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Friday, December 31, 2010

CS610 Assignment 3

CS 610 Computer Networks
Assignment # 03
Fall 2010
         Total Marks = 20
Deadline 
Your assignment must be uploaded / submitted before or on January 5, 2011
Upload Instructions
Please view the assignment submission process document provided to you by the
Virtual University.

Rules for Marking
Please note that your assignment will not be graded if:
•  It is submitted after due date
•  The file you uploaded does not open
•  The file you uploaded is copied from someone else or from internet
•  It is in some format other than .doc

Objective
The assignment has been designed to enable you to develop the:
•  Understanding about routing algorithms

Note: Material that is an exact copy from handouts or internet would be graded
zero marks. Your solution should consist of the material found through different
sources and written in your own words.

Assignment Statements:
a). Summarize the difference between classful IP address and classless IP
address in tabular format. 
(Your answer should not increase more than one page)
(10 marks)

b.) Show your IP address by using DOS command “ipconfig” and answer the
 following.         (2 x 5 marks) 
(i)  Show your IP address and subnet mask
(ii)  Convert the IP address and Subnet mask into binary representation.
(iii)  What is the class of your IP address in classful scheme and why?
(iv)  Find your host number and network number in classful and classless
scheme, also gives the reason to your answers.
(v) Given the address 23.56.7.91, find the beginning address i.e.
network address 


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Solution


How Classless and Classful Routing protocol operate in Routing?


Classful
Routing protocols do not carry subnet mask information on their routing updates. This makes them unsuitable for hierarchical addressing that require Variable Length Subnet Mask (VLSM) and discontiguous network. Classless routing protocols do carry subnet mask information on their routing updates. 

RIP v1 and IGRP are classful routing protocols. RIP v2, EIGRP, OSPF, and BGP are classless routing protocol. 

When running a classful routing protocol on a network, make sure you use the same subnet mask everywhere. Otherwise, routing black holes can occur. 

Classless 
Routing protocols extend the standard Class A, B, or C IP addressing scheme by using a subnet mask or mask length to indicate how routers must interpret an IP network ID. Classless routing protocols include the subnet mask along with the IP address when advertising routing information. Subnet masks representing the network ID are not restricted to those defined by the address classes, but can contain a variable number of high-order bits. Such subnet mask flexibility enables you to group several networks as a single entry in a routing table, significantly reducing routing overhead. Classless routing protocols includes RIP v2 and OSPF, Border Gateway Protocol version 4 (BGP4) and Intermediate System to Intermediate System (IS-IS).


Q:

What is the difference between classless and Classful IP address?


Your default class addresses are Class A 0-127, Class B - 128-191 Class C - 192-223 for the 1st octet values 

Classful IP addresses are IP addresses that follow this standard subnet ranges for class A, B, C so a Classful router protocol like ripv1 will always assume that the address 172.16.1.2 has a subnet mask of 255.255.0.0 even if you want it to have a subnet of 255.255.255.0 so on a Classful router protocol 172.16.1.2 will always have the range 172.16.0.0 - 172.16.255.255 (because the value 172 in the 1st octet falls in the Class B range of 128-191 and class B addresses have the subnet mask set to 255.255.0.0)

Classless IP addresses mean that the address range is determined by the subnet mask and hence the same address 172.16.1.2 255.255.255.0 will now be looked at as having its range as 172.16.1.0 - 255 because 255.255.255.0 corresponds to that range. P.S. Rip was updated to support this (ripv2)

Classful Vs Classless Address
Hello friends in this post i am again going to tell you some more interesting concepts of networking. In this post i am going to tell you what the difference between classfull and classless address is.

 [class1.jpg]


Classful addressing:
In the Classful addressing system all the IP addresses that are available are divided into the five classes A,B,C,D and E, in which class A,B and C address are frequently used because class D is for Multicast and is rarely used and class E is reserved and is not currently used. Each of the IP address belongs to a particular class that's why they are Classful addresses. Earlier this addressing system did not have any name but when classless addressing system came into existence then it is named as Classful addressing system. The main disadvantage of Classful addressing is that it limited the flexibility and number of addresses that can be assigned to any device. One of the major disadvantages of Classful addressing is that it does not send subnet information but it will send the complete network address. The router will supply its own subnet mask based on its locally configured subnets. As long as you have the same subnet mask and the network is contiguous, you can use subnets of a Classful network address.

[classless.gif]


Classless Addressing:
Classless addressing system is also known as CIDR (Classless Inter-Domain Routing).Classless addressing is a way to allocate and specify the Internet addresses used in inter-domain routing more flexibly than with the original system of Internet Protocol (IP) address classes. What happened in Classful addressing is that if any company needs more than 254 host machines but far fewer than the 65,533 host addresses then the only option for the company is to take the class B address. Now suppose company needs only 1000 IP addresses for its host computers then in this (65533-1000=64533) IP addresses get wasted. For this reason, the Internet was, until the arrival of CIDR, running out of address space much more quickly than necessary. CIDR effectively solved the problem by providing a new and more flexible way to specify network addresses in routers. A CIDR network address looks like this:

192.30.250.00/15

The "192.30.250.00" is the network address itself and the "15" says that the first 15 bits are the network part of the address, leaving the last 17 bits for specific host addresses. One more advantage of classless addressing is that classless protocol sends subnet information. This allows you to create discontiguous networks with any given Classful network address.
         

                              

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