Naveed1414
Subject: internet architecture and protocols
Question 1
(A) Determine the Network ID, First Valid Host, Last Valid Host, and Broadcast ID of the
following network address/mask pairs?
(1) 172.16.10.15/20
Ans: Since the subnet mask of this IP is 255.255.240.0. So, to find out range we subtract 240 from 256 and
get 16, which implies that,
Network ID = 172.16.10.0/20
First Valid Host = 172.16.10.1/20
Last Valid Host = 172.16.10.14/20
Broadcast ID = 172.16.10.15/20
(2) 192.168.10.15/26
Ans: Since the subnet mask of this IP is 255.255.255.192. So, to find out range we subtract 192 from 256 and
get 64, which implies that,
Network ID = 192.168.10.0/26
First Valid Host = 192.168.10.1/26
Last Valid Host = 192.168.10.62/26
Broadcast ID = 192.168.10.63/26
(B) An ISP supplies a class B network of 136.210.0.0 to an enterprise that requires ten networks each to
support 110 users. What is the network mask that would be configured in each workstation and what would
be the NetID, Subnet Number?
Ans: To fit in 110 users in a subnet we would take 27, Therefore
27-2 = 128 – 2 = 126 (110 users can fit in)
So, we have 7 bits for the hosts which we will subtract from 32 since it is an IPv4 Address to get the bits for
network,
32 – 7 = 25 network bits of given Class B address
The subnet mask of the given Class B address would then be 255.255.255.128 which will tell us the range for
each subnet that we need for the users. Hence, the ten networks for 110 hosts each would be written as,
136.210.0.0
136.210.0.128
136.210.1.0
|
|
|
136.210.4.128
So, the NetID would be 136.210.0.0
And since this is a Class B address then subnet number would be 16 – 7 = 9 bits.
Question 2
(A) An IPv6 packet consists of a base header and a TCP segment. The length of data is 128,000
bytes (jumbo payload). Show the packet and enter a value for each field.
Ans: Since the length of payload in IP Datagram can be of maximum 65,535 bytes, but here we need a
longer payload of 128,000 bytes for which we can use the jumbo payload option to define its longer
length. However, the jumbo payload should also be at a multiple of 4 bytes. So, all of this can be pictured
as,
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(B) Configure the following network using following addressing table. Write all commands and procedures
for assigning the IP address on computer, servers and router. What is link local address in each interface
of router?
Addressing Table
Device
Router
Sales
Billing
Accounting
Design
Engineering
CAD
Interface
G0/0
G0/1
Link-local
NIC
NIC
NIC
NIC
NIC
NIC
IPv6 Address/Prefix
2001:DB8:1:1::1/64
2001:DB8:1:2::1/64
FE80::1
2001:DB8:1:1::2/64
2001:DB8:1:1::3/64
2001:DB8:1:1::4/64
2001:DB8:1:2::2/64
2001:DB8:1:2::3/64
2001:DB8:1:2::4/64
Default Gateway
N/A
N/A
N/A
FE80::1
FE80::1
FE80::1
FE80::1
FE80::1
FE80::1
Ans: First, we enable unicast-routing on the router so it is enabled to forward IPv6 packets. We will use the
following command for it,
Router(config)#ipv6 unicast-routing
Next, we will configure both the interfaces of the router with the given IPv6 Address and Link-local Address by
the following commands,
Router(config)#int GigabitEthernet0/0
Router(config-if)#ipv6 address 2001:DB8:1:1::1/64
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Router(config-if)#ipv6 address FE80::1 link-local
Router(config-if)#no shut
Router(config-if)#exit
Router(config)#int GigabitEthernet0/1
Router(config-if)#ipv6 address 2001:DB8:1:2::1/64
Router(config-if)#ipv6 address FE80::1 link-local
Router(config-if)#no shut
Now we configure the given IP Addresses on each of the nodes by opening the Desktop tab first, then going into
IP configuration and set the IPv6 Address and Gateway according to given addressing table. All 6 nodes follow
the same procedure.
As for what is the link-local address in each of interface of router, it is Fe80::1 as evident by this screencap below,
Question 3
[A] Find the interface identifier of the Ethernet physical address of your computer using the format
defined for Ethernet addresses.
Ans: My Physical Address is C6-46-19-6F-76-71, the interface identifier for this can be found by flipping
the seventh bit of the first octet and adding FFFE in the middle and write the result in the colon hex
notation at the end.
So, for the first step,
C6 = 11000110
This will be changed to,
C4 = 11000100
Now after adding FFFE in the middle, the interface identifier in colon hex notation is
C446:19FF:FE6F:7671
[B]
[i] Compare and contrast IP version 4 protocol with IP version 6.
IPv4
1. IPv4 has a 32-bit address length
2. Address representation of IPv4 is in decimal
3. In IPv4 checksum field is available
4. IPv4 has a header of 20-60 bytes.
IPv6
1. IPv6 has a 128-bit address length
2. Address Representation of IPv6 is in hexadecimal
3. In IPv6 checksum field is not available
4. IPv6 has header of 40 bytes fixed
[ii] Compare contrast OSI model with TCP/IP model.
OSI
1. OSI is a generic, protocol independent standard,
acting as a communication gateway between the
network and end user
TCP/IP
1. TCP/IP model is based on standard protocols around
which the Internet has developed. It is a
communication protocol, which allows connection of
hosts over a network
2. In OSI model the transport layer guarantees the 2. In TCP/IP model the transport layer does not
delivery of packets
guarantees delivery of packets. Still the TCP/IP model
is more reliable
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3. OSI is a reference model around which the networks 3. TCP/IP model is, in a way implementation of the
are built. Generally, it is used as a guidance tool
OSI model
4. It has 7 layers
4. It has 4 layers
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