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Re: The in-your-face hijacking example, was: Re: Who is announcing bogons?

  • From: Jon Mitchell
  • Date: Thu May 01 12:43:59 2003 
On Wed, Apr 30, 2003 at 12:34:07PM -0400, Kai Schlichting wrote:

> In unrelated news: can someone explain to me the exact meaning of multiple
> AS numbers enclosed in {}'s (or []'s as far as RIS RIPE's display is
> concerned) at the end of the AS path?
> 
> *  162.33.64.0/19   207.246.129.6                          0 11608 2914 3356 14390 {22714,27481} i
> *                   4.0.4.90              1080             0 1 701 14390 {22714,27481} i
> *                   203.194.0.5                            0 9942 1 701 14390 {22714,27481} i
> *                   192.205.31.33                          0 7018 3356 14390 {22714,27481} i
> *                   195.66.224.82        31502             0 4513 3356 14390 {22714,27481} i
> *                   216.140.2.59           981             0 6395 3356 14390 {22714,27481} i
> 

This means the address space was aggregated by a different AS than
originated it, for instance parts of 162.33.64.0/19 were originated by
AS 22714 and 27481, but AS 14390 aggregated these to the prefix above.  By
using the AS_SET notation, one can prevent the loss of origination AS
information allowing loop avoidance.


-Jon