Basic Information For Configuration Of Routers

Published Date: 02 Nov 2017

This report discusses the most important concepts in networking, IP addressing, sub-netting and dynamic routing protocol (RIP). In addition, it gives a practical case scenario of Routing Information Protocol, its versions and enhancements in due course. Variable Length Subnet Mask (VLSM) concepts are also explained.

CHAPTER 1

1 INTRODUCTION

This report mainly discusses about two major topics in computer networks, Internet Protocol Addressing and Dynamic Routing Protocol (RIP). Also we are going to discuss about the concepts of sub-netting and VLSM, which are the most important topics in the networking world. In addition to this we discuss about the versions of Routing Information Protocol

1.1 Introduction to Labs

The first course, Introduction to Computer Networks has five labs. Each labs session provided us the basic information to handle and work on networking devices, which are more important in networking field. It also provided hands on experience towards all the equipments.

1.2 Objectives

The main objective of this lab is to provide sound knowledge of fundamentals relating to the networks where most important concepts are covered both in theory and practical. In OSI model, the functions of Network layer as how router connects and routes two different networks are explored and also importance of dynamic routing is explained. Moreover, the lab clearly elaborates the concept of sub-netting and VLSM.

1.3 Laboratories Achievements

During the five labs, my-self and my group members configured the high-end routers available in the equipment room. This gave us deep knowledge about these devices and what they are capable of doing. We also used sniffer PC`s to get a clear picture of how the encapsulation process happens during packet transfer.

1.4 Outline

The material in this report is organised into four chapters and appendices. The chapters deal with the following topics:

Chapter 2: Configuration of routers.

Chapter 3:IP addressing

Chapter 4:VLANs

Chapter 5: Routing Information Protocol

Chapter 6: Conclusion

CHAPTER 2

CONFIGURATION OF ROUTERS

2.1 Introduction

In this chapter we will be explaining about the procedures that should be followed to configuring the cisco routers which will be described by the routing protocols, global parameter settings, and command –line access, we will be grilling into each of this topics. Studying these parameters are the basic concepts for the configuration on start up.

2.2 Default configuration

At the time we reboot a router, there will be some basic configurations that are already been performed. All the WAN and LAN interfaces that have been created, VTY and console ports configured and also the inside interface of the network address. We can use the following command to see the default configuration of a router.

show running-config

2.3 Basic information for configuration of routers

We need to gather some information depending on the plan of the network before configuring our network

• If you want to set up Internet connection, we have to collect the following information:

– Point-to-Point Protocol client name that was assigned to your login name

– Point-to-Point authentication type: Handshake Authentication Protocol (CHAP)

– Authentication Protocol (PAP)

– PPP password to access your Internet service provider .

– Domain Name System server IP address and the gateways.

• If you want to set up IP routing:

– Firstly we have generate an addressing scheme for our IP network.

– Determine the IP routing parameter information which includes ATM permanent virtual circuits (PVCs), and IP address. These PermanentVirtualCircuits parameters are typically virtual circuit identifier (VCI), virtual path identifier (VPI), traffic shaping parameters.

2.4 Configuring global parameters

The following are the common steps that are to be followed for the configuration of the routers.

Step 1: configure terminal

By using this command we will be entering into the global configuration mode

Example:

Router> enable

Router# configure terminal

Router(config)#

Step 2: hostname name

This command will specify the name of the router. We should specify the name of the router in the name space which is mentioned above.

Example:

Router(config)# hostname RouterA

Router(config)#

Step3:enable secret password

This command is to prevent unauthorized access to the routers. In general we wont keep any passwords to the routers in our laboratory.

Example:

Router(config)# enable secret radi

Router(config)#

Step 4: no ip domain- look up

This command will discard the typos(errors).

Example:

Router(config)# no ip domain-lookup

Router(config)#erfaces

2.5 Dealing with different interfaces

2.5 a Configure the Fast Ethernet WAN Interface

The following are the steps to configure Fast Ethernet interfaces:

Step 1:

interface type number

Example:

Router(config)# interface fastethernet 5

Router(config-int)#

Step 2:

ip address ip-address mask

Example:

Router(config-int)# ip address 190.164.12.1

255.255.128.0

Router(config-int)#

Step 3:

no shutdown

Example:

Router(config-int)# no shutdown

Router(config-int)#

Step 4 :

exit

Example:

Router(config-int)# exit

Router(config)#

2.5 b Configuration of a Loopback Interface

Loop back interface is used by the router to check its own TCP\IP stack.

Step 1 :

interface type number

By executing this command we can enter configuration mode for the loopback

interface

Example:

Router(config)# interface Loopback 1

Router(config-int)#

Step 2:

ip address ip-address mask

This command will set the IP address and subnet mask for loop back interface.

Example:

Router(config-int)# ip address 11.128.1.0

255.255.0.0

Router(config-int)#

Step 3 :

Exit

Returns from loop back mode to global configuration mode.

Example:

Router(config-int)# exit

Router(config)#

These are the details about the router configuration and we have tested and experienced each of the commands and also configured the interfaces which are mentioned above.

