North American Network Operators Group

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RE: CIDR Report

  • From: Owen DeLong
  • Date: Sat May 13 14:09:53 2000

> I've mentioned this before, so I'll just note it lightly.
> There are a growing number of companies (dot-coms are only one of them) that have small head-count (<4000), but are spread out from Sydney to New York, with many "lone eagles" in the MST zone. They could probably do everything on a portable /24. However, with everyone filtering out announcements less than /20, such companies are encouraged to drop NAT, and use other methods to justify a /19, just so they can participate in peering (I won't say whom, one is a CTI development company). The VPN solution is cute, but the entire VP then becomes single-homed, at the VPN gateway (The alternative is that each location gets their own /24, linked by a VPN, to the other /24s, there are serious performance issues with this approach and hte /24 may only represent a single actual user). All of this burns IP addresses. 
Or you build a VPN with multiple gateways, and accept the consequences when a gateway
drops and you are rerouted to another gateway.  This is usually rare, and most
users will retry their HTTP request or other session at least once before calling
for assistance.  It's not pretty, but it is feasible.

(Each gateway has it's own NAT pool that it exchanges with the world.  Each office
on the VPN is dynamically routed to the closest gateway.)

> The point: Filtering BGP announcements costs in IP space allocations. There is a mathmatical relationship between IP address allocations, table sizes, and routing policies. Also, part of the relationship is determined by client business requirements.
> Organizations are becomeing more geophysically diffused, with many end-nodes actually participating in multiple organizations. This is only starting now (I still see over 100K nodes actually doing this), it will get much worse.
Yes, that is true.  I think the long term solution is bigger routing tables with
faster lookups and longer prefixes.  CIDR was a hack to get us through a time
when router memory and speed constraints were creating serious problems in
routing the global internet.  I believe this problem is mostly solved, and that
modern routers are capable of handling a much larger routing table.  As such,
I think the need for optimization has shifted to IP space utilization and topological
efficiency.  Deaggregating routes to be able to use effective MEDs would also
benefit from this going forward.

I know this doesn't fit with Randy's religion, but it's not the first time I
have disagreed with Randy.


> > -----Original Message-----
> > From: [email protected] [mailto:[email protected]]On Behalf Of
> > Mikael Abrahamsson
> > Sent: Saturday, May 13, 2000 2:10 AM
> > To: n[email protected]
> > Subject: Re: CIDR Report
> > 
> > 
> > 
> > On Sat, 13 May 2000 [email protected] wrote:
> > 
> > > But if you look at the last 250 days or so you see that the 
> > table has
> > > grown by more than 16k routes.  So we are seeing growth at 
> > 300% of what we
> > > saw for the last 5 plus years.  It also looks annoyingly 
> > geometric or
> > > perhaps exponential, instead of the nice linear growth 
> > since CIDR was
> > > introduced.  
> > 
> > If you just check from 01/01/99 to date then it looks linear 
> > or at least
> > close to linear.
> >  
> > I guess it *could* be that growing amount of new companies getting
> > internet access is increasing. Is there any data that show "CIDR GAIN"
> > from the cidr report, so we can see if the increase corresponds to an
> > increase in (perhaps unneccessary) smaller announcements in 
> > larger blocks,
> > or if it is actually just a lot more blocks allocated that needs to be
> > routed. Any stats on arin/ripe/apnic new allocations of 
> > blocks in the same
> > timeframe? Both in terms of IP adresses and in number of blocks of IP
> > adresses. This would also give us some kind of hint as to 
> > when IPv4 space
> > will be exhausted (or are there already projections about this?)
> > 
> > -- 
> > Mikael Abrahamsson    email: [email protected]
> >