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June 2012

How to build  CISCO Network Server

If you are used to working with home networking gear, you will be used to an integrated device that “does it all”. On a home network, you may have one box that is a cable/DSL modemrouter, firewall, switch, and wireless access point all in one. It is amazing all the functions they can fit into one box.
If you are studying Cisco networking and learning about how businesses use these devices, you may be wondering why there is so much importance on the differences between a switch, router, firewall, and other network devices. If the home user can have all these devices combined into one, why doesn’t the business user do this as well? So, now, here we try to find out what the main differences between these network devices.
Integrated devices
Just like home devices, business devices have become more and more consolidated over time but not to the extent that the home devices have. Network administrators in a business network are more comfortable having separate devices and even like the idea. This is because network administrators like to be able to isolate problems down to a certain device and they like to be able to know the performance capabilities of every device. If you use an integrated router, switch, and firewall all into one device, troubleshooting, managing, and understanding the performance capabilities of that device gets complicated. I’m not saying that this isn’t done. You can buy a big & expensive, chassis-based, Cisco 6500 series switch and have almost all these functions on different blades of the switch. This may be fine for a larger business with a group of administrators but to a medium size business and a single network administrator, many times, this is a scary thought.
Keep in mind that for a medium or large size business, these integrated home devices won’t work because they don’t offer all the features required. The standalone routers, switches, and firewalls have many more features than these integrated devices do.
But what is the difference between these devices anyway? Let’s cover the three most popular devices.
Router
A router is a hardware device and has the function of routing packets between networks. A router works at Layer 3 of the OSI model – the Network Layer. This is the layer that the IP protocol works at. Most routers today are IP routers that examine the source and destination IP addresses of each packet, look up the destination of the packet in the router’s IP routing table, and route that packet on its way. In the event that the destination is not listed in the routing table, the router will either send the packet to a default router (if it has one) or drop the packet. Routers are usually used to connect a local area network to a wide-area network (a LAN to a WAN) but can also be used to segment large local area networks (LAN’s).
Routers prevent broadcasts. Another way of saying this is that routers form a broadcast domain. So, if your network is being deluged by IP broadcasts, you need to subnet your network into two or more smaller networks. Those networks would be connected by a router and that router wouldn’t allow broadcast traffic to flow between subnets.
Routers use routing dynamic protocols like OSPF, RIP, or BGP to learn routes from other routers. Router can also use static routes that are entered by the administrator.
Routers replace the Ethernet MAC address of the source device with their own MAC address when they send a packet out an interface. When the response to that packet comes back, the new source of the packet is sending the response to the destination of the router. The router receives this, replaces the source address, changes the destination address to the original address, and sends the packet back to the original sender. This is a complex topic that we could spend a whole article covering so this is only meant to provide the most basic understanding of how this works.
To show the routing table on the router, use the show ip route command. Here is an example of what a routing table looks like on a router:
show the routing table on the router
Switch
A switch is a hardware device that works at Layer 2 of the OSI model – data link. The data link layer is where the Ethernet protocol works.
A switch switches Ethernet frames by keeping a table of what MAC addresses have been seen on what switch port. The switch uses this table to determine where to send all future frames that it receives. In Cisco terminology, this table is called the CAM table (content addressable memory). In general, the proper term for this table is the bridge forwarding table. If a switch receives a frame with a destination MAC address that it does not have in its table, it floods that frame to all switch ports. When it receives a response, it puts that MAC address in the table so that it won’t have to flood next time.
A switch is a high-speed multiport bridge. This is why bridges are no longer needed or manufactured. Switches do what bridges did faster and cheaper. Most routers can also function as bridges.
You might be asking how a hub fits into this mix of devices. A hub is a multiport repeater. In other words, anything that comes in one port of a hub is duplicated and sent out all other ports of the hub that have devices attached. There is no intelligence to how a hub functions. A switch is a vast improvement over a hub in terms of intelligence, for many reasons. The most important of those reasons is how the bridge forwarding table works. Intelligent (smart) switches have made hubs obsolete because they can do more at the same cost of a dumb hub. For this reason, hubs are rarely used or sold any longer.
To see this bridge forwarding table (CAM table) on a Cisco switch just type: show mac-address-table
Here is an example:
Cisco switch-show mac-address-table
Firewall
A firewall is used to protect more secure network from a less secure network. Generally, firewalls are used to protect your internal/private LAN from the Internet.
A firewall generally works at layer 3 and 4 of the OSI model. Layer 3 is the Network Layer where IP works and Layer 4 is the Transport Layer, where TCP and UDP function. Many firewalls today have advanced up the OSI layers and can even understand Layer 7 – the Application Layer.
There are a variety of different types of firewalls and we won’t go into that in this article so let’s just talk about the most popular type of firewall – a stateful packet inspection (SPI) hardware firewall. An example of a SPI hardware firewall is a Cisco PIX firewall. This is a dedicated appliance and it looks a lot like a Cisco router.
A SPI firewall is stateful because it understands the different states of the TCP (transmission control protocol) protocol. It knows what is coming and what it going and keeps track of it all. Thus, if a packet tried to come in but it wasn’t requested, the firewall knows that and drops it.



