Friday 31 January 2014

Network Topology

Network Topology

Topology refers to physical arrangement of computers, cables, and switches or networking devices.

there are main 6 topology.

  1. Bus topology
  2. Ring topology
  3. Star topology
  4. Mesh topology
  5. Hybrid Topology
  6. Tree Topology

Bus topology

a bus topology is a type of network setup where each computer and network device is connected to a single cable.


Advantages of a Bus Topology

  • Easy to connect a computer or peripheral to a linear bus.
  • Requires less cable length than a star topology.

Disadvantages of  Bus Topology

  • Entire network shuts down if there is a break in the main cable.
  • Terminators are required at both ends of the backbone cable.
  • Difficult to identify the problem if the entire network shuts down.
  • Not meant to be used as a stand-alone solution in a large building.


Ring Topology


In Ring Topology, all the nodes are connected to each-other in such a way that they make a closed loop. Each workstation is connected to two other components on either side, and it communicates with these two adjacent neighbors. Data travels around the network, in one direction. Sending and receiving of data takes place by the help of TOKEN.

Advantages of Ring Topology

  • This type of network topology is very organized. Each node gets to send the data when it receives an   empty token. This helps to reduces chances of collision. Also in ring topology all the traffic flows in only one  direction at very high speed.
  • Even when the load on the network increases, its performance is better than that of Bus topology.
  • There is no need for network server to control the connectivity between workstations.
  • Additional components do not affect the performance of network.
  • Each computer has equal access to resources.

Disadvantages of Ring Topology

  • Each packet of data must pass through all the computers between source and destination. This makes it slower than star topology
  • If one workstation or port goes down, the entire network gets affected.
  • Network is highly dependent on the wire which connects different components. 
  • MAU’s and network cards are expensive as compared to Ethernet cards and hubs. 


Star Topology

a Star topology is one of the most common network setup where each of the devices and computers on a network connect to central hub or switch.

Advantages of a Star Topology
  • Easy to install and wire.
  • No disruptions to the network then connecting or removing devices.
  • Easy to detect faults and to remove parts.

Disadvantages of a Star Topology

  • Requires more cable length than a linear topology.
  • If the hub or concentrator fails, nodes attached are disabled.
  • More expensive than linear bus topologies because of the cost of the concentrators.


Mesh Topology

A network setup where each computer and network device is interconnected with one another, allowing for most transmissions to be distributed, even if one of the connections go down. This topology is not commonly used for most computer networks as it is difficult and expensive to have redundant connection to every computer. 

Advantage of Mesh Topology

  • Mesh topology provide more path for communication
  • high speed data transmission
  • low packet overhead
  • less traffic in a network

Disadvantage of Mesh Topology


  • High installation Cost.
  • Require more complex network structure

Hybrid Topology


Hybrid, as the name suggests, is mixture of two different things. Similarly in this type of topology we integrate two or more different topologies to form a resultant topology which has good points(as well as weaknesses) of all the constituent basic topologies rather than having characteristics of one specific topology. These combination of topologies are done according to the requirements of the organization.





Tree Topology

A tree topology connects multiple star networks to other star networks


Router Configuration

Components of Router


  • Console port : This Port is used for configure a Router.
  • 10/100 Ethernet Port : This port is used to connect LAN, or Switches
  • Serial Port : It is used for Router-Router Communication
  • Aux : It is used for connecting a modem.

Router RAM

  • SDRAM : Router running on this RAM, If Router is switch off, Data(Configuration with out saved) will be lost.
  • NVRAM : During a Start up, Router is booted from this RAM, 

Router works in two mode
  1. User mode
  2. Privilege mode
When IOS is loaded by router Ram, By Default the router is in User mode
In this mode router is secure. Various Encryption Method is applied on it.

In Privilege Mode, We can configure the router.

step by step command for configure the router.

When router is in User Mode, Then prompt is looked like this.
 For transferring from user mode to Privilege Mode we have to write enable command
In Privilege Mode,the prompt is looked like this


the various command for security, Router startup message, interface configuration,etc..


R1(config)#hostname R1
the command hostname is used for changing name of host

R1(config)#banner motd "This is Router 1"
this command is used for displaying message "This is Router 1",when router start

R1(config)#enable secret abdul :
this command set password abdul, for changing User Mode to Privilege Mode.

R1(config)#line console 0
R1(config-line)#password console
R1(config-line)#login
R1(config-line)#exit
line console is set to configuration mode on console port.
password console is set password console on the console port. when user want to configure router through console port, this password is compulsory.
login make password activate on console port

R1(config)#interface fa 0/0
R1(config-if)#ip address 20.0.0.01 255.0.0.0
R1(config-if)#no shutdown

interface fa 0/0 is used to configure fast Ethernet port of router
here we assign ip using ip address 20.0.0.1 255.0.0.0 command
no shutdown is used for putting port on.

