Saturday, 19 December 2020

IP Routing

What is IP Routing?

IP routing is the field of routing methodologies of Internet Protocol (IP) packets within and across IP networks. This involves not only protocols and technologies but includes the policies of the worldwide organization and configuration of Internet infrastructure. In each IP network node, the following IP routing involves the determination of a suitable path for a network packets from a source to its destination in an IP network. Therefore the process uses static configuration rules or dynamically obtained status information to select specific packet forwarding methods to direct traffic to the next available intermediate network node one hop closer to the desired final destination, a total path potentially spanning multiple computer networks.

Networks are separated from each other by specialized hosts, called gateways or routers with specialized software support optimized for routing. In routers, the following packets arriving at an interface are examine for source and destination addressing and queue to the appropriate outgoing interface according to their destination address and a set of rules and performance metrics. Therefore the rules are encoded in a routing table that contains entries for all interfaces and their connected networks. However, if no rule satisfies the requirements for a network packet, it is forward to a default route. Routing tables are maintains either manually by a network administrator, or updated dynamically with a routing protocol. Routings rules may contain other parameters than source and destination, such as limitations on available bandwidth, expected packet loss rates, and specific technology requirements.

Routing Protocol

A routing protocol is a software mechanism by which routers communicate and share information about the topology of the network, and the capabilities of each routing node. It thus implements the network-global rules by which traffic is direct within a network and across multiple networks. However, different protocols are often uses for different topologies or different application areas. For example, the Open Shortest Path (OSPF) protocol is generally use for routing packets between subnetworks within an enterprise and the Border Gateway Protocol (BGP) is use on a global scale. Therefore BGP is the standard of worldwide Internet routing.

Types of IP Routing

The following types of IP routing are

  1. Static
  2. Default
  3. Dynamic

1. Static Routing

In static routing, administrator manually adds routes in each router’s routing table.

Command

Ip route < destination network > < mask > < next hop add or exit interface > < administrative distance > < permanent

Example: IP route 192.168.10.0    255.255.255.0   192.168.20.1

To show routing table

# show ip route

2. Default Routing

Default routing use in sub network where there is only one way.

Example: IP route 0.0.0.0   0.0.0.0   192.168.20.1

Administrative distances

Administrative distance is used to rate the trust worthiness of routing information received on a router from a neighbour router.

Default administrative distance

The following default administrative distance are

Connected interface                                      0

Static route                                                      1

EIGRP                                                                90

IGRP                                                                  100

OSPF                                                                  110

RIP                                                                     120

External EIGRP                                                170

Unknown                                                          255 (this route will never be used)

3. Dynamic Routing

Protocols are used to find networks and update routing tables on routers. Therefore the routing protocols used to determine the path. Example: RIP, IGRP, OSPF, etc, and routed protocols that carries the packets, Example: IP, IPX, and AppleTalk.

Learn about Bootstrap Protocol (BOOTP)

  

Internet Protocol Address (IP Address)

Internet Protocol Address (IP Address) Explained

           IP-ADDRESS is a logical address or software address which mentions the network & host in Hierarchical manner. It is a 32 bit address in 4 Octet Eight.

There are two types of IP Addresses

  • Public IP Address
  • Private IP Address

e.g.     1st Octet             2nd                   3rd                       4th

         11111111  .   11111111     .  11111111   .11111111     = 32 bit

            (eight)                  (eight)                     (8)             (eight)

                                    10          0  0  5

                                  Net ID     Host ID

CLASSES OF IP- ADDRESS

The classes of IP Addresses have 5 types of classes they are

CLASS                                          RANGE

A                                                1-126  ( 127- loopback address (or) Self Pinging Address)   To check the connectivity of LAN

B                                                128-191

C                                                192-223

D (Multicasting)                       224-239

E  ( Defense & Research)       240-255

Small concept: 1         1        1       1        1        1       1        1

                        128     64      32     16       8        4       2        1

e.g.  255    255        255

      -128     -64        -32

      127      191        223

ISP- INTERNET SERVICE PROVIDER (PUBLIC ADDRESS FOR WAN)

