A Good tutorial article and time line re the Next Gen IP Protocol, IPv6, aka IPng.
Enjoy, Frank C.
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IPv6 cuts address chaos
August 25, 1998 InfoWorld via NewsEdge Corporation
Definition
IPv6: The next generation of the dominant networking protocol. This
upgrade from IPv4 will include improvements such as simplified
routing and increased address space to better support business
computing.
IPv6 -- the next-generation networking protocol -- is coming, and it
promises to change the way corporate networks and the Internet
work. An infrastructure issue that's more akin to a new banking
regulation than a hot new technology that you can leverage for
competitive advantage, IPv6 (also referred to as IPng or, simply, v6)
will eliminate some of IPv4's shortcomings that have appeared as a
result of the global Internet explosion. IPv6 is a much-needed
improvement, promising easier-to-obtain IP addresses, cheaper and
faster routing, and such features as quality of service (QOS) and
encryption for your enterprise.
The transition from IPv4 to IPv6, though, won't be painless. Efforts to
provide backward compatibility between IPv6- and IPv4-based
applications and routers definitely will help ease the transition within
your enterprise. However, your IT staff, including network engineers
and programmers, will be most affected by the change to the new
protocol.
Although it will be quite some time before we're faced with IPv6-only
networks, the specification's core elements are more or less in place.
Your IT organization should begin implementing the new protocol on
a test network to gain familiarity with IPv6 and avoid incompatibilities
within your enterprise.
How it works
Currently, IPv4 uses 32-bit addresses, which are represented as 4
bytes with dots between them. Although in theory the 32 bits allow
more than 4 billion hosts, the need to simultaneously give out many
addresses significantly reduces the number of those available. Even
if 4 billion hosts were available, the addresses would run out before
too long.
IPv6 uses 128-bit addresses, offering a theoretical maximum of 340
trillion, trillion, trillion hosts. As with IPv4, the reality is that the
number of available IPv6 addresses will be less than the theoretical
maximum. However, even a pessimistic estimate based on routing
inefficiencies and a host of other factors still would allow 1,564
addresses per square meter of earth, said Christian Huitama, a key
founder and developer of the Internet. An optimistic estimate
suggests there would be 665 million billion addresses per square
meter.
Another drawback to IPv4 has been the way in which addresses are
assigned; it's difficult to tell where a given address is located, either
geographically or with regard to network topology. Because of this
inefficiency, Internet backbone routers maintain huge tables of where
to send information for any given address. The end result is an
inelegant network design that creates too much work for the routers
and slows their performance.
IPv6 will reduce this addressing chaos by ensuring that addresses
are given out in an elegant hierarchy. Large Internet service
providers will receive huge blocks of addresses and pass out smaller
blocks of those addresses to subscribers who, in turn, may pass on
increasingly smaller address blocks.
Using this hierarchical scheme, IPv6 can represent large blocks of
addresses by a single entry in routing tables. This will simplify
routing, allowing backbone routers to look at only small parts of an
address to determine the packet's destination. In addition, the
hierarchical model will reduce the cost and complexity of Internet
routers.
IPv6 also includes improved packet headers, which are quite different
than IPv4's packet headers. IPv6 uses a header with a fixed size of 24
bytes. In contrast, IPv4's packet header is variable in size, which
creates more work for routers because they must look at more
information than they actually need to forward packets to their
destination.
With IPv6 there will be the capability to define additional features
such as QOS by using a chaining mechanism. To keep the header as
simple as possible, the essential packet data (for example, source and
destination) resides in the standard IPv6 header, and one field of the
header specifies whether the payload begins after the header or
whether there's another header.
Additional IPv6 header types include routing information, security
encapsulation (encryption), and fragmentation. Each of these
headers has the same "next header" field, which specifies how the
data succeeding it should be treated -- as the payload or as an
additional header.
IPv6 also offers improved extensibility. IPv4 currently lacks a
mechanism for adding features, such as encryption, at the protocol
level. Although features can be added by using additional protocols,
such as Reservation Protocol, or RSVP, for QOS, it's an inelegant
patch. The Internet Engineering Task Force has designed IPv6 so the
protocol can be extended as needed without having to completely
redesign it.
The enterprise role
IPv6 isn't just a technical solution to a technical problem. The current
and future use of IP networks in business has spurred many of the
changes being implemented in IPv6. Within your enterprise, IPv6 will
simplify routing and reduce network administration.
In an effort to ease the transition to the new protocol in your
enterprise, the specification provides IPv6-in-IPv4 tunneling, which
allows IPv6 packets to travel over networks that only support the
older protocol. Tunneling is being used today to create the 6bone, an
international, experimental IPv6 network that runs over the Internet.
This kind of interoperability is key to making the transition to IPv6 as
easy as possible.
To further smooth the transition, much is being done to maximize
application compatibility with IPv6. For example, such protocols as
TCP, UDP, ICMP, OSPF, BGP, and even RIP are being upgraded to
comply with IPv6. Unfortunately, because most OSes require
applications to know about IP addresses, your in-house developers
will need to update most applications to support IPv6 addresses.
There already are many applications that support IPv6, though most
are in the experimental stage and evolving as changes are made to
the protocol specification.
Most of the available IPv6 applications are network utilities, such as
Telnet and FTP, but there is an IPv6-compatible version of the
Apache Web server available.
Finally, IPv6 will reduce network administration by obviating the
need for Dynamic Host Configuration Protocol (DHCP) on many
networks. IPv6 allows autoconfigurable hosts by using the host
Media Access Control address for part of the IPv6 address combined
with Remote Desktop Protocol, or RDP. Although this lessens the
need for protocols such as DHCP, network- or platform-specific
information still will need such a mechanism. After many years of
dealing with host-address configuration issues, we were delighted
with this aspect of IPv6's design.
