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Re: Blackholes and IXs and Completing the Attack.

  • From: Rick Astley
  • Date: Sun Feb 03 02:09:41 2008
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I see your point, but I think maintaining the box for the control session would also require a decent amount of work.
Presumably, since you must all adhere to some quasi-standard to communicate with the control peer, you could probably also agree on creating a standard BGP community (ie. 64666:666 & no-export) to use and just skip the middle man.

Granted, I am kind of new as well, and I assume if the solution were that simple more people would be using it.

On Feb 2, 2008 9:07 PM, Ben Butler <[email protected]> wrote:
Agreed, but when you have >100 peers that is still a fair bit of work.  I know technically how to do it and am doing this with transits but then there are only seven of those.  It is not a question of how or can, but should / is it valuable / constructive?
The starting point in the thought process having just done it for transits was right ok, now how do we sensibly scale this to apply it at IXes without everyone having to run round contacting everyone else and to see if there was an easier way of doing things, hence the suggestion.  Plus it keeps things nice a separated, your IX peering sessions announce just the main prefixes, the session to the "blackhole reflector" can be in a separate peer-group and you only send the /32s to the reflector.  You don't have to worry about who uses which communities as each member that chooses to peer with the reflector is able to apply an inbound routemaps of their own choosing to any prefixes they receive from this reflector at each individual IX.
Given that an ISP has elected to Complete the attack on a host that is being DoSed, for whatever reason, and they have chosen to send blackhole announcements to transit the logical extension seems to be to automate the sending of them to IXs to try to further cut down on traffic.  This seems like a easy way, internally you just community tag on the trigger box for where you want the announcement to go, transit, internal, customers, IX all,1 2 not 3 - whatever - and BGP sends it out. Easy, and a single system to send out all updates when you choose to and easy to remove when you want to take it out again.
If you subscribe to completing the attack as a strategy, then the suggestion seemed like an easy way of rolling it out to the next logical point after transit.
Kind Regards