IPv4 Header Fields (Cksum)

Total Len

Fragment ID

Source Address

Destination Address

Header

checksum

Frag Offset

TTL

protocol

TOS

ver

IHL

(options)

32 bits wide

cksum: Internet

checksum computed

over full IP header.

Does not cover data!

Must change as dgram

is routed due to TTL

decrement (can be

done incrementally).

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