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DOTS WG                                                  R. Dobbins, Ed.
Internet-Draft                                            Arbor Networks
Intended status: Informational                                 S. Fouant
Expires: May 4, 2017                             Corero Network Security
                                                              D. Migault
                                                                Ericsson
                                                            R. Moskowitz
                                                          HTT Consulting
                                                               N. Teague
                                                            Verisign Inc
                                                                  L. Xia
                                                                  Huawei
                                                        October 31, 2016


                Use cases for DDoS Open Threat Signaling
                    draft-ietf-dots-use-cases-02.txt

Abstract

   The DDoS Open Threat Signaling (DOTS) effort is intended to provide a
   protocol that facilitates interoperability between multivendor
   solutions/services.  This document presents use cases to evaluate the
   interactions expected between the DOTS components as well as the DOTS
   exchanges.  The purpose of the use cases is to identify the
   interacting DOTS component, how they collaborate and what are the
   type of informations to be exchanged.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 4, 2017.







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Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology and Acronyms  . . . . . . . . . . . . . . . . . .   4
     2.1.  Requirements Terminology  . . . . . . . . . . . . . . . .   4
     2.2.  Acronyms  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Use Cases Scenarios . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  CPE Intra-domain DDoS Mitigation  . . . . . . . . . . . .   4
     3.2.  Service/System Intra-domain DDoS Mitigation . . . . . . .   5
     3.3.  Orchestrating Intra-domain DDoS Mitigation  . . . . . . .   6
     3.4.  Inter-domain DDoS Mitigation  . . . . . . . . . . . . . .   6
   4.  Use Cases Taxonomy  . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  DOTS Client Taxonomy  . . . . . . . . . . . . . . . . . .   7
     4.2.  DOTS Server Taxonomy  . . . . . . . . . . . . . . . . . .   9
     4.3.  DOTS Message Taxonomy . . . . . . . . . . . . . . . . . .  10
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Appendix A.  Use Cases  . . . . . . . . . . . . . . . . . . . . .  12
     A.1.  Primary Use Cases . . . . . . . . . . . . . . . . . . . .  14
       A.1.1.  Automatic or Operator-Assisted CPE or PE Mitigators
               Request Upstream DDoS Mitigation Services . . . . . .  14
       A.1.2.  Automatic or Operator-Assisted CPE or PE Network
               Infrastructure Element Request to Upstream Mitigator   16
       A.1.3.  Automatic or Operator-Assisted CPE or PE Attack
               Telemetry Detection/Classification System Request to
               Upstream   Mitigator  . . . . . . . . . . . . . . . .  17
       A.1.4.  Automatic or Operator-Assisted Targeted Service/
               Application Request to Upstream Mitigator . . . . . .  19
       A.1.5.  Manual Web Portal Request to   Upstream Mitigator . .  21



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       A.1.6.  Manual Mobile Device Application Request to
               Upstream Mitigator  . . . . . . . . . . . . . . . . .  23
       A.1.7.  Unsuccessful Automatic or Operator-Assisted CPE or
               PE Mitigators Request Upstream DDoS Mitigation
               Services  . . . . . . . . . . . . . . . . . . . . . .  25
     A.2.  Ancillary Use Cases . . . . . . . . . . . . . . . . . . .  26
       A.2.1.  Auto-registration of DOTS clients with DOTS   servers  26
       A.2.2.  Auto-provisioning of DDoS countermeasures . . . . . .  26
       A.2.3.  Informational DDoS attack notification to
               interested and authorized third parties . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27

1.  Introduction

   Currently, distributed denial-of-service (DDoS) attack mitigation
   solutions/services are largely based upon siloed, proprietary
   communications paradigms which result in vendor/service lock-in, and
   as a side-effect make the configuration, provisioning, operation, and
   activation of these solutions a highly manual and often time-
   consuming process.  Additionally, coordination of multiple DDoS
   mitigation solutions/services simultaneously engaged in defending the
   same organization against DDoS attacks is fraught with both technical
   and process-related hurdles which greatly increase operational
   complexity and often result in suboptimal DDoS attack mitigation
   efficacy.

