Re: [Sidrops] draft-sidrops-rpkimaxlen

Matthias Waehlisch <> Sun, 24 February 2019 13:50 UTC

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Date: Sun, 24 Feb 2019 14:50:21 +0100
From: Matthias Waehlisch <>
To: "Sriram, Kotikalapudi (Fed)" <>
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Subject: Re: [Sidrops] draft-sidrops-rpkimaxlen
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Hi Sriram,

On Sun, 24 Feb 2019, Sriram, Kotikalapudi (Fed) wrote:

> >> A better definition of minimal ROA as outlined above will take care of
> >> the misunderstanding. The draft did recognize that the IP prefixes
> >> planned to be announced in the future or intermittently (when needed)
> >> may be included in the ROA. Please see the following paragraph from
> >> Section 5.1:
> >>
> >  This is not very helpful. "when needed" is fuzzy. Needed in six month?
> >Do you know when a DDoS occurs? The draft supposes that needed is very
> >short-term.
> The draft does not presuppose when the prefixes may need to be 
> announced. The time frame is up to the prefix owner. Once the prefix 
> owner decides what prefixes (currently announced or intended to be 
> announced) should be covered by the ROA (or ROAs), the draft merely 
> offers recommendations for minimizing the attack surface. The example 
> in Section 5.1 illustrates this for the DDoS case. (One more example 
> can be added there to further drive home the point.) The example is 
> agnostic about if/when the DDoS mitigation prefixes may need to be 
> announced.
  sorry but I really don't see how this limits the attack surface, in 
case where the configured more specific prefix is announced very 

> >  What I tried to say is that the authors of the wiki page draw
> >incorrect conclusions, probably based on misleading insights from the
> >draft.
> I read the DECIX wiki page.  It is not clear to me what you mean by 
> incorrect conclusions on that page with regard to ROA/maxlength . I 
> would appreciate if you can clarify or cite some examples.
  To give one example: Your draft suggests to not use the max length 
field, which means "ROA generation software MUST use the prefix length 
as the max length if the user does not specify a max length." [RFC 7115]

  Option 3 in the wiki page, they will set the max length to the max 
length of the IP version (e.g., /32 for v4). This is different to your 

  Based on what you wrote, each member that intends to send a 
blackholing announcement would need to create a corresponding ROA. 
Option 3, actually, tries to solve the problem when members forget to do 


Matthias Waehlisch
.  Freie Universitaet Berlin, Computer Science