Re: v6 subnet size for DSL & leased line customers
First, thanks everyone for the discussion. I learned more from this than a LOT of other discussions on IPv6. I now have a plan and I didn't before... It looks to me that one really has to know his customer's needs to plan out the allocation of IPv6 space. That leads me to believe that a /56 is going to work for everyone on this network because, at this time, only very, very few of our largest customers might possibly have a need for more than 256 /64 subnets. In fact, almost all household DSL customers here only have one LAN and I could get away with /64s for them because they wouldn't know the difference. But in an effort to simplify the lives of the network folks here I am thinking of a /56 for everyone and a /48 on request. Now I just gotta wrap my brain around 4.7x10^21 addresses for each customer. Absolutely staggering. scott --- randy@psg.com wrote: From: Randy Bush <randy@psg.com> To: Joel Jaeggli <joelja@bogus.com> CC: nanog@merit.edu Subject: Re: v6 subnet size for DSL & leased line customers Date: Thu, 27 Dec 2007 13:19:27 +0900
vendors, like everyone else, will do what is in their best interests. as i am an operator, not a vendor, that is often not what is in my best interest, marketing literature aside. i believe it benefits the ops community to be honest when the two do not seem to coincide. If the ops community doesn't provide enough addresses and a way to use them then the vendors will do the same thing they did in v4.
i presume you mean nat v6/v6. this would be a real mess and i don't think anyone is contending it is desirable. but this discussion is ostensibly operators trying to understand what is actually appropriate and useful for a class of customers, i believe those of the consumer, soho, and similar scale. to summarize the positions i think i have heard o one /64 subnet per device, but the proponent gave no estimate of the number of devices o /48 o /56 o /64 the latter three all assuming that the allocation would be different if the site had actual need and justification. personally, i do not see an end site needing more than 256 subnets *by default*, though i can certainly believe a small minority of them need more and would use the escape clause. so, if we, for the moment, stick to the one /64 per subnet religion, than a /56 seems sufficient for the default allocation. personally, i have a hard time thinking that any but a teensie minority, who can use the escape clause, need more than 256. hence, i just don't buy the /48 position. personally, i agree that one subnet is likely to be insufficient in a large proportion of cases. so keeping to the /64 per subnet religion, a /64 per site is insufficient for the default. still personally, i think the one /64 subnet per device is analogous to one receptacle per mains breaker, i.e. not sensible.
there are three legs to the tripod network operator user equipment manufacturer They have (or should have) a mutual interest in: Transparent and automatic configuration of devices.
as you have seen from chris's excellent post [0] on this one, one size does not fit all. this is likely another worthwhile, but separate, discussion.
The assignment of globally routable addresses to internet connected devices
i suspect that there are folk out there who equate nat with security. i suspect we both think them misguided.
The user having some control over what crosses the boundry between their network and the operators.
yup randy --- [0] - <http://www.merit.edu/mail.archives/nanog/msg04887.html>
On Thu, 27 Dec 2007 18:08:10 -0800 "Scott Weeks" <surfer@mauigateway.com> wrote:
First, thanks everyone for the discussion. I learned more from this than a LOT of other discussions on IPv6. I now have a plan and I didn't before...
It looks to me that one really has to know his customer's needs to plan out the allocation of IPv6 space. That leads me to believe that a /56 is going to work for everyone on this network because, at this time, only very, very few of our largest customers might possibly have a need for more than 256 /64 subnets. In fact, almost all household DSL customers here only have one LAN and I could get away with /64s for them because they wouldn't know the difference. But in an effort to simplify the lives of the network folks here I am thinking of a /56 for everyone and a /48 on request.
Out of curiosity, what in form would a request for a /48 need to be? A checkbox on the application form, or some sort of written justification? Remember that with an initial RIR allocation of a /32, you've got 65K /48s ... so they're pretty cheap to give away.
Now I just gotta wrap my brain around 4.7x10^21 addresses for each customer. Absolutely staggering.
