AS prepending

Jon Lewis jlewis at lewis.org
Fri Apr 8 15:27:13 UTC 2005


On Fri, 8 Apr 2005, Philip Lavine wrote:

> I am prepending my AS 3 times to the un-preferred ISP.
> Both ISP's are my peers.

Ok...I just wanted to be sure you weren't prepending their ASN in which
case loop detection would stop them from accepting your routes.

> The un-preferred ISP claims the see my advertisement yet they do not add
> it to their routing table (suggests filtering??). They claim all the

Does the un-preferred ISP actually have no route back to you, or just not
the one you sent to them?  Depending on how things are setup, they may
prefer your preferred ISP for reaching you.  If you want "un-preferred
ISP" to reach you directly, but still be "un-preferred", you may want to
see if they have communities you can tag your advertisement with that
would cause them to prepend your routes when propogating them to their
peers.

----------------------------------------------------------------------
 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
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