 From ISP only we get IP-ADDRESS

PRIVATE IP – ADDRESS

CLASS A :- 10.0.0.0  to 10.0.0.255

            10.0.0.0 for 1 N/W Max IP-Addresses possible in Class A - 2536*256*256 = 1,67,77,216

CLASS B:-172.16.0.0 to 172.31.255.255

[ Private N/W = 16] Max IP-Addresses for 1 N/W in Class B  - 256*256 =65,536

CLASS C :- 192.168.3. to 192.168.255.255

            Max IP-Addresses for 1 N/W  in Class C – 256 =256

HOST ID

             IP Addresses of the Host is called as Host ID

e.g.   CLASS A         CLASS B             CLASS C

            10.0.0.1       172.168.10.1          192.168.10.1

NET ID

            The network Address of the Host is called as Net ID

e.g. CLASS A        CLASSB               CLASS C

       10.0.0.0            172.168.0.0          192.168.0.0

DEFAULT GATEWAY

             It is the IP-Addresses given in a network ,which enables all the client computers to communicate with Router . The starting Address of any N/W should be the gateway Address for that N/W.




EASY TABULATION

                                       CLASS A             CLASSB             CLASS C

IP-ADDRESSES             1 to 126                   128 to 191             192 to 223

HOST ID                    N.H.H.H                  N.N.H.H                 N.N.N.H
NET ID                       N.0.0.0                     N.N.0.0                  N.N.N.0
SUBNET MASK        255.0.0.0                  255.255.0.0           255.255.255.0

Learn about Subnet Mask

  

IEEE 802.1X

What is IEEE 802.1X?

IEEE 802.1X is an IEEE standard for post based network access control (PNAC). It is a part of IEEE 802.1 group of networking protocols. It provides an authentication mechanism to devices wishing to attach to a LAN or WLAN. IEEE 802.1X defines the encapsulation of the extensible authentication protocol (EAP), which is known as “EAP over LAN” or EAPOL. EAPOL was originally designed for IEEE 802.3 Ethernet in 802.1X-2001, but it was clarified to suit other IEEE 802 LAN technologies such as IEEE 802.11 wireless and fiber distribution data interface (ISO 9314-2) in 802.1X-2004. 802.1X authentication involves three parties such that a supplicant, an authenticator, and an authentication server.

The supplicant is a client device such as laptop that can be able to attach to the LAN or WLAN. The term “supplicant” is also used interchangeably to refer to the software running on the client that provides credentials to the authenticator. The authenticator is a network device which provides a data link layer between the client and the network and can allow or block network traffic between the two, such as an Ethernet switch or wireless access point.

The authentication server is typical trusted server that can receive and respond to the requests for network access, and can tell the authenticator if the connection is to be allowed, and various settings that should apply to that client’s connection or setting. Therefore the authentication server typically run software supporting the RADIUS and EAP protocols. In some cases, the authentication server software may be running on the authenticator hardware.

Typical Authentication Procedure

The typical authentication procedure consists of

  • Initialization
  • Initiation
  • Negotiation
  • Authentication


Learn about IEEE 802.11b

   

IEEE 802.11

What is IEEE 802.11?

IEEE 802.11 is a part of the IEEE 802 set of local area network (LAN) protocols and specifies the set of media access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) Wi-Fi computer communication in various frequencies, including but not limited to 2.4 GHz, 5 GHz. 6GHz, and 60 GHz frequency bands. The base version of the standard was released in 1997, and has had subsequent amendments. The standard and amendments provide the basis for wireless network products using the Wi-Fi brand.

IEEE 802 are the world’s most widely used wireless computer networking standards, used in most home and office networks to allow laptops, printers and smartphones to communicate to each other and access the Internet without connecting wires. They are created and maintained by the Institute of Electrical and Electronics Engineers (IEEE) LAN/MAN standards committee (IEEE 802).

