Re: Using /126 for IPv6 router links
the general intent of a class B allocation is that it is large enough for nearly everybody, with nearly everybody including all but the largest of organisations. That would, indeed, work if we weren't short of class B networks to assign. Would you clarify? Seriously?
we used to think we were not short of class B networks randy
In message <m2sk9rsobb.wl%randy@psg.com>, Randy Bush writes:
the general intent of a class B allocation is that it is large enough for nearly everybody, with nearly everybody including all but the largest of organisations. That would, indeed, work if we weren't short of class B networks to assign. Would you clarify? Seriously?
we used to think we were not short of class B networks
Really? Do you have a citation? It should have been clear to anyone that thought about it that IPv4 address where not big enough to support every man and his dog having a network. I know when I was getting my first class B address block in '88 that it was obviously not sustainable but I'll get one while I can because that and class C's were all that were available and it could be justified under the rules as they stood then. CIDR when it came along didn't change my opinion, though it did delay the inevitable as did PNAT. I don't see the same thing with /48 as the basic allocation provided RIR's don't do greenfield all the time but instead re-allocate blocks when they are not maintained. Always doing greenfield allocations will exhaust any allocation scheme in time. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org
On Thu, 28 Jan 2010 00:26:34 +1100 Mark Andrews <marka@isc.org> wrote:
In message <m2sk9rsobb.wl%randy@psg.com>, Randy Bush writes:
the general intent of a class B allocation is that it is large enough for nearly everybody, with nearly everybody including all but the largest of organisations. That would, indeed, work if we weren't short of class B networks to assign. Would you clarify? Seriously?
we used to think we were not short of class B networks
Really? Do you have a citation? It should have been clear to anyone that thought about it that IPv4 address where not big enough to support every man and his dog having a network.
If you dig into it a bit, you find that the original addressing plan was a single network octet, and 3 node octets. The earliest document I can find that describes 32 bit IP addresses is Internet Engineering Note 5, March 1977 (http://www.isi.edu/in-notes/ien/ien5.pdf), page 68 (69 of the .pdf), and a diagram on page 74 (page 75 .pdf). IEN 91, May 1979 (http://www.isi.edu/in-notes/ien/ien91.txt), also describes the earliest 32 bit IP address format, and how to map link layer addresses, such as ARPANET addresses into the "Local address" portion. RFC760, January 1980, also specifies that format of addressing. RFC791, September 1981, is where it changed to classes. So IP addresses were structured and deployed with a single network octet and 3 node octets for more than 4 years. I think that is evidence that 32 bit IP addresses were never originally designed to support a world wide network that the Internet has become, that fixed network and node portions are the preferred way to do network addressing (and if you look at all the other protocols that have existed, excepting CLNS (a "fixed" copy of IPv4 apparently), they've all done it that way), and that classes, subnets and then classless addressing have all fundamentally been very been neat hacks to make 32 bit addressing support far more devices than was ever expected.
I know when I was getting my first class B address block in '88 that it was obviously not sustainable but I'll get one while I can because that and class C's were all that were available and it could be justified under the rules as they stood then.
CIDR when it came along didn't change my opinion, though it did delay the inevitable as did PNAT.
I don't see the same thing with /48 as the basic allocation provided RIR's don't do greenfield all the time but instead re-allocate blocks when they are not maintained. Always doing greenfield allocations will exhaust any allocation scheme in time.
Mark
-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org
On 28/01/2010, at 1:51 AM, Randy Bush wrote:
the general intent of a class B allocation is that it is large enough for nearly everybody, with nearly everybody including all but the largest of organisations. That would, indeed, work if we weren't short of class B networks to assign. Would you clarify? Seriously?
we used to think we were not short of class B networks
We also used to have a protocol with less total addresses than the population of the planet, let alone subnets. In 2000::/3, assuming we can use 1 in every 4 /48s because, well, I'm being nice to your point, we still have 1300 /48s per person. http://www.wolframalpha.com/input/?i=%28%282%5E45%29%2F4%29%2Fearth+populati... And that's /48s. What if say 50% of the address space is /48s and 50% of the address space is /56s? Then we have 675,000 networks per person. If we botch that up then we've done amazingly badly. Then we'll move on to 4000::/3. -- Nathan Ward
participants (4)
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Randy Bush