It seems that most people look at IP addresses as hardware-like, host identifiers, that are close to the "assembly language level" of the Internet, if there was such a thing. In an expanded address space, it can help to look at IP addresses as "opaque handles". In other words, they are just numbers that are passed around in the huge distributed computer system called the IPv4 Internet core. Low-level routers just happen to agree that they should advance packets in certain directions based on the values of those numbers. Routers are sort of like dumb ALUs that do not contribute much to the computation being done. If you look at packets with extended addresses, it is very much like moving from 8086 real mode addressing to 386 segmented or 486 virtual memory addressing. The addresses become logical offsets and less tied to the hardware routers. This is especially true, if new address spaces are arranged around the edges and the core is simply used for transport. With this arrangement, the task of the core is to look at the extended addressing bits and move the packets from one side of the core to the other as quickly as possible. The opaque 32 bit handles only become interesting once the packet gets to a destination where it is unwrapped for "execution"...using the ALU and distributed CPU metaphor. Now, with extended address bits the focus shifts from the 32 bit handles to the extra bits and the way they come about. In the IPv8 Plan, 2,048 TLD Authorities are tasked with being the keeper of the 11 extended address bits. Each authority can have a different Address Management plan and the 32 bit handles can have very different meanings depending on the agreements between the parties that use these extended addresses. The Address Management plan may not have anything to do with the low-level details of routing, especially across the IPv4 core. In some cases there may be very little routing that occurs based on the 32 bit handle once the packet traverses the IPv4 core. In the IPv8 Plan, the assumption is that the IPv4 core provides reliable 32 bit routing and DNS. The DNS can be used to dynamically discover which IPv4 addresses should be used as ports for tunnels from one side of the core to another. This is handled based on look-ups using the extended address bits, not the 32 bit handles. This is why it is useful to tie a TLD to the extended address bits and why with 11 bits, there can be 2,048 TLDs. For most of the TLDs, the Address Management plan or the "addressing mode", using CPU terms, would naturally be "real mode" (i.e. the 32 bit handle is indeed a host address and routing is normal). As people begin to do more research with true object-oriented platforms distributed on a large scale, other addressing modes and Address Management plans can be developed. The DNS can once again be used to encode the PSW of the TLD. The Program Status Word can indicate which addressing mode is being used and other global information. This allows for variety in the number and types of modes allowed and the mode can be controlled globally. In summary, if one looks at a packet with an IPv8 43 bit address, they have to look at the 11 extended address bits and they have to map those to a particular TLD which in turn can be used to discover the addressing mode in use which determines how those extended address bits are used. In most cases, the 11 bits are used to traverse the core and the 32 bits are used to route from there, in other cases more interesting uses can be developed for the 32 bit quanitities which many people view as IP addresses, but which will eventually become opaque handles. Jim Fleming Unir Corporation IBC, Tortola, BVI