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Re: BGP AS Sets in the wild

  • From: Danny McPherson
  • Date: Tue Aug 23 22:20:15 2005


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




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