UDP (User Datagram Protocol) is a simple OSI transport layer protocol for client/server network applications based on Internet Protocol (IP). UDP is the main alternative toTCP and one of the oldest network protocols in existence, introduced in 1980.
UDP is often used in videoconferencing applications or computer games specially tuned for real-time performance. To achieve higher performance, the protocol allows individual packets to be dropped (with no retries) and UDP packets to be received in a different order than they were sent as dictated by the application.
THE USER DATAGRAM PROTOCOL (UDP):

TCP/IP contains two transport protocols:

•   UDP
•   TCP
UDP:

  UDP is less complex and easier to unders tand. It does not provide the type of
service a typical application expects.

CHARACTERISTICS OF UDP:

UDP has the following characteristics.

•   It is an end-to-end protocol . It provides application-to -application communication.
•   It provides connectionless service.
•   It is a Message-Oriented protocol.
•   It uses best-effort delivery service.
•   It follows arbitrary interaction.
•   It is operating system independent.

THE CONNECTIONLESS PARADIGM:

  UDP does not need to pre-establish communication and also there is no need to
terminate communication. UDP allows an app lication to delay long  intervals between two
messages. There are no Control Messages; only Data Messages. So it has very low
overhead. 

MESSAGE-ORIENTED INTERFACE:

  UDP offers application programs a Message -Oriented Interface. It does not divide
messages into packets for transmission and does not combine messages for delivery.
Let’s discuss its advantages and disadvantages.

ADVANTAGES:
 
•   Applications can depend on protoc ol to preserve data boundaries.

DISADVANTAGES:

•   Each UDP message must fit into a single IP datagram. 
•   It can result to an inefficient  use of the underlying network.
•   
UDP COMMUNICATION SEMANTICS:

  UDP uses IP for all delivery, that is, same best effort delivery as IP.
To use UDP, an application must either be immune to the problems or
programmer must take additional steps to detect and correct problems.

EXAMPLES:

•   Audio transmission
•   On-line shopping application

ARBITRARY INTERACTION:

  UDP follows four types of interaction

•   1-to-1:     One application can communicate with one application.
•   1-to-many:      One application can communicate with many applications.
•   Many-to-1:   Many applications can communication with one
application.
•   Many-to-many:  Many applications can communicate with many
applications.

UDP Datagrams

UDP network traffic is organized in the form ofdatagrams. A datagram comprises one message unit. The first eight (8) bytes of a datagram contain header information and the remaining bytes contain message data.
A UDP datagram header consists of four (4) fields of two bytes each:
  • source port number
  • destination port number
  • datagram size
  • checksum
UDP port numbers allow different applications to maintain their own channels for data similar to TCP. UDP port headers are two bytes long; therefore, valid UDP port numbers range from 0 to 65535.
The UDP datagram size is a count of the total number of bytes contained in header and data sections. As the header length is a fixed size, this field effectively tracks the length of the variable-sized data portion (sometimes called payload). The size of datagrams varies depending on the operating environment but has a maximum of 65535 bytes.
UDP checksums protect message data from tampering. The checksum value represents an encoding of the datagram data calculated first by the sender and later by the receiver. Should an individual datagram be tampered with or get corrupted during transmission, the UDP protocol detects a checksum calculation mismatch. In UDP, checksumming is optional as opposed to TCP where checksums are mandatory.


Introduction

It has now been close to 30 years since the current Internet Protocol Version 4 - IPv4 - was implemented as the underlying protocol for the Internet. While it has served its purpose admirably for all these years, with an ever expanding user base and a growing number of IP-enabled devices, there are serious concerns about it's limited feature set as well as robustness not to mention the all important factor, scalability.
IPv6

The Internet Protocol Version - IPv6 - is being developed as a critical technology meant to address all those concerns. It is expected to not only provide better services for existing technologies and applications but also meet growing demands of new devices like cellular phones, and IP-based services, such as online gaming and Voice over Internet Protocol (VoIP).

#1) IPv6 provides a substantially larger IP address space than IPv4 

Every computer or online device that needs to connect to the Internet requires a globally unique IP address. IPv4 uses 32 bits for an IP address that allows about 4 billion unique IP addresses. When IPv4 was introduced in the 1970s and accepted as the protocol for the Internet, they did not foresee this explosion in the popularity of the Internet or the extent to which online technologies would become all pervasive. It was therefore firmly believed that these 4 billion addresses would be sufficient to cover any future growth of the Internet.

To give an analogy, consider a mailman having to deliver a letter to the correct person in a community. As long as each one of the residents has a unique identifiable address, the mailman will have no trouble in identifying the address and delivering mail to the right individual.

