The Data Link Layer Parameters

Published Date: 02 Nov 2017

The report illustrates the basic information of serial connection, IP addressing, VLAN and routing protocols. It has mainly four sections. The first section describes the basics of serial connections in WAN topologies and the cables use in those connections.

Second section explains the IP terminologies in the network. In addition to this, it shows the classification of IPv4 addressing. It also explains the necessity of subnetting and its use in VLSM.

Third section describes the VLAN networks of switches. It also gives some basic commands to configure VLAN networks to increase security and decrease overhead of the network.

The last section shows the requirement of routing protocols in the network. It describes the different types of routing protocols based on their characteristics. Moreover, it gives detail description of RIP and its types.

INTRODUCTION

Serial Connections

In WAN technologies, serial connections are used for communication between networks. For example X.25, frame relay, ISDN and ATM technologies use serial connections. There are two types of serial connections (1) Synchronous Line (2) Asynchronous Line. Serial connections are full duplex. Most serial connections are in synchronous transmission mode. (Serial Connections, 2013).

IP Addressing

It a logical number which assign to a network device for communication purpose. IP address is a unique identifier of the network device. There are two types of IP addressing (1) IPv4 (2) IPv6. IPv4 is contains 32 bits for addressing while IPv6 is has 48 bits. IPv4 addressing is the oldest IP terminology which has two parts, a network part and a host part. According to these two parts of addressing bits, IPv4 addressing has five different classes. The range of IPv4 addressing is 0 – 255. Each IPv4 address has one subnet mask which indicate the class of that IP address and it is also help full to get network address of that IP address. Basically, IP addressing is very use full in routing protocols.

VLAN

VLAN provides logical grouping of different network devices. We can configure VLAN on switches. By using VLANs, we can improve security of the network and the performance of the network also increases.

C:\Users\HARSH\Desktop\cisco-switch-vlans.jpg

Figure 1. VLAN Networks (Net Tipps, 2011)

The above figure shows VLAN network. In this network one particular network device can communicate within same VLAN. So basically it also decreases the area of broadcast domains also. In VLAN administrator can easily handle network traffic and increase security of the network.

RIP

When one network device wants to communicate to other devices which are in different networks then we must implement the routing protocols. RIP is a distance vector routing protocol. Meaning that, it calculate it path using number of hopes between source and destination. In RIP maximum 15 hopes are allowed to reach at destination. It is one of the dynamic routing protocols means it updates its routing table automatically using the update which it gets from the other routers. There are three types of RIP. (1)RIPv1, (2) RIPv2, (3)RIPng (RIP, 2013).

Outline

The material in this report is organised into 9 chapters. The chapters deal with the following topics:

Chapter 2.....Serial Connections

Chapter 3.....IP Addressing

Chapter 4.....VLAN

Chapter 5.....Routing Protocols

Chapter 6.....Methodology

Chapter 7.....Configuration of Network

Chapter 8.....Laboratory Experiments and Results

Chapter 9.....discusses the results of all experiments and draws conclusions. The chapter also provides some recommendations and suggestions for any future work.

Serial Connections

This chapter explains the requirements of the serial connections in network topologies. It will introduce some common features and give the information to build the network using serial connections. In addition to this, it will describe the synchronous lines and asynchronous lines. At the end, it summaries all the information of serial connections.

Synchronous Line

In synchronous line, the data are transmitted by synchronizing the transmission at both the end, transmitter as well as receiver. A clock signal is used for synchronization. In this type of transmission, start and stop bit is not used. Therefore we can send more message and make the use of bandwidth more efficient. It is easier and simpler process of transmission. Generally DB-60 V.35 connector is used for these interfaces in the network. The following diagram shows the Winchester type DB-60 V.35 connector (Synchronous Serial Interface, 2013).

C:\Users\HARSH\Desktop\CAB-V35FC__17421.1331678801.1280.1280.JPG

Figure 2. DB-60 V.35 Connector (Serial Connection, 2012)

Physical Layer Parameters

In WAN topology, generally the connections are made between DCE (Data Circuit Equipment) and DTE (Data Terminal Equipment). The DCEs are the end communication devices across the network. E.g. personal computers, terminals, network host. The DCE devices provide the communication between DTEs. E.g. modems, switches (Serial Connections, 2013).

Generally three parameters are configured for physical layers and they are following.

