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I have my head around IPv4. I can subnet, work out hosts and can even take it back down to 1's and 0's and calculate using Binary, the correct addresses. I understand all the IP settings I need to know and I can use Ping and ipconfig to solve issues.
Now enters IPv6. Native in Vista and Windows Server 2008. Added onto Windows XP.
I understand
the XXX.XXX.XXX.XXX format of an IP address with it's associated netmask but
what madness is IPv6?
We needed a solution to the
problem to our dwindling supply of IP addresses. Almost everyone has "always
on" broadband and lots of devices are now also using IP addresses. Rfids,
Fridges, cars and lots more. We are chewing through IPv4 addresses faster
than ever and we are at a point where there are not many free ones left.
Yes, NAT can reduce the numbers of IP addresses on the public network, that
are required, but there are now more networks and devices so NAT will not
stop this avalanche of IP use. Now comes IPv6 Internet Protocol version 6
(IPv6) greatly improves on IPv4 by vastly increasing the number of available
addresses and by enabling more efficient routing, simpler configuration,
built-in IP security, better support for real-time data delivery, and other
essential enhancements. It has a huge address space It has address re numbering, hierarchy
and mobility. It
has multicast and anycast.
Heightened security
flow labels
high performance
jumbograms (packets larger than 64 kb) Take a look at
this PowerPoint
slide deck. So
why do I hate IPv6? While IPv6 is designed to
work with the 128-bit IPv6 addresses of the source and the destination
hosts, computer users are likely to experience difficulty in using and
remembering the IPv6 addresses of the computers with which they want to
communicate. The good news ... Unique names, which are
easier to remember, can be used instead. This is much the same way
DNS works today. So how are IP addresses
calculated? Hence the
familiar xxx.xxx.xxx.xxx For IPv6, the
128-bit address is divided along 16-bit boundaries, and each
16-bit block is converted to a 4-digit hexadecimal number
and separated by colons. The resulting representation is
called colon-hexadecimal. The following is
an IPv6 address in binary form: The 128-bit
address is divided along 16-bit boundaries, as follows: Each 16-bit block
is converted to hexadecimal and delimited with colons. The
result is: IPv6
representation can be further simplified by removing the
leading zeros within each 16-bit block. However, each block
must have at least a single digit. With leading zero
suppression, the address representation becomes: Some types of addresses
contain long sequences of zeros. To further simplify the representation of
IPv6 addresses, a contiguous sequence of 16-bit blocks set to 0 in the
colon-hexadecimal format can be compressed to :: (known as double-colon).
(Until you get a grasp on this, this
starts to make the address harder to understand. Stick with
it and you will
eventually understand). Zero compression can
only be used to compress a single contiguous series of 16-bit blocks
expressed in colon-hexadecimal notation. You cannot use zero compression to
include part of a 16-bit block. For example, you cannot
express FF02:30:0:0:0:0:0:5 as FF02:3::5. An IPv6 prefix is
written in address/prefix-length notation. For
example, 21DA:D3::/48 is a route prefix and
21DA:D3:0:2F3B::/64 is a subnet prefix. Just to confuse you, IPv4
implementations commonly use a dotted decimal representation
of the network prefix known as the subnet mask (e.g.
255.255.255.0).
A subnet mask is not used in
IPv6. Only prefix-length notation is supported.
How many hosts?
With IPv6, it is hard to conceive that the IPv6 address space will be
consumed. To
help put this number in perspective, a 128-bit address space provides
655,570,793,348,866,943,898,599 (6.5 × 1023) addresses for every square
meter of
the Earth's surface. It
is this huge amount of IP spaces available that has lead us into such a
complicated IP
addresses scheme. The
following table shows the allocation of the IPv6 address
space by FPs.
Notes: For more in-depth
information on IPv6 and allocations look
here How do I give myself an IP? If you have IPv6 turned on, your
network interface cards should be getting IPv6 link-local addresses by
default, so they're ready to go. This means you can bring a group of people
together for a meeting and have instant connectivity without needing a
router, or servers, or any kind of outside tools. Whether that connectivity
will do you any good is a separate issue as it depends on what applications
you want to use, and if they support IPv6. This magic is performed by using the
network cards MAC address. The MAC is used as the low-order 64 bits of a
unicast network address. MAC addresses are 48 bits long. The EUI-64 standard
explains how to stretch IEEE 802 addresses from 48 to 64 bits, by inserting
the 16 bits 0xFFFE at the 24th bit of the IEEE
802. Because the prefix length is fixed and
well-known, during the initialization phase of IPv6 NICs, the system builds
automatically a link-local address. After a uniqueness verification, this
system can communicate with other IPv6 hosts on that link without any other
manual operation. With IPv4 it was possible
to skip over understanding the binary math behind IPv4 addresses by
memorizing the various classes and their address ranges. That will not work
for IPv6. Get yourself an IP address calculator and learn how work out the
conversions and calculations, or IPv6 will forever be a pain in your side.
Multicast Multicast in IPv6 is
similar to the old IPv4 broadcast address a packet sent to a multicast
address is delivered to every interface in a group. The IPv6 difference is
it's targeted. Anycast
An anycast address is a
single address assigned to multiple nodes. A packet sent to an anycast
address is then delivered to the first available node. This provides a form
of both load-balancing and automatic failover. Just
like in IPv4, addresses are assigned to interfaces, and a single network
host or node can have multiple interfaces, or a single interface
with multiple addresses. Every interface is required to have at least one
unicast address, and beyond that you can load it up with addresses however
you like. Lets break down the IPv6
IP address Take this IPv6 Example The prefix identifies it
as a global unicast address (Look at the allocation table above and you will
see the
global routing prefix) The address has three
parts: the network identifier (ID), the subnet, and the interface identifier
(ID).
It looks simpler already ! The subnet and interface
IDs are controlled by you/your machine. IPv4 addresses are
represented like:
0000:0000:0000:0000:0000:0000:192.168.1.25 As the machine's IPv6
address is made up of a network portion and a machine portion (network identifier, the subnet, and the
interface). The machine portion
should be the 64 bit MAC address which is fixed. (This is explained
earlier). This leaves less for you to actually work out. When you think about it, as
the network portion (Network identifier) is made up of the site's internal
network number, the ISP number, the ISP's ISP number and so on up to the
local backbone number.
If a site changes its ISP then their IPv6 addresses change, they must
renumber everything. This sounds painful. As all these addresses will be
easily referenced via DNS and as you will mainly be working with the
hostnames, maybe IPv6 will become
something that is just there. Something you can leave set to automatically
address itself. The only static device would be the servers and routers.
Everything else links by name and for your older applications, by IPv4. Now
the headache seems to be gone. If everything is happy to negotiate and work
out it's own address and just work, it would be a wonderful world. If
however you need to fault find or subnet, you will need to know this
information back to front. IPv6 is here to stay. Don't try and
remember all this. Get a good IPv6 Calculator and work with what you are
given. Eventually it will all make sense.
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