Internet 6

Benefits of IPv6
Improved efficiency in routing and packet handling
Support for autoconfiguration and plug and play
Support for embedded IPSec
Enhanced support for Mobile IP and mobile computing devices
Elimination of the need for network address translation (NAT)

Increased number of multicast addresses, and improved support for multicast
What is IPv6?
IPv6 header format
IPv6 extension headers
IPv6 addressing
IPv6 Operation


Stateless autoconfiguration and renumbering of IPv6 nodes
Path Maximum Transfer Unit (MTU)
DHCPv6 and Domain Name Server (DNS)
IPv6 Deployment
Dual-stack backbone
IPv6 over IPv4 tunneling
IPv6 Challenges
Why Test IPv6 Technology?










Appendix: Sample IPv6 Test Plans
IPv6 Conformance Test
IPv6/IPv4 Forwarding Performance Test
Tunneling Functional Test
Tunneling Performance Test
IPv6 Routing Performance and Scalability Test


Copyright (c) 1998-2003 Ixia. All rights reserved.

 

The information in this document is furnished for informational use only, is subject to change without notice, and should not be construed as a commitment by Ixia. Ixia assumes no responsibility or liability for any errors or inaccuracies that may appear in this document.

Ixia and the Ixia logo are trademarks of Ixia. All other companies, product names, and logos are trademarks or registered trademarks of their respective holders.
 

The need for a new Internet Protocol is well understood and accepted in the networking industry. Requirements for more address space, simpler address design and handling at the IP layer, better QoS support, greater security, and an increasing number of media types and Internet-capable devices have all contributed to drive the development ofInternet Protocol version 6 (IPv6). This paper reviews the basics of IPv6, its deployment, and strategies for managing the transition from IPv4 to IPv6. Most importantly, the paper identifies key areas for IPv6 testing, and prescribes an appropriate testing methodology for each of them.


IPv4, the current version of the Internet Protocol deployed worldwide, has proven remarkably robust, easy to implement, and interoperable with a wide range of protocols and applications. Though substantially unchanged since it was first specified in the early 1980s, IPv4 has supported the scaling of the Internet to its current global proportions. However, the ongoing explosive growth of the Internet and Internet services has exposed deficiencies in IPv4 at the Internet抯 current scale and complexity. IPv6 was developed specifically to address these deficiencies, enabling further Internet growth and development.

The most important issue addressed by IPv6 is the need for increased IP addresses: IPv4抯 32-bit address space is nearly exhausted, while the number of Internet users continues to grow exponentially. This need is exacerbated by the continual introduction of addresshungry Internet services and applications (Internet-enabled PDAs, home and small office networks, Internet-connected vehicles and appliances, IP telephony and wireless services, etc.). The exhaustion of IPv4 addresses has been long anticipated, and various techniques have been introduced to extend the life of the existing IPv4 infrastructure, including Network Address Translation (NAT), Dynamic Host Configuration Protocol (DHCP), and Classless Inter-Domain Routing (CIDR).

While these techniques provide a workaround for the lack of address space, they fail to meet the requirements of the Internet抯 end-to-end architecture and peer-to-peer applications. Additionally, residential broadband Internet requires always-on, always-contactable global addresses, which are unsupportable with current IP address conversion strategies, pooling, and other temporary allocation techniques.

The global need for IP addresses has even added political force to the drive for IPv6 implementation. For latecomers to the Internet explosion, IPv6 is the only solution that will accommodate billions of new users. Many countries, such as China and Japan, have legislated an implementation schedule for IPv6 to meet their urgent deployment needs.

Simply stated, IPv6抯 ample (128-bit) address space provides an adequate number of globally unique addresses to support the anticipated growth and development of the Internet for the foreseeable future. However, as the following section illustrates, IPv6 is much more than just a software fix to provide more IP addresses.

 

 

 

. IPv6 address format.
Benefits of IPv6

Aside from the increased address space, IPv6 offers a number of other key design improvements over IPv4.
Improved efficiency in routing and packet handling
IPv6抯 very large addressing space and network prefixes (Figure 1) allow the allocation of large address blocks to ISPs and other organizations. This enables an ISP or enterprise organization to aggregate the prefixes of all its customers (or internal users) into a single prefix and announce this one prefix to the IPv6 Internet.

Within the IPv6 address space, the implementation of a multi-leveled address hierarchy provides more efficient and scalable routing. This hierarchical addressing structure reduces the size of the routing tables Internet routers must store and maintain.

Though the IPv6 header is larger, its format is simpler than that of the IPv4 header. The IPv6 header removes the IPv4 fields for Header Length (IHL), Identification, Flags, Fragment Offset, Header Checksum, and Padding, which speeds processing of the basic IPv6 header. Also, all fields in the IPv6 header are 64-bit aligned, taking advantage of the current generation of 64- bit processors.
Support for autoconfiguration and plug and play
The need for plug-and-play autoconfiguration and address renumbering has become increasingly important to accommodate mobile services (data and voice) and Internetcapable appliances. IPv6抯 built-in address autoconfiguration feature enables a large number of IP hosts to easily discover the network and obtain new, globally unique IPv6 addresses. This allows plug-and-play deployment of Internet-enabled devices such as cell phones, wireless devices, and home appliances.

