AS-set diffusion experiments 2005-06-20

Last update: Fri 24 Jun 2005


The announcements were designed to discover how far large AS-sets are propagated, and thus how effective our active probing techniques can be, in today's Internet with today's IPv4 operational practices.

Announcement schedule

The announcements were sent out by all the RIS route collectors on 2005-06-20 according to the following schedule:
10:00 UTC12654 12654 {2121}12654 12654 {2121}
10:30 UTC
12:00 UTC12654 12654 {5*2121}12654 12654 {10*2121}
12:30 UTC
14:00 UTC12654 12654 {25*1221}*12654 12654 {50*1221}*
14:30 UTC
16:00 UTC12654 12654 {75*2121}12654 12654 {100*2121}
16:30 UTC
18:00 UTC12654 1265412654 12654

* The announcement of AS-sets containing AS1221 instead of AS2121 was due to a configuration error.

Preliminary Results

The RIS route collectors were queried 29 minutes after each announcement (1 minute before it was withdrawn) to determine which RIS peers received the announcement and which did not.

Main results

The results show that the length of AS-sets announced does not significantly influence the acceptance of the prefix, which leads us to believe that filtering on the length of an AS-set is not a common practice. There was no significant difference between the 75-AS set and the 100-AS set, which suggests that Cisco routers do not filter 75-AS sets by default (the
documentation of the bgp maxas-limit command is ambiguous on the matter).

In more detail

We grouped the RIS peers according to their behaviour:

As can be seen, the results are rather noisy, and we are considering repeating the announcements under different conditions (e.g. announcing the prefix for a longer period to eliminate the effects of dampening, announcing it from only one location to eliminate the effects of anycast, etc. etc.) to obtain more reliable results.