IP datagram format

ver

length

32 bits

data

(variable length,

typically a TCP

or UDP segment)

16-bit identifier

Internet

checksum

time to

live

32 bit source IP address

IP protocol version

number

header length

(bytes)

max number

remaining hops

(decremented at

each router)

for

fragmentation/

reassembly

total datagram

length (bytes)

upper layer protocol

to deliver payload to

head.

len

type of

service

“type” of data

flgs

fragment

offset

upper

layer

32 bit destination IP address

Options (if any)

E.g. timestamp,

record route

taken, pecify

list of routers

to visit.

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