Address clustering intuition
curtis at ans.net
Fri Nov 10 17:13:29 UTC 1995
In message <Pine.BSD/.3.91.951109231025.12829C-100000 at vbc.net>, Jim Dixon write
> On Thu, 9 Nov 1995, Alan Hannan wrote:
> > ] I've formed an intuition that, if all IP addresses were portable (ie.
> > ] independent of ISP) and assigned on a strictly geographic basis, then
> > ] there would *automatically* be clustering of addresses equivalent to
> > ] that obtained from CIDRization as a result of marketplace forces and
> > ] the practicalities of technology.
> > While this would perhaps increase the 'possibility' of aggregation
> > increase, it ignores the fact that networks are laid out w/ wires
> > and planned logically wrt tariff issues and existing infrastructure
> > and capacity.
> I don't see that this is relevant. If I call PacBell in San Jose,
> it's a 408 number. In San Francisco, it's a 415 number. What does
> this have to do with wires etc? The point is that every telephone
> company knows where 408 is and how to route traffic to it.
> Jim Dixon jdd at vbc.net
> VBCnet GB Ltd +44 117 929 1316 fax +44 117 927 2015
> VBCnet West Inc +1 408 971 2682 fax +1 408 971 2684
One of the reasons this has worked out so neatly for the phone system
is that there has historically only been one last mile provider for a
given area code and exchange. Where there are multiple LECs or CAPs,
they interconnect within the area code (within the boundary of
aggregation), which is not true of the US Internet for any aggregation
boundary smaller than the whole country and even less true in Europe.
If you call my house on one phone line it is in the 203-775 NPA-NXX.
The other phone line is in 203-740. The 775 number space ran out of
room. The whole numbering plan is a mess and area codes are being
split. If another LEC comes along (or an IXC acting as a LEC) I don't
expect to get a number in either 775 or 740, I'd very likely get an
NPA-NXX number assigned to the CO of the competetive LEC. That
reflects the topology of the phone system. It just happens that their
is currently generally one LEC provider within an area code and where
there is more they split the numbering on NXX. If I change LECs, I
would expect to lose my phone number and renumber, or pay extra. If
the phone ran DNS and long distance calling was free, it wouldn't
matter to me if area codes were assigned to geographic regions or
The topic of geographic vs. topologic aggregation was hashed out 2-3
years ago in the BGP and BGPD (now CIDRD). It was discussed ad
nauseum on CIDRD and big-internet. Please don't repeat the same
discussion on NANOG.
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