   The DDoS Open Threat Signaling (DOTS) effort is intended to provide a
   protocol that facilitates interoperability between multivendor
   solutions/services.  As DDoS solutions/services are broadly
   heterogeneous among different vendor, the primary goal for DOTS is to
   provide a high level interaction with these DDoS solutions/services
   such as initiating or terminating the the service/solution.  In
   addition, DOTS is limited to DDoS and may be used by a node under
   attack.  More specifically, DOTS does not intend to become a generic
   purpose used to orchestrate different DDoS mitigation services/
   solutions and the use of DOTS by node under a DDoS attack is expected
   to impact the design of the DOTS protocol.  As a result, although
   DOTS may be used in the future for further signaling, the current
   document limits DOTS to a DDoS signaling protocol.  It should be
   noted that DOTS is not in and of itself intended to perform
   orchestration functions duplicative of the functionality being
   developed by the [I2NSF] WG; rather, DOTS is intended to allow
   devices, services, and applications to request mitigation assistance
   and receive mitigation status updates from systems of this nature.

   This document provides use cases where DDoS mitigation is handled
   using DOTS.  The use case presented in the document are intended to
   clarify what interactions are envisioned with DOTS, as well as the



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   nodes interacting using DOTS.  In both cases, the use cases are
   expected to provide inputs for the design of DOTS.

2.  Terminology and Acronyms

2.1.  Requirements Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.2.  Acronyms

   This document makes use of the same terminology and definitions as
   [I-D.ietf-dots-requirements], except where noted.

3.  Use Cases Scenarios

   This section provides a high level description of scenarios addressed
   by DOTS.  These scenarios are described in more details in
   Appendix A.  In both sections, the scenarios are provided in order to
   illustrate the purpose of DOTS.  They are not limitative and other
   use cases are expected to appear during the deployment of DOTS.

   All scenarios presents a coordination between the DDoS target, the
   DDoS attack telemetry and the mitigator.  The coordination and
   communication between these entity depends, for example on the
   characteristic or functionality of the equipment, the reliability of
   the information provided by DDoS attack telemetry, the business
   relationship between the DDoS target domain and the mitigator.

   More explicitly, in some cases, the DDoS telemetry attack may simply
   activate a DDoS mitigation, whereas in some case, it may collaborate
   by providing some information.  In some cases, the DDoS mitigation
   may be orchestrated, which includes selecting an specific appliance
   as well as starting/ending a mitigation.

3.1.  CPE Intra-domain DDoS Mitigation

   The most elementary scenario considers a equipment such as a CPE that
   when overloaded sends an alert to specific equipment located
   upstream.  In most cases, these very basic equipment are unlikely to
   diagnose whether an DDoS attack is ongoing or not and detection as
   well as potential mitigation is left to the upstream equipment.

   In most deployment, the upstream equipment belong to the same domain
   as the CPE.  In such case, it is not expected that a specific
   contract is established between the CPE and the DDoS mitigation



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   service.  The CPE and concerned traffic is likely to be identified by
   the source of the alert, which also imply the mitigator is aware of
   the nature of the equipment as well as the architecture of the
   domain.

   The DDoS mitigation service may be for example an equipment that is
   located on path or a controller that will configure the network to
   the traffic to be analyzed and mitigated is redirected to a dedicated
   vendor specific equipment or solution.  The DDoS mitigation service
   may be activated only for the traffic associated to the CPE sending
   the alert or instead to the traffic associated to all CPE.  Such
   decision are not part of DOTS, but instead depends on the policies of
   the network administrator.

   The DDoS mitigation service is expected to acknowledge the reception
   of the alert in order to avoid retransmission.  This may become an
   issue for example if an ISP receives alerts from all CPEs multiple
   time.  However, it is unlikely that in such cases the CPE will follow
   the status of the mitigation.  Instead, as the DDoS mitigation
   service and the CPE belongs to the same administrative domain, it is
   expected that the decision of mitigating or not, as well as the
   decision to end an ongoing mitigation will be left to DDoS mitigation
   service without notice to the CPEs.

3.2.  Service/System Intra-domain DDoS Mitigation

   This section considers that some more specialized equipment are
   sending the DDoS alert.  As opposed to the CPE, these equipment are
   likely to provide reliable information about the ongoing attack.
   Such equipment could typically be a telemetry system, or a specific
   target service such as a specific instance of web server, or a
   specific web application detecting application specific attacks.

   Such information is likely to be carried in the alert and taken into
   account by the DDoS mitigation service to proceed to further action.
   Typically a telemetry system may indicate selectors of the suspicious
   traffic as well indicators or qualification of the detected attack.
   As the telemetry system is expected to monitor multiple aspect of the
   traffic.  Similarly when an attack is detected by the target service.
   The destination of the alert is likely to receive alert from multiple
   different services (DNS, HTTP, TCP, UDP, application layer
   specific...).  Such information is likely to be trusted and
   considered by the mitigator to apply the appropriated security
   appliance.