The autoconfiguration feature also makes it simpler and easier to renumber an existing network. This enables network operators to manage the transition from one provider to another more easily.
Support for embedded IPSec
Optional in IPv4, IPSec is a mandatory part of the IPv6 protocol suite. IPv6 provides security extension headers, making it easier to implement encryption, authentication, and virtual private networks (VPNs). By providing globally unique addresses and embedded security, IPv6 can provide end-to-end security services such as access control, confidentiality, and data integrity with less impact on network performance.
Enhanced support for Mobile IP and mobile computing devices
Mobile IP, defined in an IETF standard, allows mobile devices to move around without breaking their existing connections ?an increasingly important network feature. Unlike IPv4, IPv6 mobility uses built-in autoconfiguration to obtain the Care-Of-Address, eliminating the need for a Foreign Agent. In addition, the binding process allows the Correspondent Node to communicate directly with the Mobile Node, avoiding the overhead of triangular routing required in IPv4. The result is a much more efficient Mobile IP architecture in IPv6.
Elimination of the need for network address translation (NAT)
NAT was introduced as a mechanism to share and reuse the same address space among different network segments. While it has temporarily eased the problem of IPv4 address shortage, it has also placed a burden on network devices and applications to deal with address translation. IPv6抯 increased address space eliminates the need for address translation, and with it, the problems and costs associated with NAT deployment.

IPv6 maintains and extends support for existing Interior Gateway Protocols (IGPs) and Exterior Gateway Protocols (EGPs). For example, OSPFv3, IS-ISv6,RIPg and MBGP4+ have been well defined to support IPv6.
Increased number of multicast addresses, and improved support for multicast.
IPv6 multicast completely replaces IPv4 broadcast functionality, by handling IPv4 broadcast functions such as router discovery and router solicitation requests. Multicast saves network bandwidth and improves network efficiency.


The IPv6 header has been streamlined for efficiency (Figure 2). The new format introduces the concept of an extension header, allowing greater flexibility to support optional features. Fields in the IPv6 header are:

Version: 4-bit Internet Protocol version number, value = 6. Traffic Class: 8-bit traffic class field, similar to type of service in IPv4. Flow Label: 20-bit flow label, used to identify traffic flow for additional control on quality of service. Payload Length: 16-bit unsigned integer, length of the IPv6 payload. Next Header: 8-bit selector, used to identify the type of header immediately following the IPv6 header. Hop Limit: 8-bit unsigned integer, decremented by 1 by each node that forwards the packet. The packet is discarded if Hop Limit is decremented to zero. Source Address: 128-bit address of the originator of the packet. Destination Address: 128-bit address of the intended recipient of the packet.

The extension header is optional in IPv6. If present, extension headers immediately follow the header field. IPv6 extension headers have the following properties:

They are 64-bit aligned, with much lower overhead than IPv4 options. They have no size limit as with IPv4. The only limitation is the size of IPv6 packet. They are processed only by destination node. The only exception is the Hop-by- Hop header option. The Next Header field of the base IPv6 header identifies the extension header.

 

 

. IPv4 and IPv6 header formats.

When multiple extension headers are present in a same IPv6 packet, they occur in this order:

The Hop-by-Hop header carries information that needs to be examined by all the nodes along the delivery path. When present, the Hop-by-Hop option always follows immediately after the basic IPv6 header. The Destination header carries additional information that can be examined only by the destination node. The Routing header is used by the source node to list all the nodes the packet needs to traverse on the path to its destination. The Fragmentation header is used by the source to indicate that the packet has been fragmented to fit within the maximum transmission unit (MTU size). In IPv6, unlike IP4, packet fragmentation and assembly are done by the end nodes instead of routers, which further improves the efficiency of the IPv6 network. The Authentication and Encapsulating Security Payload headers (AH and ESP) are used in IPSec to provide security services to ensure the authentication, integrity, and confidentiality of a packet.

The 128-bit IPv6 address is separated into eight 16-bit hexadecimal numbers divided by colons (??. The preferred format is xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx, for example: 2031:0000:1F1F:0000:0000:0100:11A0:ADDF.. The following conventions are also used to represent IPv6 addresses, including ways to shorten them and make them easier to represent:

Leading zeros can be removed. ?:?represents one or more groups of 16 bits zeros, and can only appear once in an address. For example, 2001:0:13FF:09FF:0:0:0:0001 = 2001:0:13FF:09FF::1 The lower four 8 bits can use decimal representation of IPv4 addresses. For example, an IPv4-compatible IPv6 address is 0:0:0:0:0:0.192.168.0.1. Unlike an IPv4 node, an IPv6 node allows more than one type of IP address: unicast, anycast, and multicast. An address used to identify a single interface. A packet destined for a unicast address is delivered to the interface identified by that address. Based on the reachability of the packets, unicast supports the following address types.

Global unicast address. An address that can be reached and identified globally. A global unicast address consists of a global routing prefix, a subnet ID, and an interface ID (Figure 3). The current global unicast address allocation uses the range of addresses that start with binary value 001 (2000::/3), one-eighth of the total IPv6 address space.

Site-local unicast address. An address that can only be reached and identified within a customer site, similar to IPv4 private address 10.0.0.0/8 and 192.168.0.0/16. the site-local unicast address contains a FEC0::/10 prefix, subnet ID, and interface ID (Figure 4).

Link-local unicast address. An address that can only be reached and identified by nodes attached to the same local link. A link-local unicast address uses a FE80::/ 10 prefix and an interface ID (Figure 5).

 

 

 

. Global unicast address format.

 

 

 

. Site-local unicast address format.

 

 

 

. Link-local unicast address format.

The anycast address is a global address that is assigned to a set of interfaces belonging to different nodes (Figure 6). A packet destined to an anycast address is routed to the nearest interface. The anycast address has the following restrictions: An anycast address must not be used as source address of IPv6 packet. An anycast address must not be assigned to an IPv6 host. It may be assigned to an IPv6 router. As in IPv4, a multicast address is assigned to a set of interfaces belonging to different nodes. A packet destined to a multicast address is routed to all interfaces identified by that address. The IPv6 multicast address uses the FF00::/8 prefix, 1/256 of the total IPv6 address space (Figure 7).