The 802.11 family consists of a series of half-duplex over the air modulation techniques that use the same basic protocol. The 802.11 protocol family employs carrier-sense multiple access with collision avoidance whereby equipment listens to a channel for other users including non 802.11 users before transmitting each packet.

Standard and Amendments

The following IEEE standards association standard and amendments are such as

  • 1997-IEEE 802.11
  • 1999-IEEE 802.11a
  • 1999-IEEE 802.11b
  • 2001-IEEE 802.11c
  • 2001-IEEE 802.11d
  • 2005-IEEE 802.11e
  • 2003-IEEE 802.11f
  • 2003- IEEE 802.11g
  • 2004-IEEE 802.11h
  • 2004- IEEE 802.11i
  • 2004- IEEE 802.11j
  • 2007- IEEE 802.11
  • 2008- IEEE 802.11k
  • 2009- IEEE 802.11n
  • 2010- IEEE 802.11p
  • 2008- IEEE 802.11r
  • 2011- IEEE 802.11s
  • Cancelled- IEEE 802.11t
  • 2011- IEEE 802.11u
  • 2011- IEEE 802.11v
  • 2009- IEEE 802.11w
  • 2010- IEEE 802.11y
  • 2012- IEEE 802.11-2012
  • 2012- IEEE 802.11aa
  • 2013- IEEE 802.11ac
  • 2012- IEEE 802.11ad
  • 2014- IEEE 802.11af
  • 2016-IEEE 802.11-2016
  • 2016- IEEE 802.11ah
  • 2016- IEEE 802.11aj
  • 2018-IEEE 802.11aj
  • 2018-IEEE 802.11ak
  • 2018- IEEE 802.11aq

In Process

1. 2020- IEEE 802.11ax

2. 2020- IEEE 802.11ay

3. 2020- IEEE 802.11az

4. 2020- IEEE 802.11ba

5. 2020-IEEE 802.11bb

6. 2020-IEEE 802.11bc

7. 2020-IEEE 802.11bd

8. 2020-IEEE 802.11be

9. 2020-IEEE 802.11md

Learn about Distributed System

   

IEEE 802.11b

What is IEEE 802.11b?

IEEE 802.11b-1999 or 802.11b, is an amendment to the IEEE 802.11 wireless networking that extends throughput up to 11 Mbit/s using the same 2.4 GHz band. A related amendment was incorporated into the IEEE 802.11-2007 standard. 802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly use today in their 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac and 802.11ax versions to provide wireless connectivity in the home, office and some commercial establishments. Wi-Fi is an unofficial retronym for 802.11b.

802.11b is use in a point-to-multipoint configuration, wherein an access point communicates via an omnidirectional antenna with mobile clients within the range of the access point. Typical range depends on the radio frequency environment, output power and sensitivity of the receiver. Allowable bandwidth is share across clients in discrete channels. A directional antenna focuses transmit and receive power into a smaller field which reduces interference and increases point-to-point range. Designers of such installations who wish to remain within the law must however be careful about legal limitations on effective radiated power.

Some 802.11b cards operate at 11 Mbit/s, but scale back to 5.5, then to 2, then to 1 Mbit/s (also known as Adaptive Rate Selection) in order to decrease the rate of re-broadcasts that result from errors.

Channel

Center Frequency

Frequency Data

1

2.412 GHz

5 MHz

2

2.417 GHz

5 MHz

3

2.422 GHz

5 MHz

4

2.427 GHz

5 MHz

5

2.432 GHz

5 MHz

6

2.437 GHz

5 MHz

7

 2.443 GHz 

5 MHz

8

2.447 GHz

5 MHz

9

2.452 GHz

5 MHz

10

2.457 GHz

5 MHz

11

2.462 GHz

5 MHz

12

2.467 GHz

5 MHz

13

2.472 GHz

5 MHz

14

2.484 GHz

5 MHz

Note: Channel 14 is only allowed in Japan, Channels 12 & 13 are allowed in most parts of the world.

Learn about IEEE 802.11

  

IEEE 802.11g

What is IEEE 802.11g?

