Re: [v6ops] new draft: draft-colitti-v6ops-host-addr-availability

Sander Steffann <sander@steffann.nl> Mon, 06 July 2015 12:46 UTC

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From: Sander Steffann <sander@steffann.nl>
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Subject: Re: [v6ops] new draft: draft-colitti-v6ops-host-addr-availability
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Hi,

> A new draft has been posted, at http://tools.ietf.org/html/draft-colitti-v6ops-host-addr-availability. Please take a look at it and comment.

Nice draft, and very much needed. I only have a few comments on 8.2. Address space management:


> In IPv4, all but the world's largest IPv4 networks can be addressed
> using RFC 1918 space.  The total size of net 10 is roughly 2^24 (16
> million) endpoints, with each endpoint receiving one IPv4 address.
> In IPv6, that is equivalent to assigning one /64 per host out of a
> /40.  Under current RIR policies, a /40 is easy to obtain for an
> enterprise network.

I wouldn’t say that a /40 is easy to obtain for enterprise networks. The usual size is a /48. Of course the networks that actually use all of 10/8 would should no problem getting a /40, but that isn’t true for all enterprises.

Suggested new text:

"""
In IPv4, all but the world's largest IPv4 networks can be addressed
using RFC 1918 space.  Many networks can be numbered with e.g.
192.168.0.0/16 which has roughly 2^16 (65536) endpoints, with each
endpoint receiving one IPv4 address. In IPv6, that is equivalent to
assigning one /64 per host out of a /48.  Under current RIR policies,
a /48 is easy to obtain for an enterprise network.

Networks that need a bigger block of RFC 1918 space use 10.0.0.0/8 
which is is roughly 2^24 (16 million) endpoints. The equivalent in
IPv6 would be assigning a /64 per host out of a /40. Enterprises of
such size can easily obtain a /40 under current RIR policies.
"""

or something similar.

> In other words, assigning a single IPv6 /64 per
> host is as feasible as assigning a single IPv4 address per host.
> 
> Currently, residential users receive one IPv4 address and a /56 or
> /60 IPv6 prefix.

I know lots of ISPs that give residential users a /48. I'm afraid this text might suggest giving them small(er) sizes. Maybe change it to:

"""
Currently, residential users often receive one IPv4 address and a /48,
a /56 or even something as tiny as a /60 IPv6 prefix.
"""

Ok, maybe leave the "even something as tiny as" bit out ;)  But that's the message I would like to give to the reader.

> While such networks do not have enough space to
> assign a /64 per device, today such networks almost universally use
> SLAAC.
> 
> Unlike IPv4 where addresses came at a premium, in all these networks,
> there is enough IPv6 address space to supply clients with multiple
> IPv6 addresses.

+1000

Cheers,
Sander