IPv6

Challenge to IPv4

Carrying our analogy forward a little more, let us now imagine our community to expand so much that it is not possible to give each individual a unique address. One solution could be that one group of individuals is given a unique address, from where the mailman is directed to the address of the specific individual. As a result, tracking a person and delivering information to the right individual becomes that much more complex. Further, what if a person wants a separate address for his home mail and another for his office mail?
IPv6
Today the Earth's population stands at around 6.6 billion while the Internet has a population of just 1.3 billion, which is not even 22% of the entire world's population. Quite clearly there will be more and more people connecting to the Internet in the very near future. Also, with great advances being made in converging communication technologies like data, audio, video and voice, over IP, there is still tremendous scope for the Internet to evolve and expand.
People will be increasingly using multiple devices like Personal Digital Assistants (PDAs), laptops, telemetric devices or game consoles, some of them from a home network. It is clear therefore, that the demand for IP addresses will increase, and increase exponentially and in fact, estimates indicate that the IPv4 addresses will be exhausted by November 2010.

As in the analogy we presented earlier, approaches like Network Address Translation (NAT) are used to translate between a unique global IP address and multiple private IP addresses. For example, people with dial-up services share one modem between ten subscribers thereby saving about 90% of addresses as compared to the case where each subscriber would have had a unique global IP address. Further, even corporate users employ the same method of letting many computers share a single address thereby conserving addresses. However, this brings in added complexity in both network hardware and software.

How does IPv6 provide a solution?

IPv6 uses 128 bits for IPv6 addresses which allows for 340 billion billion billion billion (3.4x1038) unique addresses. To get an idea of the scale involved, consider the entire IPv4 space as being contained in an iPod, then the new IPv6 space would be the size of the Earth. From these numbers, it can be seen that with IPv6, it is possible to provide billions of addresses to each person and ensure that any device that has to be connected to the Internet will have a unique IP address.

The first advantage of an enhanced address space is that in the absence of NAT, there is less complexity in the network hardware and software, and configuring a network becomes much simpler. Secondly, it makes it possible to truly envisage a networked home wherein the different gadgets and appliances would be on the network which would require that each such device have a unique IP address. Finally, the large availability of IP addresses removes any obstacles that existed previously in the full deployment of wireless and mobile devices.

2) IPv6 provides better end-to-end connectivity than IPv4 

The most exciting applications to emerge in recent days are peer-to-peer applications such as multi-player online games, video-conferencing (streaming media), file sharing and VoIP. In peer-to-peer networking, a group of computers can communicate directly with each other and do not need a central server. Peer-to-peer applications demand end-to-end connections between unique IP addresses.

IPv6


Challenge to IPv4

As mentioned earlier, the shortage of addresses caused by IPv4 has been overcome to some extent by using NAT, which basically translates one unique global address to multiple private addresses. In the absence of unique IP addresses for each end, NAT creates difficulty in ensuring proper end-to-end services. The present solution is for the application developer to engineer special NAT traversal techniques or to have additional servers to simulate peer-to-peer communication.

IPv6
Consider an EPABX service, which handles many internal numbers. After dialing an EPABX number, a further connection needs to be established to one of the many internal phones. Any interruption in the call will require that the EPABX number be dialed again and the connection reestablished. This is completely avoided in case of dial-ups between two independent telephone numbers.

How does IPv6 provide a solution?

IPv6 with its large address space no longer requires NAT and can ensure true end-to-end connectivity. This means peer-to-peer applications like VoIP or streaming media can work very effectively and efficiently with IPv6.

3)IPv6 has better ability for autoconfiguring devices than IPv4 

Whenever a node plugs in and wants to be part of a network, IP address information and router information is required to properly configure the node and get it running. In the past, when there were fewer devices and computers in a network running IP, almost all of them were statically configured and IP addresses were manually assigned. However, with the rapid proliferation of personal computers (PC) and other IP-enabled devices, for efficient device management and reusing of resources, it became absolutely essential to consider some kind of autoconfiguration.

IPv4 uses the stateful address autoconfiguration protocol, Dynamic Host Configuration Protocol (DHCP). In the stateful autoconfiguration model, a host obtains the interface addresses as well as other required information such as the configuration information and parameters from a server. The DHCP server maintains a manually administered list of hosts and keeps track of which addresses have been assigned to which hosts.

IPv6

[Source: Cisco]


Challenge to IPv4

With even more computers and devices using IP, there was need for an IP protocol that would ensure easy and automatic configuration of devices and routers. Further, new devices that are using IP now are getting simpler and may be used in environments where particular server dependencies may not be acceptable.

How does IPv6 provide a solution?

IPv6 offers automatic configuration and more importantly, simple configuration mechanisms. Known as plug-and-play autoconfiguration, these capabilities are way beyond what IPv4 currently offers. IPv6 offers DHCPv6, which is an autoconfiguration similar to IPv4 DHCP and offers stateful address autoconfiguration. In addition, IPv6 also offers stateless or serverless address autoconfiguration.
IPv6


In stateless autoconfiguration, a host can automatically configure its own IPv6 address and does not need any assistance from a stateful address server. Entire IPv6 prefixes rather than just an address are delivered to a device. This particular feature enables routers to easily autoconfigure their interfaces and can be used very effectively in broadband access networks to dynamically provide customer gateways.

