Comparison between IPv4 options and IPv6 extension headers:
Comparison
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1. The header length field is eliminated in IPv6 because the
length of the header is fixed in this version.
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2.The
service type field is eliminated in IPv6. The priority and flow label fields
together take over the function of the service type field.
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3.The total length field is
eliminated in IPv6 and replaced by the payload length field.
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4.The identification, flag, and
offset fields are eliminated from the base header in IPv6. They are included
in the fragmentation extension header.
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5.The TTL field is called hop
limit in IPv6.
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6.The protocol field is replaced
by the next header field.
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7.The header checksum is
eliminated because the checksum is provided by upper-layer protocols; it is
therefore not needed at this level.
|
8.The option fields in IPv4 are
implemented as extension headers in IPv6.
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IPv6 ADDRESSES:
Despite all short-term solutions, address depletion is still
a long-term problem for the Internet. This and other problems in the IP
protocol itself have been the motivation for IPv6. An IPv6 address is
128 bits long.
TRANSITION FROM IPv4 TO IPv6:
Because of the huge number
of systems on the Internet, the transition from IPv4 to IPv6 cannot happen
suddenly. It takes a considerable amount of time before every system in the
Internet can move from IPv4 to IPv6. The transition must be smooth to prevent
any problems between IPv4 and IPv6 systems.
1.Dual Stack
2.Tunneling
3.Header Translation
Type prefixes for IPv6 addresses:
Type Prefix
|
Type
|
Fraction
|
0000 0000
|
Reserved
|
1/256
|
0000 0001
|
Unassigned
|
1/256
|
0000 001
|
ISO network addresses
|
1/128
|
0000 010
|
IPX (Novell) network
addresses
|
1/128
|
0000 011
|
Unassigned
|
1/128
|
0000 1
|
Unassigned
|
1/32
|
0001
|
Reserved
|
1/16
|
001
|
Reserved
|
1/8
|
010
|
Provider-based
unicast addresses
|
1/8
|
Type prefixes for IPv6 addresses (continued):
Type Prefix
|
Type
|
Fraction
|
||
011
|
Unassigned
|
1/8
|
||
100
|
Geographic-based
unicast addresses
|
1/8
|
||
101
|
Unassigned
|
1/8
|
||
110
|
Unassigned
|
1/8
|
||
1110
|
Unassigned
|
1/16
|
||
1111
|
0
|
Unassigned
|
1/32
|
|
1111
|
10
|
Unassigned
|
1/64
|
|
1111
|
110
|
Unassigned
|
1/128
|
|
1111
|
1110
|
0
|
Unassigned
|
1/512
|
1111
|
1110
|
10
|
Link local
addresses
|
1/1024
|
1111
|
1110
|
11
|
Site local
addresses
|
1/1024
|
1111
|
1111
|
Multicast addresses
|
1/256
|
|