Dave,
On 2012-03-28 09:28, Dave Taht wrote:
> On Thu, Mar 22, 2012 at 3:50 PM, Brian E Carpenter <
> [email protected]> wrote:
>
>> On 2012-03-22 12:33, homenet issue tracker wrote:
>>> #4: Use of ULAs
>>>
>>> CN1 in the -02 text says ULAs should be provisioned by default. Do we
>>> agree?
>> Yes, by the CER (MUST).
>>
>> It's much less clear for all other routers on site. I would prefer that
>> no other router provisions a ULA prefix if the CER has already delegated
>> one.
>>
>
> Since it is nearly impossible to learn a subnet prefix that is unused
> unless all devices share a routing protocol, I have generally preferred to
> generate unique ULAs per routing device.
Our two statements are not inconsistent... obviously, if a router comes
up and does not hear about a ULA prefix from another router, it may be
appropriate to generate a new one. But if we have a prefix delegation
mechanism in place, that may be sufficient.
>
>
>>> And if so, should they be preferred over globals?
>> Yes.
>>
>>
> This part I don't quite understand. I would prefer global prefixes to
> always take precedence over ULAs.
> I'd like ULAs to try to talk only to ULAs. ULAs should not escape into the
> global DNS, but should end up in local dns.
ULAs should really only be used to talk to ULAs, so when I say 'prefer ULAs',
I mean prefer a pair of ULAs to a pair of globals. In case it isn't clear,
in my mind the problem is always address *pair* selection. So that means
that a host should do something like this in the default case:
Do I have a ULA?
If yes, does the other guy have a ULA (in the same prefix)?
If yes, use the two ULAs.
Else, use two globals.
I'm hoping 3484bis will result in this.
>
> Even with 'happy eyeballs', having a means to disable a ULA -> global
> connection by default saves 100s of ms in the bad cases.
Agreed.
Brian
>
>>> The new
>>> 3484-bis has changed so they are not *unless* a specific /48 for the
>> site
>>> is added to the 3484 policy table with higher precedence than globals.
>> We
>>> should design something that works when disconnected from the Internet.
>> We'll have to deal with whatever 3484bis ends up saying. If it does
>> require an explicit policy table entry table, that will require
>> a mechanism, associated with the prefix delegation mechanism.
>>
>
> OK, I will re-read, thx for the update..
>
>
>>> Also, we currently say nothing about ULA-only devices and their
>>> reachability from outside the homenet; do we want to?
>> I don't see what there is to say; they aren't reachable, and that's
>> a feature.
>>
>> Brian
>> _______________________________________________
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>>
>
>
>
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