4) IPv6 contains simplified Header Structures leading to faster routing as compared to IPv4 

The present IP uses a Datagram service to transfer packets of data between point to point using routers. The IPv4 packet header structure contains 20 bytes of data, such that it contains within the header, all possible options thereby forcing intermediate routers to check whether these options exist and if they do, process them before forwarding them. In the IPv4 packet header, these options have a certain maximum permitted size.

IPv6

Challenge to IPv4

The IPv4 header has two main problems that are instrumental in slowing down throughput - each packet must be processed and checksum computed, and each router that processes a packet must process the option field. This can cause a gradual degradation in performance during the forwarding of the IPv4 packets.
IPv6

How does IPv6 provide a solution?

When compared to IPv4, IPv6 has a much simpler packet header structure, which is essentially designed to minimize the time and efforts that go in to header processing. This has been achieved by moving the optional fields as well as the nonessential fields to the extension headers that are placed only after the IPv6 header. Consequently, the IPv6 headers are processed more efficiently at the intermediate routers without having to parse through headers or recompute network-layer checksums or even fragment and reassemble packets. This efficiency allows for reduced processing overhead for routers, making hardware less complex and allowing for packets to be processed much faster.

Another feature of the IPv6 header structure is that the extension header allows for more flexible protocol inclusions than what IPv4 does. In contrast, IPv6 extension headers have no such restriction on the maximum size. They can be expanded to accommodate whatever extension data is thought necessary for efficient IPv6 communication. In fact, a typical IPv6 packet contains no extension header and only if intermediate routers or the destination require some special handling, will the host sending the packets add one or more extension headers depending on the requirement. This new extension header makes IPv6 fully equipped to support any future need or capabilities.

5) IPv6 provides better security than IPv4 for applications and networks

The Internet has functioned for the last three decades with IPv4 as the underlying protocol. However, because of this end-to-end model, IPv4 was designed with almost no security in mind and assumes that the required security will be provided at the end nodes. For example, consider an application such as email that may require encryption services - under IPv4, it is the responsibility of the email client at the end nodes to provide those services. Today, the Internet faces threats such as Denial of Service Attacks, Malicious code distribution, Man-in -the-middle attacks, Fragmentation attacks and Reconnaissance attacks.

IPv6

Challenge to IPv4

IPv6

Network Address Translation (NAT) and Network Address Port Translation (NAPT) were used to provide some level of protection against some of the threats mentioned above using methods such as firewalls. Also the introduction of the IPSec protocol, allowed some communication to be encrypted but its implementation in IPv4 is optional and the whole responsibility of ensuring secure communication still lies with the end nodes. However, new applications like mobile e-commerce and portals demand end-to-end security.
How does IPv6 provide a solution?

In IPv6, IPSec is a major protocol requirement and is one of the factors in ensuring that IPv6 provides better security than IPv4.

IPSec contains a set of cryptographic protocols for ensuring secure data communication and key exchange. The main protocols used are:

1.Authentication Header (AH) protocol, which enables authentication and integrity of data.
2.Encapsulating Security Payload (ESP) protocol, which enables both authentication and integrity of data as well as privacy of data.
3.Internet Key Exchange (IKE) protocol. This protocol suite helps to initially set up and negotiate the security parameters between two end points. It then also keeps track of this information so that the communication stays secure till the end.

Thus, IPv6 ensures that there are end-to-end security mechanisms that will provide authentication and encryption abilities to all applications and thereby eliminates the need for applications themselves to have integrated support for such abilities. The added benefit of using the same security mechanisms for all applications is that setting up and administering security policies becomes a lot simpler. IPv6 allows for complete end-to-end security thereby allowing for a new set of personalized services to be deployed such as mobile e-commerce services that rely on secure transactions.

6) IPv6 gives better Quality of Service (QoS) than IPv4

The present IP uses a Datagram service to transfer packets of data between point to point using routers. The IPv4 packet header structure contains 20 bytes of data, such that it contains within the header, all possible options thereby forcing intermediate routers to check whether these options exist and if they do, process them before forwarding them. In the IPv4 packet header, these options have a certain maximum permitted size.

IPv6

[Source: N3]

Challenge to IPv4

In IPv4, the Type of Service field or the Differentiated Services Code Point field in the packet header, has a very specific task of classifying the packet and defining what kind of service is expected by the packet, while being delivered through routers across the network. This is typically done through devices in the network, which will classify the packets based on the needs of the particular application. However, this also means that not all QoS-compliant devices are compatible with one another.

How does IPv6 provide a solution?

QoS is given a special boost in the IPv6 protocol with the IPv6 header containing a new field, called Flow Label field that defines how particular packets are identified and handled by the routers. The Flow Label field allows packets that belong to a particular flow, in other words, that start from a particular host and head to a particular destination, to be identified and handled quickly and efficiently by the routers.

