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

[Mark ZZZ Smith <[e-mail]>]

----- Original Message -----
> From: Liubing (Leo) <[e-mail]>
> To: v6ops WG <[e-mail]>
> Cc: "[e-mail]" <[e-mail]>
> Sent: Monday, 26 May 2014 10:36 PM
> Subject: [v6ops] ULA draft revision #2 Regarding isolated networks
> 
> Hi, All
> 
> We're going to update the ULA draft. Before making a new version, I think it 
> would be helpful to confirm/discuss several important topics which were 
> discussed in last IETF meeting. 
> 
> I'd like to discuss the topics in different mail threads respectively.
> (Current Draft link: 
> http://tools.ietf.org/html/draft-ietf-v6ops-ula-usage-recommendations-02)
> ******************************************************************************
> 
> #2 Regarding isolated networks
> 
> Current draft is a little blurry on what the "isolated" means. Based 
> on former discussion, we'll make it more comprehensive description as the 
> following (just a summary, not the specific revision wording):
> 
> - "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.


> - "Isolated to all networks" or "Isolated to the public 
> Internet". These are two separate scenarios. However, in the perspective of 
> adopting ULAs, there is no essential difference between them. So long as it 
> doesn't connect to the global Internet, ULAs fit them as well. Comparing to 
> other alternatives (an arbitrary GUA, or documentation prefixes), ULAs could 
> provide a lower possibility of collision if they are generated according to the 
> standard method. And the ACL rules for ULAs are much convenient to be set than 
> arbitrary prefixes, to prevent the prefixes leaked if the isolated networks 
> occasionally connected to the global networks. 
> 
> Please send your comments. Thanks a lot!
> 
> Best regards,
> Bing
> 
> _______________________________________________
> v6ops mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/v6ops
>