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Drivers for Transitioning to IPv6

by Brady Hicks

Copyright 2021, Faulkner Information
Services. All Rights Reserved.

Docid: 00018234

Publication Date: 2106

Report Type: TUTORIAL

Preview

IPv6 is the successor to IPv4, and is regarded as critical to the Internet’s
continued growth as a platform for innovation and economic development. However,
with a high demand for IPv6
expertise, there continues to remain growing pains in the proliferation of IPv6 applications
and services. Although these issues diminish each year, there remain a number of
considerations in regard to transitioning to an IPv6 deployment. This tutorial
takes a look at some of the factors driving its increasing use.

Report Contents:

• Executive Summary
• Description
• Benefits
• Possible Pitfalls
• Implementation
• Web Links

Executive Summary

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IPv6 is the most-recent generation of the IP protocol suite, succeeding IPv4 for
enterprise, intranet, and consumer Internet applications. The
protocol – which was originally described in RFC 2460 – is designed to resolve
infrastructure issues and provide streamlined administration, tighter security,
and an enhanced addressing scheme. Other benefits include support for isochronous
(real-time) transmission and multicasting, improved network-level security, auto
configuration, more efficient data packet routing, and embedded Quality of
Service functions.

With proper planning and testing, a migration to
IPv6 can be accomplished with a manageable amount of disruption, as a number of
mechanisms have been developed to ensure compatibility and aid in the
transition. A successful IPv6 deployment still hinges on
the ability of network administrators and integrators to have IPv4 and
IPv6
networks running in a parallel environment. However, many
organizations will soon need to implement a cutover solution and transition from running
IPv6 in tandem
with
IPv4 networks. The complexity of Internet and attached IP
intranets are complicating cutover transition strategies. Non-compliant
products need to be phased out as IPv4
applications approach
product-replacement lifecycles. IT personnel also need to be
adequately and rapidly trained in deploying and administering the new protocol.

Description

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IPv6 has a number of features designed to address the shortcomings of IPv4,
including a new IP header format, a larger address space, a more efficient
routing infrastructure, stateless and stateful address configurations, enhanced
security, and standardized Quality of Service (QoS) support. The use
of peer-to-peer, mobile, always-on Internet applications and the
roll-out of wireless data services have driven the need to hasten the
implementation
of
IPv6. Additionally, the deployment of IP-enabled devices in a host of
new
applications such as smartphones, tablets, and home appliances has challenged the
limitations of
IPv4. IPv6 also provides for enhancements in
areas such as routing and network auto-configuration, more efficient
network
usage, increased security, and support for real-time data and
multicasting.

Many IPv6 gurus believe that IPv6 and IPv4
will
need to coexist for another 10 to 15 years and run side-by-side during the
transition. Others, however, feel the demand for IP mobility and other
IPv6
“killer” applications will shorten the coexistence period to as
little as five years. The Office of Management and Budget (OMB) mandates that US federal
agencies begin to use the IPv6 protocol and, as
the future is now at hand, the OMB mandates are now predicating a
deployment strategy for the private sector.

Since IPv6 is not backwards compatible with IPv4,
organizations will have to change their network infrastructure and systems to
deploy IPv6. Organizations should understand the risks of deploying
IPv6, as well as strategies to mitigate such risks. Detailed planning will
enable an organization to navigate the process smoothly and securely.

Benefits

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Transitioning to IPv6 provides several potential benefits for current
IPv4-based networks:

• Addressing – The address field in IPv6 is 128 bits, while
  IPv4 uses only 32 bits. IPv6 also provides three modes of addressing –
  unicast, anycast, and multicast – while IPv4 only permits unicast
  where packets are sent to a specific address. Anycast simplifies
  routing and multicast permits the same message to be sent to multiple
  hosts with a single address.
• Configuration – One of
  the innovative benefits of IPv6 is how it is configured. While IPv6
  addresses can still be configured manually or leased from a DHCP
  server, there is also an automatic configuration utilizing Universal
  Plug and Play (UPnP). If an un-configured device tries to connect to a
  network that doesn’t offer a DHCP server, the device can look at
  either the network’s router or the other devices on the network and
  determine an address that would be appropriate for it to use. This
  technique is referred to as link local addressing.
• Performance – The IPv6 protocol is designed so that
  Internet backbone routers will have much smaller routing tables than
  they have with IPv4. Instead of knowing every possible route, the
  routing
  tables will include routes to only those connected directly
  to
  them. The IPv6 protocol will contain the rest of the information
  necessary for a packet to reach its destination. IPv6 reduces the
  number
  of header fields by eliminating unnecessary data and expediting
  router
  handling. It is designed to make the protocol more efficient by
  keeping
  overhead to a minimum. In IPv6, the required components are moved to
  the
  front of the header. Optional components are moved to an extension
  header. This means that if optional components are not used, the
  extension headers are not necessary, which reduces the packet
  size.
• Class of Service – IPv6 provides a flow label to identify
  data
  types for special treatment and also separates congestion-controlled
  from non-congestion-controlled data to aid transmission of
  isochronous
  data, such as multimedia streams. These capabilities, although
  available
  in IPv4 through such mechanisms as RSVP, are central to the IPv6
  structure and will be available on any conforming system.
• Standardized QoS – The QoS implementation is set up so
  that
  routers can identify packets belonging on an individual QoS
  flow/packet
  basis. Routers will have the ability to allocate the necessary
  amount of
  bandwidth to those packets based on the flow/packet QoS
  instructions.
  Furthermore, QoS instructions are included in the IPv6 packet
  header.
  This means that the packet body can be encrypted, but QoS will still
  function because the header portion containing the QoS instructions
  is
  not encrypted.
• Mobility – Mobile IPv6 specifies routing support to
  permit an
  IPv6 host to continue using its home address as it moves around the
  Internet. Mobile IPv6 supports transparency above the IP layer,
  including maintenance of active TCP connections and UDP port
  bindings.

