As IPv4 addresses become exhausted, IPv6 is steadily entering our daily lives, and most infrastructure now supports IPv6. However, migrating to IPv6 is not simply a matter of reconfiguring devices from IPv4 to IPv6鈥攊t is a systematic engineering effort. Below, we analyze the key considerations, using H3C routers as an example.
1. Most applications do not care about the underlying network protocol (IP), but some do, such as instant services using the Session Initiation Protocol (SIP). The creators of SIP made a serious mistake by embedding IP address information into SIP message headers. Vendors and SIP application developers must redesign their applications to support IPv6 information in SIP headers.
2. Multiple WAN links are a standard practice for most enterprises. The hierarchical structure of IPv6 address design simplifies routing tables by summarizing routes into aggregate routes. However, IPv6 designers did not account for the need for private addresses or multiple WAN links, while enterprises want both security and resilience. Creating a multi-homed or IPv6 address translation strategy requires close collaboration with your service provider to obtain your own IPv6 address space.
3. Most routers and switches support IPv6, but how these network devices forward IPv6 packets varies. High-capacity core routers process packets on dedicated hardware (such as ASICs or network processors) to accelerate IPv4 forwarding. However, the hardware architecture often does not support IPv6; this means the router processes IPv6 packets on a general-purpose processor, resulting in slower forwarding speeds and reduced capacity.
4. IPv6 support is still very limited, especially for services like MPLS and residential Internet. As a result, homes or remote workers using FiOS cannot use IPv6 services without tunneling protocols. Many home routers also do not support IPv6, and many Internet architects worry that Carrier-Grade NAT (CGN) breaks the end-to-end Internet model; this means carriers can restrict unwanted services by not allowing them to penetrate NAT.
In any case, CGN may currently be the only viable solution to address not only the IPv4-to-IPv6 interworking problem, but also to minimize IPv4 and IPv6 route propagation, thereby reducing the resource load on carrier edge routers.
5. A network is not just composed of routers, switches, and computers. WAN optimization and management platforms, provisioning and change management programs, sensors and M2M devices, and management tools must all be considered when purchasing IT products. IT engineers must analyze whether they support