The History Of Serial Connections

Published Date: 02 Nov 2017

Wide area network which covers a large geographical area in terms which connects to many LANs via either serial connections or parallel connections. In which parallel connections sends data at a time on a set of lines and not suitable for longer communications because probability of errors and delays. But where as in serial connections used in wide area networks such as ATM: Asynchronous Transfer Mode and ISDN: Integrated services digital network, data sent at one time and its provides faster communication. In our laboratory the assignment deals with the serial connections to establish a point to point connection between the routers and to ensure successful transmission the ping command is used. In serial connections mainly three parts are discussed which are synchronous lines, asynchronous lines and frame analysis.

1.2 SYNCHRONOUS LINES

In synchronous line transmission mode the sender and the receiver managed to get a clock sequence in order to ensure a correct transmission of data. In laboratory usually a DB-60Z V.35 connector is used as a synchronous line transmission connector which uses a DB-60 connector in one end and either DB-60 or Winchester-type connector at another end.

Figure 1.2.i DB-60 Connector

Source (http://www.cromwell-intl.com/tcpip/network-cables.html)

1.2.1 PHYSICAL LAYER PARAMETERS

Every Wide area network technology has got its own physical layer interface standards and which in terms define about connection between two ends DTE and DCE. DTE: Data Terminal Equipment i.e. user end. DCE: Data Circuit-Terminating Equipment i.e. source end. In lab we find these two ends, so to find which end is DTE or DCE we use the following command

show controller serial <interface number>

To ensure with clocking information the clock rate command is used. The default data rate for the standard serial interface is up to 2 Mbps, Other types of serial interfaces support bit rates up to 52 Mbps. Use the command to change the bit rate.

clock rate<rate in bps>

the bandwidth command is used to get the bandwidth information.

bandwidth<kbps>

The default data encoding scheme used in standard serial interface is non return to zero (NRZ). And some times Non return to zero inverted (NRZI) encoding is used. To communicate, both ends should agree the encoding scheme.

nrzi-encoding

To return default condition, use command

no nrzi-encoding

the above mentioned commands are used in router configuration if mode

1.2.2 DATA LINK LAYER PARAMETERS

The data in serial interfaces can be encapsulated in data link protocols such as HDLC: High Level Data Link Control Protocol and PPP: Point to Point Protocol

For complete list of protocols that are supported can know by following command encapsulation

encapsulation <protocol> used in router configuration if mode

1.2.3. NETWORK LAYER PARAMETERS:

In the network layer, IP address can be assigned to the serial interface for the purpose of the routing. While assigning the IP address, mask address also assign with it. IP address can be assigned with the mask by using the command

ip address<address> <mask> used in router configuration if mode

1.3. FRAME ANALYSIS:

The traffic analyzers are used to connect the different routers in a network capturing the frame by using ping command.

<destination ip address> used in router mode

1.4 ASYNCHRONOUS LINES:

Asynchronous transfer mode treats each character individually which sent whole character at a time the receiver will samples every bit this is not suite for large blocks of data. Usually each character contains 5 to 8 bits, start bit is one, and stop bits are two bits. In this parity bit will be one bit. This mode takes more time in data 1transmission due to the overhead bits in the each character. The data transmitted with the overhead bits so a possible error can be occurred in the receiver. A framing error also occurred due to the noise conditions. Asynchronous transmission is simple and cheap but it is inefficient entirely compare to the synchronous.

The show line command is used to list all the lines of asynchronous and their numbers

show line on router

Asynchronous interface can be configured by following steps:

The interface a sync command is used to create an asynchronous interface.

interface async no

The encapsulation command is used to select a data link protocol.

encapsulation <protocol>

The use async mode dedicated command is used to enable mode

async mode dedicated

Use the following command to assign the ip address

ip address

the above commands are used in configuration mode

IP Addressing

2.1 PREFACE TO IP:

Internet protocol is a well known protocol in TCP/IP as a network layer protocol. One of the services of this protocol includes addressing known as IP addresses. As like to identify a location of the particular houses in a area by providing home numbers the IP addressing is used to identify a particular device on a internetwork. 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 and it uses a 32 bit logical address.