The Flow Label Field thus ensures that there is more efficient delivery of information from one end to another without the possibility of it being modified by intermediate systems. This ensures a high degree of QoS especially for peer-to-peer applications like VoIP and other real-time applications.
IPv6


7) IPv6 provides better Multicast and Anycast
abilities compared to IPv4 


In a multicast technique a packet is copied from one stage down to another in a hierarchical tree-like structure, instead of sending it from the source directly. This means that there are fewer packets in the network thereby optimizing bandwidth utilization and also reducing the resources required at each network node. This multicast technique is particularly useful when streams of information have to be made available to a wide variety of connected devices and not just one single destination. For example multicast technique is used to relay audio data, video data, news feeds, financial data feeds and so on.

IPv6

[Source: Cisco]

Challenge to IPv4

IPv6

The biggest problem with IPv4 multicast is that it is possible only on subnets and most Internet routers are not configured to support IPv4 multicast. For effective use of multimedia applications it should be possible to address different hosts, which belong in different subnets.
How does IPv6 provide a solution?

IPv6 extends the multicasting capabilities of IPv4 by offering a large multicast address range. Obviously, this limits the degree to which the information packets have now to be propagated and significantly improves the network efficiency.

IPv6 also improves dramatically on the concept of anycast services, which is available, though in a very minimal form in IPv4. In anycast services, packets are not sent to all the nodes in the network but only to the nearest reachable member. A typical application where anycast would be of tremendous use is say, while discovering a server of a given type e.g. a DNS server, among a group of servers. It will also provide redundant paths to other servers so that if for some reason, the route to the primary server becomes unavailable, in the next session, a connection will be provided to the next server in the group.

8) IPv6 offers better mobility features than IPv4 

When we consider IP mobility features we are essentially considering features that
would be useful for:

Mobile devices, which can change their location but would like to retain existing connections.
Mobile networks that provide mobility to a group of devices
Ad-hoc networking in which some of the devices stay connected to the network or in the vicinity of the network only for the short duration of a communications session

When a mobile node is not at home, it conveys information about its present location, also called, care-of-address to the home agent. Now if a node wants to communicate with this mobile mode, it will first send the information packets to the home address. The home agent receives these packets and using a table, sends these packets to the care-of-address of the mobile node.

IPv6

Challenge to IPv4

Mobile IPv4 requires a special router in the location of the mobile node to properly receive calls. Also, route optimization is available to mobile IPv4 only through an optional set of extensions. There is also an ingress filtering problem in mobile IPv4 since the correspondent node uses the home address as the source address of the packet and there may be confusion on which IP addresses it should be allowed to accept or not.
IPv6

How does IPv6 provide a solution?

With IPv6, mobility support is mandatory by the use of Mobile IPv6 (MIPv6). Route optimization is a built-in feature for mobile IPv6. Further, features like Neighbor Discovery and Address Auto-configuration allow mobile nodes to function in any location without needing the services of any special router.

MIPv6 can be used to achieve seamless mobility by allowing handovers between different access technologies say from example from a cellular network to a wireless network, with minimum interruption to ongoing connections. There is no ingress-filtering problem in Mobile IPv6 because the correspondent node uses the care-of address as the source address.

These devices increasingly demand delivery of converged voice, video and data, which is made possible through a standard called the IP Multimedia Subsystem (IMS) standard. However IMS requires that each mobile device have a unique IP address, which is a persistent IP address in order to ensure full bi-directional services.

IPv6 through its large address space ensures that each mobile device can have its own unique IP address. Further, Mobile IPv6 makes use of the extension headers to add powerful capabilities such as route optimizations between mobile nodes, when roaming between different 3G networks

9) IPv6 offers ease of administration over IPv4

When an existing network is to be expanded or two networks to be merged, or when service providers are changed, a network needs to be renumbered, as a new address scheme will be assigned to it.

IPv6

Challenge to IPv4

With an IPv4 network, all the work of network renumbering and assigning of new address schemes would have had to be done manually.
IPv6

How does IPv6 provide a solution?

IPv6 provides capabilities so that network renumbering can happen automatically. Thus, network renumbering with IPv6 will no longer requires manual reconfiguration of each host and router and makes for smoother switchovers or mergers.

Another useful administrative feature of IPv6 is its multihoming technique. In this simultaneous connections are established to two ISPS. When service to one ISP is lost, there is a back-up connection to the Internet. This ensures far greater reliability of services, as there is more than one path from the host to the destination.

10) IPv6 follows the key design principles of IPv4, thereby permitting a smooth transition from IPv4.

IPv4 has been successfully deployed the world over for many years now and its popularity is a testament to the success of its design. IPv6 follows many of the same design features that made IPv4 so successful. This makes it possible to have a smooth transition from IPv4 to IPv6. There are many commercially attractive applications in the market today that require IPv6 and may tempt many to go in for a rapid transition to IPv6. However, IPv4 applications will be used for some time to come and the process of transition from IPv4 to IPv6 must be a gradual one.

