25-02-2013, 12:21 PM
ProCurve Networking - IPv6 – The Next Generation of Networking
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Introduction
IPv4 (or IP, as it is known) is the basis of the TCP/IP communication protocols which are used to
transport data, voice and video packets over the Internet. Internet Protocol version 6 (IPv6) is
the next generation network protocol which has been standardized to replace the current
Internet protocol version 4. It holds great promise to be the backbone of the next generation
Internet and offer a significant improvement over IPv4 in terms of scalability, security, mobility
and convergence. The basic framework of the IPv6 protocol was standardized by IETF (Internet
Engineering Task Force) in the 1990s. However, there is still ongoing development of certain
advanced aspects of the protocol.
This paper provides an introduction to IPv6 by discussing the potential business benefits
resulting from deploying IPv6 technology. To understand how we get these benefits, we look into
some of the technical features and advantages of IPv6. We then look at the transition
mechanisms developed to enable a seamless migration from IPv4 to IPv6. Finally, we analyze
some deployment issues and strategies to prepare an adoption plan for deploying IPv6 in an
enterprise.
Benefits from IPv6
The new features of IPv6 result in a number of business benefits:
o Lower network administration costs: The auto-configuration and hierarchical addressing
features of IPv6 will make networks easy to manage.
o Optimized for next generation networks: Getting rid of NAT re-enables the peer-to-peer
model and helps in deploying new applications. E.g. communications and mobility
solutions such as VoIP
o Protection of company assets: Integrated IPSEC makes IPv6 inherently secure and
provides for a unified security strategy for the entire network.
o Investment protection: The transition and translation suite of protocols helps in easy and
planned migration from IPv4 and IPv6, while allowing for co-existence in the transition
phase.
IPv6 Technology Features and Benefits
Let us look at what technical features IPv6 adds beyond IPv4 and what benefits they provide:
Larger number of addresses
IPv6 has 128 bit addresses, as compared to 32 bits for IPv4 addresses. This results in a very
large increase in the number of IP addresses available and has a number of advantages. It gets
rid of scenarios where there is an IP address scarcity and NAT needs to be deployed to fix the
issue. Getting rid of NAT results in a simplified network configuration and it reduced hardware
and software complexity. The large number of IPv6 addresses also helps in the future vision of a
networked home where various appliances and gadgets in a home will be networked and
manageable over the Internet. The increasing deployment of wireless and mobile devices will
also not be cramped by IP address scarcity issues.
End-to-end connectivity
IPv4 needed NAT in certain situations in order to conserve scarce IP addresses. Unfortunately,
NAT does not work well with peer-to-peer applications like VoIP. IPv6 eliminates the need for
NAT and thus restores end-to-end connectivity. As a result, peer-to-peer applications work well
with IPv6. Also, certain higher layer protocols like FTP have a similar issue with NAT and need
specialized software to work through NAT. Such application protocols like FTP can be enabled
much more easily with IPv6.
Efficient routing
IPv6 has a more streamlined header as compared to IPv4. This reduces the processing overhead
for routers resulting in less hardware complexity and faster packet processing. Also, hierarchical
addressing in IPv6 allows for proper address space allocation resulting in smaller routing tables
and more efficient routing in the overall network.
It also makes it easier for network administrators to assign/track addresses.
Auto-configuration
IPv6 provides auto-configuration of IP addresses on IPv6-enabled devices. This greatly improves
scalability and manageability of networks. New devices can be directly connected to the network
without manually configuring IP addresses or having a DHCP server. Also, administrators can
easily migrate a large number of devices from one network to another.
Security
IPv6 makes IPSEC mandatory, thus providing a solid security framework for Internet
communication. IPSEC can be used to implement both encryption and authentication. A number
of IPv4 implementations do not enable IPSEC, thus resulting in less security.
Mobility and multicast enhancements
IPv6 provides further enhancements for mobile IPv6 which helps with today’s wireless networks.
The addition of scope field for multicast has improved the framework for multicast traffic. Also,
the IPv6 anycast address type can be used for efficient host location.
The IPv6 Protocol Family
IPv6 is not just a single isolated protocol. IPv6 encompasses a family of protocols which will
augment/replace the existing IPv4 family of protocols. The IPv6 protocol family includes the
basic IPv6 protocol with its new addressing architecture. It also includes a vastly expanded
ICMPv6 protocol which provides autoconfiguration and neighbor discovery (similar to the ARP
functionality in IPv4), Path MTU discovery (important because only originating node can
fragment packets in IPv6), error and informational messaging (including pingv6), multicast
Listener discovery (similar to IGMP for IPv4) and mobile IPv6 related functionality.
DHCPv6 is the new version of DHCP for IPv6. Note that since IPv6 supports autoconfiguration of
IP addresses, DHCPv6 is not always required. DHCPv6 has been completely redesigned and is
only conceptually similar to DHCP. It also has additional functionality such as server originated
reconfiguration and authentication.
The Transition to IPv6
The big question is not whether IPv6 will be widely deployed successfully in the Internet – it is
how and when.
There are three transition mechanisms available to deploy IPv6 on IPv4 networks and they may
be used in any combination:
Dual Stacks
In this method, both IPv4 and IPv6 co-exist on a device/node. Depending on which node it is
talking to, the application will use IPv4 or IPv6 as appropriate. This may also be determined by
the DNS response to a node-name. If DNS returns a v4 address, IPv4 will be used. If DNS
returns a v6 address, IPv6 will be used.
Tunneling
The tunneling mechanism encapsulates IPv6 packets in IPv4 packets and can be used by 2 IPv6
nodes to communicate with each other over an IPv4 network. There are 2 ways to do tunneling:
Automatic tunneling uses IPv4-compatible IPv6 addresses to add a route to a special IPv6 prefix
which points to a tunnel destination. Any packets destined for a v4-compatible address will be
sent through the tunnel.
In Configured tunneling, the address of the tunnel exit point is configured on the tunnel entry
point and similar encapsulation is used. A combination of automatic and configured tunneling can
also be used to route IPv6 packets across a v4 network. Teredo, ISATAP, 6to4 and 6over4 are
other tunneling mechanisms.
Teredo encapsulates IPv6 packets over UDP which allows them to pass through NAT nodes.
ISATAP can be used by v6 hosts on a v4 network without any IPv6 routers using a specially
constructed ISATAP address. 6to4 also uses a special prefix for tunneling.