June 2008 will be a milestone for IPv6 adoption. By that time, U.S. military and government agencies must source IPv6-capable hardware and software. For most IT managers, the switch to IPv6 will be an onerous transition involving extensive equipment, application and protocol tests.
While NAT (Network Address Translation) has staved off one of the most prominent drivers for a next-generation IP architecture—namely, too few public addresses—government adoption will almost certainly increase IPv6 use in the private sector. Growing IPv6 adoption in the rest of the world, along with military and federal use of the technology, is setting the stage for significant changes in the way network managers operate and troubleshoot IP infrastructure.
In IPv6, routers advertise their presence using the same protocol that network nodes use to learn about neighbors. Default gateways, which were designated either explicitly in endpoint network configuration or more commonly assigned via DHCP (Dynamic Host Configuration Protocol) Version 4, are now distributed through nodes that listen on the network for address assignment and other available services. This means many troubleshooting routines that network managers now use as second nature must be relearned in an IPv6 world.
For example, network managers accustomed under IPv4 to checking in a routers ARP (Address Resolution Protocol) cache to learn the association of a MAC (Media Access Control) address to an IP address must, in IPv6, learn to look elsewhere, as the new protocol has dispensed with ARP, replacing it with the Neighbor Discovery protocol. On Windows machines, this means running netsh from the command line to query a neighbor machine residing on the same network to fetch this association information.