Technology time line
There is no question that IPv6 will be adopted. We just don't know
how fast the new protocol will spread throughout the Internet. For
that reason, IT shops should ensure that any new equipment already
supports IPv6. In addition, you should start identifying older
equipment that isn't upgradable to IPv6.
Perhaps the most difficult part of the transition from IPv4 to IPv6 will
be for those who have to work with the new protocol. Network
engineers will need to learn a host of new skills to deal with IPv6,
from troubleshooting to basic router configuration.
Also, as with any new technology, those who understand IPv6 will
be in great demand for a long while. This, of course, will translate into
higher labor costs for IT shops that want to contract IPv6 transition
services. Having someone in-house who's well-versed in IPv6 could
mean huge savings down the road.
Beyond staff, network infrastructure will need the most work.
Although routing will improve, it will still require quite a bit of work
to implement. You'll need to upgrade routers with newer firmware and
replace IPv4 static routers with IPv6 equivalents. And though old
routing protocols such as RIPng will remain, this is probably a good
time to move to a more robust routing protocol such as Open
Shortest Path First, or OSPF, which will support IPv6.
There will also come a time when you'll need to migrate your client
hardware to IPv6. We can only hope that OS vendors include some
migration tools in their next few releases, but vendors such as
Microsoft and IBM have been notably silent on the matter.
Fortunately, you can gradually migrate your entire network to IPv6 --
but it's never too early to start planning for it. There's bound to be
some equipment that simply won't work with IPv6.
Beyond the network, your developers should start thinking about
IPv6 issues now if their applications in any way make use of network
communications over IP. We expect that many applications will break
when IPv6 appears -- and even more will break when IPv4 entirely
ceases to exist.
Finally, your organization should start working with IPv6, in
prototypical installations at least. The sooner you become familiar
with the protocol, the easier the transition. You can obtain functional
IPv6 stacks for most popular operating systems. We recommend
using Windows NT's experimental IPv6 stack if you want to focus
mostly on application issues, or the Linux IPv6 (part of the 2.1 kernel)
if you really want to get deep into IPv6.
You also can connect to the 6bone. Getting the stacks loaded,
finding a pseudo-Top Level Aggregator, or p-TLA, provider, and
getting everything working takes quite a bit of work; but it's well
worth the effort for the experience and the capability to test IPv6
applications and equipment in an Internet environment.
IPv6 is a vast improvement over its predecessor, IPv4, offering
simplified routing, increased address space, and greater extensibility.
But moving to IPv6 won't be easy. Although IPv6-only networks may
be 10 years away, building an experimental IPv6 network and laying
the foundation for the new protocol in your current applications and
network will help prepare your organization for the inevitable switch
to IPv6.
Brooks Talley is the test manager at the InfoWorld Test Center. He
can be reached at brooks_talley@infoworld.com.
Evolution of the Internet and IPv6
1968 - Packet-switched networks appear
1969 - Arpanet appears, using Network Core Protocol; Four hosts on
Arpanet
1977 - 100 hosts on Arpanet
1983 - TCP/IP becomes standard Internet protocol; term "Internet" is
coined
1984 - 1,000 hosts on the Internet
1987 - 10,000 hosts on the Internet
1989 - 100,000 hosts on the Internet
1990 - Arpanet ceases to exist
1992 - 1 million hosts in the Internet; IP multicast first implemented
1995 - Core IPv6 protocols defined
1996 - 10 million hosts on the Internet
2010 - Internet expected to be 100 percent compliant with IPv6
IPv6 resources
The 6bone (experimental IPv6 backbone running over the Internet) -
6bone.net
IPv6 for Lunux faq - terra.net
Microsoft Research's IPv6 stack - research.microsoft.com
IPng information and resources -
playground.sun.com
THE BOTTOM LINE
IPv6 completely redefines IP addressing and routing, and adds key
features. Both network infrastructure and programming will be greatly
affected by the transition from IPv4 to IPv6. Your networking and
application development professionals will need time to get up to
speed on IPv6 -- if you start preparing now, you will be ready for the
change.
Pros: Greatly expands address space; simplifies routing; supports
encryption; includes Anycast for sending a packet to any one of
several destinations; backward compatible; extensible.
Cons: Challenging to learn; IP addresses difficult to remember; will
break older applications.
IPv6: The once and future protocol
Problems solved by IPv6
The following are some of the shortcomings rectified in the new
protocol specification.
Problem IPv4 solution IPv6 solution
Address-space Network Address Greatly increased
shortage Translation address space
Encryption Add-on protocols Built into packet header
(e.g., IP Security
protocol, Point to
Point Tunneling
Protocol)
Quality of service No real solution Built into packet header
Finding closest No solution Anycast
instance of resource
Finding local router Dynamic Host Remote Desktop Protocol
Configuration Protocol built into protocol
(DHCP) and BootP can specification
give out the
information
Ensuring unique address DHCP Uses Media Access Control
address in network address
Adding new features New protocols run on Chained headers allow
for
top of IP future expansion
IPv6 stacks up
To help ease your transition to this new networking protocol, you
can use one of these functional IPv6 stacks, which work with the
most popular operating systems.
Vendor Operating system Status
Digital Equipment Alpha Digital Unix Prototype
IBM AIX 4.3 Released
Linux 2.1 experimental kernel Experimental
Microsoft Windows NT 4.0 Prototype
Sun Microsystems Sun Solaris 2.5 and 2.51 Prototype
Vendor URL
Digital Equipment digital.com
IBM austin.ibm.com
Linux linux.org
Microsoft microsoft.com
Sun -
playground.sun.com
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