Figure: 2.1 A typical internetwork with IP addressing

2.1.1 BINARY AND DOTTED DECIMAL REPRASENTATION:

A typical IP address uses 32 bits to form a IP address. Therefore 232 combinations of IP addresses are possible Usually it is in binary representation so the devices can easily get through by that address. For our convenience the 32 bit address is divided in to four sections each of 8 bits called bytes or octets

Figure 2.1.1 IP address format

Then each octet of binary number numbers converted in to dotted decimal notation for understanding of numbers in decimal which is usually between 0 and 255. The figure 2.1.1 explains a typical 32 bit address in both dotted and binary representation.

Figure 2.1.1.a : binary to decimal conversion

The figure 2.1.1.1 explains how a binary number is converted to decimal number for example a binary number 10010110=128+0+0+16+0+4+2+0=150

2.2 NETWORK CLASSES :

For easier communication the IP address is divided in to network classes in a typical 32 bits of 4 octets the leftmost bits for network identity and right most bits for host indentification

IP= Network ID + Host ID

Figure 2.2 SUMMARY OF CLASSES

The valid range of network address in each class are described below figure

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 2.1 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.

2.3 SUBNETTING :

Sub-netting 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. Sub netting has got several advantages like IP wastage is less and broadcast domain is divided in to even smaller domains for efficient use

For a given IP address we can find the Network ID and Host ID by performing AND operation on

2.3.1 SUBNETMASKING

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.

For a given IP address we can find the Network ID and Host ID by performing AND operation by subnet mask i.e. /xx notation. A typical /xx is represents as example /24 in binary will be 11111111.11111111.11111111.00000000

Example: 115. 16. 193. 6 / 21

01110011 00010000 11000001 00000110

11111111 11111111 11111000 00000000

…………………………………………..|………………………..

01110011 00010000 11000000 00000000 – Network ID(logical AND)

……………………………………………………………………….

Broadcast ID will get by adding 111 11111111 to Network ID

Subnet Mask – 11111111.11111111.11111000 i.e. 255.255. 248.0

Network ID – 01110011.00010000.11000000 i.e. 115.16. 192.0

Broadcast ID -01110011.00010000.11000111.11111111 i.e. 115.16.199.25

Number of subnets calculated by using 2N and number of valid hosts will be calculated 2N-2

2.4 VARIABLE-LENGTH SUBNET MASKS (VLSM)

When a sub-netted network is further subdivided to form sub-nets it’s 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.

Figure 2.4 Implementation of VLSM

2.5 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.

4 ROUTING INFORMATION PROTOCOL

4.1 INTRODUCTION:

RIP is abbreviated as Routing information protocol is a dynamic routing protocol in which information of packet transmission is handled by dynamically which means router decides the routing path rather than fixed path by sender in static routing. The dynamic routing protocol it self divided into two different categories 1) Distance vector protocol 2) 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

4.2 ROUTING INFORMATION PROTOCOL version 2

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.

4.2.1 CONFIGURATION

The main function of the router is to send the packets to different networks connected to it based on traffic and routing table. The data can be reach the destination by following routing techniques 1) Static routing : in which a preplaned route is assigned for data by sender 2) Dynamic routing : this defines packets may individually can use any router to reach the destination.

In order to configure the routing in lab first we have to configure the given pod by choosing routers individually and giving IP address to interfaces that available in diagram at laboratory manual make sure with the switch default configuration and we have to ensure all interface links are UP before proceeding we use commands like router rip and version 2 for enabling rip after completion of that we can also check for routing paths to all networks by the command show ip route

Figure 4.2 configuration of RIP

4.2.2 STATIC AND DEFAULT ROUTERS :

The dynamic routing protocol is used for better performance and the advantage of the dynamic routing protocol is that if it requires it may changes the network topologies. Most probably the dynamic routing protocol is used unless they think overhead wastage for small networks then static routing protocol used for those purposes.

The disadvantage of the static routing protocol is that it fixes a network topology the change of adaption of network topology is not allowed in case of failure.

A special case of static routing protocol is default routing protocol in which the static route avoid all destination routes in the routing table. But it indicates router to forward all traffic to the next hop. When packets are needed to be forwarded, router tries to find next hop to their destination in the routing table.

4.3 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.

5 CONCLUSIONS AND RECOMMENDATIONS

4.1 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.