The Cidr Report

Sun Dec 1 23:57:07 UTC 1996

Well I did a bit of digging at the sudden difference we are seeing. A
lot of this points to different levels of aggregation at different
points in the Internet. I took a dump from Bill's box at ?LA? and from the
xara.net router I use at Mae-east and saw one immediate example of
this. Here's the prefixes announced out of the 206.16/16 (belongs to
CERFNET) block.

First from xara.net (12 prefixes)
---------------------------------

206.16.0.0/16 in AS1740
206.16.192.0/18 in AS6077
206.16.96.0 in AS6332
206.16.97.0 in AS6332
206.16.98.0 in AS6332
206.16.99.0 in AS6332
206.16.102.0 in AS6332
206.16.105.0 in AS6332
206.16.106.0 in AS6332
206.16.111.0 in AS6332
206.16.112.0 in AS6332
206.16.113.0 in AS6332

Then Bill's router (59 prefixes)
--------------------------------

206.16.12.0 in AS4262
206.16.16.0 in AS4262
206.16.18.0 in AS1740
206.16.20.0 in AS1740
206.16.21.0 in AS1740
206.16.22.0 in AS1740
206.16.23.0 in AS1740
206.16.26.0 in AS1740
206.16.29.0 in AS1740
206.16.32.0 in AS4262
206.16.40.0 in AS4262
206.16.41.0 in AS4262
206.16.42.0 in AS4262
206.16.44.0 in AS4262
206.16.47.0 in AS4262
206.16.48.0 in AS4262
206.16.74.0 in AS4262
206.16.77.0 in AS4262
206.16.78.0 in AS4262
206.16.81.0 in AS4262
206.16.82.0 in AS4262
206.16.85.0 in AS4262
206.16.86.0 in AS4262
206.16.87.0 in AS4262
206.16.90.0 in AS1740
206.16.91.0 in AS1740
206.16.92.0 in AS1740
206.16.93.0 in AS1740
206.16.94.0 in AS4262
206.16.95.0 in AS1740
206.16.96.0 in AS1740
206.16.96.0 in AS6332
206.16.97.0 in AS6332
206.16.98.0 in AS6332
206.16.99.0 in AS6332
206.16.100.0 in AS1740
206.16.102.0 in AS6332
206.16.105.0 in AS1740
206.16.105.0 in AS6332
206.16.106.0 in AS6332
206.16.107.0 in AS1740
206.16.108.0 in AS1740
206.16.109.0 in AS1740
206.16.111.0 in AS6332
206.16.112.0 in AS6332
206.16.113.0 in AS6332
206.16.140.0 in AS4262
206.16.141.0 in AS4262
206.16.142.0 in AS4262
206.16.143.0 in AS4262
206.16.150.0 in AS1740
206.16.160.0 in AS1740
206.16.188.0 in AS1740
206.16.0.0/16 in AS1740
206.16.10.0/23 in AS4262
206.16.136.0/22 in AS4262
206.16.168.0/21 in AS4262
206.16.176.0/22 in AS4262
206.16.192.0/18 in AS6077

This is not to pick on CERFNET but just to highlight a problem of
actually tracking the size of the routing table in general. This 
CERFnet case seems to be this way becuase it is a direct peer of
Bill's box even though I can see no reason why the more specifics are
needed.

Looking a little more it seems a large amount of more specifics are being
announced to Bill's boxe which aren't being announced to the xara.net
router. Perhaps ISPs are taking more care at places like MAE-East with
their outbound filters than they are at Bill's peering point even though
Bill only has 6 active EBGP neighbors and the xara.net router has 39
;-(.

At this point I am pretty happy with using a well connected box at
MAE-East as the point of reference. Bill, if you want to start your
own your collection and make the data available feel free from your
vantage piont. 

		--Tony

 bmanning at ISI.EDU (Bill Manning) writes:
  * > 
  * > > This is what I see from this neck of the woods:
  * > 
  * > which is not very useful with no historical data.
  * > 
  * 
  * 	True enough.  Perhaps tony would be willing
  * 	to share his methods so the results may be
  * 	comparable.  I've got about two months worth
  * 	of data off sandbax.
  * 
  * 
  * -- 
  * --bill