RE: We hit half-million: The Cidr Report

[Kate Gerry <kate () quadranet com>]

Already working on aggregating as much as I can. I was checking  my tables the other day and I think I saw another 
provider advertising their /18 as /24s, it made me sick.

--
Kate Gerry
Network Manager
kate () quadranet com

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-----Original Message-----
From: NANOG [mailto:nanog-bounces () nanog org] On Behalf Of Patrick W. Gilmore
Sent: Tuesday, April 29, 2014 9:23 AM
To: NANOG list
Subject: Re: We hit half-million: The Cidr Report

> The remainder of the prefixes (45%) shares the same origin AS and the same path.
> The could be TE prefixes, but as they are identical to their covering 
> aggregate its hard to appreciate exactly what the engineering intent 
> may be. I could make a wild guess and call these 45% of more specifics 
> to be an act of senseless routing vandalism. ( :-) ) This number has been steady as a % for the past three years.

This could easily be TE, and a type of TE which would be trivially fixed.

Let's take a simple example of a network with a /22 and 4 POPs. They have the same transit provider(s) at all 4 POPs 
and a small backbone to connect them. Each POP gets a /24.

A not-ridiculous way to force their transit provider to carry bits instead of clogging their backbone while still 
ensuring redundancy would be to announce the /22 at all four POPs and the individual /24 at each individual POP. This 
creates four /24s and a covering /22 with exactly the same path, but still has "use" as TE.

Of course, it would be trivial for the network to clean up their act by attacking no-export to the /24s. But some 
people either do not know it exists, know how it works, or know BGP well enough to understand it would not harm them. 
Or maybe they are just lazy: "What's 3 extra prefixes in half a million?"

The answer to the last question is, frankly, nothing. But 3 prefixes for 30K ASNs is an ass-ton. (That's a technical 
term meaning "lots & lots".)


This is a good time for a marketing effort. Let's see if we can get the table back under 500K. Everyone check your 
announcements. Are you announcing more specifics and a covering aggregate with the same path? Can you delete the more 
specific? Can you add no-export or another community to keep the more specifics from the global table?

If you are unsure, ask. I think it would be rather awesome if we saw a quick reversal in table growth and went back 
under 500K, even if it was short lived. ESPECIALLY if we can do it before we hit 512K prefixes. Would prove the 
community still cares about, well, the community, not just their own network. Because on the Internet, "your network" 
is part of the "community", and things that harm the latter do harm the former, even if it is difficult for you to see 
sometimes.

Who will be the first to pull back a few prefixes?

--
TTFN,
patrick

On Apr 29, 2014, at 03:31 , Geoff Huston <gih () apnic net> wrote:

> On 29 Apr 2014, at 12:39 pm, Valdis.Kletnieks () vt edu wrote:
>
> > On Mon, 28 Apr 2014 21:59:43 -0400, "Patrick W. Gilmore" said:
> > > > On Apr 28, 2014, at 19:41, Chris Boyd <cboyd () gizmopartners com> wrote:
> > > > I'm in the middle of a physical move.  I promise I'll take the 3 
> > > > deagg'd /24s out as soon as I can.
> > > Do not laugh. If everyone who had 3 de-agg'ed prefixes fixed it, the 
> > > table would drop precipitously. We all have to do our part.
> >
> > Do we have a handle on what percent of the de-aggrs are legitimate 
> > attempts at TE, and what percent are just whoopsies that should be re-aggregated?
>
> I made a shot at such a number in a presentation to NANOG in Feb this 
> year
> (http://www.potaroo.net/presentations/2014-02-09-bgp2013.pdf)
>
>
> If you assume that Traffic Engineering more specifics share a common 
> origin AS with the covering aggregate, then around 26% of more 
> specifics are TE advertisements. This number (as a percentage) has 
> gwon by 5% over the past three years
>
>
> If you assume that Hole Punching more specifics are more specifics 
> that use a different origin AS, then these account for 30% of the more specifics in today's routing table.
> This number has fallen by 5% over the past three years.
>
> The remainder of the prefixes (45%) shares the same origin AS and the same path.
> The could be TE prefixes, but as they are identical to their covering 
> aggregate its hard to appreciate exactly what the engineering intent 
> may be. I could make a wild guess and call these 45% of more specifics 
> to be an act of senseless routing vandalism. ( :-) ) This number has been steady as a % for the past three years.
>
> Interestingly, it's the hole punching more specifics that are less 
> stable, and the senseless routing vandalism more specifics that are more stable than the average.
>
> thanks,
>   Geoff