Clock Rate

Bandwidth

Encoding Scheme

Data Link Layer Parameters

At data link layer the encapsulation is done using different protocols. For example PPP, HDLC, SDLC and LAPB. Generally in CISCO devices the HDLC protocol is used. But for non CISCO devices PPP is used and this is the standard protocol for encapsulation (Serial Connections, 2013).

Network Layer Parameters

In general, point-to-point connection has no requirement of IP address because it has only one destination. But if the network become complex then an interface must has an IP address for routing purpose (Serial Connections, 2013).

Asynchronous Lines

Generally, this type of transmission is not used in modem networks. Asynchronous mode is used to configure router using console port or it can be used between a printer and personal computer. The best example of this line is shown in laboratory where an asynchronous connection is made between the routers and terminal servers. Asynchronous lines are slow and because of this it can be use in backup mechanism between two nodes in the network. The cable used for asynchronous transmission is EIA/TIA-232. Sometimes RJ-45 cable is also used to support asynchronous interface. The following figure shows the EIA/TIA-232 cable (Serial Connections, 2013).

C:\Users\HARSH\Desktop\CAB-SS-232MT.jpg

Figure 2. EIA/TIA-232 (Computer Cable Store, 2013)

Difference between Synchronous Line and Asynchronous Line (Asynchronous Line, 2013)

Asynchronous transmission is cheaper than synchronous transmission because it does not require synchronization at any side of the network.

Asynchronous transmission is faster than other transmission. E.g. Data entry from Keyboard.

Synchronous transmission has lower overhead, so throughput is higher.

Synchronous transmission is more complex than asynchronous transmission and its components are also costly.

Summary

From the above chapter, we come to know about difference between synchronous transmission and asynchronous transmission. Generally, in serial connection between two routers, we use synchronous mode and for configuration we use asynchronous modes. Most of the serial connection uses synchronous transmission. These both have their own advantages and disadvantages and according to that we use efficient mode in network connections.

IP ADDRESSING

This chapter explains the requirement of IPv4 address in the network topology and it also gives the details description of different classes of IPv4 addressing. It shows the necessity of subnet mask, why subnetting is necessary in network and how can we achieve subnetting. It describes VLSM also.

IP Terminology

In network, every device must have one unique number to communicate with other devices. This number is called as IP address. Its range is between 0.0.0.0 to 255.255.255.255. It is a logical address of the network device not a physical address (address of NIC). It is a 32 bit binary number which distribute in 4 octets. These 32 bits contains the network bits as well as host bits (IP Addressing, 2013).

There are two types of IP address

Private IP Address

When a network device is not directly connected to the WAN topology then private address is used. Generally it is used in LAN (Local Area Network). There are three range are available for private IP address.

10.0.0.0 – 10.255.255.255

172.16.0.0 – 172.31.255.255

192.168.0.0 – 192.168.255.255

Public IP Address

When a network device want to communicate directly to the WAN then public IP address is used to assign that device.

Network Class

The IP address contains a network part and a host part. According to these two parts there are five different classes are available in IP addressing.

Figure 3. IPv4 Classification (IPv4 Addressing, 2013)

The above figure shows the classification of network classes. The details of these five different classes are following.

Class A

Range : 0.0.0.0 to 127.0.0.0

Subnet Mask : 255.0.0.0

Total Networks : 27

Host per Network : 224

[Note: 0.0.0.0 is not used in addressing because it is used as default path in routing protocols. 127.0.0.0 range is used in loopback addressing.]

Class B

Range : 128.0.0.0 to 191.255.255.255

Subnet Mask : 255.255.0.0

Total Networks : 214

Host per Network : 216

Class C

Range : 192.0.0.0 to 223.255.255.255

Subnet Mask : 255.255.255.0

Total Networks : 221

Host per Network : 28

Class D

Range : 224.0.0.0 to 239.255.255.255

[Note: It is used for multicast addresses.]

Class E

Range : 240.0.0.0 to 255.255.255.255

[Note: It is used for research purpose.]

Subnet Masks

A subnet mask is used for logical division of IP address. It divides a IP address into two parts (1) Network Part (2) Host Part. We expressed IP address in CIDR notation. The following example shows the CIDR notation.

E.g. 192.168.12.0/24 means network part has 24 bits and host has 8 bits.

We can find our network address by AND operation. To get network address of one particular IP address, we do AND operation between IP address and its subnet mask.

Subnetting

Subnetting is used to make efficient use of address space. It partitions the address into smaller part and each part is known as subnet. It reduces the network traffic and overheard also (Subnetwork, 2013).