IPv6

A successful IPv4 to IPv6 transition mechanism is one in which IPv6 elements are incorporated into the network while at the same time compatibility is maintained with the pre-existing, large base of IPv4 hosts and routers. Thus, for some time to come, IPv6 hosts and routers must interact and function with the existing IPv4 network infrastructure.

A number of such transition mechanisms have been defined that allow for the two networks to co-exist till such a time that a complete migration to IPv6 is not feasible.

Using Dual IPv4/IPv6 Stack implementations such as Tunneling, Dual IPstack
Using Network Address and Protocol Translators


Windows 7



Windows 7 All Version ACTIVATOR
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Microsoft Genuine Advantage programs, including Windows GenuineAdvantage, help you determine whether or not your copy of Windows is genuine. Genuine Windows software is published by Microsoft, properly licensed, and supported by Microsoft or an authorized partner, giving you full capabilities, access to all the latest updates, and confidence that
you are getting the experience you expect. Microsoft continues to invest in education, engineering, and enforcement in order to more effectively combat software piracy.



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How to - Do Not Track Me! Stop Online Ad Tracking

Cookies are small bits of information that websites store on your computer to track the places you have visited on the Web. They help sites create advertisements targeted for a specific customer, which ad network tracking specialists say increases the effectiveness of the advertisements. Have you ever noticed an Internet advertisement for a product you just searched for? The reason the advertisers knew your preferences was because of ad tracking.
Avoiding being tracked by cookies, while still maintaining Web usability, is the Holy Grail for Web users. There are a few steps you can take to avoid ad tracking. First, download a modern browser like Firefox. Internet Explorer is notoriously bad at keeping your computer secure and untrackable. Install the Firefox Add-on Flashblock. Flashblock stops Adobe’s Flash application from storing cookies that enable you to be tracked anywhere on the Web. Install the Firefox Add-on NoScript. This unique whitelist-based script blocking approach prevents the use of JavaScript security vulnerabilities, both known and unknown.
Next, do some deep cleaning with tracking cookie removal.
To remove tracking cookies in Internet Explorer, Open Internet Options by clicking the Start button, clicking Control Panel, clicking Network and Internet, and then clicking Internet Options. Click the General tab, and then, under Browsing history, click Delete. Under Cookies, click Delete cookies, and then click Yes to confirm that you want to delete them. Click Close, and then click OK.
To remove tracking cookies in Firefox, click on the Tools menu and select Clear Recent History. Set the time range to Everything. Click the arrow next to Details and select Cookies from the list. Make sure that items you do not wish to delete are unchecked and click Clear Now.
To remove tracking cookies in Google Chrome, click on the wrench icon on the browser toolbar. Select Options, then the Under the Hood tab. Click Content Settings, then Cookies. To delete all cookies, select Remove All.



In recent years, online tracking companies have begun to monitor our clicks, searches and reading habits as we move around the Internet.
If you are concerned about pervasive online web tracking by behavioral advertisers, then you may want to enable Do Not Track on your web browser. Do Not Track is unique in that it combines both technology (a signal transmitted from a user) as well as a policy framework for how companies that receive the signal should respond.
As more and more websites respect the Do Not Track signal from your browser, it becomes a more effective tool for protecting your privacy. EFF is working with privacy advocates and industry representatives through the W3C Tracking Protection Working Group to define standards for how websites that receive the Do Not Track signal ought to response in order to best respect consumer's choices. 
The following tutorial walks you through the enabling Do Not Track in the four most popular browsers: Safari, Internet Explorer 9, Firefox, and Chrome.
Safari
On the menu bar at the top of your screen, click on Preferences.
Select the Advanced preferences panel, shown in the screenshot below.
Check the box at the bottom of the menu labeled "Show Develop menu in menu bar."
On the menu bar at the top of your screen, click on Develop, shown in the screenshot below.
Click on "Send Do Not Track HTTP Header."
Congratulations. You have enabled Do Not Track on your Safari browser.
Internet Explorer 9
On the menu bar at the top of your screen, click the Tools button, which is shaped like a gear.
Point to Safety, and then click Tracking Protection, shown in the screenshot below.
Go to the Manage Add-on dialog box, shown in the screenshot below.
Click Tracking Protection List, and then click the Enable button in the lower right-hand corner of the box, shown in the screenshot below.
Congratulations. You have enabled Do Not Track on your Microsoft Internet Explorer 9 browser.
Firefox
On the menu bar at the top of your screen, click on Preferences.
Select the Privacy tab, shown in the screenshot below.
At the top of this menu, check the box labeled "Tell websites I do not want to be tracked."
Congratulations. You have enabled Do Not Track on your Firefox browser.
Google Chrome
To enable Do Not Track in Chrome, you will need to install the Do Not Track browser extension.
On the menu bar at the top of your screen, click on Window.
In the Window menu, click on Extensions.
Chrome will display a control panel which shows all of the extensions you have installed on your browser, shown in the screenshot below.
If you do not have any extension installed, click the Browse the gallery, shown above. If you have extensions installed already, scroll to the bottom of the control panel and click the Get more extensions link. These links will take you to the Chrome Web Store, shown in the screenshot below.
In the search box in the upper left hand corner, type "Do not track."
Select the Do Not Track extension. EFF recommends the extension written by Jonathan Mayer and click "Add to Chrome."
In the drop down menu, shown in the screenshot below, click "Add."
Congratulations. You have installed the Do Not Track extension on your Chrome browser.




