Re: A tunneling proposal

[Tony Li <tli@Procket.com>]

 | > >> Modern routers don't fall over with 100,000 routes in them.  But
 | > >> initial table load and BGP convergence times when paths change are
 | > >> both a lot longer than many would like.
 | 
 | > >Ok, but is that enough reason to throw out the current way of
 | > >multihoming?
 | 
 | >         Yes.
 | 
 | Well, I disagree. Slow initial sync and convergence times are bad, but
 | outlawing current multihoming is very bad as well. And I'm certaintly
 | not convinced this is well-optimized. Not much is.


You are welcome to disagree.  However, the facts of the matter are very
clear.  If the Internet is to grow, it will continue to add 'sites' to it,
almost indefinitely.  Some percentage of those sites will want to
multihome.  Under the current multihoming architecture, those sites will
appear in the DFZ routing table.  If the growth rate of those sites exceeds
Moore's law, then it will be become exceedingly expensive to support the
routing subsystem.

It is vital to the life of the net that the routing subsystem continue to
scale well.  The price of this scalability is the discipline to adhere to
a scalable architecture.

Are you willing to pay that price?


 | > >> The size of individual routing state entries in modern routers has
 | > >> been the subject of a great deal of optimization over the years.
 | > >> Don't expect to see it improved by an order of magnitude or even by
 | > >> a factor of two.
 | 
 | > >Really?
 | 
 | >         Yes.
 | 
 | So how does this relate to my experience that the amount of memory used
 | by BGP table entries is the same as six years ago?


Your experience does not match mine.


 | > >Do we have any inidication that the global routing table is growing
 | > >faster than the Moore's Law rate?
 | 
 | > As I recall, tli has made precisely this claim in the past.  I'm
 | > strongly inclined to just take tli's word on such a point.


To be 100% accurate: I made the point that the rate of growth is increasing
and that if left unchecked, this implies that the growth will someday
exceed Moore's law.


 | I'm not even talking about economics, but just basic functionality and
 | human nature: how are you going to convince someone stop doing something
 | that works for them to help some greater good, that doesn't show obvious
 | signs of needing help? "Global warming? Let me turn up the airco..."


We're well aware that we have a tragedy of the commons scenario.  The first
step has to be to convince you that the IPv6 routing architecture needs to
be something scalable.


 | If there really is a limit above which global routing breaks down, we
 | should implement some policies to prevent the number of routes from
 | reaching this limit. This means forcing existing ASes to aggregate, and
 | limiting the growth in the number of ASes. That way, SCTP-like solutions
 | become more attractive.
 | 
 | But I think we can:
 | 
 | 1. optimize protocols


This has been in progress for 8 years.


 | 2. optimize implementations


This has also been in progress for 8 years.


 | 3. look for alternative ways to aggregate, for instance on geography


Local geographic aggregation (i.e. metro aggregation) has issues about
forced connectivity that we are not able to regulate.  Global geographic
aggregation (i.e., at the continental scale) has been struck down as a bad
idea. 

If you ignore history, you're doomed to repeat it.  Just like this
conversation.

Tony