Ever calculated how many Ethernet nodes you can attach to a single LAN with 2^46 unicast addresses? That's a staggering number too. Regards, Mark.
scott
--- randy@psg.com wrote:
From: Randy Bush <randy@psg.com> To: Joel Jaeggli <joelja@bogus.com> CC: nanog@merit.edu Subject: Re: v6 subnet size for DSL & leased line customers Date: Thu, 27 Dec 2007 13:19:27 +0900
vendors, like everyone else, will do what is in their best interests. as i am an operator, not a vendor, that is often not what is in my best interest, marketing literature aside. i believe it benefits the ops community to be honest when the two do not seem to coincide. If the ops community doesn't provide enough addresses and a way to use them then the vendors will do the same thing they did in v4.
i presume you mean nat v6/v6. this would be a real mess and i don't think anyone is contending it is desirable. but this discussion is ostensibly operators trying to understand what is actually appropriate and useful for a class of customers, i believe those of the consumer, soho, and similar scale.
to summarize the positions i think i have heard o one /64 subnet per device, but the proponent gave no estimate of the number of devices o /48 o /56 o /64 the latter three all assuming that the allocation would be different if the site had actual need and justification.
personally, i do not see an end site needing more than 256 subnets *by default*, though i can certainly believe a small minority of them need more and would use the escape clause. so, if we, for the moment, stick to the one /64 per subnet religion, than a /56 seems sufficient for the default allocation.
personally, i have a hard time thinking that any but a teensie minority, who can use the escape clause, need more than 256. hence, i just don't buy the /48 position.
personally, i agree that one subnet is likely to be insufficient in a large proportion of cases. so keeping to the /64 per subnet religion, a /64 per site is insufficient for the default.
still personally, i think the one /64 subnet per device is analogous to one receptacle per mains breaker, i.e. not sensible.
there are three legs to the tripod network operator user equipment manufacturer They have (or should have) a mutual interest in: Transparent and automatic configuration of devices.
as you have seen from chris's excellent post [0] on this one, one size does not fit all. this is likely another worthwhile, but separate, discussion.
The assignment of globally routable addresses to internet connected devices
i suspect that there are folk out there who equate nat with security. i suspect we both think them misguided.
The user having some control over what crosses the boundry between their network and the operators.
yup
randy
---
[0] - <http://www.merit.edu/mail.archives/nanog/msg04887.html>
-- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
On Fri, 28 Dec 2007 12:57:45 +0900 Randy Bush <randy@psg.com> wrote:
Ever calculated how many Ethernet nodes you can attach to a single LAN with 2^46 unicast addresses?
you mean operationally successfully, or just for marketing glossies?
Theoretically. What I find a bit hard to understand is peoples' seemingly complete acceptance of the 'gross' amount of ethernet address space there is available with 46 bits available for unicast addressing on a single LAN segment, yet confusion and struggle over the allocation of additional IPv6 bits addressing bits for the same purpose - the operational convenience of having addressing "work out of the box" or be simpler to understand and easier to work with. Once I realised that IPv6's fixed sized node addressing model was similar to Ethernet's, I then started wondering why Ethernet was like it was - and then found a paper that explains it : "48-bit Absolute Internet and Ethernet Host Numbers" http://ethernethistory.typepad.com/papers/HostNumbers.pdf Regards, Mark. -- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
On Fri, Dec 28, 2007, Mark Smith wrote:
Once I realised that IPv6's fixed sized node addressing model was similar to Ethernet's, I then started wondering why Ethernet was like it was - and then found a paper that explains it :
"48-bit Absolute Internet and Ethernet Host Numbers" http://ethernethistory.typepad.com/papers/HostNumbers.pdf
Question. Whats the ethernet 48-bit MAC space usage atm? Does anyone have a graph showing an E-Day? :) Adrian
On Fri, 28 Dec 2007 13:36:56 +0900 Adrian Chadd <adrian@creative.net.au> wrote:
On Fri, Dec 28, 2007, Mark Smith wrote:
Once I realised that IPv6's fixed sized node addressing model was similar to Ethernet's, I then started wondering why Ethernet was like it was - and then found a paper that explains it :
"48-bit Absolute Internet and Ethernet Host Numbers" http://ethernethistory.typepad.com/papers/HostNumbers.pdf
Question. Whats the ethernet 48-bit MAC space usage atm? Does anyone have a graph showing an E-Day? :)
Apparently there's a foreseeable one, hence EUI-64s. Novell'll have to extend their IPX node addressing to 64 bits. Regards, Mark. -- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
On Dec 27, 2007, at 11:19 PM, Mark Smith wrote:
On Fri, 28 Dec 2007 12:57:45 +0900 Randy Bush <randy@psg.com> wrote:
Ever calculated how many Ethernet nodes you can attach to a single LAN with 2^46 unicast addresses?
