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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Shim6 vs PI addressing
On Thu, Mar 02, 2006 at 02:21:45AM -0800, Owen DeLong wrote: > Yes, I am well aware of 32bit ASNs. However, some things to consider: > 1. Just because ASNs are 32 bits doesn't mean we'll instantly > issue all 4 billion of them. The reality is that we probably > only need about 18 bits to express all the ASNs well need for > the life of IPv6, but, 32 is the next convenient size and there's > really no benefit to going with less than 32. It's probably worth using this juncture to point out that exactly the same principle applies to the bit-width gap between IPv4 and IPv6: the fact that IPv6 gives 128 bits doesn't mean we're going to allocate all of them right away. The number of networks in use is not driven by the size of the address space; it's driven by the number of enterprises who wish to connect to the Internet, the number of sites at which they wish to connect, the number of interfaces they wish to use to carry out their interconnections, and the number of hosts they're bringing along with each connection. Notice that none of that has anything to do with the version number of the protocol which those hosts are speaking. By any way you measure it, Internet growth is a function of end-user demand, not a function of the number of bits in an IP address. We can spend another decade talking about how to manage routing table growth if we really want to, but during that decade the routing table is going to *keep growing anyway*. If we want to prevent it from growing, the only real way to do it is going to be at the demand side -- which is another way of saying that we'd need to address and control all of the clauses I iterated through two paragraphs ago. When you distill *that* message to its essence, you can restate it like this: "We can control the growth of the IP routing table by making it harder for people to connect their networks to the Internet." Because that's what the advocates for IPv6 universal PA space are *really* saying, once you remove all the smoke and mirrors. ... which neatly explains a major reason for why IPv6 hasn't taken off, and why shim6 remains vapourware despite many years of discussion and the presence of a clear, unambiguous demand for a solution to the multihoming problem. What's the way out? Acknowledgement of the fact that the size of the routing table is a function of the size of the Internet. Y'know, one of those "duh!" statements. If we expect the Internet to grow past 32-bit limitations, we're going to have to expect the routing table to grow past the constraints which that 32-bit world has imposed upon it. Solving *that* problem is, IMHO, overwhelmingly preferable to breaking multihoming and handing routing policy decisions over to the viruses and worms which control each host. (note that I'm not pretending that solving the routing table growth problem is -easy-, it's just plainly obvious to me that it'll need to be solved anyway, and the IPv6 PA advocacy that keeps coming up seems to be an exercise in denial...) - mark -- Mark Newton Email: [email protected] (W) Network Engineer Email: [email protected] (H) Internode Systems Pty Ltd Desk: +61-8-82282999 "Network Man" - Anagram of "Mark Newton" Mobile: +61-416-202-223
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