802.11g is the third modulation standard for wireless LAN. It works in the 2.4 GHz band (like 802.11b) but operates at a maximum raw data rate of 54 Mbit/s. Using the CSMA/CA transmission scheme, 31.4 Mbit/s is the maximum net throughput possible for packets of 1500 bytes in size and a 54 Mbit/s wireless rate (identical to 802.11a core, except for some additional legacy overhead for backward compatibility).

In practice, access points may not have an ideal implementation and may therefore not be able to achieve even 31.4 Mbit/s throughput with 1500 byte packets. 1500 bytes is the usual limit for packets on the Internet and therefore a relevant size to benchmark against. Therefore smaller packets give even lower theoretical throughput, down to 3 Mbit/s using 54 Mbit/s rate and 64 byte packets. Also, the available throughput is shared between all stations transmitting, including the AP. Both downstream and upstream traffic limited to shared total of 31.4 Mbit/s using 1500 byte packets and 54 Mbit/s rate.

IEEE 802.11g-2003 or 802.11g is an amendment to the IEEE 802.11 specification that operates in the 2.4 GHz microwave band. Standard has extended throughput up to 54 Mbit/s using the same 20MHz bandwidth as 802.11b uses to achieve 11 Mbit/s. This specification under the marketing name of Wi-Fi has been implement all over the world. The 802.11g protocol is now Clause 19 of the published IEEE 802.11-2007 standard, and Clause 19 of the published IEEE 802.11-2012 standard.

802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly use today in their 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac and 802.11ax versions to provide wireless connectivity in the home, office and some commercial establishments. Wi-Fi G is an unofficial retronym for 802.11g. 802.11g is fully backwards compatible with 802.11b.

Learn about IEEE 802.11e

   

IEEE 802.11x

 

What is IEEE 802.11x?

802.11x is generic term to refer to the IEEE 802.11 standard for defining communication over a wireless LAN (WLAN). 802.11, commonly known as Wi-Fi, specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. These standards are used to implement WLAN communication in 2.4, 3.6 and 5 GHz frequency bands. The term is not officially used or defined. Rather, it refers to the common flavors of Wi-Fi, most notably 802.11a, 802.11b, 802.11g, and 802.11n.

Some of the known IEEE standards association standard and amendments are

802.11-1997: The original standard released in 1997 provided 1-2 Mbps transmission speed in the 2.4 GHz band using Frequency Hoping Spread Spectrum (FHSS) or Direct Sequence Spread Spectrum (DSSS). It is currently obsolete.

802.11a: Provides a transmission speed of up to 54 Mbps in the 5 GHz band using Orthogonal Frequency-Division Multiplexing (OFDM).

802.11b: Works in the 2.4 GHz band and can provide up to 11 Mbps speed with a fallback rate to 5.5, 2 and 1 Mbps. 802.11b only uses DSSS.

802.11g: Provides a maximum speed of 54 Mbps in the 2.4 GHz band. 802.11g uses OFDM and DSSS and is backwards compatible with 802.11b.

802.11n: Provides up to 150 Mbps throughput using spatial multiplexing. It uses the both 2.4 and 5 GHz band.

Learn about IEEE 802.11g

  

Internet Protocol (IP)

What is Internet Protocol (IP)?

The internet protocol is a set of rules by which data sent from source computer to destination computer over internet. The data that traveled across the internet is divided into smaller pieces called packets. The internet protocols information is attached to each packet. Based on IP addresses in the packet headers, it delivers the packets from the source host to the destination host, then internet protocols defines the packet structure that encapsulates the data to be delivered.

Each computer (or host) that connects to the internet has unique IP address that identifies from all other computers on the internet. Therefore the transport protocols is used in combination with internet protocols, the most common transport protocols are TCP and UDP. The original Transmission Control Protocol (TCP) was introduced by Vint Cerf and Bob Kahn in 1974. The first major version of the internet protocols is Internet Protocol Version 4 (IPv4) is the dominant protocols of the Internet and its successor is Internet Protocol Version 6 (IPv6).

What is IP Address?