Table 1 compares some of the critical features in IPv4 with those
of IPv6.

Possible Pitfalls

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The initial number of existing IPv4 devices that are not upgradeable to
IPv6 or
that require major transitional integration to an all IPv6
world has begun to diminish. New computers and networking devices are now
fully IPv6 capable. This, however, does not address the IPv6
deficiencies
of a diminishing number of legacy IPv4 devices.

Primary obstacles tend to include economic-related
issues, challenges, related to migration, and security.

Economic Factors

Cost always ranks as a major concern for implementing any new technology.
Though the ultimate necessity for IPv6 remains clear, the need to start
the migration is also becoming a strategic and economic factor. Operating a dual-stack network to
accommodate both versions will be more expensive and probably require more
people than running either version alone. As functionality shifts from IPv4
to
IPv6, network architecture has to evolve, network management must be
redesigned, and routing protocols need to be changed. This will put an
operational and deployment
strain on many
organizations.

The costs that will be incurred in the transition to IPv6 are no longer a
matter for debate. The reality is complicated by costs such as
labor resist easy quantification and estimation. In short, the transition
will
be an expense, possibly very expensive. Organizations such as ISPs can
expect
higher costs than end-user organizations.

Regardless, IPv6 is an
inevitability,
making it less a question of how much it will cost and more of when the implementation
will
occur.

Migration Challenges

More than nine years since the official establishment of IPv6, the standard
still faces difficulty gaining adoption, with Google recently estimating²
that just 35 percent of its users access its services over it.

Renumbering to the new scheme can be difficult to estimate. New devices
come
with IPv6 preinstalled and will automatically
reconfigure, but many other components such as routers (rules, etc.),
hard-coded
IP addresses in software, and licenses tied to IP addresses will need to be
manually adjusted. The length and complexity of the new addresses will make
manual
configuration work error-prone. Delays in DNS propagation of the new
addresses could
lead to additional problems.

As previously mentioned, many organizations will encounter problems
migrating
their large installed base of IPv4 hardware and software systems to IPv6,
which
may prove labor intensive. In addition, they will have to operate an IPv4
network and IPv6 network in parallel until they can abandon the
predecessor. The very nature of IPv6 makes it challenging to utilize the
same
systems and it will require organizations to expand their hardware
deployments to
maintain the same capacity. Since IPv6 comprises substantially more address
space than IPv4, it will require additional capacity. For example, older
routers will not be able to support the same number of IPv6 addresses as it
did
with IPv4, meaning organizations will have to deal with latency and
management
problems. The effect of IPv6 on quality of service and overall performance
remains
somewhat uncertain, making it difficult for organizations to predefine
service
levels. 

Security

IPSec is completely integrated into IPv6. Any
computer that is running IPv6 will support IPSec encryption,
regardless
of the computer’s operating system. IPv6 supports authentication and
privacy, providing a basic security level for all applications,
independently of higher-level protocols such as S-HTTP and SSL. It
mandates the use of IPSec.

In some respects, however, network security may get worse before it gets
better for
organizations moving to IPv6. The standard’s anticipated benefits will not
manifest themselves until IPv6 is successfully implemented by partners,
customer
organizations, and so on. Short-term security problems will parallel those
experienced under IPv4 and will likely increase as organizations run both
standards in parallel. This is true simply because running both will
increase
their risk of attack as well as network security requirements.

