On 2009-09-30 10:10, Templin, Fred L wrote:
> Brian,
>
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]] On Behalf Of
>> Brian E Carpenter
>> Sent: Tuesday, September 29, 2009 1:05 PM
>> To: Dong Zhang
>> Cc: [email protected]; Templin, Fred L; [email protected];
>> [email protected]
>> Subject: [BEHAVE] What is a site? [Re: [Softwires]Some Thought about
>> theAutomatic Tunnel Address
>>
>> On 2009-09-29 19:28, Dong Zhang wrote:
>> ...
>>>> Part of the problem with site-local was that the scope was ambiguous.
>>> Agree.
>>>> the term is not rooted in a discrete object with a position in the
>>>> topology, contrast with autonomous system or prefix.
>>> Just because of this point, it would better confirm the scope of
>>> "site" when talking about it in case misunderstanding and confusion.
>> It may be impossible. Actually I'd be very interested to hear any comments
>> about the approach to defining address scope that we have taken in
>> draft-carpenter-behave-referral-object. Maybe what we call a "limited scope"
>> is a site? This should be discussed at a BOF in Hiroshima. Comments on the
>> grobj mailing list please:
>> [email protected]
>> https://www.ietf.org/mailman/listinfo/grobj .
>
> I'm not sure it is impossible to define "site"; a site is
> just a logical or physical partition (bounded by site border
> routers) within a connected routing region. As long as the
> nodes within the site remain associated with their site
> border routers, they are still within the same site.
>
> Back to site-locals, my understanding was that RFC4193
> ULAs were introduced in part to accommodate sites that
> partition or merge. As long as each site border router
> configures and advertises a its own ULA prefix, there
> would be no ambiguity regarding the scope over which
> the ULA applies.
That can change if you use the ULA over a VPN to another "site",
or if the scope is chopped up with a NAT. I think it's rather
a different thing for a human to understand what the effective
scope is, compared with all hosts knowing algorithmically the
scope of an arbitrary address. I think Dong Zhang is asking for
an algorithmic definition.
Brian
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