IP address is a unique identifier address assigned to host, each IP address contains series of characters, for example 172.16.1.1. Therefore it connects with the browser via the internet to provide information to the users. IP address translates into human-readable domain names via DNS which the users can access websites without memorizing series of characters. The internet protocols packet will contains both the IP address of the sender host and receiver host.Error! Filename not specified.

Example of IP address

Learn about Portocol

  

Internet Message Access Protocol (IMAP)

What is IMAP?

IMAP stands for “Internet Message Access Protocol” is an internet standard protocol that stores email messages on a mail server, but allows the email clients to manage (view and manipulate) the messages from the mail server over TCP/IP, they were stored locally on the email client’s computing device. The IMAP server was typically listen on port number 143 and IMAP over SSL is assigned the port number 993. IMAP was designed with the goal of permitting complete management of an email box by multiple email clients, therefore the clients generally leave messages on the server until the user explicitly deletes them, Virtually all modern e-mail clients and servers support IMAP, which along with the earlier POP3 (Post Office Protocol 3) are the two most prevalent standard protocols for email retrieval. The webmail service providers are such as Outlook.com, Gmail, and Yahoo! Mail also provide support for both IMAP and POP3.

The Internet Message Access Protocol is an Application Layer internet protocol that allows email clients to access email on a remote mail server. Incoming emails messages are sent to an email server that stores messages in the recipient’s email box. The user retrieves the messages with an email client that uses one of a number of email retrieval protocols. While some clients and servers preferentially use vendor-specific, proprietary protocols, almost all support POP and IMAP for retrieving email – allowing free choice between many email clients such as Pegasus Mail or Mozilla Thunderbird to access these servers, and allows the clients to be used with other servers.

Benefits of Using IMAP

  • Allows you to access email messages from anywhere.
  • Allows you to access email messages in different devices (smartphones, laptops, tablets, computers, etc.)
  • It only downloads a message when you click on it
  • Attachments are not automatically download by IMAP
  • IMAP can be used offline just like POP

Learn about Routing Protocol

  

Thursday, 17 December 2020

ISDN

What is ISDN?

ISDN stands for “Integrated Services Digital Network” is a set of communication standards that enables the digital transmission of voice, video, data, and other network services over the telecommunication networks and it operates over copper-based systems to provide higher data speed and better quality than analog transmission. It is a circuit-switched telephone network system for voice or data and it also allows access to packet-switched networks.

The main future of ISDN is that on the same telephone line it can integrate both voice and data at the same time and ISDN was design to run on the digital telephone system. In some areas, ISDN found as a major market application for internet access, in which ISDN typically provides a maximum of 128 kbit/s bandwidth in both upstream and downstream directions. Through channel bonding, it can achieve a greater data rate that is the ISDN B-channels of three or four BRIs (Six to eight 64 kbit/s channels) are bonded. In the OSI model, ISDN is also used with specific protocols, such as Q.931 where it acts as a network layer, data link layer, and physical layer.

History of ISDN

The first telecommunication technology Integrated Services Digital Network was defined in 1988 by the CCITT organization and therefore, which is now the ITU-T (International Telegraph and Telephone Consultative Committee). Prior to ISDN, the classic telephone system only used to transmit voice signals, with some special service available for data. ISDN was commonly used as high-end internet service in the 1990s to 2000s and offered by many ISPs as a faster alternative to dial-up internet access, nowadays ISDN is still used in some network connections, but it is rarely used for internet access.

However, in a videoconference, ISDN provides continuous voice, video, and text transmission between the individual (desktop) and group (room) videoconferencing systems. The technology used is the H.320 standard for audio coding and video coding, including audio codecs such as G.711 Pulse Code Modulation (PCM), G.728 (CELP), and Discrete Cosine Transform (DCT), and video codecs such as H.261 and H.263.

ISDN Network Architecture

ISDN Network Architecture

Variants of ISDN Interfaces

Basic Rate Interface (BRI)

It supports two 64 kbps bearer channels (or B channels) for a data transfer rate of 128 kbps.