Figure 3. Subnetting (Subnetting Operation, 2013)

The above figure shows that a number of host bits become a part of subnet and this is how subnetting is done. The number of subnets = 2n – 2, where n is the number of bits of subnet part of IP address. [Note: All 0’s and 1’s can’t be a valid subnet] (IPv4 Addressing, 2013).

VLSM

Variable Length Subnet Mask is one of the concepts of subnet mask which provides more than one subnet mask in network. It is kind of hierarchy of subnetted network address. The following figure shows the example where VLSM is used.

Figure 3. VLSM (IPv4 Addressing, 2013)

Summary

From this chapter we come to know about the requirement of IP address in the network. We also get the information of different classes of IP addressing. This chapter also helpful to understand the advantages to subnetting and the use of subnetting in VLSM.

VLAN

This chapter explains that why we need VLAN and how VLAN works in our network. It also gives some advantages of the VLAN and at the end it summaries all the information of VLAN.

Need of VLAN

In router we can’t create a small broadcast domain so it increases the traffic of the network and it decreases the performance of the network also. But using switch we can solve this problem. By implementing VLANs on switch we can create small broadcast domains. Therefore, a frame broadcast only its own VLAN. VLAN is a kind of logical grouping different network devices. In VLAN we can create individual collision domain for each device that attach with switch port (Lammle, 2007).

Generally, VLAN works in layer 2 of the OSI reference model. Cisco uses VTP, which is used to maintain consistency across the network.

Advantages

Admin can easily add, move and change network by configuring switch port with appropriate VLAN.

Admin can put a higher level security on one particular VLAN, so that normal user can’t access some resources which are very important.

VLAN is independent from physical topology. Meaning that it does not depend on geographic location.

When network traffic increases, VLAN can reduce by discarding the unnecessary destination.

By implementing VLANs, we can increase no of broadcast domains but their broadcast area decreases.

It increases the available bandwidth to the user then the user use bandwidth in shared network.

Summary

From this we come to about the functionality of VLANs. Basically VLAN is used to reduce the broadcast traffic of the network and mean while it reduce the overhead of the network. It also provides a high level security in switched networks. It is easy to implement and admin can easily manage this protocol.

ROUTING PROTOCOLS

This chapter describe that why we need to implement routing protocols and how routing works and in our network. In addition to this, it explains the types of routing used in network and the need of AD in these protocols. It describes the details description of the RIP.

How Routing Works In The Networks?

Once a physical network is built then we need a protocol which can help to communicate a device to other network device (To communicate between different VLANs). We use routing protocols to send a packet from source to destination. For that router must have following information to implement a routing protocol (Lammle, 2007).

A destination address of the network.

All the possible routes to reach other networks.

The efficient routes that can be used to send a packet to destination network.

With the help of all above information router build one routing table which is helpful to communicate to other networks. Router also maintains this routing table so that admin come to know about the update of the network topology.

There are two types of routing in the network.

Static Routing

An administrator has to enter the routing information manually. Generally, static routing is used in small networks.

Dynamic Routing

Router builds routing table by communicating to other routers using the same protocols. When network is more complex then dynamic routing is used. E.g. RIP, IGRP, EIGRP, and OSPF.

Routing Protocols

There are two types of routing protocols, which are following

Interior Gateway Protocol (IGP)

IGP is used when routers are in the same autonomous system (AS). An autonomous system is the collection of routers in the same domains. In IGP all the routers use the same routing table. RIP, IGRP, EIGRP, OSPF are the examples of IGP.

Exterior Gateway Protocol (EGP)

EGP is used when routers are in the different autonomous system (AS) and want to communicate with each other. BGP is the example of the EGP.

The following figure shows the Classification of different routing protocols.

Figure 5. Routing Protocols Classification (Dynamic Routing, 2011)

Administrative Distance

An administrative distance is the integer value of the routing information. This value has range from 0 to 255. According to this value router choose the path for routing.

Figure 5. Administrative Distance (Cisco, 2013)

Above figure shows the AD values for different routing protocols. In routing protocols, lower the value of AD higher the priority. If the two routes have same AD value then router uses the metrics (e.g. hop count) and according to metrics it selects the path for routing. If both AD and metrics values are same then router do load balancing between that two link.

