Problem 3- Network Layer

1.    How does a host get an IP address? How does a network get the subnet part of an IP address? How does a provider get a block of IP addresses? What is the principle behind these procedures?

2.    A router has three interfaces. How many IP addresses will it have?

3.    Convert the following 48 bit MAC addresses to IPv6 Modified EUI-64 Identifiers :

a.    3994:A707:D0CB

b.    49A7:94D0:07CD

c.    A9A6:D094:CD07

d.    B9CD:EF20:9496

Problem 4- Data Link Layer:

a)    Suppose nodes A, B, and C each attach to the same broadcast LAN (through their adapters). If A sends thousands of IP datagrams to B with each encapsulating frame addressed to the MAC address of B, will C's adapter process these frames? If so, will C's adapter pass the IP datagrams in these frames to the network layer C? How would your answers change if A sends frames with the MAC broadcast address?

b)   How big is the MAC address space? The IPv4 address space? The IPv6 address space?

c)   State the reason why an ARP query is sent within a broadcast frame? When a response sent within a frame with a specific destination MAC address?

d)  In CSMA/CD, after the 7^th collision, what is the probability that a node chooses K=12? In case, if the result is K=5, then it corresponds to a delay of how many seconds on a 10Mbps Ethernet?

e)    Suppose a computer is moved from one department to another. Does the physical address need to change? Does the IP address need to change? Does it make a difference if the computer is a laptop?

 

here is your answer: 1. Host gets its IP Address from DHCP server. DHCP (Dynamic host configuration protocol) dictates how a host a assigned an IP address

Network part of a subnet by default is assigned based on the class of the IP Address the address belongs to. Class A have a default subnet of /8. Class B has a default subnet of /16 and class C has a default subnet of /24

A provider is assigned a block of IP Addresses by subnetting a bigger network. A network is subnetted to create multiple networks and each network has a multiple hosts.

This process is called Subnetting

2. Each interface of a router is in it's own network. So, They will have their own network.

3. Convert MAC to EUI-64

a. 3994:A707:D0CB

Series of steps are Split MAC in the middle

3994:A7 07:D0CB

Insert FF:FE in the middle

3994:A7FF:FE07:D0CB

Convert first 8 bits to binary

0011 1001 94:A7FF:FE07:D0CB

Flip 7th bit

0011 1011 94:A7FF:FE07:D0CB

Convert back to HEX

3B 94:A7FF:FE07:D0CB

3B94:A7FF:FE07:D0CB

b) 49A7:94D0:07CD

Insert FF:FE

49A7:94FF:FED0:07CD

Flip 7th bit

4BA7:94FF:FED0:07CD

c) A9A6:D094:CD07

Inserting FF:FE

A9A6:D0FF:FE94:CD07

Flip 7th bit

ABA6:D0FF:FE94:CD07

d) B9CD:EF20:9496

Inserting FF:FE

B9CD:EFFF:FE20:9496

Flip 7th bit

BBCD:EFFF:FE20:9496

problem 4

Answer:----------

a). Answer: C's adapter will process the frames, but the adapter will not pass the datagrams up the protocol stack.If the LAN broadcast address is used, then C's adapter will both process the frames and pass  the datagrams up the protocol stack.

b). MAC address space has 48 bits.The IPv6 address space has 128 bits.

c). The reason an ARP query is sent within a broadcast frame is as follows: in order for a sender to send an IP datagram the sender must know both the IP address and the MAC address. In order to get the unknown MAC address the sender will send an ARP query as a broadcast message across the LAN. Each node will receive this message and determine that it is a broadcast message. That node/adapter will then send the message up to its own ARP module. Each ARP module checks to see if that IP address matches its IP address. If it does, it will send the ARP response back to the sender with the MAC address inside a frame of the packet .

d).

The physical address does not change . It is globally unique to the computer's NIC card.

The IP address may need to be changed to reflect a new subnetwork id and host id.

The situation is the same for laptops.