Verio Decides what parts of the internet to drop

James Smith jsmith at
Mon Dec 6 18:11:16 UTC 1999

Based on past experiences, I would say that the big backbone providers
shouldn't do any filtering at all.  Then, the lower tiers can do all the
filtering they want, and still rely on default routing to send the packets
to the backbone.  It may not be the prettiest way to route traffic, but
this would allow smaller ISPs to filter if they cannot afford buying
bigger equipment to hold all the routes.  Since the tier-1 guys are the
glue of the Internet, they should be required to take everyone routes.

James Smith, CCNA
Network/System Administrator

2140 Winston Park Drive, Suite 203
Oakville, ON, CA L6H 5V5         
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On Mon, 6 Dec 1999, Andrew Bender wrote:

> Dr. Li wrote:
> > Date: Fri, 03 Dec 1999 23:35:18 -0800
> > From: Tony Li <tony1 at>
> > Subject: Re: Verio Decides what parts of the internet to drop
> > 
> > I'll also note that this would also decrease the pressure on the address
> > space.  No need to go get a /19 if I can get my /23 globally advertised.
> > : 
> > :
> > The correlation with route flap should be re-examined.  I suspect that this
> > is no longer a driving force and is more than adequately compensated for by
> > having flap damping parameters that scale geometrically with the prefix
> > length.
> To state an obvious extension of these ideas:
> Without relief, space registrants are thus incented to (continue to) subvert the
> spirit of the allocation scheme in order to overcome its deficiencies. In doing
> so, a trend toward lower (shorter) "characteristic prefix length" is created by
> networks that would otherwise be suited by smaller allocations closer to their
> actual occupancy. 
> Metastability in interdomain routing is currently maintained by an algorithm [1]
> that suppresses oscillations to an acceptable level, deferring treatment of
> another "interesting problem" [2,3]. If distinctions between highly aggregated
> networks and large, underoccupied ones are progressively obscured, strategies
> that inversely correlate prefix length with oscillatory period may be
> circumvented. 
> Past experience [*] suggests that further detraction from the elusive "global
> routing stability" is more poignant and at greater issue to operators than the
> combined problems of address occupancy and table population. 
> Indeed, it seems that a review of operational policy is in order.
> Regards,
> Andrew Bender
> Total Network Solutions, Inc.
> [1] C. Villamizar, R. Chandra, R. Govindan. RFC 2439.
> [2] K. Varadhan, R. Govindan, and D. Estrin. Persistent route oscillations in
> inter-domain routing. USC/Information Sciences Institute, 1996.
> [3] T. Griffin, G. Wilfong. An Analysis of BGP Convergence Properties. Computer
> Communication Review, October 1999.
> [*]

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