   Note that within a single domain it likely that the service or the
   telemetry system are most accurate equipment to qualify the attack.
   As a result, not providing the information is likely to re-do the



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   analysis phase.  Providing the information while sending the alert
   avoid re-processing the analysis.  Instead the mitigator uses
   directly the information to redirect the traffic to the appropriated
   specialized appliance.

   For the same reasons as the CPE, as mitigation of the DDoS Service is
   performed in a single administrative domain, the source of the alert
   may not manage the end of the mitigation service and leave such
   decision to the administrator of domain or the DDoS mitigation
   service.

3.3.  Orchestrating Intra-domain DDoS Mitigation

   This section presents a generalization of the Service/System intra-
   domain scenario.  Orchestration goes one step further and considers
   that the information carried by the alert could have some management
   purpose.  This includes explicitly starting / ending a mitigation as
   well as selecting a specific DDoS mitigation service.  This differs
   from the previous case in that the source of the alert does not leave
   anymore the decision on how to mitigate the attack by the mitigator.
   Instead the mitigator is orchestrated.

   Typical example of orchestrators could be a network administrator
   that monitors the traffic and initiates manually a DDoS mitigation
   from its web portal.  Orchestration may also applied automatically by
   an orchestrator.

3.4.  Inter-domain DDoS Mitigation

   In the case of inter-domain mitigation, it is expected that the DDoS
   mitigation service has more resource, know-how than the target
   domain.  As a result, there is little benefit of sharing the
   information collected in the target domain.  In addition, the
   relation between the two domains are also expected to be described
   into a pre-agreed contract.  In that sense, the alert can be
   restraint to an activation of the DDoS mitigation service.

   On the other hand, has there is a contract agreement, it is also
   expected that target domain is able to stop the DDoS mitigation
   service itself, and that the end of the mitigation is not
   unilaterally provided to the DDoS mitigation service.

4.  Use Cases Taxonomy

   The purpose of DDoS Open Threat Signaling DOTS is to enable the
   coordination of multiple vendor DDoS mitigation services/systems.
   DOTS communication is a communication between a DOTS Client and a
   DOTS Server.  A DOTS Client or DOTS Server can be hosted on different



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   nodes which are associated to different functionalities, and thus
   leading to different expectations from DOTS.  This section provides a
   classification of the DOTS Client, the DOTS Servers as well as the
   different type of exchanges.

   The high level classification is then illustrated on concrete nodes
   and examples.  Appendix also illustrate the current classification
   with scenario and complete description of the process.

4.1.  DOTS Client Taxonomy

   DOTS Client initiates a DOTS communication in order to alert an DDoS
   attack is ongoing or to coordinate a DDoS mitigation.  Coordination
   of a DDOS Mitigation with DOTS includes initiating/terminations of an
   DDoS mitigation service/system as well as controlling the status of
   an ongoing DDoS mitigation.

   Note that the section only considers DOTS Client that are actually
   initiating an exchange with a DOTS Server, and nodes that simply
   relay DOTS messages are not considered here.

   Here are the categories of DOTS Client envisioned in this document:

   (a)  DOTS Client alerting a DDoS attack is ongoing

        i)     hosted on the target attack

        ii)    hosted on a monitoring service/system

   (b)  DOTS Client coordinating an DDoS attack mitigation

        i)     hosted on an orchestrator

        ii)    hosted on administrative GUI

   When the DOTS Client is hosted on the attack target.  The DOTS Client
   mostly raised an alert to the DDoS Mitigation service/system.  When a
   alert is raised by the node under attack, very little information is
   expected to be provided by DOTS Client to the DDoS mitigation
   service/system.  More particularly telemetric information or
   characteristics of the attack are likely to be unreliable as the host
   is already overload.  As a result, such DOTS Client may raise an
   alert without any additional information.  Eventually, information
   such as the asset under attack which can simply be configured.  The
   asset under attack is especially useful for the DDoS mitigation
   service/system to indicate the origin of the alert.  It is not
   necessary, for example, if the origin of the alert is implicit.  The
   origin of the alert my be implicit, for example when DOTS Clients are



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   authenticated or when the device is identified by the links (i.e when
   the host is a CPE).  Note also that the asset to protect is only
   informational and optional.  This information may be spoofed, and the
   DDoS mitigation is likely to be derived from the authentication of
   the alert.  In most cases, the DDoS mitigation has been pre-agreed
   between the host under attack and the DDoS mitigation service/system.

