Re: [Dots] WGLC for use cases draft - until July-1.

["Konda, Tirumaleswar Reddy" <[e-mail]>]

Hi Daniel,

My comments and nits

1)

   The current scenario describes the case where the DDoS Target is in
   the enterprise network while the secondary DMS is provided by the
   upstream ITP.  An alternate use case may consider the scenario where
   the ITP informs the enterprise network it is involved into an ongoing
   attack or that infected machines have been identified.  In this case
   the DOTS client and DOTS server roles are inverted.  The DOTS client
   is located in the ITP network and the DOTS server is hosted in the
   enterprise network.  The enterprise network is then responsible to
   perform the DDoS Mitigation.  In some case the DDoS Mitigation may be
   delegated back to the upstream ITP, as described in this section.

Comment>  If the DMS in the enterprise network is not capable of detecting outgoing DDoS attack, how will the signaling from the DOTS client in the upstream ITP to the DOTS server in the enterprise network help it to detect and mitigate the outgoing DDoS attack ?


2)
   Once the requesting Enterprise Network is confident that the DDoS
   attack has either ceased or has fallen to levels of traffic/
   complexity which they can handle on their own or that it has received
   a DOTS DDoS Mitigation termination request from a downstream
   Enterprise Network or DDoS Mitigation Service Provider, the
   requesting Enterprise Network DOTS client sends a DOTS DDoS
   Mitigation termination request to the DDoS Mitigation Service
   Provider.

Comment> In the above line, I don't get "that it has received a DOTS DDoS Mitigation termination request from a downstream Enterprise Network or DDoS Mitigation Service Provider".
I think you mean "or notified by the DDoS Mitigation Service Provider that the DDoS attack has stopped"

3)

   The pre-arrangement typically includes the agreement on the
   mechanisms used to redirect the traffic to the DDoS Mitigation
   Service Provider, as well as the mechanism to to re-inject the

 >>>>>>>>>>>>>>>>>>>>>>>>>>> Remove "to"

4)

   o  DDoS Mitigation Service: designates a DDoS service provided to a
      customer and which is scoped to mitigate DDoS attacks.  Services
      usually involve Service Level Agreement (SLA) that have to be met.
      It is the responsibility of the service provider to instantiate
      the DDoS Mitigation System to meet these SLAs.

   o  DDoS Mitigation System (DMS): A system that performs DDoS
      mitigation.  The DDoS Mitigation System may be composed by a
      cluster of hardware and/or software resources, but could also
      involve an orchestrator that may take decisions such as
      outsourcing partial or more of the mitigation to another DDoS
      Mitigation System.

Nit> For better readability you may want to define "DMS" followed by "DDoS Mitigation Service"

5)
   DOTS is at risk from three primary attacks: DOTS agent impersonation,
   traffic injection, and signaling blocking.  The DOTS protocol must be
   designed for minimal data transfer to address the blocking risk.

Comment> A MITM attacker can drop all the DOTS signal channel traffic, designing the DOTS signal channel protocol for minimal data 
transfer will not address the MITM attack.

6)
   One consideration could be to minimize the security technologies in use at any one
   time.  The more needed, the greater the risk of failures coming from
   assumptions on one technology providing protection that it does not
   in the presence of another technology.

Comment> The DOTS signal and data channels are using TLS for mutual authentication, confidentiality and data integrity. I don't see the need for the above lines.

7)
   When the DDoS mitigation is finished on the DMS, the orchestrator
   indicates to the telemetry systems as well as to the network
   administrator the DDoS mitigation is finished.

Comment> I think you mean the DDoS attack has stopped. You may want to rephrase the line.

8)
   Upon receiving the DOTS request for DDoS mitigation from the network
   administrator, the orchestrator coordinates the DDoS mitigation
   according to a specified strategy.  Its status indicates the DDoS
   mitigation is starting while not effective.

Comment> You may want to clarify the DOTS client will later be notified that the DDoS mitigation is effective.

9) If the network administrator decides to start the
   mitigation, they order through her web interface a DOTS client to
   send a request for DDoS mitigation.  

Nit> The above line is not clear, who are "they" in the above line ? 

10) This request is expected to be associated with a context that identifies the DDoS mitigation selected.
  
Comment> I don't understand the context of the above line.

11)   Upon receiving the DOTS request for DDoS mitigation from the network
   administrator, the orchestrator coordinates the DDoS mitigation
   according to a specified strategy.

Comment> What is the specified strategy (you may want to give an example) ?

12)
The status of the DDoS mitigation indicates the orchestrator is in an analyzing phase.
Comment> DOTS signal channel draft does not indicate the mitigation status is in analyzing phase (Please see "Table 2: Values of 'status' Parameter" in the draft).

13)
The orchestrator begins collecting various information from various  telemetry systems in order to correlate the measurements and provide  an analysis of the event.
Comment> The orchestrator would anyway be collecting data from various telemetry systems for correlation.

14) These systems are configured so that when an
   event or some measurement indicators reach a predefined level to
   report a DOTS mitigation request to the orchestrator.  The DOTS
   mitigation request may be associated with some element such as
   specific reporting.

Comment> what do you mean by "some measurement indicators" and "specific reporting" (looks vague to me) ?

15) Figure 4 (DDoS Orchestration) includes both internal and external DDoS mitigation systems, but the usage of internal and external DDoS mitigation systems in 
       not discussed in section 3.3.

16) Redirection to the DDoS
   Mitigation Service Provider typically involves BGP prefix
   announcement eventually combined with DNS redirection, while re-
   injection may be performed via tunneling mechanisms such as GRE for
   example.

Comment> You may want to clarify the scrubbed traffic is re-directed to the Enterprise network via the tunneling mechanism.

17) Of course, such mechanisms needs to be regularly tested and
   evaluated.

Comment> The above line does not look relevant to this document.

18)   Once the requesting Enterprise Network is confident that the DDoS
   attack has either ceased or has fallen to levels of traffic/
   complexity which they can handle on their own or that it has received
   a DOTS DDoS Mitigation termination request from a downstream
   Enterprise Network or DDoS Mitigation Service Provider, the
   requesting Enterprise Network DOTS client sends a DOTS DDoS
   Mitigation termination request to the DDoS Mitigation Service
   Provider.

Comment> It's not clear how the requesting Enterprise network will learn the DDoS attack has ceased ?

-Tiru