Subject: [Dots] My review of draft-ietf-dots-architecture-03

From: kaname nishizuka <[email-masked]>
Date: Thu, 8 Jun 2017 11:56:40 +0900

Hi all,

Much appreciate the intensive work on the draft.
Here are my comments about the draft based on -03

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# 1.3 (5th item: The mitigation capacity)
"In either case, the upstream DOTS server may redirect a request to another DOTS server."

According to 3.2.3, DOTS server may make recursive signaling in case the mitigation capacity is insufficient.
proposing text:
"In either case, the upstream DOTS server may redirect or recurse a request to another DOTS server."

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# 1.3 (last item: coupling of channels)
"The signal and data channels may be loosely coupled, and may not terminate on the same DOTS server."

 From server side, can we say this?
"The signal and data channels may be loosely coupled, and may not be initiated from the same DOTS client."
It is clearer for me if both texts are supplied.

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What do you think about supplying alternative path information form DOTS client?
It will allow valid traffic to reach the attack target.
Some existing solutions are providing such kind of "clean pipe" which may be a dedicated line or tunnel like GRE.
I feel it requires too much specification and it's vendor specific, but it could solve looping problem related to multiple providers.

==
[[EDITOR’S NOTE: we request working group feedback and discussion of operational considerations relating to coordinating multiple provider responses to a mitigation request.]]

Attack traffic will come from multiple ingress point if the target network is multi-homed.
If the protection points are not overlapping among multiple providers, it is natural to ask for help to each provider.
For example, if an enterprise is connected with ISP A and ISP B, it would want to activate the DDoS protection service of ISP A and ISP B via DOTS.
However, some traffic redirection method like BGP and DNS can be overlapped among those providers.
 From operational point of view, the operators will avoid such kind of overlapping of the protection points but it depends on the situation and it is beyond the scope of DOTS.