2.6 Summary

In this chapter I have explained about the basic configuration of routers which will be done in a step by step manner and explained about the default router configuration .If we want check whether the routers are being configured we need each other and check whether the packets are being sent .We also explained the configuration of various interfaces and also about the different configuration modes.

CHAPTER 3

IP Addressing

Introduction:

This chapter focuses on a detailed over-view of IP addressing scheme, IP classes and IP services to meet network requirements. Further this chapter breaks down the idea of sub-netting and VLSM (variable length subnet mask) concepts which are on top of the stack.

3.1 IP OVER-VIEW

IP address or internet protocol addressing is a name or a label given to network devices via which a device or a host communicates with other devices. IP address is an address in the real sense of the term. IP address is represented in dotted decimal notation. Each decimal number represents one octet (8-bits). However, the TCP / IP sees the IP address in binary form. The IP address is 32-bits. Therefore 232 combinations of IP addresses are possible. The IP address is divided into 4 octets each of which is 8-bits.

Figure 3.1 Dotted Decimal System representation

The above diagram represents the Dotted Decimal representation of IP addressing scheme. Each blocks in the figure 2.1 are filled with 0’s or 1’s which depends upon the IP Address. IP version 4 addressing scheme can address up to 232 = 4294967296 unique hosts. IANA- Internet Assigned Numbers Authority controls numbers for protocols, the Country Code Top Level Domains and maintains the IP Address allotments.

IP address is a combination of Network address and Host address.

IP = Network ID + Host ID

SUMMARY OF CLASSES

Figure 3.2 SUMMARY OF CLASSES

IP Classes

IP address is classified into five different classes as mentioned in the below table 3.1.

Class

Range

Subnet mask

Network

Host

Class – A

0-126

255.0.0.0

27-2

224 – 2

Class – B

128-191

255.255.0.0

214-2

216 – 2

Class – C

191-223

255.255.255.0

221-2

28 – 2

Class – D

224-239

255.255.255.255

Reserved for Multicast

Class – E

Research purpose

Table 3.1 IP Classes in brief

Table 2.1 shows the IP Address classes and its range. A Class A network address, the first byte is assigned to the network address and the three remaining bytes are used for the node address. Similarly a Class B and Class C network address, the first two and three bytes are assigned to the network address and the remaining two and one bytes are used for the node address respectively.

Reason for -2 in the Network ID:

The two combinations all 0's and all 1's are not valid because they are reserved for some functions mentioned below.

All 1's in class A Network ID produces 127.0.0.0, which is a Loop back Network. 127.0.0.1 - Loop back address used for trouble shooting purpose.

All 0's combination represents " ANY ", which means 0.0.0.0

Reason for -2 in the Host ID:

Here again two combinations are not valid since it is reserved for some functions mentioned below.

All 1's in the Host portion represents a broadcast. Example: 10.255.255.255 (Class A).

2. All 0's in the Host portion represents an entire network. Example: 10.0.0.0 (Class A).

3.3 Subnet Masks

A subnet mask is a logical division of an IP address into network and host portion. By making all network bits as "1" and all host bits as "0", a subnet mask can be generated.

3.4 Subnetting

Subnetting is made use when we want to take one network address and create smaller network groups. It is a process of logically dividing the network address of an IP into subnets. The technique behind sub-netting is borrowing or stealing the bits from the host position. The number of bits depends on the number of subnets. This breaks the single broadcast domain into smaller broadcast domain.

Why do we go for sub-netting?

Less IP wastage.

Single broadcast domain is divided into smaller broadcast domain.

Reduces the number of system unnecessarily receiving and processing packets.

Example:

192.168.100.41/27 – Here /27 denotes the number of 1 bits occupied by the network portion. In the above example 23 = 8 sub-networks can be created and 25-2 = 32 hosts can be accommodated in each of the 8 subnets.

Here, 192.168.100.0 represents the network address and 192.168.100.255 denotes the broadcast IP of the 192.168.100.0 network.

Variable-Length Subnet Masks (VLSM)

When a subnetted network is further subdivided to form sub-nets it is called as VLSM (Variable-length subnet mask). VLSM avoids wastage of IP address. And also it provides scalability i.e. if we add a new branch office we need not change all the subnets.

VLSM1

Figure 3.3 Implementation of VLSM

3.5 IP Version 6

IPv6 is an enhancement of IPv4. IPv6 is 128 bits in length. Therefore 2128 address are possible. It is expressed in Colon Hexa Decimal System. It provides more security. IPv6 was developed to overcome the bottle neck problems of IPv4.

Address exhaustion problem.

Provides better performance.

Improved management.

More secure.

3.6 Summary

IP address is a name or a label given to network devices via which a device or a host communicates with other devices. To divide networks into different smaller groups sub-netting and VLSM are used. IPv6, advancement of IPv4 makes the installation of network layer simple.

CHAPTER 4

VLANs

4.1 Introduction

In this chapter we will see how to configure virtual Local Area Networks (VLANs). A VLAN is a switched network which is segmented logically by project team, application or function without considering the location of users. By using VLANs we can connect the end users even though they are not located in the same LAN segment.

