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What is the complete size of an IP Packet?

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up vote 5 down vote accepted

There is no default size, it varies, ranging from 20 to 65535 bytes including the minimal header size. An IP packet with a length of only 20 bytes is unlikely however, it would only be possible with a packet without payload or data. The header length can vary between 20 and 60 bytes, the header contains information about the packet/protocol and no actual packet data is included in the header.

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is it true that they are separated by a null 0 character? – user4323 Feb 12 '11 at 19:43
@user4323 No it isn't, where did you get that information? – BloodPhilia Feb 12 '11 at 19:46
I didn't but is there a separation bit or does the server define it? – user4323 Feb 12 '11 at 20:57
@user4323 The header defines a packet size, so the receiver knows where a new packet SHOULD start. If it doesn't comply with the header, a transmission error has occured. – BloodPhilia Feb 12 '11 at 21:00

Depends what's in it. IPv4 packets have a header that is a minimum of 160 bits, but have an variably-sized options field (up to 480 bits that will be padded out to be an even multiple of 32 bits) and a variable size of payload.

You also have a TCP tag - TCP segments also have a header than is a minimum of 160 bits plus up to 320 bits of options field - which, again is padded out to be a multiple of 32 bits in necessary - and a variable payload size. The TCP segment will then be used as the payload of the network layer protocol packet which, in TCP's case, is almost always IP so the absolute minimum size of a TCP message as it reached the data link layer would be 320 bits, plus the size of the payload.

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