ITC-542 internetworking with TCP and IP 8

ITC-542 Internetworking with TCP/IP 8 Chandana Withanage


Switching is technique in data communication, which transfer data from one device or interface to another interface.

Packet Switching

This technique refers to protocols in which message divided in to packets before they sent.

Circuit Switching

It is simple technique, which used in telecommunication. In this technique network established a circuit between two nodes and terminal before user connected

1.Circuit switching is old and expensive, also used for telephone calls (PSTN) while packet switching modern

2. In circuit switching physical circuit or channel established between source and destination of data and message before going to sent. In packet switching data or message broken in to packets before they sent.

3. Circuit switching has a fixed bandwidth between source and destination of a call and bit stream transparent while packets switching contain several packets so it can send very quickly.


IP address belongs to class, A which has Subnet

To find out subnet mask of above IP we need subnet, so find out subnet we need calculate hosts therefore first we need to calculate answer b

To accumulate 700 hosts we need to consider 2^10 as subnet because we cannot take lower than 700. So 2^10 1024 and for usable host need -2 value deduct for network address and broad cast address because 1 is network address and 1 is broad cast address. So that 1024-2= 1022 usable hosts

Now we have subnet and we can find dotted decimal notation and slash notation.

We have IP address of class A so subnet mask is a normal IP address has 8+ 8+8+8= 32 bits of address

And here we got 10 as hosts so it should be NNNNNNNN.SSSSSSSS.SSSSSSHH.HHHHHHHH 11111111.11111111.111111HH.HHHHHHHH So dotted decimal notation is and for slash notation it would be 8+8+6=22

So slash notation would be /22 or

To find network address we need to take IP address and subnet mask and which ever comes common we need to consider as network address. Calculation is as follow: 00010001 11010100 01011000 01101111 11111111 11111111 11111100 00000000

Network address 00010001 11010100 01011000 00000000

So network address in decimal would be

To find boradcast address we need to take IP address and inverted subnet mask and all the things we need to consider as broadcast address. Calculation is as follow:

And for broadcast address 00010001 11010100 01011000 01101111 00000000 00000000 00000011 11111111 broadcast address 00010001 11010100 01011011 11111111 and in decimal it would be

R1 is more critical than R2 because it has more routers than R2 . So there are many chances of data transmission failure and it creates big problem for network operation. If R1 is lost or disconnect so it will effect on remaining two routers and if R2 disconnects than it will just effect on one routers so to restore the backup it is easier for R2 because only one router's data will be lost and R1 two routers data will lost so R1 is more crucial than R2.


IP packages includes eight Components, a header adding module, a processing module, a module Forwarding, a fragment virtualization module, a reassembly module, a routing table an MTU table and a reassembly table. It is significant to know reassembly difficulties virtualization. The IP is a fewer Link Protocol and no assurance, the wreckages reach in order as well the packet fragments from one datagram can be bury diversified with fragments from Another data gram.

The key function of reassembly is to find datagrams which a fragment fits and orders the fragments fitting to the similar reassemble and datagrams. This is finished separate by the conclusive endpoint of the IP messages. Therefore datagrams at an middle routers on unique sides of a physical. The router on the other endpoint of this MTU link will not reestablish datagrams to its unique formal. It will transfer fragments depressed on the web.

There are a sufficiently motives why the result was made to appliance IP reassembly in this method. So Possible the most significant one is that fragment can income dissimilar directions to obtain from the source address to destination address, Another router May not understand entire fragmented message. Another Reason is that by having routers we need to concern about reassembling fragments would outstanding their difficulty. Finally, we will see reassembly of messages which is requires delaying for all the fragmented messages and those are reassemble Before sending messages. It will slow down the process as well.

Since routers do not THEY can reassemble fragments immediately forward it to the entire ultimate recipient. Their Are Some Drawbacks and one of Them Is That It results in smaller fragments traveling along roads over Than if intermediate reassembly occurred. Increase the chances of this fragment was going missing and the Entire Being discarded message for example the 1,300-byte fragments would not be reassembled back into a 3,300-byte datagram at the end of the 1,000-MTU link. If the next link after that one also had an MTU of 3,300, we would have to send three frames, each encapsulating a 1,300-byte fragment, instead of a single larger frame, which is slightly slower.



Dynamic Host configuration Protocol it is client/ server based protocols. Hosts to retrieve IP addresses use it. Before DHCP some other protocols were used


Reverse Address Resolution Protocol, it was designed for provide IP address to booted computer. Nowadays RARP deprecated for two causes first it used the broad cast service of the data link layer that means a RARP sever must be present in each network. Second RARP can provide only the IP address of the computer but today computer need following four pieces of information

a. The IP address of the computer

b. The subnet mask of the computer

c. The IP address of a router

d. The IP address of a name computer


The Bootstrap Protocol is the pre runner of DHCP. It is client/ server which designed for reduce two deficiencies of RARP protocols , first BOOTP server can be anywhere in the Internet and second it can prove all pieces of information mentioned above. However some situation in which we need dynamic configuration protocols for example when a host move from one physical layer to another, its physical address change and some time when a host wants a temporary IP address to be used for a period of time. BOOTP cannot handle this situation because binding because binding between physical and IP address. Is static and fixed. But DHCP devised to handle these drawbacks


ICMP stands for Internet Control Message Protocol which is basic protocol of the IP Suite and mostly used by network computer.

Main function of ICMP is it always reports error message to the original source

ICMP message could be divided in to two major categories

a. Error - reporting message

b. Query message

Error - Reporting Message

Main function of ICMP is to reports error and following five types error can be handled by ICMP


TCP/IP GUIDE (n.d.) IP Message reassembly process viewed 2nd April, 2010 from:

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