Quality of Service and performance characterization of IPv6 relative to IPv4

CHAPTER III: METHODOLOGY

III.1 INTRODUCTION

This third chapter describes the process for setting up an Netowrk test lab. The study will involved the use of networking concepts. In this study, the migration methodology will be used with well-defined steps.

This chapter also presents the software tools and hardware needed to achieve these purposes.

III.2 MIGRATION METHODOLOGY

The migration methodology has been developed by IETF in order to aid the network migrator to analyze and simplify the migration process. The migration methods the IETF recommends are dual stacks and tunneling.

III.3 STEPS IN MIGRATION METHODOLOGY

The ideal migration methodology project plan should be broken down into steps, which mirror the overall project development phases. These steps consist of:^35(*)

1. Determining Requirement

2. Understanding the existing System

3. Decision making

4. Testing

5. Deploying

6. Management

Each of these phases will be defined in further detail in the following sections. These steps will significantly impact the outcome of this project.

III.3.1 Determining Requirements

The first step is to determine what equipments have to be used and software that are required to accommodate the new technologies that can support IPv6.

III.3.2 Understanding the existing system

The second step in any new implementation is to understand what is currently on existing network. Current benchmarks of the IPv4 protocol traffic must be obtained so they may be compared with benchmarks for the new IPv6 traffic.

III.3.3 Decision making

The next step in the migration process is to decide among transitions strategies mechanisms which one can be used. This step focuses on finding the best migration method. The migration methods the IETF recommends are dual stacks and tunneling. The dual stacks method refers to IP nodes that support IPv4 and IPv6 protocols. The tunneling approach advocates running IPv6 packets over existing IPv4 infrastructures.

III.3.3.1 Dual Stack Transition Mechanism (DSTM)

Dual stack implies providing complete implementations of both versions of the IP (IPv4 and IPv6).

The most straightforward way for IPv6 nodes to remain compatible with IPv4-only nodes is by providing a complete IPv4 implementation.

IPv6 nodes that provide complete IPv4 and IPv6 implementations are called "IPv6/IPv4 nodes". IPv6/IPv4 nodes have the ability to send and receive both IPv4 and IPv6 packets. They can directly interoperate with IPv4 nodes using IPv4 packets, and also directly interoperate with IPv6 nodes using IPv6 packets.

Even though a node may be equipped to support both protocols, one or the other stack may be disabled for operational reasons. Here we use a rather loose notion of "stack". A stack being enabled has IP addresses assigned, but whether or not any particular application is available on the stacks is explicitly not defined.

Thus, IPv6/IPv4 nodes may be operated in one of three modes:

· With their IPv4 stack enabled and their IPv6 stack disabled.

· With their IPv6 stack enabled and their IPv4 stack disabled.

· With both stacks enabled.

IPv6/IPv4 nodes with their IPv6 stack disabled will operate like IPv4-only nodes. Similarly, IPv6/IPv4 nodes with their IPv4 stacks disabled will operate like IPv6-only nodes. IPv6/IPv4 nodes may provide a configuration switch to disable either their IPv4 or IPv6 stack.

The figure below show dual-stack mechanism

Figure 3: Dual Stack

Source: Own drawing

III.3.3.1.1 Address Configuration

Because the nodes support both protocols, IPv6/IPv4 nodes may be configured with both IPv4 and IPv6 addresses. IPv6/IPv4 nodes use IPv4 mechanisms (e.g., DHCP) to acquire their IPv4 addresses, and IPv6 protocol mechanisms (e.g., stateless address autoconfiguration [RFC 2462] and/or DHCPv6) to acquire their IPv6 addresses.^36(*)

* ³⁵ http://www.usipv6.com/6sense/2005/oct/06.htm (October 19, 2006)

* ³⁶ http://www.ipv6.nectec.or.th/rfc2893.html (October 31, 2006)