The first is
deemed generally exportable, because it does not address issues of
confidentiality (i.e., the concealment of information), while the second
may be restricted to use within certain countries only, depending on the
method of encryption.




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The Authentication Header provides an important mechanism that has been
lacking in the existing Internet, that of ensuring that a packet did indeed come from
the specific origin given in the packet's source address and also was not tampered
with during transmission.

The Encapsulation Header is a mechanism to provide for encrypted information
transmission. The IPv6 specification does not identify what encryption technique is to
be used, only how data are to be identified as having been encrypted


Encryption prevents third parties from extracting information from the Internet that they
are not entitled to have (and also provides an additional means for preventing the
insertion of counterfeit packets into a communication link).




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Autoconfiguration

One of the most important new capabilities provided by IPv6 is that of automatically
configuring the network addresses of equipment newly added to a network.

Concept use: plug and play

Some basic capabilities have already been in use for dealing with these problems.
They include the Address Resolution Protocol (ARP) for determining a physical
address from an IP address, the Reverse Address Resolution Protocol (RARP) for
determining a node's own IP address during initialization, the Bootstrap Protocol
(BOOTP) for a similar purpose, and the Dynamic Host Configuration Protocol
(DHCP) to provide a basic allocation and release of IP addresses on an as-needed
basis. However, these protocols are in addition to the Internet Protocol itself, and
therefore, their availability and use are not consistent across the Internet

IPv6 resolves this by making autoconfiguration capability part of the basic protocol.
The addressing scheme, by including link-local addresses and multicasting addresses,
provides the tools for allowing a node to configure itself.


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IPv6 Address Characteristics


An IPv6 addresses consists of 16 bytes (octets), making it 128 bits
long (figure H.1)


Hexadecimal Colon Notation
To make addresses more readable, IPv6 addresses protocol
 specifies hexadecimal colon notation
128 bits are divided into eight sections, each two bytes in length.
Two bytes in hexadecimal notation require 4 hexadecimal digits.
Therefore, the Addresses consists of 32 hexadecimal digits, with
 every four digits separated by a colon.


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Figure H.1 IPv6 address


       128 bits = 16 bytes = 32 hex digits


      11111011101100…………………………………………………11111111111111111111111




      FDEC     BA98       7654 3210 ADBF                                    BBFF   2922   FFFF




                              Fahrul Hakim jab. Tek kom dan rangkaian upm
IPv6 Address Abbreviation

•Although the IP address, even in hexadecimal format is very long,
 many of the digits are zeros.
•In this case, we can abbreviate the address.
•The leading zeros of a section (four digits between two colons) can
 be omitted.

REMEMBER!!!!!!!!!!!!!!!!!!!!!!
Only the leading zeros can be dropped, not the trailing zeros.
For e.g. see Fig H.2




                          Fahrul Hakim jab. Tek kom dan rangkaian upm
Figure H.2 Abbreviated address

   unabbreviated

   FDEC : BA98 : 0074 : 3210 : 000F : BBFF : 0000 : FFFF




      abbreviated

     FDEC : BA98 : 74 : 3210 : F : BBFF : 0 : FFFF




                                 Fahrul Hakim jab. Tek kom dan rangkaian upm
 Further Abbreviations
Further abbreviations are possible if there are consecutive sections
Consisting of zeros only.

We can remove the zeros altogether and replace them with a double
Semicolon. Fig. H.3 shows the concept.




                           Fahrul Hakim jab. Tek kom dan rangkaian upm
Figure H.3 Abbreviated address with consecutive zeros

             abbreviated

               FDEC : 0 : 0 : 0 : 0 : BBFF : 0 : FFFF




                       FDEC : : BBFF : 0 : FFFF


                     More abbreviated



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Partial Address

Sometimes we need to refer to only part of the address,
Not all of it.

To do so, place a slash after the digits you wish to keep and
Follow it with the number of digits kept.

For e.g. figure H.4 shows how the first six sections can be
Written in a shortened form.




