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This report shall be about comparing Static IPv6 unicast addressing, to the various means by which unicast addressing can be dynamically assigned to an IPv6 host. Within this, services, infrastructure and configuration shall be discussed with the advantages and disadvantages for each separate approach.
A recommendation approach for a small organization of 1000 machines will be given, with justification of why this is recommended.
What is IPv6 and Why Use It?
IPv6(Internet Protocol Version 6) is said to be the next generation protocol for the internet. This is designed to have a lot of advantages over its predecessor (Internet Protocol Version 4). Both versions define how data is sent from one computer to another over packet-switched networks.
It contains control and addressing information to route packets for the next generation internet. It is believed that the expansion of the internet is very important and that upgrades are sometimes warranted.
Both IPv4 and IPv6 will continue to be data-oriented protocols for the internet for years to come.
IPv6 will address the main problem of its predecessor, which is the availability of IP addresses left to connect computers in a packet-switched network. It has a very large address space which consists of 128 bits compared to the smaller 32 bits used IPv4.
This means that the number of available unique addresses to 2^128, this is a significant increase in available addresses for connecting computers to the internet. This has all been possible with the invention of IPv6. This new addressing scheme will eliminate the need for Network Address Translation, which causes several networking problems within end to end nature of the internet.
Differentiation of Static and Dynamic Address Assignment
The IP addresses from local ISP's(Internet Service Providers) are assigned in one of two ways, these are:
- Set to an IP address which will remain the same for months or even years at a time. This is known as a Static IP Address. This is assigned directly to the device from the ISP.
- Set to an IP address which will only be good for a limited amount of time, this will be changed according to the policy agreed by the ISP's DHCP server. This is known as a Dynamic IP address. Rather than being assigned an address directly, using the DHCP(Dynamic Host Configuration Protocol) protocol, it searches through a Pool of IP addresses on the server, finds one that is not in use and assigns it to the machine. This means that the IP address may change the next time the machine is turned on or off by the user.
As Static IP addresses are the same for an indefinite amount of time, some networking software packages require a static IP for use. Static addresses are only assigned once.
Dynamic IP addresses are usually used within large networks where machines/computers are frequently rebuilt/reconfigured. They are also used where a limited amount of addresses are available to shared between a high number of computers.
Dynamic Address Assignment Methods
Stateful autoconfiguration for IPv6 requires servers to provide the bulk of the configuration information, this includes certain network information for obtaining a Aggregatable Global Unicast address. To obtain configuration information, the machine much locate a DHCPv6 server, by listing for it. It will then issue a unicast DHCPv6 request. If there is no server on the local subnet then a Relay/Agent will forward on the request to a server on behalf of the computer. The server will respond with a replay which will contain all of the configuration information for the machine.
Advantages of Stateful:
- Security - host registration can be enforced and can selectively provide network services to registered hosts or even deny access to any unregistered hosts.
- Aggregation - An address hierarchy can be built for address aggregation.
- Control - the service can control the distribution of address from a central location.
- Renumbering - When new ISP's are chosen to replace the older ones, new addresses are easily distributed with this service.
Disadvantages of Stateful:
- Costly - as DHCP Servers are needed.
- "In the absence or failure of static or stateful (DHCP) address configurations, an operating system may assign an IP address to a network interface using state-less autoconfiguration methods, such as Zeroconf."
Stateless Auto Configuration is a very important feature of IPv6. It allows any devices connected to an IPv6 network to connect to the internet without any support in the form of DHCP server. The DHCP server holds a pool of IP addresses which are dynamically assigned to devices for a specific amount of time. This method simplifies the process of allocating IP addresses by getting rid of the need for DHCP servers.
Advantages of Stateless:
- Cost Effective - As no DHCP Servers are needed
- Allows Hot plugging of Network devices(This is when a machine connects to the network and automatically configures its self to be used on the IPv6 Network, without any interaction)
- Does not require the support of a DHCP Server
- Suitable for Wireless network
Disadvantages of Stateless:
- Relying on multicast discovery mechanisms
- Using address space inefficiently
- Lacking in Security and control over policy and access