Primary Rate Interface (PRI)

It supports 30 B channels and two additional channels in a single E1 connection, providing a data transfer rate of 2,048 kbps.

Always on Dynamic ISDN (AODI)

It is a consistent ISDN connection that uses the X.25 protocol and supports speeds up to 2 Mbps.

Broadband ISDN (B-ISDN)

A B-ISDN relies mainly on the evolution of fiber optics and according to CCITT B-ISDN is best described as ‘a service requiring transmission channels capable of supporting rates greater than the primary rate.

Narrow ISDN (N-ISDN)

It was an attempt to replace the analog telephone system with a digital one. It supports 64 kbit/s channels as a basic unit of switching. Its major contribution was frame relay and therefore, it describes telecommunication that carries voice information in a narrow band of frequencies.

ISDN Services

ISDN provides a fully integrated digital service to users and there are three categories of services such as

  • Bearer Services
  • Teleservices
  • Supplementary Services

Bearer Services

Bearer network provides transfer of information likes voice, video and data between users without the network manipulating the content of the information. Therefore, it provides using circuit switched, packet switched, frame switched, and cell switched networks. In this, it defines as ISDN standards. It belongs to the first three layers of OSI model.

Teleservices

Tele network provides transfer of information between users with manipulating the content of the information in network. It includes telephony, telefax, videotex, telex and teleconferencing. In this, the ISDN yet not become standards. It belongs to the layers four to seven of OSI model.

Supplementary Services

Supplementary services provide an additional functionality to the bearer services and teleservices. The supplementary services are such as reverse charging, call waiting, and message handling.

Principles of ISDN

The various principles of ISDN as per ITU-T recommendation are

  • Intelligence in the network
  • Layered protocol architecture
  • To support voice and non-voice applications
  • To support switched and non-switched applications
  • Variety of configurations
  • Reliance on 64-kbps connections

Benefits of ISDN

It provides a number of significant advantages over analogue systems they are.

  • Faster call connection
  • Enables two simultaneous telephone calls to be made over the same line simultaneously.
  • Digital stream can carry any form of data from voice to faxes and internet web pages to data files - this gives the name 'integrated services'.
  • Data can be sent more reliably and faster than with the analogue systems.
  • Noise, distortion, echoes and crosstalk are virtually eliminated.

Learn about Domain Name System (DNS)

  

InfiniBand

What is InfiniBand?

InfiniBand (IB) is a standard of computer networking communications which used in high performance computing that features very low latency and high throughput. It is use for data interconnect both among and within computers and it also used as either a direct or switched interconnect between servers, as well as an interconnect between storage systems. It is design to be scalable and uses a switched fabric network topology.

InfiniBand


In 2014, it was most commonly used interconnect in supercomputers. Mellanox and Intel manufacture InfiniBand host bus adapters and network switches. In February 2016, it was reports that Oracle Corporation had engineered its own InfiniBands switch units and server adapter chips for use in its own product lines and by third parties. Therefore Mellanox IB cards are available for Solaris, FreeBSD, RHEL (Red Hat Enterprise Linux), SLES (SUSE Linux Enterprise Server), Windows, HP-UX, VMware, and AIX. An interconnect, InfiniBands competes with Ethernet, Fibre Channel, and Intel Omni-Path. The technology is promotes by the InfiniBand Trade Association.

InfiniBand uses a switched fabric topology, as opposed to early shared medium Ethernet. All transmissions begin or end at a channel adapter. Therefore each processor contains a host channel adapter (HCA) and each peripheral has a target channel adapter (TCA). These adapters can also exchange information for security or quality of service (QoS).

Learn about Collisions

  

IEEE 802.11e

What is IEEE 802.11e?

IEEE 802.11e-2005 or 802.11e is an approved amendment to the IEEE 802.11 standard that defines a set of Quality of Service (QoS) enhancements for wireless local area network (LAN) applications through modifications to the media access control (MAC) layer. The standard is considers of critical importance for delay-sensitive applications, such as voice over wireless LAN and streaming multimedia. The amendment has been incorporate into the published IEEE 802.11-2007 standard.