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Figure H.4 Partial address


            Full address

               FDEC : 0 : 0 : 0 : 0 : BBFF : 0 : FFFF




                    FDEC : : BBFF/96

                         Partial address




                             Fahrul Hakim jab. Tek kom dan rangkaian upm
Categories of Addresses

IPv6 defines 3 types of addresses:


 Unicast Address
 Anycast Address
 Multicast Address




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Unicast Addresses

Defines a single computer. The packet sent to a unicast
 address should be delivered to that specific computer. (Unique)
UA is Basic type of address used to send a message to a single
 destination.
Once known as point-to-point addresses.
Unicast addresses form the largest number and most familiar
 category of IP addresses, and there is little changed in IPv6 from
Previous versions of the Internet Protocol in terms of how such
 addresses are used.
Most addresses visible to and used by end-users will be unicast
 address.



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Multicast Addresses

The multicast provides a capability to replace the original concept
Of packet broadcasting. See the different between broad/multicast.

A multicast address defines a group of computers that may or may
Not share the same prefix and may or may not be connected to the
Same physical network.

A packet sent to a multicast address should be delivered to each
Member of the set.




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Anycast Address
Anycasting and anycast addresses are new concepts in IPv6.

Researchers had begun to explore methods for anycasting under IPv4,
but there was no obvious way to implement this feature within the
limitations of that protocol.

The new capabilities of IPv6 allowed the inclusion of this capability.

An anycast address defines a group of computers whose addresses have
the same prefix.

For e.g., all computers connected to the same physical network share
the same prefix address.

A packet sent to an anycast address should be delivered to exactly one
Of the members of the group – the closest or most easily accessible.



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Address Space Assignment
•The address space has many different purposes.
•The designers of the IP addresses divided the address space
 into two parts, with the first part called the type prefix.

•This variable-length prefix defines the purpose of the address
•The codes are designed such that no code is identical to the
 first part of any other code.

•In this way, there is no ambiguity; when an address is given,
 the type prefix can easily be determined. See table H.1.

See fig. H.5 the IPv6 address format.
                           Fahrul Hakim jab. Tek kom dan rangkaian upm
Figure H.5 Address structure




                                          128 bits

    variable                                                       variable




   Type prefix                                                      Rest of address




                               Fahrul Hakim jab. Tek kom dan rangkaian upm
Table H.1 Type prefixes for IPv6 addresses
    Type Prefix         Type                                                         Fraction
    0000 0000           Reserved                                                     1 / 256
    0000 0001           Reserved                                                     1 / 256
    0000 001            NSAP (network service access point)                          1 / 128
    0000 010            IPX (Novell)                                                 1 / 128
    0000 011            Reserved                                                     1 / 128
    0000 100            Reserved                                                     1 / 128
    0000 101            Reserved                                                     1 / 128
    0000 110            Reserved                                                     1 / 128
    0000 111            Reserved                                                     1 / 128
    0001                Reserved                                                     1 / 16
    001                 Reserved                                                     1/ 8
    010                 Provider-based unicast address                               1/ 8
    011                 Reserved                                                     1/ 8
    100                 Geographic unicast address                                   1/ 8
    101                 Reserved                                                     1/ 8
    110                 Reserved                                                     1/ 8
    1110                Reserved                                                     1 / 16
    1111 0              Reserved                                                     1 / 32
    1111 10             Reserved                                                     1 / 64
    1111 110            Reserved                                                     1 / 128
    1111 1110 0         Reserved                                                     1 / 512
    1111 1110 10        Link local addresses                                         1 / 1024
    1111 1110 11        site local addresses                                         1 / 1024
    1111 1111           Multicast addresses                                          1 / 256
                                       Fahrul Hakim jab. Tek kom dan rangkaian upm
 Provider-Based Unicast Address
The provider-based address is generally used by a normal host as a
Unicast address. The address format is shown in fig. H.6.
Field for the provider-based are as follows:

Type identifier: This 3-bit field defines the address as a provider-based
Address.

Registry identifier. This 5-bit field indicates the agency that has
Registered the address. Currently 3 registry centers have been defined:

INTERNIC (code 11000) is the center for North America
RIPNIC (code 01000) is the center for European registration
APNIC (code 10100) is for Asian and Pacific countries.


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Cont’d.
Provider identifier. This variable-length field identifies the provider for
Internet access. A 16-bit length is recommended for this field.

Subscriber identifier. When an organization subscribes to the Internet
through a provider, it is assigned a subscriber identification. A 24-bit
length is recommended for this field.

Subnet identifier. Each subscriber can have many different subnetworks
and each network can have different identifiers. The subnet identifier
defines a specific network under the territory of the subscriber. A 32-bit
length is recommended for this field.

