KWS,
Question: what do u mean by the 4 bits and 32 bits
> words.
The IHL is 4 bits in size, this normally has the
value of 5 decimal or 0101 binary. Read the
terminology 32 bit words as meaning 32 bit amounts.
Therefore if the value in the IHL field is 5 then the
size of the IP Header is 5 x 32 bit amounts or 160
bits.
160 bits divided by 8 (bits in an Octet) yields 20
octets, which is the standard IP Header Length.
Question: How do we arrive to the figure 65,535
> octects ?
The total length FIELD is 16 bits wide. The maximum
positive integer that can be represented in a 16 bit
field is ((2 raised to the power of 16) -1)
or 65536 -1 i.e 65535.
Question : 576 octects is the same as 576 bytes and
> how can it fit into the
> total length of 16 bits which is 2 bytes.
You appear to be confused here. The CONTENTS of the 16
bit field is the size of the headers and data that are
about to follow. So you have a total length field that
has a value within it of, for example 576 or in binary
(0000001001000000) This is the total length of the
Data and Headers that are about to follow the IP
Datagram.
Regards,
Phil.
--- KW S wrote: > Dear all
>
> I am reading RFC760 (IP protocol) and have the
> following questions.
>
> IHL : 4 bits
>
> Internet header length is the length of the internet
> header in 32 bits words
>
> Question: what do u mean by the 4 bits and 32 bits
> words
>
>
> Total length :16 bits
>
> Total length is the length of the IP packets in
> octect including the
> internet headers and data. This field allows the
> length of a packet to be up
> to 65,535 octets.
>
> Question: How do we arrive to the figure 65,535
> octects
>
> Such long packets are impractical for most host and
> networks.
>
> All hosts must be prepared to accept datagram of up
> to 576 octects
>
> Question : 576 octects is the same as 576 bytes and
> how can it fit into the
> total length of 16 bits which is 2 bytes
>
> Thanks
> kws
[EMAIL PROTECTED]
--- KW S wrote: > Dear all
>
> I am reading RFC760 (IP protocol) and have the
> following questions.
>
> IHL : 4 bits
>
> Internet header length is the length of the internet
> header in 32 bits words
>
> Question: what do u mean by the 4 bits and 32 bits
> words
>
>
> Total length :16 bits
>
> Total length is the length of the IP packets in
> octect including the
> internet headers and data. This field allows the
> length of a packet to be up
> to 65,535 octets.
>
> Question: How do we arrive to the figure 65,535
> octects
>
> Such long packets are impractical for most host and
> networks.
>
> All hosts must be prepared to accept datagram of up
> to 576 octects
>
> Question : 576 octects is the same as 576 bytes and
> how can it fit into the
> total length of 16 bits which is 2 bytes
>
> Thanks
> kws
[EMAIL PROTECTED]
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