Newsgroup: it.fan.marco-ditri
Titolo: IPv6 address allocation comments


[...]
During a discussion between IETF and RIR experts at the Adelaide IETF,
a suggestion was made that it might be appropriate to allocate /56 prefixes
instead of /48 for homes and small businesses. However, subsequent
analysis has revealed significant advantages in using /48 uniformly. 
This note is an update following further discussions at the Pittsburgh 
IETF.
[...]
Also note that it is widely expected that all IPv6 subscribers,
whether domestic (homes), mobile (vehicles or individuals), or 
enterprises of any size, will eventually possess multiple always-on 
hosts, at least one subnet with the potential for additional
subnetting, and therefore some internal routing capability. 
Note that in the mobile environment, the device connecting
a mobile site to the network may in fact be a third generation
cellular telephone. In other words the subscriber allocation unit 
is not always a host; it is always potentially a site.
[...]
The question naturally arises whether giving a /48 to every
subscriber represents a profligate waste of address space.
Objective analysis shows that this is not the case. A /48
prefix under the Aggregatable Global Unicast Address (TLA) 
format prefix actually contains 45 variable
bits, i.e. the number of available prefixes is 2**45
or about 35 trillion (35,184,372,088,832). If we take the
limiting case of assigning one prefix per human, then the 
utilization of the TLA space appears to be limited to 
approximately 0.03% on reasonable assumptions. 
More precisely,
 - RFC 1715 defines an "H ratio" based on experience in
   address space assignment in various networks. Applied
   to a 45 bit address space, and projecting a world
   population of 10.7 billion by 2050 (see
 
http://www.popin.org/pop1998/
 ), the required
   assignment efficiency is log_10(1.07*10^10) / 45 = 0.22.  
   This is less than the efficiencies of telephone numbers and 
   DECnetIV or IPv4 addresses shown in RFC 1715, i.e. gives
   no grounds for concern.
 - We are highly confident in the validity of this analysis,
   based on experience with IPv4 and several other address spaces,
   and on extremely ambitious scaling goals for the Internet
   amounting to an 80 bit address space *per person*. Even so,
   being acutely aware of the history of under-estimating demand,
   we have reserved more than 85% of the address space (i.e. the
   bulk of the space not under the Aggregatable Global Unicast 
   Address (TLA) format prefix).   
   Therefore, if the analysis does one day turn out to be wrong, 
   our successors will still have the option of imposing much more 
   restrictive allocation policies on the remaining 85%.
 - It has been suggested that even if the above analysis is valid
   for terrestrial and near-Earth networks, it may fail for
   interplanetary networking and beyond. This is conceivable, but 
   the challenges in dealing with packet transit times of many minutes
   or more, and with such remote deployment, are such as to turn 
   addressing into a side issue.
 - For transient use by non-routing hosts (e.g., temporary addresses 
   acquired and released while passing through wireless cells, and 
   for stand-alone dial-up users who prefer transient addresses for 
   privacy reasons), a prefix longer than /48 would be OK. But a
   subscriber who wants "static" IPv6 address space ought
   to be allocated a /48 for the reasons given above.
[...]
It is not obvious, however, that all edge networks are likely to be 
recursively subnetted; an individual PC in a home, or a single cell in a 
mobile telephone network, for example, may or may not be further 
subnetted (depending whether they are acting as gateways to personal, 
home, or vehicular networks). When a network number is delegated to a place 
which will not require subnetting, therefore, wisdom suggests that it be given 
a single 64 bit prefix - perhaps shared among the dial-in connections to the 
same ISP router. It is suggested that business practices therefore consider 
whether the edge network is or is not likely to be recursively subnetted, 
and allocate /48 or /64 prefixes accordingly. However this decision may be 
taken in the knowledge that there is objectively no shortage of /48s,
and the expectation that personal, home and vehicle networks will
become the norm.
[...]
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Come mai non è arrivato anche in ML ?
-- 
ciao,
id

 ICFAQ 3.01 - Manuale italiano di Internet 
http://bertola.eu.org/icfaq/
 <
---------------------> NO, NON FACCIO PARTE DEL GCN <---------------------

Come mai non è arrivato anche in ML ?
secondo me ti hanno bannato. :)
--
Layos [gir n°19]
I magi non erano ne tre ne quattro, erano infiniti...
Nicola Mancino [Presidente del Senato]

secondo me ti hanno bannato. :)
?? bong ??
ma xchč? č arrivato sul serio in ML ??
-- 
ciao,
id

ma xchè? è arrivato sul serio in ML ??
non ho nemmeno idea di che ML tu stia parlando, era un joke.


non ho nemmeno idea di che ML tu stia parlando, era un joke.
si scusa non ho visto la faccina :)
mi riferivo alla Mailing List di IPv6
era un msg interessante e chiedevo come mai non l'avesse anche postato
nella ML, solo quello :)	
-- 
ciao,
id

nella ML, solo quello :)	
Perche` chi e` interessato a quelle cose probabilmente e` iscritto anche
alla mailing list del WG, lo scopo di 
ip...@lists.linux.it
[1] e` piu`
ristretto.
[1] Di cui ricordo l'esistenza a tutti i lettori...