R1#show ip int brief
this command is used for showing all the configuration of interfaces

R1#copy run start
this command is used for saving a current configuration on NVRAM.

Thursday 30 January 2014

Internet protocol versions

Why we use Internet protocol?
-Internet protocol is a method or protocol, through which we can sent out data from one computer to another.

Different version of Internet Protocols
IP version 1 to 3 were not formally assigned.
IP version 4 (IPv4)- TCP/IP , having a 32 bit address. it is currently used.
IP version 5- Streamed Protocol (ST), Connection Oriented internet level Protocol.
IP version 6 (IPv6) having 128 bit address, designed for replacement of IPv4.

Difference Between IPv4 and IPv6
Internet Protocol version 4 (IPv4)
Internet Protocol version 6 (IPv6)
Source and destination addresses are 32 bits (4 bytes) in length.
Source and destination addresses are 128 bits in length.
IP header includes a checksum.
IP header does not include a checksum.
IP header includes options.
All optional data is moved to IPv6 extension headers.
IPSec support is optional.
IPSec support is required in a full IPv6 implementation.
No identification of payload for QoS handling by routers is present within the IPv4 header.
Payload identification for QoS handling by routers is included in the IPv6 header using the Flow Label field. For more information.
Address Resolution Protocol (ARP) uses broadcast ARP Request frames to resolve an IPv4 address to a link layer address.
Uses multicast Neighbor Solicitation messages for address resolution.
Internet Group Management Protocol (IGMP) is used to manage local subnet group membership.
Uses Multicast Listener Discovery (MLD) messages to manage local subnet group membership.
Addresses must be configured either manually or through Dynamic Host Configuration Protocol (DHCP).
Addresses can be automatically assigned using stateless address auto configuration, assigned using Dynamic Host Configuration Protocol version 6 (DHCPv6), or manually configured.
Uses host address (A) resource records in the Domain Name System (DNS) to map host names to IPv4 addresses.
Uses host address (AAAA) resource records in the Domain Name System (DNS) to map host names to IPv6 addresses.
Uses broadcast addresses to send traffic to all nodes on a subnet.
There are no IPv6 broadcast addresses. Instead, multicast scoped addresses are used. For more information.
Fragmentation is supported at originating hosts and intermediate routers.
Fragmentation is not supported at routers. It is only supported at the originating host. For more information.

Networking Protocols

what is network protocols?
-network protocol is used defines rules and conventions for communication between network devices

Internet protocols
Internet Protocol (IP)is the primary network protocol used on the Internet, developed in the 1970s. On the Internet and many other networks, IP is often used together with the Transport Control Protocol (TCP) and referred to interchangeably as TCP/IP.
Besides Internet Protocol(IP) itself, higher-level protocols like TCP, UDP, HTTP, and FTP all integrate with IP to provide additional capabilities.

Routing protocols
Routing protocols are designed specifically for use by network router on the Internet. Common routing protocols include EIGRP, OSPF and RIP.

DIFFERENT PROTOCOLS AND THERE USE
Protocol Name
Use
Port no.
Telnet
Used for remote connection
23
FTP (File Transfer Protocol)
Transmission of files in network
21
TFTP(Trivial File Transfer protocol)
a technology for transferring files between network devices.
60
NFS(Network File sharing)
Sharing of files in a particular network
2049
SMTP(Simple Mail Transfer Protocol)
Used for sending  e-mail
25
POP (Post Office Protocol)
Used for Receiving of e-mail
110
IMAP4(Internet message access protocol)
Used for  retrieval a e-mail
993
TLS (Transport Layer Security)
It provide security of data
With IMAP : Port 993
With POP  : Port 995
With SMTP: Port 465
RTP(Real Time Protocol)
Live streaming Or live Chatting

Xwindow
Generate graphical window
Start form 6000
HTTP(HyperText Transfer Protocol)
Used for transferring of HTML data
80
SSH(secure Shell)
Work same as TELNET,But in secure way
22
NTP(Network Time Protocol)
Used for maintaining Time accurate in a network
123
NNTP
Used for transferring of news in a network
119
SCP (Secure Copy Protocol)
Copy a file in network.Most used in linux operating system.
22
IGMP(Internet Group Message Protocol)
Used for group messaging

LPR(Line Printer Daemon Protocol)
Used for printing purpose
515
DNS(Domain name service)
Name resolution
53
DHCP(Dynamic Host Configuration Protocol)
Assign IP automatically
For server : 67
For client : 68