RIP

RIP is a distance vector protocol. It uses the hop count to select the best path for routing. In RIP maximum 15 hops are allowed to reach at destination host. Meaning that, 16 hops are taken as unreachable host. For small network RIP is best option for routing protocols but for large network it is insufficient. RIP supports load balancing based on hops (Lammle, 2007).

Types Of RIP

RIPv1

It is class full routing protocol. RIPv1 does not support the VLSM (Variable Length Subnet Mask). Therefore, router does not send subnet mask in its update and all the routers use same subnet mask for routing. RIPv1 does not support authentication. RIPv1 broadcast its routing table into the network.

RIPv2

It is classless routing protocols. It supports variable length subnet mask. RIPv2 multicasts its routing table using 244.0.0.9. Because of this reason RIPv2 reduce the traffic into the network

RIPng

It supports IPv6 addressing. RIPv2 encode its next hop for routing table while RIPng needs specific encoding of its next hop for the entry of routing table.

RIP Timers

RIP uses different timers for routing and they are following. [Text Book]

Update Timer

It is used to send routing updates to other router in the network. Default update timer for RIP is 30 seconds. Admin can change this timer according to his requirement.

Invalid Timer

It is used to determine that particular path is not valid in network. Its default value is 180 seconds. If router does not get any update for one particular path up to 180 seconds then it send one update that this route is invalid to other routers in the network.

Holddown Timer

When router receives the update of unreachable route then it will enter into holddown state. Router keeps itself into this state, until it gets the new path or the default 180 seconds expires.

Flush Timer

This timer starts when a route become invalid. Its default value is 240 seconds. After 240 seconds it sends update of that unreachable path to its neighbours and deletes the entry from the routing table.

Summary

The above chapter described the information of different routing protocols. In addition to this, it shows the comparison of dynamic routing and static routing. It shows detail description of RIP and its different types. It also described the timers which are used in RIP.

METHODOLOGY

This chapter explains the method of VLAN implementation and RIP implementation. It also describes the subnetting of IP address. It will give step by step process to configure interface as well as protocol also.

IP Addressing

Subnet Mask

From chapter 3 we show that subnet mask is help full to get the address of network of one particular IP address. For that we need to do AND operation between IP address and its subnet mask. The following example shows it.

201.212.10.40/29 Host Part

< --------------------------- Network Part ---------------------- >< --- >

1 1 0 0 1 0 0 1 1 1 0 1 0 1 0 0 0 0 0 0 1 0 1 0 0 0 1 0 1 0 0 0

AND 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 Subnet Mask

= 1 1 0 0 1 0 0 1 1 1 0 1 0 1 0 0 0 0 0 0 1 0 1 0 0 0 1 0 1 0 0 0 Network

Subnet Mask : 255.255.255.248

Network Id : 201.212.10.40

Broadcast Address : 201.212.10.47

VLSM

In VLSM, we use hierarchy of subetted network address. The following example shows the example of VLSM. In this 172.16.0.0/16 is subnetted into different subnet which has mask of 30 bits in length.

C:\Users\HARSH\Desktop\lab 3.png

Figure 6. VLSM Example (IPv4 Addressing, 2013)

VLAN Implementation

We will follow the following procedure to implement VLAN network.

At Router

Configure the applicable interfaces by assigning IP addresses which are connected to the switch ports.

Make those interfaces administratively up.

At Switch

Create VLANs and assign a unique name to that VLAN.

Assign VLAN number to switch port according to requirement.

Ping the devices which are in same VLANs to check whether they are configure properly or not.

Routing Protocols

In chapter 5, we show that we need to implement routing protocols for communication between different VLANs.

RIP

We will follow the following procedure to implement RIP protocol for routing.

Configure the applicable interfaces of the router by assigning IP addresses to all.

Make those interfaces administratively up.

Enable RIP version 2 at all routers.

Enter the directly connected network to the router.

Disable auto summary of network address.

Ping the devices between different network to check whether RIP is implement properly or not.

Static Routing

We will follow the following procedure to implement static routing.

Configure the applicable interfaces of the router by assigning IP addresses to all.

Make those interfaces administratively up.

Enter the route manually to reach at destination network including next hop address.

Ping the devices between different network to check whether static routing is implement properly or not.

Summary

The above chapter explains the method of implementing different protocols like RIP, static routing. It also describes the step to setup VLANs and RIP into the network. In addition to this it shows how we can get network address using subnet mask of the IP address.

CONFIGURATION OF NETWORK

This chapter describes the different commands which are used to configure different network. In this we will see the configuration of VLAN network, RIP (Routing Information Protocols) and static routing.