   When the DOTS Client is hosted on a monitoring system, the monitoring
   system may raise an alert an attack is ongoing.  Unlike the host
   under attack, the monitoring system is expected to have sufficient
   resource so it is not itself overload and impacted by the ongoing
   attack.  As a result, the DOTS Client is more likely to provide
   additional information associated to the alert, as this information
   is expected to be reliable.  The type of information associated may
   be associated to the asset to protect and eventually some information
   qualifying the attack.  On the other hand, the information associated
   also depends on how the what has been agreed with DDoS mitigation
   service/system.  In most cases, when a DDoS attack is detected all
   the traffic is redirected to the DDoS mitigation procedure has been
   agreed between the DDoS mitigation service/system and the entity
   hosting the monitoring service.  In such cases, very few information
   is needed.

   When the DOTS Client is hosted on an orchestrator, the DOTS Client
   contacts the DDoS mitigation service/system to initiates a DDoS
   mitigation.  The orchestrator is responsible for setting the network
   to redirect the traffic to the DDoS mitigation service/system.  If
   the DDoS mitigation service/system is not available, the orchestrator
   is responsible to find an alternative.  Again the orchestrator is
   likely to provide additional information to the DDoS mitigation
   service/system.  For example, typical information may be the asset to
   protect, as well as the specific mitigation function requested.  On
   the other hand, the service is usually expected to be associated to
   the mitigation service, and so may not be explicitly specified.  In
   addition, the DOTS Client is also expected to control how the DDoS
   mitigation is performed.  More specifically, it is expected that the
   DOTS Client can terminate the DDoS mitigation.  In addition, the DOTS
   Client should have sufficient information to decide how to operate
   next.  For example, it should be able to check if the mitigation is
   ongoing as well as the efficiency of the mitigation.

   When the DOTS client is hosted on an administrative system, the DOTS
   Client may be triggered by the network administrator to initiate a
   DDoS mitigation.  In this case, the DOTS Server is likely to be an
   orchestrator, and all necessary information may be provided so the
   DDoS mitigation can be initiated.  This includes, the asset to be
   protected, the action expected to be performed by the orchestrator,
   the DDoS mitigation service/system to contact...



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   Note that information associated by the DOTS Client to a request for
   mitigation is not limited.  However, as DDoS mitigation systems are
   highly heterogeneous, if there is a need to provide interoperability
   between the vendors and DDoS mitigation services/systems, that
   actions provided by a DOTS Clients remains small and accepted by all
   services/systems.  As a result here are the envisioned optional
   information provided by the DOTS Client.

   (a)  recommended asset to protect (IP, port).  This information
        specifies the expected action from the DDoS mitigation service/
        system.

   (b)  optional DDoS Mitigation Contract ID: which references the
        contract agreed out-of-band.  This information specifies the
        expected action from the DDoS mitigation service/system.

   (c)  optional Requested Service: which designates the function or
        service associated to the DDoS mitigation service/system.  This
        information specifies the expected action from the DDoS
        mitigation service/system.

   (d)  optional DDoS attack information (suspected attack, telemetry ):
        This information is expected to help the mitigation service/
        system to diagnose the ongoing attack.

   In both cases, the DOTS Client sends a request for DDoS mitigation to
   the DOTS Server, and expects the DDoS mitigation service/system
   mitigates the DDoS attack.  The difference between sending a request
   for DDoS mitigation as an alert or for coordinating an DDoS
   mitigation is that an alert is a request to completely outsource the
   mitigation, whereas the coordination requires additional control over
   the DDoS mitigation.  An alert may be acknowledged by the DOTS Server
   to acknowledge the reception whereas during the coordination, the the
   DOTS server may acknowledge the initiation of the DDoS mitigation.

4.2.  DOTS Server Taxonomy

   DOTS Servers terminate the DOTS communication.  The DOTS Server is
   typically hosted on a DDoS mitigation service/system or an
   intermediary node such as an orchestrator.

   The DOTS Server is expected to be the entry point of a DDoS
   mitigation service/system.  Some DOTS Client do not expect any
   interaction from the DOTS Server, once a DDoS mitigation has been
   requested.  This is especially true for DOTS Client hosted on attack
   target.  Other DOTS Client hosted on orchestrators or DDoS mitigation
   service/systems are likely to expect for the DOTS Server a
   confirmation the system accepts the DDoS mitigation task.



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   Respectively, these DOTS Client are also likely to expect a
   confirmation when a DDoS mitigation termination has been requested.
   In addition, DOTS Server are also expected to provide information
   related to the mitigation status when requested by the DOTS Client.
   In addition, it is also expected that the DOTS Server could provide
   some status report of the DDoS mitigation on a push basis.

4.3.  DOTS Message Taxonomy

   The core essential messages to coordination an heterogeneous set of
   DDoS mitigation services/system needs to be small and enable future
   options.  Here are the different exchanges envisioned in this
   document between a DOTS Client and a DOTS Server.