IP Address classes were the original organizational structure for IP addresses. The specific address class would determine the maximum potential size for a computer network. The address class would define which of the specific bits of the address would be used to identify the network and network identification, the bits to identify the host computer and host ID, and total number of host subnets permitted per network. Five total classes of IP addresses were defined, class A through E. Although the IP class term will commonly be used to describe the difference between one network and another, the practical use of addressing is not commonly used any more. It has been replaced with classless addressing where a netmask can be assigned to any IP address range.

What is an IP Address?

An Internet Protocol (IP) address is a numeric label consisting of a 32 bit number assigned to a network capable device that uses IP for communication. The address fundamentally serves two purposes: location addressing and computer host or network interface identification. The address indicates where the connected device resides with the majority of hosts/devices still using the IPv4 (Internet Protocol Version 4) form of addressing. A significant limitation of the legacy IPv4 addressing is that it supports less than 4.3 billion total addresses. Based on the rapid growth of the Internet and related technologies, the use of IPv4 is not sustainable for the long term. In the mid-1990’s, the new IPv6 technique was developed which makes use of 128 bits for the IP address. IPv6 technology continues to be deployed, albeit slowly. The Internet Assigned Numbers Authority (IANA) is responsible under the IETF for management of the IP address space allocation globally. Beneath the IANA, there are five regional Internet registries (RIRs) that are responsible for allocating IP address blocks to Internet service providers (ISPs) and other trusted organizations.

Where Are IP Addresses Defined?

The Internet Protocol is defined in, RFC 791: Internet Protocol, published in 1981. The protocol is designed to be used in a packet-switched computer network and provides for the transmission of data packets (defined as datagrams) from source devices to destinations. The source and destination devices are identified by a fixed length address defined by the protocol. The specification also takes into account fragmentation of data and the reassembly of longer blocks of data when required. The IP specification does not address data reliability, flow control, sequencing, quality of service, etc. These aspects are handled by supporting technologies such as the TCP (transmission control protocol). The four key mechanism used in the IP definition are: type of service, time to live, options, and the header checksum. Type of service is used to indicate the quality of service desired intended to be used by routers (or gateways) to select the transmission parameters applicable for the network or forwarding of the information. Time to live indicates the upper bound on how long the datagram or data packet should be forwarded until dropped. Options allow for control functions implemented for specific networks such as special routing, security, or timestamps but are not otherwise required for standard communication. The header checksum is used to ensure that the data packet has been transmitted correctly. If the checksum fails, the datagram should be dropped.

What Are the IP Address Classes?

There were five IP address classes in use before the majority of industry switched to classless routing. There were A, B, C, D, and E. Class A addresses were used for networks with a very large number of total hosts. Class B was designed for use on medium to large networks, and C for small local area networks (LANs). Class D and E were set aside for multicast and experimental purposes. In the following table, the four octets that make up an IP address (a, b, c, and d respectfully) are displayed in how they were distributed in classes A, B, and C.
classes A, B, and C.
ClassIP AddressNetwork IDHost ID
Aa.b.c.dab.c.d
Ba.b.c.da.bc.d
Ca.b.c.da.b.cd
IP Address Classes IP Address Classes
Class A IP Address
Class A IP addresses were used for networks that had a large number of hosts on the network. The class permitted up to 126 networks by using the first octet of the address for the network identification. The first bit in this octet was always fixed or set to be zero. The following seven bits in the octet were then set to one which would complete the network identification. The remaining octets (24 bits) represented the hosts ID and would allow up to 126 networks with 17 million hosts per network. In a Class A address, the network number values start at the number 1 and end at 127.

Class B IP Address

Class B IP address were assigned to medium to large networks. They allow 16,384 networks by using the first two octets in the address for the network identification. The first two bits of the first octet are fixed to 1 0. The next 6 bits along with the following octet then complete the network identification. The third and fourth octet (16 bits) then represents the host ID. This allows approximately 65,000 hosts per network. Class B network number values start at 128 and finish at 191.

Class C IP Address

Class C IP addresses were used in small LAN configurations. They allow for approximately 2 million networks by using the first three octets of the address for the network identification. In a Class C address, the first three bits are fixed to 1 1 0. In the following three octets, 21 bits make up the network identification. The last octet then represents the host identification. This allows for 254 hosts per network. A Class C network number value starts at 192 and ends at 223.