IEEE 802.11e Specifications

  • Original 802.11 Media Access Control (MAC)
  • Distributed Coordination Function (DCF)
  • Point Coordination Function (PCF)

Media Access Control (MAC) Protocol Operations



A diagram of the 7-layer OSI model with the modifications made by the 802.11 standard and the 802.11e amendment

The 802.11e enhances the DCF and the PCF, through a new coordination function: the hybrid coordination function (HCF). Within the HCF, there are two methods of channel accessed, similar to those defined in the legacy 802.11 MAC: HCF Controlled Channel Access (HCCA) and Enhanced Distributed Channel Access (EDCA). Both EDCA and HCCA define Traffic Categories (TC). For example, emails could be assigned to a low priority class, and Voice over Wireless LAN (VoWLAN) could be assigned to a high priority class.

  • Enhanced Distributed Channel Access (EDCA)
  • Hybrid Coordination Function (HCF) Controller Channel Access (HCCA)

Other IEEE 802.11e Specifications

  • Automatic Power Save Delivery
  • Block Acknowledgements
  • NoAck
  • Direct Link Setup

Learn about IEEE 802.11X

  

Hybrid Topology

 Hybrid Topology

Hybrid Topology is the combination of two or more different Topology. For example combination of bus topology, ring topology and star topology. A network is connected to the two or more ring topology and also connected with a star topology. The example for ring topologies is in one department and star topologies in another department is combined to form hybrid topology, an large hybrid network example is internet.

Advantages

  • Its Troubleshooting is easy.
  • In this type of topology easy to increase a size that is scalable.
  • It contains a Network flexibility.
  • Reliable

Disadvantages

  • It design is more complex.
  • Its hub is costly.
  • Its infrastructure is also very costly.

Hybrid Topology


In above diagram it shows the transmission of data from one node to another node with the help of wired area networks. It connects both star and ring network protocols for data transmission. The components are connected to this network are bridges, switches or hubs and nodes.

FORMULA

The N stands for networks, n-1 stands for a number of nodes subtract with numerical 1 and then both divided by 2. It defined by using the formula given below

                N (n-1)/2

Where,

n - no of system

Learn about Bus Topology

 

Gnutella

 



What is Gnutella?

Gnutella is a large peer-to-peer network, it was celebrated two decades of existence on 14th March 2020 and it has millions of users for peer-to-peer file sharing. It was the first peer-to-peer network of its kind, leading to other, later networks adopting the model. However in June 2005, Gnutella's population was 1.81 million computers increasing to over three million nodes by January 2006. In late 2007, it was the most popular file-sharing network on the Internet with an estimated market share of more than 40%.

 

History of Gnutella

In early 2000, the Gnutella is also called a first client from which the network got its name was developed by Justin Frankel and Tom Pepper of Nullsoft, soon after the company’s acquisition by AOL. On March 14 the program was made available for download on Nullsoft’s servers. Therefore the event was prematurely announced on Slashdot, and thousands downloaded the program that day.  The source code was to be released later, under the GNU General Public Licence (GPL). However the developers never got the chance to accomplish this purpose.

The next day the AOL stopped the availability of the program over legal concerns and restrained Nullsoft from doing any further work in the project. However this did not stop Gnutella, after few days, the protocol have been reverse engineered, and compatible free and open source clones began to appear. This parallel development of different clients by different groups remains the modus operandi of Gnutella development today.

Gnutella Search and Retrieval Protocol


Gnutella did once operate on a purely query flooding -based protocol. The outdated Gnutella version 0.4 network protocol employs the following five different packet types, such that

  • ping: discover hosts on network
  • pong: reply to ping
  • query: search for a file
  • query hit: reply to query
  • push: download request for firewalled servants

These are mainly concerned with searching the Gnutella's network and file transfers are handled using HTTP.

