Questions#$1$: Answer the following questions about transport layer protocols:

a$.$ What are the main functions of the transport layer?

b$.$ Is there any difference between the transport layer protocols in performing these

functions? Explain your answer.

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Question#$2$:

Consider host M which transmits five back$-$to$-$back TCP segments to host N$.$ The first segment starts

with sequence number $430,$ and each segment contains $520$ bytes of data. Suppose that the second

segment is lost and assuming that the receiver is buffering segments which arrive out of order, answer

the following questions:

a$.$ What is the use of timers in TCP protocol? Should timer be set to long or short periods?

b$.$ Which technique is used in TCP to overcome the problem of long timeout periods?

c$.$ Draw a timing diagram which illustrates interaction between host M and host N using TCP

reliable data transfer. The diagram should address the following requirements:

$$ Assuming that the sender is using the technique named in $($b$),$ show segments exchanged

between host M and host N such that all the five packets eventually are received by host

N$.$

$$ Show data segment, ACKs, sequence number, number of bytes, timers, and timeouts.

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Question#$3$:

Consider the router and the three attached subnets below $($A$,$ B$,$ and C$).$ The number of hosts is also

shown below. The subnets share the $23$ high$-$order bits of the address space: $160\mathrm{.}215\mathrm{.}74\mathrm{.}0/23.$

Spring $2024$

Assign subnet addresses to each of the subnets $($A$,$ B$,$ and C$)$ so that the amount of address space

assigned is minimal, and at the same time leaving the largest possible contiguous address space

available for assignment if a new subnet were to be added. Then answer the following questions:

a$.$ What is the difference between public and private addresses on the Internet? What is their

purpose of use $($benefit$)?$

b$.$ Is the provided address space public or private?

c$.$ How many addresses are in the given address space?

d$.$ What is the subnet address of subnet A$?($use CIDR notation$)$

e$.$ What is the broadcast address of subnet A$?$ What is the use of this address?

f$.$ What is the subnet address of subnet B$?($use CIDR notation$)$

g$.$ What is the first host address in subnet B$?$

h$.$ What is the subnet address of subnet C$?($use CIDR notation$)$

i$.$ What is the last host address of subnet C$?$Consider the router and the three attached subnets below $(A,B,$ and $C).$ The number of hosts is also shown below. The subnets share the $23$ high$-$order bits of the address space: $160\mathrm{.}215\mathrm{.}74\mathrm{.}0/23.$