Subject: [v6ops] ULA discussion again

From: "Leo Liu(bing)" <[email-masked]>
Date: Tue, 13 Mar 2012 03:01:50 +0000

Hi, all

We've submitted a new version of draft-liu-v6ops-ula-usage-analysis, please check it at:
http://tools.ietf.org/html/draft-liu-v6ops-ula-usage-analysis-02

There're a number of changes according to the discussion in last meeting. For your convenience, I'd like to summarize them as the following:

The use cases were simplified as 4:
-  ULA only.
ULA is good solution for isolated networks. For ULA can be used for internal communications without having any permanent or only intermittent Internet connectivity. It is on-demand and supports internal routing.
For connected networks, ULA+NAT is also meaningful in some scenarios where nodes have very constrained resource to support ND/DHCP. However, this draft doesn't consider ULA+NAT a recommendation for normal IPv6 deployment.

-  ULA+PA
the main purpose of using ULA along with PA is to provide a logically local routing plane separated from the globally routing plane. The benefit is to ensure stable and specific local communication regardless of the ISP uplink failure. This benefit is especially meaningful for the home network or private OAM function in an enterprise.
And we consider the separated local routing plane is also beneficial for renumbering, for when renumbering, it is not easy to keep the local communication immune of global routing plane change.

-  Special routing/prefix
If you have a special routing scenario, of which [draft-baker-v6ops-<http://tools.ietf.org/html/draft-baker-v6ops-b2b-private-routing>b2b-private-routing<http://tools.ietf.org/html/draft-baker-v6ops-b2b-private-routing>] is an example, for various reasons you might want to have routing that you control and is separate from other routing.
Since the NAT64 pref64 is just a group of local fake addresses for the DNS64 to point traffic to a NAT64, the pref64 is a very good use of ULA. (It is now been used in the some real network deployment.)

- As identifier
As in RFC6281, ULA can be used as upper-layer identifiers for it is easy to be grabbed in an IPv6 enabled node. It is a good use of ULA.

And we have some conclusions:
O  ULAs have been successfully deployed in a diverse set of
      circumstances including large private machine-to-machine type
      networks, enterprise networks with private systems, and within
      service providers to limit Internet communication with non-public
      services such as caching DNS servers and NAT64 translation
      resources.

   o  ULAs do not provide any intrinsic security benefit, but the
      characteristic that they cannot be routed on the internet may be
      leveraged as part of a multilayer security policy to limit the
      communication with the internet.

   o  ULAs are self-assigned and unique. Self-assigned allows for
      network deployments independent of RIR policy or documentation
      requirements. The fact that ULA require randomization within the
      prefix ensures that ULA is an improvement over RFC1918<http://tools.ietf.org/html/rfc1918> deployments
      which were likely to collide when internal networks merged.

Your comments are expected.
Thanks.