   (a)  DOTS MITIGATION CONTROL messages are used by the DOTS Client to
        initiate or terminate a DDoS mitigation.  The initiator the
        termination can be specified by the action type START or STOP.
        Such message can carry some additional options that specify
        additional information such as the asset under attack for
        example.  These DOTS MITIGATION CONTROL messages are expected to
        be ACKed by the DOTS Server, in order to indicate the DOTS
        Server will perform the requested action.  In any other case an
        error is expected to be returned. ven in the case of a DOTS
        Client sends an alert, ACK is recommended so the DOTS Client
        stop sending the alert.

   (b)  DOTS MITIGATION INFORMATIONAL message are left for any
        additional interaction between a DOTS Client and DOTS Server
        regarding an ongoing request.  INFORMATIONAL message can be
        ignored by the receiver if it does not not understand the the
        requested information or options.  In the current document an
        informational message can be the status of the ongoing
        mitigation.

   (c)  DOTS ERROR contains the errors associated to a request.

   DOTS OPTIONS: options can be used to indicate some optional
   information.  The option is expected to specify whether the DOTS
   Server can ignore it or must return an error if it is not understood.
   Options are not message, but part of the message.

5.  Security Considerations

   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.





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   Impersonation and traffic injection mitigation can be managed through
   current secure communications best practices.  DOTS is not subject to
   anything new in this area.  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.

   Additional details of DOTS security requirements may be found in
   [I-D.ietf-dots-requirements].

6.  IANA Considerations

   No IANA considerations exist for this document at this time.

7.  Acknowledgments

   TBD

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

8.2.  Informative References

   [APACHE]   "Apache mod_security", <https://www.modsecurity.org>.

   [I-D.ietf-dots-requirements]
              Mortensen, A., Moskowitz, R., and T. Reddy, "Distributed
              Denial of Service (DDoS) Open Threat Signaling
              Requirements", draft-ietf-dots-requirements-03 (work in
              progress), October 2016.

   [RFC6335]  Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
              Cheshire, "Internet Assigned Numbers Authority (IANA)
              Procedures for the Management of the Service Name and
              Transport Protocol Port Number Registry", BCP 165,
              RFC 6335, DOI 10.17487/RFC6335, August 2011,
              <http://www.rfc-editor.org/info/rfc6335>.

   [RRL]      "BIND RRL", <https://deepthought.isc.org/article/AA-
              00994/0/Using-the-Response-Rate-Limiting-Feature-in-BIND-
              9.10.html>.



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Appendix A.  Use Cases

   This section provides a high-level overview of likely use cases and
   deployment scenarios for DOTS-enabled DDoS mitigation services.  It
   should be noted that DOTS servers may be standalone entities which,
   upon receiving a DOTS mitigation service request from a DOTS client,
   proceed to initiate DDoS mitigation service by communicating directly
   or indirectly with DDoS mitigators, and likewise terminate the
   service upon receipt of a DOTS service termination request;
   conversely, the DDoS mitigators themselves may incorporate DOTS
   servers and/or DOTS clients.  The mechanisms by which DOTS servers
   initiate and terminate DDoS mitigation service with DDoS mitigators
   is beyond the scope of this document.

   All of the primary use cases described in this section are derived
   from current, real-world DDoS mitigation functionality, capabilities,
   and operational models.

   The posited ancillary use cases described in this section are
   reasonable and highly desirable extrapolations of the functionality
   of baseline DOTS capabilities, and are readily attainable in the near
   term.

   Each of the primary and ancillary use cases described in this section
   may be read as involving one or more DDoS mitigation service
   providers; DOTS makes multi-provider coordinated DDoS defenses much
   more effective and practical due to abstraction of the particulars of
   a given DDoS mitigation service/solution set.

   Both the primary and ancillary use cases may be facilitated by direct
   DOTS client - DOTS server communications or via DOTS relays deployed
   in order to aggregate DOTS mitigation service requests/responses, to
   mediate between stateless and stateful underlying transport
   protocols, to aggregate multiple DOTS requests and/or responses, to
   filter DOTS requests and/or responses via configured policy
   mechanisms, or some combination of these functions.

   All DOTS messages exchanged between the DOTS clients and DOTS servers
   in these use cases may be communicated directly between DOTS clients
   and servers, or mediated by one or more DOTS relays residing on the
   network of the originating network, the network where upstream DDoS
   mitigation service takes place, an intervening network or networks,
   or some combination of the above.