Implementation

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IPv6 is designed as a
natural evolution from IPv4. Providing an
incremental
transition from IPv4 to IPv6 is crucial for the success of IPv6. During the
transition period, it will be essential to maintain compatibility with the
existing installed base of IPv4 hosts and routers, and to facilitate
seamless
communication between the two protocols. Planning and testing are the top steps toward ensuring success.
Transition requires careful planning,
and the full impact on network operation, software, and the budget are needs to
be
considered. The challenge will be to break down the barriers of “acceptance
comfort zones” that a generation of IPv4-savvy engineers and
developers have grown accustom to. The path of least resistance has
been to make IPv4 adaptable. Transitional strategies
and
technologies are becoming the focus of equipment manufacturers, service
providers, and developers as further reliance on IPv4 can only lead to
a
“critical mass” of diminishing resources for Internet growth.

Transition Approaches

The transition process can be approached in one of four main ways:

• Dual-Stack – A mechanism for communicating with both IPv4 and
  IPv6
  devices coexisting in a dual-layer IP backbone. It supports
  applications
  such as Telnet, SNMP, and others over an IPv6 transport. All routers would
  need to be upgraded.
• Overlay Tunnels (Network Integration) – A technique to facilitate
  IPv6
  deployment and enable communications between IPv6 networks over an IPv4
  network or the Internet. IPv6 traffic is encapsulated within IPv4
  packets for
  the duration of the transit path across the IPv4 network.
• Dedicated Data Links – IPv6 domains communicate using the same
  Layer 2
  infrastructure as IPv4, but over separate Frame Relay, optical links, or
  DWDM.
• MPLS Backbones – Allows isolated IPv6 domains to communicate over
  an
  MPLS IPv4 backbone. Little change is required to backbone infrastructure
  because forwarding is based on labels, not the IP header.

Transition Model

In a somewhat simplistic model, the transition process could be also
viewed
as consisting of two components: transition to IPv6 hosts and transition to
IPv6 routing.

Transition to IPv6 Hosts. IPv6 transition is based on the assumption
that every IPv6 host would have dual stacks: IPv6 and IPv4. Such a dual host
would also have an application programming interface (API) that would
support
IPv4 and IPv6. The API is likely to be an extension of the current IPv4
API. Implementing an IPv6 stack on hosts and developing IPv6-capable APIs is
essential. These steps, however, are by no means sufficient to make IPv6
useful. In fact, until a sufficient number of networking applications are
ported to IPv6-capable APIs, it would be unrealistic to assume widespread
use
of IPv6. Therefore, the impact of supporting IPv6 is
likely to spread across the whole TCP/IP stack, from the network layer all
the
way up to the application layer. Organizations should not underestimate the
amount of effort needed to accomplish this, nor the potential for
introducing
software bugs during the modifications.

Transition to IPv6 Routing. Transition to IPv6 routing assumes
deployment of routers that would be able to support both IPv4 and IPv6
routing
protocols and packet forwarding. The routing protocols that are expected to
be
used with IPv6, at least initially, are mostly straightforward extensions
of
the existing IPv4 routing protocols. To minimize interdependencies, the transition to IPv6 routing assumes
that there
will be noncontiguous IPv6 segments throughout the Internet. These segments
could be as large as a collection of many routing domains, or as small as a
single IP subnet or even a single host. IPv6 connectivity among hosts in
different segments is supported by tunneling IPv6 over IPv4
(RFC2529). The
use of IPv4 tunnels to carry IPv6 traffic over IPv4-only routers is an
essential component of the IPv6 routing transition.

Other Transition Techniques. Other techniques include
automatic tunnels, configured tunnels, and network address translation:

• Automatic and Configured Tunnels – IPv6
  transition allows for two types of tunnels: automatic and manually
  configured, where new sites will be reached using mechanisms such as 6to4 to
  determine the egress side address of the tunnel. The use of automatic
  tunnels imposes two important preconditions: IPv6 addresses of the hosts
  that are reachable through automatic tunnels must be IPv4 compatible, and
  IPv4 addresses that are used to form IPv6 addresses of these hosts
  (IPv4-compatible addresses) must be routable. In addition, the use of
  automatic tunnels is currently defined only when the remote endpoint of a
  tunnel is a host. Its tunnel end-points are automatically determined by
  using IPv4 compatible IPv6 addresses as specified in RFC2373. Use of
  automatic tunnels between routers is not defined. The use of manually configured tunnels does not require hosts to have
  IPv6
  addresses that are IPv4-compatible, eliminating two of the preconditions
  associated with using automatic tunnels. A configured tunnel is created by
  manual configuration. This is achieved by building a virtual link (tunnel)
  between two IPv6
  routers. Keep
  in
  mind that as the number of manually configured tunnels grows, the
  manageability
  of tunnels configured manually would deteriorate.
• Network Address Translation – IPv4 and IPv6 nodes will coexist for a
  while
  until such time IPv6 becomes a requirement. Meanwhile, native IPv6
  hosts
  will need to communicate with IPv4 nets even if neither of them supports the
  Dual-Stack approach. The NGtrans Working Group defined translation
  techniques
  such as NAT-PT (RFC2766) providing features similar to IPv4 NAT features to
  translate between IPv4 and IPv6 addresses (and IP header formats) in an
  intranet
  or at the edge of the Internet. One technology that supports connectivity in the presence of non-unique
  addresses is NAT. This means it allows each organization connected to
  the
  Internet to reuse the same block of addresses. The use of NAT devices
  also
  allows support of hierarchical routing without requiring wide-spread
  renumbering. The only addresses that would need to be changed when an
  organization changes its Internet service provider would be the globally
  unique
  addresses that the organization uses for its external connectivity.
  Moreover,
  because information about these addresses is localized to the NAT devices,
  only
  these devices would need to be reconfigured. NAT devices allow the interconnection of hosts that have IPv6-only
  addresses
  with hosts that have IPv4-only addresses. With assigning globally unique IPv4
  addresses rendered virtually impossible, due to the exhaustion of the IPv4 address
  space, before a sufficient number of the Internet hosts would transition to
  IPv6, then NAT devices allow the transition to continue, even in the
  absence of the globally unique IPv4 addresses.

