[arin-ppml] CIDR v2.0

[bmanning at vacation.karoshi.com]

	Kevin, 
		in some ideal world, aggregation into some small set of
	"ISP" space would be fine.  but things have not worked out that way.
	for efficent address utilization, I expect we will see >24 bit allocations
	more and more.  esp if that is all you need to support a translation function.

--bill



On Tue, Sep 16, 2008 at 08:11:51AM -0500, Kevin Kargel wrote:
> The difficulty with this is that we already have problems of hardware
> that is insufficient to support the routing tables.  ISP's are already
> filtering long CIDR routes (>24bit) because there isn't sufficient
> memory or processor in the hardware to support the number of routes it
> would require.  
> 
> Your idea would work, but only if we got rid of PI space and forced
> everyone to use IP space from their ISP so that there could be efficient
> route aggregation.  If you search through threads you will see that
> there is violent opposition by end users who want to be provider
> independent.
> 
> > -----Original Message-----
> > From: arin-ppml-bounces at arin.net 
> > [mailto:arin-ppml-bounces at arin.net] On Behalf Of Iljitsch van Beijnum
> > Sent: Tuesday, September 16, 2008 5:37 AM
> > To: PPML PPML
> > Subject: [arin-ppml] CIDR v2.0
> > 
> > In the early 1990s IPv4 address space was running out. They 
> > fixed this by changing routing protocols. Maybe we should try 
> > to do that again.
> > 
> > <history>
> > 
> > In the early days of the internet you could only use IPv4 
> > addresses as blocks of 16777216, 65536 or 256 addresses. 256 
> > was too small for most people so 65536 was a popular choice, 
> > but there are only some 16000 of these class B blocks and it 
> > was looking like those would be exhausted by the mid-1990s. 
> > So they started giving people a bunch of class C blocks (256 
> > addresses each) but now the routing tables started to explode 
> > because a university that needed a single class B block 
> > before now used something like 16 class C blocks, which had 
> > to appear in routing tables individually. To fix this, 
> > routing protocols, especially BGP, were changed to be able to 
> > work with address blocks of arbitrary power of two sizes so 
> > address space and routing table slots could be managed much 
> > more efficiently. (This is "classless interdomain routing".)
> > 
> > </history>
> > 
> > Now that IPv4 address space is becoming scarce again, why not 
> > do the same thing again? But now rather than arbitrary powers 
> > of 2, we modify the protocols to work with arbitrary address 
> > ranges. I.e., 192.0.2.27
> > - 192.0.2.43.
> > 
> > To accommodate legacy routers that can't do lookups based on 
> > ranges we can put in backward compatibility mechanisms from 
> > BGP5 to BGP4 similar to the ones from BGP4 (with CIDR) to 
> > BGP3 (no CIDR).
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