Future Network Considerations

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Myth 2: We Can Patch IPv4 to Duplicate IPv6

It is understood that a migration from IPv4 to IPv6 will be a challenging process. Nevertheless, the idea that patching IPv4 will make everything all right is flawed. One example of an IPv4 patch is network address translation (NAT) that preserves IPv4 address space by intercepting traffic and converting private IP addresses into unique Internet addresses. Other examples include the various quality-of-service and security enhancements being proposed to IPv4.

These patches might prove to be valuable in certain limited and short-term scenarios, but they ultimately will limit connectivity, interoperability, and network performance. In general, IPv4 patches are no substitute for IPv6—a protocol suite that has been designed from the ground up with scalable addressing, advanced routing, security, quality-of-service, and related features from the beginning.

Future network requirements will require extremely high levels of connectivity both internally and externally to your network. We are seeing the future quickly emerging around us in the form of the World Wide Web, increased multimedia, transaction- oriented applications, and ever more interactive applications.

Myth 3: IPv6 Will Only Benefit Hierarchical Networks

The truth is that IPv6 will provide many benefits for hierarchical networks. However, there is a variety of features that it brings to the table that will benefit every level of network user. These benefits are outlined in the following list.

  Increased security and authentication that will benefit applications
  Automatic configuration features that will benefit mobile network users
  Quality of Service features already integrated into the stack will benefit interactive multimedia applications

Myth 4: Who Needs the Ability to Assign Addresses to a Large Number of Diverse Network Devices?

New and very diverse network devices are already here. Take a moment to consider what is already available for use within a business setting or home.

  Personal Data Assistants (PDAs)
  Cellular Phone/Pagers Combinations with Voice Mail
  Web Integrated Televisions
  Embedded network components within office equipment
  Embedded network components within home appliances
  Satellite links in your car
  Hand-Held Global Positioning systems

These devices are only a few steps away from being incorporated into every network; and make no mistake, the ability to log onto the Internet and check the status of your home appliances and security system is not far away. The possibilities are endless and mind-boggling.

As new devices make their way onto the Internet, they will strain the existing network fabric in ways the early IP protocol designers could hardly have imagined. IPv6 address space will enable businesses to take advantage of this yet untapped market.

IPv6 Design Goals

IPv6 has been designed to enable high-performance, scalable internetworks to remain viable well into the next century. A large part of this design process involved correcting the inadequacies of IPv4. It is only by delving into the full range of IPv6 improvements that the full benefits to enterprise networks can be evaluated.

With the advent of IPv6 comes more efficient Internet protocols with several features. The most common features appear in the following list.

  128-bit network addresses instead of 32-bit
  More efficient IP header with extensions for applications and options
  Streamlined packet design to include no header checksum
  A flow label for quality-of-service requirements
  Prevention of intermediate fragmentation of datagrams
  Built in security for authentication and encryption

These enhancements will be detailed later in the chapter. Other qualities are less tangible and relate to the fresh start that IPv6 gives to those who build and administer networks.

Addressing and Routing

IPv6 will enable Internet backbone designers to create a highly flexible and open-ended global routing hierarchy. At the level of the Internet backbone where major enterprises and Internet Service Provider (ISP) networks come together, it is necessary to maintain a hierarchical addressing system, much like that of the national and international telephone systems.

For example, large central-office phone switches only need a three-digit national area code prefix to route a long-distance telephone call to the correct local exchange. Without an address hierarchy, backbone routers would be forced to store routing table information on the accessibility of every network in the world.

As discussed in previous chapters, given the current number of IP subnets in the world and the growth of the Internet, this is not feasible. However, if there was a hierarchical addressing structure, then backbone routers could use IP address prefixes to determine how traffic should be routed through the backbone.

Currently, IPv4 uses a technique called Classless InterDomain Routing (CIDR), which allows flexible use of variable-length network prefixes. The availability of CIDR routing does not guarantee an efficient and scalable hierarchy. In many cases, legacy IPv4 address assignments that originated before CIDR do not facilitate summarization. In fact, much of the IPv4 address space was formed before the current access provider hierarchy was developed. This lack of uniformity in the current hierarchical system, coupled with the rationing of IPv4 addresses, means that Internet addressing and routing is filled with complications at all levels.

Transitioning and Implementing IPv6

Few in the industry would argue with the principle that IPv6 represents a major leap forward for the Internet and the enterprises that rely on internetworking technology.

What is not agreed upon in the industry, however, is which shape and speed the transition from IPv4 to IPv6 will take:

  Wholesale rapid adoption of IPv6 in the very near future
  Wait until address-space exhaustion and other issues force conversion

But given the magnitude of a migration that affects so many millions of network devices, it is clear that there will be an extended period when IPv4 and IPv6 will coexist at many levels on the Internet.


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OSPF Network Design Solutions
OSPF Network Design Solutions
ISBN: 1578700469
EAN: 2147483647
Year: 1998
Pages: 200
Authors: Tom Thomas

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