Subject: RE: what is a site???

From: "SESVOLD, DALE" <[email-masked]>
Date: Mon, 26 Mar 2001 07:54:46 -0600

What ever a site is defined to be one would have the following issues:
Distinct:  not necessarily uniquely numbered but able to be differentiated
from other sites with easily distinquishable routing boundry
Routable within:  sub-networks to support hierchial structure

handle this in the following manner:
Distinct:  bits 17-48 designate a separate site, can be set using bits 17-48
from globally routeable address assigned to one of the site's networks or by
creating a nearly random number as previously proposed on this list.
Routeable:  bits 49-64 are already designated for subnetting a site.

As a Network Administrator I can see the requirement to be able to set up my
our intranet routing domain, and would like to know that I will not
inadvertantly route out to another site (same designation).  An easy way to
avert this is to use bits 17-48 for site designation.

Beyond this, the loose definition of a site is adequate.

DG Ses

DALE G SESVOLD
Senior Network Engineer
MacAulay-Brown, Inc

> > However, we could take anything that fit in a /48 and call this a site.
> > I'm not sure that it would be a good idea...
> 
> I think it is a good idea, though it cannot be the _definition_ of the
> "site".
> 
> IMHO, site-local scope will be used to protect against renumbering,
> and for the networks not connected to the Internet.
> For this purpose, some connected networks serapated within a single
> geographic location _can_ be a <site>.  But a <site> is not limited to
> be an single location.
> 
> Unlike IPv4 usage of a private address, IPv6 site cannot be nested.
> So I don't think it is a good idea that you assign a <site> for a too
> small piece of networks only for the reason that they are geographically
> isolted.
> 
> Atsushi
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From: "Christian Huitema" <[email-masked]>
Date: Mon, 26 Mar 2001 08:46:41 -0800

Steve,

May I observe that the definition of a site in the "Scoped Address
Architecture" draft contains a loophole? The draft says that "A personal
residence may be treated as ... a part of a site (for example, when the
residence obtains Internet access via an employer's or school's site)."
This is in fact the classic definition of a "corporate" network, i.e.
all the systems that are hidden behind the corporate firewall(s). From a
networking point of view, there is not much difference between an
employee's home, a remote office, or even the laptop of a traveling
employee: once there are brought "behind the firewall" through some kind
of VPN tunnel, they effectively become part of the "site." 

So far, I have found two important attributes of "IPv6 sites." The first
one is the address stability: site addresses are stable, even if the
site's external prefixes change; indeed, they are only subject to
renumbering if two sites are merging. The second one is the "border
police": site local packets are not supposed to leave the site, nor to
originate outside the site; this provides a very rough form of access
control, which may be adequate for some inexpensive devices or services.
(Yes, I know perfectly well that this is weak -- at least as weak as
firewalls.)

I believe that most practical network manager will equate a site with a
corporate network, with the practical exception of large corporations
that will probably have to split their network into multiple sites, e.g.
one site per campus. Or, to put it differently, the site will be a
subset of the corporate network that enjoys its own independent
connections to the Internet. 

By the way, it is a bad idea to swallow an employee's home network into
a corporate site, as indicated in the addressing example. You definitely
don't want the employee's teen-age children to roam your network... 

-- Christian Huitema