Node identifer. The last field defines the identity of the node connected
to a subnet. A length of 48 bits is recommended for this field to make
it compatible with the 48-bit-link (physical add used by Ethernet.)
                           Fahrul Hakim jab. Tek kom dan rangkaian upm
Figure H.6 Provider-based address



                                             128 bits



            Provider        Subscriber                      Subnet                      Node
            identifier      identifier                      identifier                 identifer




    010          Registry


   3 bits         5 bits

                                INTERNIC 11000
                                RIPNIC   01000
                                APNIC    10100




                                         Fahrul Hakim jab. Tek kom dan rangkaian upm
We can think of a provider-based address as a hierarchical
Identity having several prefixes.
As shown in Figure H.7, each prefix defines a level of
Hierarchy.
The type prefix defines the type.
The registry prefix defines the registry level.
The provider prefix uniquely defines a provider.
The subscriber prefix uniquely defines a subscriber.
And
The subnet prefix uniquely defines a subnet.



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Figure H.7 Address hierarchy




                  Subnet prefix


        Subsriber prefix


Provider prefix




           Provider        Subscriber                       Subnet                     Node
           identifier      identifier                       identifier                identifer




                                        Fahrul Hakim jab. Tek kom dan rangkaian upm
IPv6 Packet Format

The IPv6 packet is shown in figure H.8. Each packet is
composed of a mandatory base header followed by the
payload.
The payload consists of two parts: optional extension headers
and data from an upper layer.
The base header occupies 40 bytes, whereas the extension
headers and data from the upper layer usually contain up to
65,535 bytes of information.



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Figure H.8 IPv6 datagram




              40 bytes                                         up to 65,535 bytes




          Base header                                               Payload



             Extension headers                        Data packet from upper layer
               (optional)




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Figure H.9 shows the base header with its eight fields.

VER
PRI
Flow label
Payload length
Next header
Hop limit
Source address
Destination address




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Figure H.9 Format of an IPv6 datagram


           VER     PRI                                                      Flow Label


                   payload length                                     Next header        Hop limit



                                      Source address




                                     Destination address


                                     Payload extension headers
                                               +
                                     Data packet from the upper layer




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Version. This 4-bit field defines the version number of the IP. For IPv6.
The value is 6.

Priority. The 4-bit priority field defines the priority of the packet with
respect to traffic congestion. E.g. if one of two consecutive datagrams
must be discarded due to its congestion, the datagram with the lower
priority will be discarded. IPv6 has 2 categories of traffic.
Congestion-controlled traffic. Noncongestion-controlled traffic.

Flow label. The flow label is a 24-bit (3 bytes) field that is designed
to provide special handling for a particular flow of data.

Payload length. This 2-byte payload length field defining the total
length of the IP datagram excluding the base header.



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Table H.2 Next header codes


    code              next header
                  0   Hop-by-hop option
                  2   ICMP
                  6   TCP
                 17   UDP
                 43   Source routing
                 44   Fragmentation
                 50   Encrypted security payload
                 51   Authentication
                 59   Null (no next header)
                 60   Destination port


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Cont’
Next header. The next header is an 8-bit field defining the header
 that follows the base header in the datagram. The next header is
either one of the optional extension headers used by IP or the header for
an upper-layer protocol such as UDP or TCP. Each extension header
also contains this field. Table H.2 shows the values of next
headers. Note that this field in version 4 called the protocol.
Hop limit. This 8-bit hop limit field serves the same purpose as the
time-to-live field in IPv4.

Source address. The source address field is a 16-byte (128-bit)
Internet address that identifies the original source of the datagram.

Destination address. The destination address field is a 16-byte
(128-bit) Internet address that usually identifies the final destination of
the datagram. However, if source routing is used, this field contains
the address of the next router.
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Table H.3 Priorities for congestion-controlled traffic

 If a source adapts itself to traffic slowdown when there is congestion, the traffic
 is referred to as congestion-controlled traffic.
 In congestion-controlled traffic, it is understood that packets may arrive delayed
 or even be lost or receive out of order.
 Congestion-controlled data are assigned priorities from 0 to 7.

