Re: [sig-policy] Need to understand logic behind assigning /64 IPv6 addr
- To: Usman Latif <osmankh at yahoo dot com>
- Subject: Re: [sig-policy] Need to understand logic behind assigning /64 IPv6 addresses
- From: John Mann <john.mann at monash dot edu>
- Date: Mon, 19 Sep 2011 15:16:07 +1000
- Cc: Skeeve Stevens <Skeeve at eintellego dot net>, "sig-policy at lists dot apnic dot net" <sig-policy at lists dot apnic dot net>
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On 18 September 2011 13:24, Usman Latif <osmankh at yahoo dot com> wrote:
I sense the recommendations for /64 assignments even to residential users looks more political than technical.
It seems that because end-hosts and other systems have already been built with more support for stateless autoconfig, this may act as a roadblock for us.First of all, the RFC-6177 does not give the reasoning behind suggesting /64 as being technically motivated but more from the perspective of growth and scalability - I for one am having a hard time imagining how a "residential site" can grow to such a length that it would need 2^64 address space. ...
For comparison, look at Netware IPX from the '80s and '90s.
* Logical networks are assigned a unique 32-bit hexadecimal address in the range of 0x1 - 0xFFFFFFFE.
* Hosts have a 48-bit node address which by default is set to the network interface card's MAC address. The node address is appended to the network address to create a unique identifier for the host on the network.
32 + 48 = 80 bits c.f. IPv6's 128 bits.
Building an IPX network was simple because hosts auto-configured themselves. No host counting or pre-registration required.
Joining 2 enterprise networks together was problematic because both sides would have used network "1", "2" ... or "A" "B" ...
If you were to add 48 bits of Site IPv6 address to IPX you get 48 + 32 + 48 = 128 bits of address.
The split between subnet and host numbers is different from normal IPv6 48 + 16 + 64
... but network interface identifiers could grow from 48 to 64 bits (e.g. one-wire device ID)
I think that this shows that 64 bits is not overly excessive for host address number.