   DOTS is intended to apply to both inter- and intra-domain DDoS attack
   mitigation scenarios.  The technical and operational requirements for
   inter- and intra-domain DOTS communications are identical.  The main
   difference is administrative in nature; although it should be noted



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   that provisioning challenges which are typically associated with
   inter- domain DOTS communications relationships may also apply in
   intra- domain deployment scenarios, based upon organizational
   factors.  All of the same complexities surrounding authentication and
   authorization can apply in both contexts, including considerations
   such as network access policies to allow DOTS communications, DOTS
   transport selection (including considerations of the implications of
   link congestion if a stateful DOTS transport option is selected),
   etc.  Registration of well-known ports for DOTS transports per
   [RFC6335] should be considered in light of these challenges.

   It should also be noted that DOTS does not directly ameliorate the
   various administrative challenges required for successful DDoS attack
   mitigation.  Letters of authorization, RADB updates, DNS zone
   delegations, alteration of network access policies, technical
   configurations required to facilitate network traffic diversion and
   re-injection, etc., are all outside the scope of DOTS.  DOTS may,
   however, prove useful in automating the registration of DOTS clients
   with DOTS servers, as well as in the automatic provisioning of
   situationally- appropriate DDoS defenses and countermeasures.  This
   ancillary DOTS functionality is described in Appendix A.2.

   Many of the 'external' administrative challenges associated with
   establishing workable DDoS attack mitigation service may be addressed
   by work currently in progress in the I2RS and I2NSF WGs.  Interested
   parties may wish to consider tracking those efforts, and coordination
   with both I2RS and I2NSF is highly desirable.

   Note that all the use-cases in this document are universal in nature.
   They apply equally to endpoint networks, transit backbone providers,
   cloud providers, broadband access providers, ASPs, CDNs, etc.  They
   are not specific to particular business models, topological models,
   or application types, and are deliberately generalizable.  Both
   networks targeted for attack as well as any adjacent or topologically
   distant networks involved in a given scenario may be either single-
   or multi-homed.  In the accompanying vector illustrations
   incorporated into draft-ietf-dots-use-cases-01.pdf, specific business
   and topological models are described in order to provide context.

   Likewise, both DOTS itself and the use cases described in this
   document are completely independent of technologies utilized for the
   detection, classification, traceback, and mitigation of DDoS attacks.
   Flow telemetry such as NetFlow and IPFIX, direct full-packet
   analysis, log-file analysis, indirection manual observation, etc. can
   and will be enablers for detection, classification and traceback.
   Intelligent DDoS mitigation systems (IDMSes), flowspec, S/RTBH, ACLs,
   and other network traffic manipulation tools and techniques may be
   used for DDoS attack mitigation.  BGP, flowspec, DNS, inline



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   deployment, and various 'NFV' technologies may be used for network
   traffic diversion into mitigation centers or devices in applicable
   scenarios; GRE, MPLS, 'NFV', inline deployment and other techniques
   may be utilized for 'cleaned' traffic re-injection to its intended
   destination.

   The scope, format, and content of all DOTS message types cited in
   this document must be codified by the DOTS WG.

   The following use cases are intended to inform the DOTS requirements
   described in [I-D.ietf-dots-requirements].

A.1.  Primary Use Cases

A.1.1.  Automatic or Operator-Assisted CPE or PE Mitigators Request
        Upstream DDoS Mitigation Services

   One or more CPE or PE mitigators with DOTS client capabilities may be
   configured to signal to one or more DOTS servers in order to request
   upstream DDoS mitigation service initiation during an attack when
   DDoS attack volumes and/or attack characteristics exceed the
   capabilities of such CPE mitigators.  DDoS mitigation service may be
   terminated either automatically or manually via a DOTS mitigation
   service termination request initiated by the mitigator when it has
   been determined that the DDoS attack has ended.

   (a)  A DDoS attack is initiated against online properties of an
        organization which has deployed DOTS-client-capable DDoS
        mitigators.

   (b)  CPE or PE DDoS mitigators detect, classify, and begin mitigating
        the DDoS attack.

   (c)  CPE or PE DDoS mitigators determine that their capacity and/or
        capability to mitigate the DDoS attack is insufficient, and
        utilize their DOTS client functionality to send a DOTS
        mitigation service initiation request to one or more DOTS
        servers residing on one or more upstream transit networks, peer
        networks, or overlay MSSP networks.  This DOTS mitigation
        service initiation request may be automatically initiated by the
        CPE or PE DDoS mitigators, or may be manually triggered by
        personnel of the requesting organization in response to an alert
        from the mitigators (the mechanism by which this process takes
        place is beyond the scope of this document).

