[ee122] [EE122] Question on IP Fragmentation
Jonathan D. Ellithorpe
jde at berkeley.edu
Thu Oct 11 19:54:39 PDT 2007
On slides 21, 22, and 23 of lecture 4, I noticed something confusing
about the length field of fragment 1 (slide 21), and the offset of
fragment 2 (slide 22). Shouldn't the offset of fragment 2 denote the
location of where data should be concatenated in memory on the receiver?
If so, I'm not sure why the length of frag 1 is 1496 and the offset of
frag 2 is 1496. It would seem to me that, if the IP header were 20
bytes, then the offset of frag 2 should be 1476, because the data of
frag 1 was 1476 bytes long, (bytes 0 to 1475 in the receiving host's
memory). Thus, frag 2's offset should be 1476, to denote where frag 2's
data should start.
Thanks for any help I can get on understanding this!
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