Re: [v6ops] ULA draft revision #2 Regarding isolated networks

[Brian E Carpenter <[e-mail]>]

Mark,

On 27/05/2014 09:57, Mark ZZZ Smith wrote:
...
>> - "Temporarily isolated" or "Forever isolated". In general, 
>> ULAs fit both cases. Whatever it is temporarily or forever, when administrators 
>> need some prefixes to be on-demand and free to use, ULAs are good choice. 
>> However, for the temporarily isolated cases, the administrator needs to consider 
>> once it gets to connected, the hosts might need to be renumbered; or NAT might 
>> be involved if renumbering is not acceptable. If renumbering or NAT for some 
>> reason is considered as heavy burden, then the administrators need to carefully 
>> consider the adoption of ULAs.
>>  
> 
> This paragraph seems to show a fundamental misunderstanding of IPv6's multi-addressing capabilities. IPv6 supports multiple concurrent addresses (from different prefixes), and can learn new ones or deprecate old ones over time. Attachment to a new network doesn't require renumbering, it requires propagating new prefixes for the hosts to use in addition to their existing ones. Primarily RFC6724 address selection will help the hosts choose the right addresses to use as source and destinations when they have multiple addresses.

I didn't read it that way. Of course an IPv6 network runs well with
multiple prefixes, which is why overlapped renumbering is possible.

As Fred Baker once pointed out, the real problem is therefore
*numbering* a network (i.e. adding a new prefix, regardless of
whether there are zero or more existing prefixes). The text needs
to be clear about that, for sure.

    Brian