Cloud Computing..

Today afternoon my friend, Binoy, called me up and asked about Cloud Computing.  I was taken by surprise by this question. Even though I heard about it many times, I couldn't explain it properly.

When I came back to desk, the first thing I did was to google about Cloud Computing..

The explanations are messy in most of the documents and to be very frank I am still reading docs to get a clear picture.

To my understanding, in Cloud Computing architecture:

1. You have a minimal configuration system with good enough internet connectivity.
2. You do everything else on internet. Be it document creation, mail and everything.
3. You effectively pay for the hardware and the services you use..

Now I am ready to take a blame on me if any of these statements are wrong. This is rather a premature document.

http://virtualization.sys-con.com/node/632257
http://webtrends.about.com/od/enterprise20/a/cloud-computing.htm
http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9006439

IPv6 Address configurations

Just thought of summarizing some key points about IPv6 ( Internet Protocol Version 6 ).

Key points about IPv6

• It has been designed to replace the age old, reliable IPv4.
• IPv4 has been very good. Has done its job.. It just cant take the current load.
• IPv6 is efficient and more secure.

Let me start with asking you guys a question ?

How do we assign an IPv6 address. Read on :-)

 
Address configuration.

stateful Address Configuaration

• Address configuration with DHCP

Stateless Address Configuration :

• Hosts automatically configure themselves.
• Addresses derived from prefixes advertised by local routers
• The presence of a router is not mandatory

IPv4 had the concept of Unicast Broadcast and Multicast. For unicast and Multicast, the explanation remains the same. There is no broadcast as such in IPv6. A good news.. :-) Less network chaos..

 Address types

 Unicast Addresses

A unicast address identifies a single interface

The following types of addresses are unicast IPv6 addresses:

Global unicast addresses

·         equivalent to public IPv4 addresses.

·         globally routable and reachable on the IPv6 portion of the Internet.

·         The three high-order bits are set to 001. The address prefix for currently assigned global addresses is 2000::/3

Local use Unicast Addresses.

There are two types of local-use unicast addresses:

·         Link-local addresses.

·         Automatically configured.

·         Always begin with FE80

·         Comparable to IPv4 APIPA ( Automatic Private Internet Protocol Addressing )

·         The scope of a link-local address is the local link.

·         Site-local addresses.

·         Equivalent to the IPv4 private address space (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16).

·         Not routed on internet.

·         A site is an organization network or portion of an organization's network that has a defined geographical location (such as an office, an office complex, or a campus).

·         Not automatically configured. Must be assigned either through stateless or stateful address configuration processes.

·         Always begin with FEC0

 

Unique local IPv6 unicast addresses

·         Designed to replace site-local addresses with an address that is private to an organization, yet unique across all of the sites of the organization.

·         All unique local addresses have the address prefix FC00::/7

·         Unique local addresses have a global scope but their reachability is defined by routing topology.

·         Organizations will not advertise their unique local address prefixes outside of their organizations or create DNS AAAA entries with unique local addresses in the Internet DNS.

 

Special addresses

·         Unspecified address

·         Unspecified address (0:0:0:0:0:0:0:0 or ::) is only used to indicate the absence of an address.

·         Equivalent to the IPv4 unspecified address of 0.0.0.0.

·         The unspecified address is never assigned to an interface or used as a destination address.

·         Loopback address

·         The loopback address (0:0:0:0:0:0:0:1 or ::1) is used to identify a loopback interface, enabling a node to send packets to itself.

·         Equivalent to the IPv4 loopback address of 127.0.0.1.

 

Compatibility Addresses

·         IPv4-compatible address

·         The IPv4-compatible address, 0:0:0:0:0:0:w.x.y.z or ::w.x.y.z (where w.x.y.z is the dotted decimal representation of an IPv4 address), is used by IPv6/IPv4 nodes that are communicating using IPv6.

·         When the IPv4-compatible address is used as an IPv6 destination, the IPv6 traffic is automatically encapsulated with an IPv4 header and sent to the destination using the IPv4 infrastructure.

·         IPv4-mapped address

·         The IPv4-mapped address, 0:0:0:0:0:FFFF:w.x.y.z or ::FFFF:w.x.y.z, is used to represent an IPv4-only node to an IPv6 node.

·          It is used only for internal representation.

·         The IPv4-mapped address is never used as a source or destination address of an IPv6 packet.

·         6to4 address

·         The 6to4 address is used for communicating between two nodes running both IPv4 and IPv6 over an IPv4 routing infrastructure.

·         The 6to4 address is formed by combining the prefix 2002::/16 with the 32 bits of a public IPv4 address, forming a 48-bit prefix.

 

 

Multicast Addresses

·         In IPv6, multicast traffic operates in the same way that it does in IPv4.

·         Always begins with “FF”.

·         Multicast addresses cannot be used as source addresses or as intermediate destinations in a Routing extension header.

Solicited Node Address.

·         Replaces the IPv4 ARP mechanism.

·         The solicited-node address facilitates the efficient querying of network nodes during address resolution.

·         The solicited-node multicast address is comprised of the prefix FF02::1:FF00:0/104 and the last 24-bits of the IPv6 address that is being resolved.

·         By using the solicited-node address, very few nodes are disturbed during address resolution.

 

Anycast Addresses

·         An anycast address is assigned to multiple interfaces.

·         Packets addressed to an anycast address are forwarded by the routing infrastructure to the nearest interface to which the anycast address is assigned.

How do I find MAC address ?

Finding MAC Address (Hardware address, Physical Address) is pretty easy.

Try the command.

C:\>getmac

If you want to know the MAC address of a system whose IP you are aware of,  you could try this.

C:\> ping <destination ip>

If you are able to ping successfully then issue

C:\> arp -a

          

Windows XP and IP v 6

IP (Internet Protocol) Version 6 is not enabled by default on Windows XP.

The Windows XP follows a dual stack model for IPv6 support. ie the IP 4 stack and IP 6 stackcan co-exist.

Here is how you can enable IP v 6 on an XP installation.

C:\> ipv6 install