Suppose a $4000$ bytes TCP message $($including the TCP header$)$ is passed to IP

for delivery across two networks of the Internet. The first network has an MTU of $1500$

bytes; the second has an MTU of $512$ bytes. Each network$$s MTU gives the size of the

largest IP datagram that can be carried in a link$-$layer frame.

$($a$)$ Give the sizes, offsets, values of offset fields in the IP headers of the sequence of

fragments delivered to the network layer at the destination host. Assume all IP headers

are $20$ bytes. Note, the IP requires that fragmentation should always happen on $8-$byte

boundaries.

$($b$)$ Path MTU is the smallest MTU of any link on the current path $($route$)$ between two hosts.

Assume that we could discover the path MTU of the path used, and that we use this value

as the MTU for all the path segments. Give the sizes of the sequence of IP packets

delivered to the network layer at the destination host