4.2 VLAN configuration mode options

We can configure VLANs (with VLAN Ids 1 to 1005) by using the following two configuration modes.

a) Config-vlan Mode

b) Database Configuration Mode

Let us discuss each of them in detail.

4.2 a) Config-vlan Mode

Firstly to access a config-vlan mode , enter the vlan into global configuration mode, specify the VLAN Id for the configuration. If we want to change the VLAN id we need to enter the VLAN or else enter multiple commands to configure a VLAN. After finishing the configuration we need to exit the config-vlan mode for the effective configuration. If we want to display the VLAN configuration we need type show vlan command.

4.2 b) Database Configuration mode

To enter into the VLAN database configuration mode we need execute vlan database command .To enter into a new VLAN id enter into an existing vlan and change the id. We can default vlan configuration or enter multiple commands to configure the vlans. When we have finished the configuration we need to type apply or exit commands for configuration to take the effect. When we type exit command, it will apply all the commands and will update the VLAN database.

4.3 Configuring normal range VLANs

The following steps are to be executed for the configuration of normal range VLANs

Step 1: configure terminal

To enter into global configuration mode.

Step 2:vlan vlan-id

To enter a vlan id we must enter into an existing vlan and modify with the requiring id.

Step 3:name vlan-name

To give a name to our VLAN ,or else a default name will be allocated.

Step 4:mtu mtu-size

To change the size of the Maximum Transmission Unit(MTU) and its optional.

Step5: remote span

Optinal

Step6: end

To return to privileged EXEC mode.

Step7: Show vlan

Displays your connections and to verify your entities.

The above steps are executed for the configuration of VLANs.

4.4 Deleting a VLAN

For deleting a VLAN we need to follow the steps which are mentioned below:

Step 1: configure terminal

To enter into global configuration mode.

Step 2:no vlan vlan-id

Remove the VLAN by vlan-id.

Step3:end

Returns to privilege EXEC mode.

Step4: Show vlan brief

To verify the removal of vlan.

The above steps are to be followed for the deletion of a vlan.

We can also create extended range VLANs.

4.5 Summary

In this chapter we have discussed the basic concept of VLANs and how they are being used. We have seen the configuration procedures for normal range and extended range VLANs, we have seen the two modes in which the VLANs can be configured. That are config-vlan mode and database configuration mode. We have also seen how to delete a VLAN from a network.

CHAPTER 5

ROUTING INFORMATION PROTOCOL

5.1 Introduction:

Routing Information Protocol is the abbreviation of RIP. RIP is a dynamic routing protocol. It advertises its network dynamically to all other connected networks. There are other dynamic routing protocols namely

RIP

OSPF

IGRP

The dynamic routing protocols itself is classified into two categories namely

DISTANCE VECTOR ROUTING

LINK STATE ROUTING

Dynamic routing protocols choose a route based upon some parameters. When the parameters are based on the number of hops in the network it is termed as Distance vector routing. Examples of Distance vector routing are Routing Information Protocol, Border Gateway Protocol etc. When the parameters are based on certain metric it is termed as Link State routing. Examples of link state routing are Enhanced interior gateway routing protocol, Open shortest path first etc.

S.no

Link state routing

Distance Vector routing

1.

They are partial. i.e. LSA that are affected by the topological change are sent

They are partial. i.e. sends all the routes all the time.

2.

Relationship is established with neighbouring router

No relationship is established with the neighboring routers

3.

Sends updates about the link in form of LSA- Link state advertisement.

Sends updates about the network ID’s itself.

Table 5.1 Distance vector routing vs link-state routing

5.1. a) Timers

Periodic updates are exchanged in Distance vector routing protocol. RIP keeps account of timers. the timers of RIP are as follows

Update timer : every 30 seconds

Invalid timer : 180 seconds

Hold down timer : 180 seconds

Flush timer : 240 seconds

5.1. b) Route poisoning:

RIP protocol will send a flash update as metric 16 when a network is down, denoting that the network is unreachable. This is called as route poisoning. Poison reverse is an acknowledgement for route poisoning.

RIPv1 vs RIPv2

RIPv1 is a simple dynamic routing protocol that sends flooded broadcast packets to advertise its network. RIPv2 is an advancement or enhancement of the version 1. The RIPv2 supports classless inter domain concept. They both make use of BELLMAN FORD algorithm.

5.3 Summary

RIP is popularly used dynamic routing protocol. The RIPv1 can only support up to 15 hops. This is a major limitation of RIPv1. The bottle neck problems of RIPv1 were resolved in RIP v2 with further more enhancements. RIP makes use Dijkstra algorithm to find the best available route in the network.

CHAPTER 6

CONCLUSIONS AND References

6.1 Conclusions

I gained immense knowledge in the networking environment through the various router configurations and by knowing the various types of cables and connectors. The labs in the first course provided me in depth knowledge about the intricate concepts in a simple way. The IP addressing lab brought an exposure to IP addressing scheme, Sub-netting, VLSM etc. In routing information protocol lab, I configured routers using dynamic routing protocols and tested its connectivity by pinging to the remote end router.