Class D IP Address

Class D IP addresses were reserved for multicasting purposes. These addresses begin with an octet in the 224-239 range. They would have leading bits of 1 1 1 0 and includes addresses from 224.0.0.0 to 239.255.255.255.

Class E IP Address

Class E IP addresses are reserved for experimental use. The first octet of these addresses ranges between 240 and 255. This range is reserved by the IETF and similar to Class D networks, should not be assigned to a host device.

What is IPv6?

The IETF identified the problem with the rapid exhaustion of the IPv4 address space several decades ago. Despite the invention of classless IP addressing, it was assessed that a new addressing protocol was required to address long term needs. IPv6 was then designed as the succeeding standard to IPv4 and released in 1995. The resulting address space was then increased from 32 to 128 bits (16 octets) and deemed to be adequate for at least the mid-term requirements for Internet growth. The design of IPv6 incorporates the idea of allowing efficient aggregation of subnet routing prefix at the router level. This results in the reduction of routing table sizes and actual address utilization rates being small on any IPv6 network segment. The design also allows for the separation of the addressing infrastructure of a local segment’s space from the addressing used to route to or from external network traffic. The large number of network addresses also allows large blocks to be assigned for a specific purpose and when required aggregated for more efficient routing. The need for more complicated addressing conservation methods such as now used in Classless Inter-Domain Routing (CIDR) is also eliminated with the implementation of IPv6.
Similar to IPv4, IPv6 reserves blocks of IP address for private use. In IPv6; however, these are referred to as unique local addresses (ULA). This block of addresses uses the routing prefix fc00::/7 that is then divided into two /8 blocks that have different implied policies. The addresses include a 40-bit pseudorandom number which minimizes the risk of address collisions if packets are routed inappropriately or sites merge. None of the current or legacy IPv6 private address prefixes are supposed to be routed on the public Internet just like the behavior expected from IPv5. Finally, despite the majority of modern operating systems now provide support for IPv6; however, it has not yet seen widespread deployment in the home networking, VoIP, and networking peripheral fields.

What is Classless IP Addressing?

After the invention of the Domain Name System (DNS), industry realized that the use of IP address classes would limit the scalability of the Internet. As a result, the IETF published RC 1518 and 1519 in 1993 to define the classless method of routing IPv4 data packets. The most recent definition of the standard occurred in 2006 under RFC 4632. Classless IP addressing was introduced as a more efficient means to make use of the IP address space when compared to Classful addressing. In classless addressing, the IP address is treated as a 32 bit stream where the boundary between the network identification and host can be at any of the bit positions. The network portion of the address is determined by the number of 1’s that are in the subnet mask being applied to the address. A subnet mask is used locally on the hosts connected to the network and are never transmitted in an IPv4 data packet or datagram. All of the hosts on the same network are configured to use the same subnet mask with the host section of the IP address being unique to the host. The classless version of address is referred to as Classless Inter-Domain Routing (CIDR) and allows networks to be divided into different-sized subnets. The system avoids wasting IP addresses through the use of the subnet mask.

How Does a Subnet Mask Work?

In classless IP address, a subnet mask is used on a network to define how many bits are used for the network address and how many are used for the host address. The subnet mask is the same for all users on a specific network. When overlay on a host address, it tells the host or device what part of the IP address is the network address and which is used for the host. Subnet masks will typically start with 255.*.*.* with the remaining digits specific to the network. Every subnet address on a large network will have its own subnet mask which in essence means the specific subnet has a subnet mask. This allows for the current form of classless IP addressing that has been in use for IPv4 networks since the 1990s.
How to calculate the Subbet mask....... 
http://www.subnet-calculator.com/

How Long Until IPv6 Is Fully Implemented?

Unfortunately, at the time of this writing the answer remains “It depends.” The discussion of running out of IP addresses has been ongoing for more than a decade, and it will likely continue to do so for at least another. The advent of Network Address Translation (NAT) and Dynamic Host Control Protocol (DHCP) has been implemented and very successful. As a result, consumers have essentially been sharing IP addresses through their ISP without really noticing for the past decade. As the popularity for “Always On,” high demand services such as video or television streaming increases; however, the quality of service realized at the user level may start to suffer. Just think if you could not watch your favorite sitcom because all of the users in your assigned addressing block with the ISP were actually 1 – Online, and 2 – Actively using their Internet connection at the same time. This rarely occurs now, but as more and more of the devices in the home become “connected” it may in the future. When / if this occurs, then a more significant shift of major service providers to IPv6 will occur. In the meantime; however, the Internet 2 research group is operating on and conducting research on what is considered to be the Internet of the future running on IPv6, providing significant quality of service improvements, and a higher data rate capacity than currently realized on networks running on the IPv4 standard. Most modern computing devices; however, are being sold with native IPv6 support so if the change does occur sooner than later consumers won’t necessarily be forced into buying a new computer.

Mr.16x9 blog

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