Software that Support Gnutella

For macOS

The following software that support by macOS are

  • Acquisition
  • Poisoned

For Windows

The following software that support by Windows are

  • Shareaza
  • Morpheus
  • KCeasy
  • CitrixWire
  • Kiwi Alpha
  • BeerShare
  • BearFlix
  • Gnucleus-GnucDNA
  • Zultrax

For Java

The following software that support by Java are

  • Phex
  • Cabos
  • LimeWire
  • FilesWire (P2P)
  • WireShare (aka LimeWire Pirate Edition)

For Cross Platform

The following software that support by Cross Platform are

  • giFT (Gnutella's Plug-in)
  • gtk-gnutella'

For Other Platforms

The following software that support by other platforms are

  • CocoGnut – RISC OS
  • Symella – Symbian

Learn about Client (Computing)

 

Tuesday, 8 December 2020

Firewall

What is Firewall?

A firewall is a network security device that monitors and controls incoming and outgoing devices based on the defined set of security rules. The purpose of a firewall is to establish a barrier between a trusted internal network and an untrusted external network (such as the internet) in order to block malicious traffic like viruses and hackers. Therefore the firewall can be hardware, software or cloud-based which monitor and control all outgoing and incoming traffic, each type of firewall having its own defined set of security rules based on this it accepts, rejects or drops that specific traffic.

Firewall Process

Types of Firewall Category

Network Firewall - Filter traffic between two or more networks and run on network hardware
Host based Firewall - Run on host computers and control network traffic in and out of those machines.

Firewall Task

  • Defend resources
  • Validate access
  • Manage and control network traffic
  • Record and report on events
  • Act as an intermediary

Types of Firewall

  • Packet-Filtering Firewalls
  • Next-Generation Firewalls (NGFW) 
  • Proxy Firewalls 
  • Network Address Translation (NAT) Firewalls 
  • Stateful Multilayer Inspection (SMLI) Firewalls 

Packet-Filter or Network Layer

Packet filter firewalls is also called network layer firewalls, to control network access it operates outgoing and incoming packet. Therefore it allows them to pass or stop based on source and destination IP address, protocols, and ports. However, in the OSI model, it mainly uses the first three layers and analyzes traffic at the transport layer protocol. It generally falls into two sub-categories, stateful and stateless. 

Next-Generation Firewalls (NGFW) 

The next-generation firewalls is a traditional firewalls technology, it has additional functionality such as application inspection, deep packet inspection, traffic inspection, SSL/SSH inspection, anti-virus, intrusion prevention systems, etc, which used to stop modern days security breaches like application-layer attacks and advanced malware attacks.

Proxy Firewalls 

A proxy firewalls is the network security system, that filters network traffic at the application layer. It is also called an application firewalls or gateway firewalls. A proxy gateway receives a request from a client inside the firewalls, where it is then evaluate against a set of rules and then sends this request to the remote server outside of the firewalls. Therefore, firewall proxy provides internet access to computers on a network, that filter, cache, control, and log request coming from client to keep the network secure. However, the proxy firewalls monitor traffic for HTTP and FTP protocols.

Network Address Translation (NAT) Firewalls

Network address translation (NAT) firewalls is actually a sorting method of the incoming packet that assures users, that only the request information is receive. Therefore it is similar to a proxy firewalls that they act as an intermediate between a group of computer and outside traffic. In this, by using a single IP address, it allows multiple devices with independent network addresses to connect to the internet, where individual IP addresses are hidden because of this IP addresses can’t be captured by hackers.

Stateful Multilayer Inspection (SMLI) Firewalls 

Stateful multilayer inspection (SMLI) firewalls filter packets at the application, network, and transport layers it uses a sophisticated form of packet filter that examines all the seven layers of the OSI model. It also examines packets to determine the state of the communication to ensure all initiated communication is only taking place with trusted sources. Therefore, each packet is examine and compared against known states of friendly packets.

Generation of Firewall

  • First Generation- Packet Filtering Firewall
  • Second Generation- Stateful Inspection Firewall
  • Third Generation- Application Layer Firewall
  • Next Generation Firewalls (NGFW)
  • Also learn about Network Address Translation (NAT)