   (d)  The DOTS servers which receive the DOTS mitigation service
        initiation requests determine that they have been configured to
        honor requests from the requesting CPE or PE mitigators, and



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        initiate situationally-appropriate DDoS mitigation service on
        their respective networks (the mechanism by which this process
        takes place is beyond the scope of this document).

   (e)  The DOTS servers transmit a DOTS service status message to the
        requesting CPE or PE mitigators indicating that upstream DDoS
        mitigation service has been initiated.

   (f)  While DDoS mitigation services are active, the DOTS servers
        regularly transmit DOTS mitigation status updates to the
        requesting CPE or PE mitigators.

   (g)  While DDoS mitigation services are active, the CPE or PE
        mitigators may optionally regularly transmit DOTS mitigation
        efficacy updates to the relevant DOTS servers.

   (h)  When the upstream DDoS mitigators determine that the DDoS attack
        has ceased, they indicate this change in status to their
        respective DOTS servers (the mechanism by which this process
        takes place is beyond the scope of this document).

   (i)  The DOTS servers transmit a DOTS mitigation status update to the
        CPE or PE mitigators indicating that the DDoS attack has ceased.

   (j)  The CPE or PE DDoS mitigators transmit a DOTS mitigation service
        termination request to the DOTS servers.  This DOTS mitigation
        service termination request may be automatically initiated by
        the CPE or PE DDoS mitigators, or may be manually triggered by
        personnel of the requesting organization in response to an alert
        from the mitigators or a management system which monitors them
        (the mechanism by which this process takes place is beyond the
        scope of this document).

   (k)  The DOTS servers terminate DDoS mitigation service on their
        respective networks (the mechanism by which this process takes
        place is beyond the scope of this document).

   (l)  The DOTS servers transmit a DOTS mitigation status update to the
        CPE or PE mitigators indicating that DDoS mitigation services
        have been terminated.

   (m)  The CPE or PE DDoS mitigators transmit a DOTS mitigation
        termination status acknowledgement to the DOTS servers.








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A.1.2.  Automatic or Operator-Assisted CPE or PE Network Infrastructure
        Element Request to Upstream Mitigator

   CPE or PE network infrastructure elements such as routers, switches,
   load-balancers, firewalls, 'IPSes', etc. which have the capability to
   detect and classify DDoS attacks and which have DOTS client
   capabilities may be configured to signal to one or more DOTS servers
   in order to request upstream DDoS mitigation service initiation
   during an attack.  DDoS mitigation service may be terminated either
   automatically or manually via a DOTS mitigation service termination
   request initiated by the network element when it has been determined
   that the DDoS attack has ended.

   In this use-case, the network elements involved are not engaged in
   mitigating DDoS attack traffic.  They are signaling for upstream
   attack mitigation assistance.  This can be an inter- or intra- domain
   use-case.

   (a)  A DDoS attack is initiated against online properties of an
        organization with DOTS-client-capable network infrastructure
        elements deployed.

   (b)  The network infrastructure elements utilize their DOTS client
        functionality to send a DOTS mitigation service initiation
        request to one or more DOTS servers residing on one or more
        upstream transit networks, peer networks, or overlay MSSP
        networks, either directly or via intermediate DOTS relays
        residing upon the requesting organization's network, the
        upstream mitigation provider's network, or both.  The scope,
        format, and content of these messages must be codified by the
        DOTS WG.  This DOTS mitigation service initiation request may be
        automatically initiated by the network infrastructure elements,
        or may be manually triggered by personnel of the requesting
        organization in response to an alert from the network elements
        or a management system which monitors them (the mechanism by
        which this process takes place is beyond the scope of this
        document).

   (c)  The DOTS servers which receive the DOTS mitigation service
        initiation requests determine that they have been configured to
        honor requests from the requesting network infrastructure
        elements, and initiate situationally-appropriate DDoS mitigation
        service on their respective networks (the mechanism by which
        this process takes place is beyond the scope of this document).

   (d)  The DOTS servers transmit a DOTS service status message to the
        requesting network infrastructure elements indicating that
        upstream DDoS mitigation service has been initiated.



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   (e)  While DDoS mitigation services are active, the DOTS servers
        regularly transmit DOTS mitigation status updates to the
        requesting requesting network infrastructure elements.

   (f)  While DDoS mitigation services are active, the network
        infrastructure elements may optionally regularly transmit DOTS
        mitigation efficacy updates to the relevant DOTS servers.

   (g)  When the upstream DDoS mitigators determine that the DDoS attack
        has ceased, they indicate this change in status to their
        respective DOTS servers (the mechanism by which this process
        takes place is beyond the scope of this document).

