Applications Benefit From IPv6: Mobile IP and 3G cell phone systems can implement IPv6 for a variety of applications, including VoIP, streaming multimedia, and Internet access. VoIP in fixed locations can also benefit from IPv6 support.
VoIP is finding more uses within large organizations, but IPv4's lack of address space and the use of NAT have made these islands of communication. Calling within an organization works, yet calling outside typically means going through a private branch ex-change (PBX) and the standard phone system. It's not uncommon for a call to start as a VoIP call, then move through at least a pair of PBXs and back to a VoIP call, instead of communicating directly between a pair of VoIP nodes, which IPv6 makes possible.
IPv6 benefits VPNs with standard encryption and authentication support. A special extension header is defined for this purpose, making it easier for software and routers to handle.
Unfortunately, IPv6 application support isn't free. Simply adding an IPv6 stack isn't sufficient. New applications need to include IPv6 support, and legacy applications must be modified to tolerate IPv6. Most applications will have to be written to take advantage of a dual IPv4/IPv6 stack, complicating this technology even more.
IPv4 support enables applications to take advantage of the existing technology, including the Internet backbone. IPv6 support can improve performance and address problems in IPv4 networks.
Attacking Routing Table Overflow: IPv4 networks must contend with growing routing tables due to an increased number of nodes. Also, the IPv4 addresses don't contain location information like IPv6, so the routers must keep track of all links for traffic passing through.
Location information in IPv6 shrinks the routing table and reduces its growth because only location information needs to be saved to handle any packets heading in that direction. Performance also is enhanced as routing decisions can be made using part of the address even though the address is larger than with IPv4. Users of IPv6 can't fully take advantage of these features until there are completely native IPv6 transports. But ways exist to make IPv4 and IPv6 transport each other's packets.
Cloudy Day:Side-by-side support for IPv4 and IPv6 is possible, yet many routing environments stick to just one for efficiency and management reasons. So movement of IPv6-based information through an IPv4 network or cloud must be handled differently than the way native protocol routing methods allow.
Standards like IETF RFC-3056 IPv6 Connection of IPv6 Domains via IPv4 Clouds, and RFC-2529, Transmission of IPv6 over IPv4 Domains without Explicit Tunnels, enable IPv6 packets to traverse an IPv4 cloud (see the figure). In this case, a 6-to-4 router is located at both ends of a tunnel through an IPv4 network. A symmetrical relationship exists between the routers, and a connection through them generates a dynamic tunnel.
Similar standards are available for moving IPv4 over IPv6. This is less of a concern because IPv4 will probably find limited use once IPv6 becomes dominant. Meanwhile, the number and size of IPv6 clouds will continue to grow. IPv6 hardware is leaning toward this.
New IPv6 Hardware:Network processing units (NPUs) like Xelerated's X10 line lead the way for high-performance routers and switches. Available in single, dual, and quad 10-Gbit/s channel packages, the X10 handles Multiprotocol Label Switching, plus IPv6 and IPv4 processing at wire speeds. Its packet-driven architecture accomplishes IPv6's multicasting, forwarding, multifield classification for traffic conditioning, and extension-header parsing.
Xelerated isn't alone in its ability to tolerate IPv6. EzChip's NP-1 also handles IPv6 at 10-Gbit/s wire speeds without external CAMs or classifier engines. Novilit, creator of the AnyWhere network stack compiler, works with IPv6 as well. AnyWhere allows the creation of any type of network stack, including IPv6, and its output can be employed for NPUs, FPGAs, or software stacks that suit most operating systems.
The lanterns are on and embedded developers can no longer ignore IPv6. Supporting both IPv4 and IPv6 will be the norm for 10 years or more, a long time for many embedded systems. So expect to see dual stacks for quite a while.