VLAN

Figure 7. VLAN Physical Topology (VLANs, 2013)

Figure 7. VLAN Logical Topology (VLANs, 2013)

7.1.1 Configure Interface

Router>enable

Router#configure terminal

Router(config)#hostname 5R4

5R4(config)#interface fastEthernet 1/1

5R4(config-if)#ip address 192.168.4.2 255.255.255.0

5R4(config-if)#no shutdown

5R4(config-if)#do show ip interface brief

By executing above commands we have configure the interface of Router 4. Similarly, we configure the applicable interfaces of remaining all routers.

Configure VLAN

Switch>enable

Switch#configure terminal

Switch(config)#hostname 5S1

5S1(config)#vlan 4

5S1(config-vlan)#name D

5S1#show vlan brief

Similarly, we create VLAN 2 and VLAN 3 also. Now we assign vlan number to the switch ports by executing following commands.

5S1(config)#interface gigabitEthernet 0/13

5S1(config-if)#switchport mode access

5S1(config-if)#switchport access vlan 4

Similarly, assign applicable vlan to different switch ports. We can check whether our network is working properly or not using, PING command.

Routing Protocols

Figure 7. RIP Logical Topology (RIP, 2013)

Configure Interface

Router>enable

Router#configure terminal

Router(config)#hostname 5R4

5R4(config)#interface fastEthernet 1/0

5R4(config-if)#ip address 192.168.52.4 255.255.255.0

5R4(config-if)#no shutdown

5R4(config-if)#do show ip interface brief

By executing above commands we have configure the interface of Router 4. Similarly we configure the applicable interfaces of remaining all routers.

Configure RIP

5R4>enable

5R4#configure terminal

5R4(config)#router rip

5R4(config-router)#version 2

5R4(config-router)#network 192.168.52.0

5R4(config-router)#network 192.168.51.0

5R4(config-router)#do show ip route

5R4(config-router)#do show ip protocols

Similarly by executing above commands in remaining Router 1, Router 2 and Router 3, we can configure RIP. We can check whether our network is working properly or not using, PING command.

Configure Static Routing

5R4>enable

5R4#configure terminal

5R4(config)#ip route 192.168.53.0 255.255.255.0 192.168.52.3

5R4(config)#ip route 192.168.50.0 255.255.255.252 192.168.51.1

5R4(config)#do show ip route

Similarly by executing above commands in remaining Router 1, Router 2 and Router 3, we can configure static routing. We can check whether our network is working properly or not, using PING command.

Summary

From the above chapter we can know that how to configure VLAN, RIP and static routing using command prompt.

LAB EXPERIMENTS & RESULTS

This chapter describes the experiments done in the laboratories and the results obtained from them.

VLAN Network

After configuring VLAN network, using "show vlan brief" command (7.1), we can know about VLANs of the network and the switch ports which assign to the different VLAN. Using "ping <destination address>" command, we can check connectivity of the network.

Routing Protocols

RIP

Using "show ip protocols" command (7.2), we can know about the implemented routing protocols of the network. After configuring RIP, "show ip route" command (7.2) is used to see routing table of the router. The routes of RIP are mention as "R" in the routing table. Using "ping <destination address>" command, we can test that RIP is implemented properly or not.

Static Routing

After configuring static routing, "show ip route" command (7.2.2) is used to see the route entry of the static routing. The static routes are denoted as "S" in the routing table. By executing "ping <destination address>" command, we can check our network connectivity.

Summary

This chapter shows that which commands are use full to check the implementation of different protocols and its connectivity of the network.

CONCLUSION AND RECCOMANADATION

CONCLUSION

From all above chapters, we get the information regarding serial communication, IP addressing, VLAN networks and routing protocols. From chapter 2, we come to know that in most serial communications, synchronous transmission is used. Chapter 3 conclude that subnetting is very useful in networking to make efficient use of addressing. From chapter 4, we get that VLANs are advisable to increase the security of the network and decrease the traffic of the network. Chapter 5 illustrates the routing protocols are necessary to communicate between different networks. In addition to this, it also concludes that dynamic routing protocols are more efficient than static routing protocol.

RECCOMANDATION

We have seen two types of routing protocols from chapter 5. If the network is small then static routing is the best option to implement routing protocols. In big and complex network dynamic routing is more efficient because administrator do not have to worry about routing table entries if network is updated. VLAN implementation is also using full to increase the security of the networks.

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