Re: BGP AS Sets in the wild

[Danny McPherson <danny () tcb net>]

On Aug 23, 2005, at 4:36 AM, Abhishek Verma wrote:

> I was looking at route-views.routeviews.org for the BGP routes and i
> dont see any AS-Sets whatsoever. Are BGP routes with AS-SETs not
> generally leaked into the wild?
>
> Is this the case?

Not quite, see below..

> I am under the impression that AS_SETs are generated whenever there
> are some routes that are aggregated.  Is there any other way also to
> generate AS_SETs in BGP?

Well, yes, but mostly via proxy aggregation type stuff, which isn't
real common these days (i.e., dynamic proxy aggregation on behalf
of downstream ASes).

Yep, quite a few (I was just looking at this a while back for something
else).  As of a few hours ago, route-views had 45 unique prefixes that
contained AS_SET path attributes.  Interestingly enough, ~60% of those
AS_SETs only contain a single AS -- hrmm.  It's also interesting to see
some of these AS_SETs, albeit only a couple, contain private AS space,
I'm wondering if some naive implementations "remote-private-as"-type
knob is letting them slip by inside AS_SETs on egress.

danny@foo% grep { oix-full-snapshot-latest.dat | wc -l
    1717
danny@foo% grep { oix-full-snapshot-latest.dat | grep \> | wc -l
      45
danny@foo% grep { oix-full-snapshot-latest.dat | grep "^...[0-9]"
*  24.223.128.0/17  129.250.0.11             1             0 2914  
1668 10796 {11060,12262} i
*  24.223.160.0/19  129.250.0.11             1             0 2914  
1668 10796 {11060,12262} i
*> 64.132.88.0/22   209.161.175.4                          0 14608  
4323 {33127} i
*> 64.132.102.0/24  209.161.175.4                          0 14608  
4323 {32510} i
*  64.132.220.0/23  129.250.0.11            17             0 2914  
4323 {18664} i
*  65.17.160.0/19   129.250.0.11             1             0 2914  
1668 10796 {11060,12262} i
*  65.189.0.0/16    129.250.0.11            17             0 2914  
3356 10796 {11060,12262} i
*  65.205.32.0/24   129.250.0.11            55             0 2914  
10913 10913 26134 {30060} i
*  65.221.0.0/19    129.250.0.11             0             0 2914 701  
11486 {15297} i
*  65.254.96.0/19   129.250.0.11             0             0 2914  
7911 2552 {25662,25887} ?
*> 66.162.17.0/24   209.161.175.4                          0 14608  
4323 {29704,65102} i
*  66.163.160.0/19  129.250.0.11             7             0 2914  
3561 26085 {14776} i
*  82.135.152.0/21  129.250.0.11             0             0 2914  
1299 8764 8764 8764 {31006,34037} i
*  128.116.0.0      129.250.0.11             0             0 2914  
7911 14041 {16519} i
*  129.19.0.0       129.250.0.11             0             0 2914  
7911 14041 {12145,16519} i
*> 129.165.192.0/18 134.55.200.1                           0 293  
10886 1701 {270,65200} ?
*  140.31.0.0       129.250.0.11             0             0 2914 701  
668 {132,3381} i
*  140.32.0.0       129.250.0.11             0             0 2914 701  
668 {22,5957,14077} ?
*  147.241.0.0      129.250.0.11             0             0 2914 701  
668 {13} i
*  147.249.0.0      129.250.0.11             0             0 2914 701  
7381 {3561,6419,12178} i
*> 168.215.137.0/24 209.161.175.4                          0 14608  
4323 {29704} i
*  200.62.40.0/22   129.250.0.11             6             0 2914  
5511 18747 {12180,23383,23520} i
*  200.85.0.0/20    129.250.0.11             0             0 2914 701  
26617 {17079} i
*  201.217.192.0/19 129.250.0.11             6             0 2914  
5511 18747 {26596} i
*  202.30.88.0/23   129.250.0.11             5             0 2914  
4766 3608 3608 3608 17832 {9494} i
*  202.224.128.0/18 129.250.0.11           258             0 2914  
4688 4688 4688 {18071} i
*  206.169.96.0/22  129.250.0.11            17             0 2914  
4323 {11636} i
*  206.169.208.0/22 129.250.0.11            17             0 2914  
4323 {21593} i
*  207.19.96.0/21   129.250.0.11             0             0 2914 701  
7381 {14455} i
*  207.133.7.0      129.250.0.11             0             0 2914 209  
721 27064 6026 {65535} i
*> 207.235.48.0/20  209.161.175.4                          0 14608  
4323 {32258,32418,32434} i
*> 207.250.94.0/23  209.161.175.4                          0 14608  
4323 {33395} i
*  208.16.208.0/21  129.250.0.11             0             0 2914 701  
7381 {14455} i
*  208.142.248.0/21 129.250.0.11             0             0 2914  
4436 14390 {27481} ?
*  208.254.0.0/19   129.250.0.11             0             0 2914 701  
11486 {12156} i
*  209.159.192.0/18 129.250.0.11            47             0 2914  
30167 20412 {14507} i
*  209.213.209.0    129.250.0.11             0             0 2914  
7911 6517 {21953} i
*> 209.234.168.0/22 209.161.175.4                          0 14608  
4323 {5710} i
*  210.23.192.0/19  129.250.0.11             4             0 2914  
9299 9299 7491 {23862} i
*  210.23.208.0/21  207.246.129.6                          0 11608  
2914 6453 7491 {23862} i
*  210.23.208.0/20  207.246.129.6                          0 11608  
2914 6453 7491 {23862} i
*  214.40.0.0/16    129.250.0.11             0             0 2914 209  
721 27064 {27065,27066} i
*  216.83.160.0/19  129.250.0.11             0             0 2914 701  
7381 {14455} i
*> 216.110.12.0/23  209.161.175.4                          0 14608  
4323 {35970} i
*> 216.110.88.0/21  209.161.175.4                          0 14608  
4323 {32868} i
*  216.203.0.0/18   129.250.0.11             0             0 2914 701  
7381 {14033,14455,35938} i
*  216.203.48.0/20  129.250.0.11             0             0 2914 701  
7381 {14455} i

-danny