you mean operationally successfully, or just for marketing glossies?
Theoretically. What I find a bit hard to understand is peoples' seemingly complete acceptance of the 'gross' amount of ethernet address space there is available with 46 bits available for unicast addressing on a single LAN segment, yet confusion and struggle over the allocation of additional IPv6 bits addressing bits for the same purpose - the operational convenience of having addressing "work out of the box" or be simpler to understand and easier to work with.
Once I realised that IPv6's fixed sized node addressing model was similar to Ethernet's, I then started wondering why Ethernet was like it was - and then found a paper that explains it :
"48-bit Absolute Internet and Ethernet Host Numbers" http://ethernethistory.typepad.com/papers/HostNumbers.pdf
Would it be possible to find the even part of this paper ? This version only has the odd numbered pages. Regards Marshall
Regards, Mark.
--
"Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
On Sat, 29 Dec 2007 15:14:25 -0500 Marshall Eubanks <tme@multicasttech.com> wrote:
On Dec 27, 2007, at 11:19 PM, Mark Smith wrote:
On Fri, 28 Dec 2007 12:57:45 +0900 Randy Bush <randy@psg.com> wrote:
Ever calculated how many Ethernet nodes you can attach to a single LAN with 2^46 unicast addresses?
you mean operationally successfully, or just for marketing glossies?
Theoretically. What I find a bit hard to understand is peoples' seemingly complete acceptance of the 'gross' amount of ethernet address space there is available with 46 bits available for unicast addressing on a single LAN segment, yet confusion and struggle over the allocation of additional IPv6 bits addressing bits for the same purpose - the operational convenience of having addressing "work out of the box" or be simpler to understand and easier to work with.
Once I realised that IPv6's fixed sized node addressing model was similar to Ethernet's, I then started wondering why Ethernet was like it was - and then found a paper that explains it :
"48-bit Absolute Internet and Ethernet Host Numbers" http://ethernethistory.typepad.com/papers/HostNumbers.pdf
Would it be possible to find the even part of this paper ? This version only has the odd numbered pages.
Hmm, you're right. The version I originally read was from somewhere else, and that was complete. I figured this one was more "original" as it's on one of the papers author's websites, so I've remembered that one, and even deleted my original electronic copy for this one. I'll try to find the other copy. Regards, Mark. -- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
On Sat, 29 Dec 2007 15:14:25 -0500 Marshall Eubanks <tme@multicasttech.com> wrote:
On Dec 27, 2007, at 11:19 PM, Mark Smith wrote:
On Fri, 28 Dec 2007 12:57:45 +0900 Randy Bush <randy@psg.com> wrote:
Would it be possible to find the even part of this paper ? This version only has the odd numbered pages.
Here's where I got the version I first read. The full text/pdf is available if you have or create yourself an ACM login : http://portal.acm.org/citation.cfm?id=800081.802680 Regards, Mark. -- "Sheep are slow and tasty, and therefore must remain constantly alert." - Bruce Schneier, "Beyond Fear"
participants (5)
-
Adrian Chadd -
Mark Smith -
Marshall Eubanks -
Randy Bush -
Scott Weeks