In order to disable IPv6 on newer OS X versions, you will need to run a command through the Terminal application. Please note that any changes to the network. Supporting IPv6 DNS64/NAT64 Networks With IPv4 address pool exhaustion imminent, enterprise and cellular providers are increasingly deploying IPv6 DNS64 and NAT64 networks. A DNS64/NAT64 network is an IPv6-only network that continues to provide access to IPv4 content through translation. Depending on the nature of your app, the transition has different implications: • If you’re writing a client-side app using high-level networking APIs such as and the CFNetwork frameworks and you connect by name, you should not need to change anything for your app to work with IPv6 addresses. If you aren’t connecting by name, you probably should be. See to learn how. For information on CFNetwork, see. • If you’re writing a server-side app or other low-level networking app, you need to make sure your socket code works correctly with both IPv4 and IPv6 addresses. What’s Driving IPv6 Adoption Major network service providers, including major cellular carriers in the the United States, are actively promoting and deploying IPv6. This is due to a variety of factors. Note: World IPv6 Launch is an organization that tracks deployment activity at a global scale. To see recent trends, visit the. IPv4 Address Depletion For decades, the world has known that IPv4 addresses would eventually be depleted. Technologies such as Classless Inter-Domain Routing (CIDR) and network address translation (NAT) helped delay the inevitable. However, on January 31, 2011, the top-level pool of Internet Assigned Numbers Authority (IANA) IPv4 addresses was officially exhausted. The American Registry for Internet Numbers (ARIN) is projected to run out of IPv4 addresses in the summer of 2015—a countdown is available. IPv6 More Efficient than IPv4 Aside from solving for the IPv4 depletion problem, IPv6 is more efficient than IPv4. For example, IPv6: • Avoids the need for network address translation (NAT) • Provides faster routing through the network by using simplified headers • Prevents network fragmentation • Avoids broadcasting for neighbor address resolution 4G Deployment The fourth generation of mobile telecommunication technology (4G) is based on packet switching only. Due to the limited supply of IPv4 addresses, IPv6 support is required in order for 4G deployment to be scalable. Multimedia Service Compatibility IP Multimedia Core Network Subsystem (IMS) allows services such as multimedia SMS messaging and Voice over LTE (VoLTE) to be delivered over IP. The IMS used by some service providers is compatible with IPv6 only. Cost Service providers incur additional operational and administrative costs by continuing to support the legacy IPv4 network while the industry continues migrating to IPv6. DNS64/NAT64 Transitional Workflow To help slow the depletion of IPv4 addresses, NAT was implemented in many IPv4 networks. Although this solution worked temporarily, it proved costly and fragile. Today, as more clients are using IPv6, providers must now support both IPv4 and IPv6. This is a costly endeavor. Figure 10-1 A cellular network that provides separate IPv4 and IPv6 connectivity Ideally, providers want to drop support for the IPv4 network. However, doing so prevents clients from accessing IPv4 servers, which represent a significant portion of the Internet. To solve this problem, most major network providers are implementing a DNS64/NAT64 transitional workflow. This is an IPv6-only network that continues to provide access to IPv4 content through translation. Figure 10-2 A cellular network that deploys an IPv6 network with DNS64 and NAT64 In this type of workflow, the client sends DNS queries to a DNS64 server, which requests IPv6 addresses from the DNS server. When an IPv6 address is found, it’s passed back to the client immediately. However, when an IPv6 address isn’t found, the DNS64 server requests an IPv4 address instead. The DNS64 server then synthesizes an IPv6 address by prefixing the IPv4 address, and passes that back to the client. In this regard, the client always receives an IPv6-ready address. See Figure 10-3. Figure 10-3 DNS64 IPv4 to IPv6 translation process When the client sends a request to a server, any IPv6 packets destined for synthesized addresses are automatically routed by the network through a NAT64 gateway. The gateway performs the IPv6-to-IPv4 address and protocol translation for the request. It also performs the IPv4 to IPv6 translation for the response from the server.
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