Deployment Scenarios

In addition to multiple mechanisms of transporting IPv6 over IPv4 core
networks, the following are other deployment scenarios.

• IPv6 over DWDM Backbones – The deployment of Dense Wave Division
  Multiplexing (DWDM) has the capability of reserving wavelengths for IPv6
  traffic in an IPv4 topology.
• IPv6 Backbone with Multiple-Protocol Labeling Switching (MPLS) – A
  topology of MPLS (an IETF standard) requires much less backbone
  infrastructure
  upgrades or reconfiguration while also supporting connectivity between
  IPv6
  networks. With MPLS networks, forwarding is based on labels rather
  than
  the IP header itself.
• Native IPv6 – Integration of IPv4 traffic over an IPv6 backbone
  usually
  follows similar rules of the IPv6 over IPv4 mechanisms.
• Tunneling IPv6 over IPv4 – A basic Transition Mechanisms
  specification
  for IPv6 hosts and routers that specifies the use of a Dual IP layer
  providing
  complete support for both IPv4 and IPv6 in hosts and routers, and
  IPv6-over-IPv4 tunneling , encapsulating IPv6 packets within IPv4
  headers to carry them over IPv4 routing infrastructures.
• IPv6 to IPv4 Translational Gateways RFC
  3142 – A proposal that
  describes
  an IPv6-to-IPv4 transport relay translator (TRT). It enables IPv6-only
  hosts to exchange {TCP, UDP} traffic with IPv4-only hosts. A TRT system,
  which
  locates in the middle, translates {TCP, UDP}/IPv6 to {TCP, UDP}/IPv4, or
  vice
  versa.

Deployment Challenges

More ISPs, government agencies,

Web site operators, network equipment vendors, application developers, and
corporations are rushing support IPv6 on their backbone networks. A few years ago,
only a handful of US organizations – including the federal government and a few
leading-edge companies – had deployed IPv6 across their networks. Today,
companies in the US and around the world are coming together to permanently
enable IPv6 for their products and services.

Deployment Opportunities

With the advent of the
smartphone, Wi-Fi, and next generation 4G networks, mobile
services providers are making the capabilities of wireless broadband services to
support mobile applications, an affordable and accessible alternative to
traditional wireline technologies.

From automobiles to refrigerators, coffee makers, and home
climate control systems,  the demand for integrated IP based smart
technologies is anticipated to lead the
in development and growth of mobile applications primarily with respect to voice
and data convergence. As global communications converge
onto a common backbone, namely the worldwide IP networks, the ability to
delivering integrated smart technology services will also be enhanced. Based on the building blocks of  IP and Session
Initiation Protocol (SIP), mobile smart technologies
are gaining momentum as the standard that will
bridge the gap of previously disparate and incommunicado networks.
In addition, the cable and satellite TV industry is transitioning from
traditional broadband based broadcast technologies to IPTV. With the
exhaustion of IPv4  addresses, billions and trillions of IPv6 capable
applications and devices will be needed to keep pace with the explosion of
ubiquitous access applications.

Web
Links

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• GSMA:
  http://www.gsma.com/
• IPv6 Forum: http://www.ipv6forum.com/
• IPv6 Portal: http://www.ipv6tf.org/
• Internet Society:
  http://www.internetsociety.org/
• North American IPv6 Task Force:
  http://www.nav6tf.org/
• World IPv6 Launch:
  http://www.worldipv6launch.org/measurements/

References

¹Hogg, Scott. "ARIN Finally Runs Out of IPv4 Addresses."
NetworkWorld.com. September 22, 2015.
²"Google | IPv6." Google.com. Accessed June 14, 2021.

About the Author

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Brady Hicks is an editor with Faulkner Information Services. He writes
about computer and networking hardware, software, communications networks and
equipment, and the Internet.

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