[ppml] Policy Proposal 2002-3

Marshall Eubanks tme at multicasttech.com
Tue Oct 7 14:44:42 EDT 2003

On Tue, 7 Oct 2003 09:56:06 -0600
 "Trevor Paquette" <Trevor.Paquette at TeraGo.ca> wrote:
> Finally a decent answer to expain historically why boundaries were moved.


The original (and still) purpose of 2002-3 was to rectify the situation faced
by small multi-homers, who get an ASN but no space directly assigned to them.
While it is true that the ranks of small multi-homers is growing, they
still remain a small portion of the total BGP table. By virtue of being
multi-homed, they have an assignment from one or more of their providers, and
if they are properly routed, then this assignment cannot be aggregated by
at least part of the net (if I multi-home to providers A and B, and have a /24
from provider A, then providers who see my A /24 addresses through provider B
cannot aggregate that /24).

So, doing micro-assignments to small multi-homers will not break CIDR and 
will not increase the size of the routing tables, but will remove the problems
found by 
those who multi-home without direct address assignments. I have found that
providers will route small assignments from ARIN as a matter of course, but to
get my /24 from UUNet routed properly by Verio took some patient pleading and
inside knowledge.

Marshall Eubanks

> > -----Original Message-----
> > From: Lea Roberts [mailto:lea.roberts at stanford.edu]
> > Sent: Tuesday, October 07, 2003 12:31 AM
> > To: Trevor Paquette
> > Cc: ppml at arin.net
> > Subject: RE: [ppml] Policy Proposal 2002-3
> > 
> > 
> > Trevor -
> > 
> > the basic problem is that old model for everyone to get 
> > direct assignments
> > from the InterNIC (or now the RIRs :-) just doesn't scale.
> > 
> > in the early 1990s, it was asserted that IPv4 addresses were being
> > consumed too rapidly.  Back then addresses were assigned in "classes". If
> > a site needed more than a /24 (Class C) they would get a /16 (Class B) and
> > class B assignments were being made at an increasingly rapid rate.  In
> > response to this, Classless InterDomain Routing (CIDR) was born and
> > addresses could be assigned more efficiently with variable "prefix"
> > lengths. (see RFC 1519, September 1993)
> > 
> > then, as Owen has said, there were problems with the explosion of routing
> > table size approaching the limits of the hardware then running in the
> > core.  the solution was to encourage hierarchical address assignment, also
> > known as provider assigned addresses, so that an ISP could aggregate a
> > number of its sites into one advertisement into the global routing table.
> > thus CIDR came to the rescure for the routing table problem as well.
> > it's taken most of these ten years for the paradigm shift to solidify and
> > I would hate to see a rush back to where individual assignments from an
> > RIR would be the norm rather than a special case.
> > 
> > note there is another dichotomy.  when ARIN makes address assignments, it
> > cannot guarantee the routability of the addresses.  there are other
> > players in the scene, e.g. the network operators.  they can negate the
> > effect of a prefix length change by refusing to accept the routes.  an
> > unroutable assignment is not worth much!  :-)
> > 
> > since ARIN was formed, one of the challenges has been to establish
> > policies that preserve the stability of the internet while allowing it to
> > continue to expand.  the struggle over micro-assignments is ongoing, many
> > of us who were around 10 years ago still feel that it is wise to be
> > cautious in changing the size of assignments.  there are ongoing studies
> > on the next potential for network instability: the convergence time after
> > route flaps, which is also related to the routing table size.
> > 
> > so while router hardware has improved, there may need to be protocol and
> > other software improvements in the backbone before advocating the end of
> > hierachical address assignments makes sense.  As the "swamp" of original
> > address assignments reminds us and as you express as a wise concern, the
> > assignment of addresses is almost completely a one way street.  once the
> > boundary is moved, we won't be able to undo the assigments should the next
> > performance barrier be reached.  thus some of us on the Advisory Council
> > are suggesting that these changes should be gradual and their effects
> > monitored carefully before moving the boundary again.
> > 
> > 		there's never a dull moment in networking land,  /Lea
> > 
> > On Mon, 6 Oct 2003, Trevor Paquette wrote:
> > 
> > >
> > > Folks used to be able to receive direct assignments from 
> > ARIN (and other registries) in the past. This ability was 
> > revoked for some reason, and it seems that no-one can remember why...
> > >
> > > I'd hate for us to go back down the same path and encounter 
> > the same problems as did our predecessors only to later go 
> > 'DOH!.. no wonder they revoked this ability'.
> > >
> > > Why was this ability revoked and the current policy put in 
> > place?? Can anyone explain that?

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