RE: Anyone else seeing "(invalid or corrupt AS path) 3 bytes E01100" ?

From: Dylan Ebner (no email)
Date: Tue Aug 18 2009 - 13:54:10 EDT

  • Next message: Ivan Pepelnjak: "RE: Anyone else seeing "(invalid or corrupt AS path) 3 bytes E01100" ?"

    Ivan-
       Thanks for posting this how-to on excessive as prepends. I have a couple of questions that some of the less BGP savvy out their may find helpfull

    1. In my enviornment, we are not doing full routes. We have partial routes from AS209 and then fail to AS7263. Is their any advantage for someone like me to do this, as we are not providing any IP transit so we are not passing the route table to anyone else?

    2. When I run the "sh ip bgp quote-regexp "_([0-9]+)_\1_\1_\1_\1_ \1_" | begin Network" I am seeing many many ASes that would be filtered by this access-list. What happens to those networks, are they unreachable from my AS, or do I just route those networks to my upstream provider and let them deal with it?

    3. This last question is a little OT, but relates to your access list
       In the event of some kind if DOS attack coming from one of a few AS numbers (in this case we will use 14793), what is the feesability of using
     ip as-path access-list 100 deny _([0-9]+)_\1_\1_\1_\1_
     ip as-path access-list 100 deny 14793
     ip as-path access-list 100 permit .*

     Would this have any affect at all, or would my pipe from my upstream still be congested with garbage traffic ?

    Thanks
    Dylan Ebner

    -----Original Message-----
    From: Ivan Pepelnjak [mailto:]
    Sent: Tuesday, August 18, 2009 2:37 AM
    To: 'randal k'; 'Adam Hebert'
    Cc:
    Subject: RE: Anyone else seeing "(invalid or corrupt AS path) 3 bytes E01100" ?

    > Anybody have a handy route-map that will deny anything with a as-path
    > longer than say 15-20? ;-)

    http://wiki.nil.com/Filter_excessively_prepended_BGP_paths

    Ivan
     
    http://www.ioshints.info/about
    http://blog.ioshints.info/


  • Next message: Ivan Pepelnjak: "RE: Anyone else seeing "(invalid or corrupt AS path) 3 bytes E01100" ?"





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