Problem $1(20$ points$)$:

Consider the protocol architecture shown in Fig. $1$ which exists at two end nodes A and B $.$

Node A is sending data to node B$.$ The header size and maximum payload size acceptable by

each of the lower three layers are as shown in Table $1.$ Note that the maximum payload for

each of these lower layers is chosen such that no fragmentation occurs at the IP or the

network access layers. Interface A and interface B depicted in Fig. $1$ are the interfaces

between the respective network access layers. Assume the application layer at node A wants

to send to node B a $1$ MB file.

Table $1$: Overhead and maximum

payload sizes for lower three layers.

Fig. $1$: Protocol architecture at nodes A and $B.$

a$)(12$ points$)$ Show the detailed structure$/$content$/$length of LAST TWO frames crossing the

A interface? Show all computations leading to your answer.

b$)(5$ points$)$ Compute the total number of bytes transmitted across the interface A$?$ What

fraction of these bytes is overhead?

c$)(3$ points$)$ If the Interface A is running at $10M\frac{b}{s},$ what is the total transmission time for

the $1$ MB file

Hint: $1$ MB is equal to $2^{20}$ bytes. Assume equal sized PDU are exchanged. For the last PDU, if payload size is

less than the maximum, padding is NOT used. Note network access layer fits integer number of IP packets $($i$.$e$.$

complete IP packets only$)$ into the network access frame.