 Priority                   M eaning
    0        No specific trafic
    1        Background data
    2        Unattended data traffic
    3        Reserved
    4        Attended bulk data traffic
    5        Reserved
    6        Interactive traffic
    7        Control traffic



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Table H.4 Priorities for noncongestion-controlled traffic
NCT refers to a type of traffic that expects minimum delay. Discarding of packets
Is not desirable. Retransmission in most cases is impossible.
In other words, the source does not adapt itself to congestion. Real time audio
And video are good e.g. of this type of traffic.
The priorities are usually assigned based on how much the quality of received data
Can be affected by discarding some packets.
Data containing less redundancy (such as low-fidelity audio or video) can be given
A higher priority 15.
Data containing more redundancy (such as high-fidelity audio or video) should
Be given lower priority.
Priority               M eaning
   8     Data with most redundancy
    .                .
    .                .
    .                .
    .                .
    .                .
    .                .
   15    Data with less redundancy
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Flow label
A sequence of packets, sent from a particular source to particular
destination, that needs special handling by routers is called a flow of
packets.
Flow label can be used to speed up the processing of a packet by a
router.
Flow label can be used to support the transmission of real-time audio
and video.
Real-time audio or video, particularly requires resources such as
high bandwidth, large buffers, long processing time, and so on.
A process can make a reservation for these resource beforehand to
guarantee that real-time-data will not be delayed due to lack of
resources.
The use of real-time data and the reservation of these resources req.
other protocols such as real time protocol(RTP) and resource
Reservation Protocol (RVSP) in addition to IPv6.
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Extension headers
The length of the base header is fixed at 40 bytes.

However, to give more functionality to the IP datagram, the base
header can be followed by up to six extension headers. Many of these
headers are options in IPv4. Fig. H.10 shows the extension header
Format.

Six types of extension headers have been defined: see fig. H.11.




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Figure H.10 Extension header format



        VER           PRI           Flow Label

          Payload length                                      Next header   Hop limit

                              Source address

                              Destination address

        Next header                   Header length


        Next header                  Header length


  .                                     .
                                        .
  .                                     .
  .
        Next header                  Header length




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Figure H.11 Extension header types

                                                                 Hop-by-hop option

                                                                 Source routing

                                                                 Fragmentation
       Externsion
       headers
                                                                 Authentication

                                                                 Encrypted security payload

                                                                 Hop-by-hop option




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 ICMPv6

Another protocol that has been modified in ver 6 of the TCP/IPP protocol
Suite is ICMP (ICMPv6). This new version follows the same strategy
and purposes of ver4. But has been modified to suit IPv6.

In addition, some protocols that were independent in ver 4 are now part
Of ICMPv6. Fig. H.12 compares the network layers of ver 4 and 6.

The ARP and IGMP protocols (ver4) are combined in ICMPv6. The
RARP protocol is dropped from the suite because it is not used often.

Fig. H.13 shows 2 broad categories of ICMP messages: error reporting
And query.
Fig. H.14 shows the 5 different error-reporting message.
Fig. H.14 shows the 4 different query message
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Figure H.12 Comparison of network layers in version 4 and version 6


     IGMP
                                                                            ARP

                                    IPv4

     ICMP                                                                   RARP




 Network layer in version 4



       ICMPv6


                                        IPv6




 Network layer in version 6
                              Fahrul Hakim jab. Tek kom dan rangkaian upm
Figure H.13 Categories of ICMP messages




                            ICMP messages




      Error-Reporting                                                     Query




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Figure H.14 Types of error-reporting messages



                               Error
                              Reporting




Destination                     Time
                                                                           redirection
unreachable                     exceed
               Packet too                                      Parameter
                  big                                          problems




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Figure H.15 Types of query message



                                        Query




      Echo
                                                                                       Group membership
 Request and reply


                Router solicitation                                        Neighbor solicitation
                And advertisement                                           And advertisement




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                Comparison between IPv4 and IPv6 headers


• The header length field is eliminated in IPv6 because the length of the
  header is fixed in this version
• The service type field is eliminated in IPv6. The priority and flow label
  fields together take over the function of the service type field
• The total length field is eliminated in IPv6 and replaced by the payload
  length field.
• The identification, flag, and offset fields are eliminated from the base
  header in IPv6. They are included in the fragmentation extension
  header.
• The TTL field is called hop limit in IPv6.
• The protocol field is replaced by the next header field.
• The header checksum is eliminated because the checksum is provided
  by upper layer protocols; it is therefore not needed in this level.
• The option field in IPv4 are implemented as extension headers in IPv6.



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