   (h)  The DOTS servers transmit a DOTS mitigation status update to the
        network infrastructure elements indicating that the DDoS attack
        has ceased.

   (i)  The network infrastructure elements transmit a DOTS mitigation
        service termination request to the DOTS servers.  This DOTS
        mitigation service termination request may be automatically
        initiated by the network infrastructure elements, or may be
        manually triggered by personnel of the requesting organization
        in response to an alert from the mitigators (the mechanism by
        which this process takes place is beyond the scope of this
        document).

   (j)  The DOTS servers terminate DDoS mitigation service on their
        respective networks (the mechanism by which this process takes
        place is beyond the scope of this document).

   (k)  The DOTS servers transmit a DOTS mitigation status update to the
        network infrastructure elements indicating that DDoS mitigation
        services have been terminated.

   (l)  The network infrastructure elements transmit a DOTS mitigation
        termination status acknowledgement to the DOTS servers.

A.1.3.  Automatic or Operator-Assisted CPE or PE Attack Telemetry
        Detection/Classification System Request to Upstream Mitigator

   CPE or PE Attack Telemetry Detection/Classification Systems which
   have DOTS client capabilities may be configured so that upon
   detecting and classifying a DDoS attack, they signal one or more DOTS
   servers in order to request upstream DDoS mitigation service
   initiation.  DDoS mitigation service may be terminated either
   automatically or manually via a DOTS mitigation service termination
   request initiated by the Attack Telemetry Detection/Classification
   System when it has been determined that the DDoS attack has ended.



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   In this use-case, the Attack Telemetry Detection/Classification does
   not possess any inherent capability to mitigate DDoS attack traffic,
   and is signaling for upstream mitigation assistance.  This can be an
   inter- or intra-domain use-case.

   (a)  A DDoS attack is initiated against online properties of an
        organization with DOTS-client-capable CPE or PE Attack Telemetry
        Detection/Classification Systems deployed.

   (b)  The CPE or PE Attack Telemetry Detection/Classification Systems
        utilize their DOTS client functionality to send a DOTS
        mitigation service initiation request to one or more DOTS
        servers residing on one or more upstream transit networks, peer
        networks, or overlay MSSP networks, either directly or via
        intermediate DOTS relays residing upon the requesting
        organization's network, the upstream mitigation provider's
        network, or both.  This DOTS mitigation service initiation
        request may be automatically initiated by the CPE or PE Attack
        Telemetry Detection/Classification Systems, or may be manually
        triggered by personnel of the requesting organization in
        response to an alert from the CPE or PE Attack Telemetry
        Detection/Classification Systems (the mechanism by which this
        process takes place is beyond the scope of this document).

   (c)  The DOTS servers which receive the DOTS mitigation service
        initiation requests determine that they have been configured to
        honor requests from the requesting CPE or PE Attack Telemetry
        Detection/Classification Systems, and initiate situationally-
        appropriate DDoS mitigation service on their respective networks
        (the mechanism by which this process takes place is beyond the
        scope of this document).

   (d)  The DOTS servers transmit a DOTS service status message to the
        requesting CPE or PE Attack Telemetry Detection/Classification
        Systems indicating that upstream DDoS mitigation service has
        been initiated.

   (e)  While DDoS mitigation services are active, the DOTS servers
        regularly transmit DOTS mitigation status updates to the
        requesting CPE or PE Attack Telemetry Detection/Classification
        Systems.

   (f)  While DDoS mitigation services are active, the CPE or PE Attack
        Telemetry Detection/Classification Systems may optionally
        regularly transmit DOTS mitigation efficacy updates to the
        relevant DOTS servers.





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   (g)  When the upstream DDoS mitigators determine that the DDoS attack
        has ceased, they indicate this change in status to their
        respective DOTS servers (the mechanism by which this process
        takes place is beyond the scope of this document).

   (h)  The DOTS servers transmit a DOTS mitigation status update to the
        CPE or PE Attack Telemetry Detection/Classification Systems
        indicating that the DDoS attack has ceased.

   (i)  The CPE or PE Attack Telemetry Detection/Classification Systems
        transmit a DOTS mitigation service termination request to the
        DOTS servers.  This DOTS mitigation service termination request
        may be automatically initiated by the CPE or PE Attack Telemetry
        Detection/Classification Systems, or may be manually triggered
        by personnel of the requesting organization in response to an
        alert from the CPE or PE Attack Telemetry Detection/
        Classification Systems (the mechanism by which this process
        takes place is beyond the scope of this document).

   (j)  The DOTS servers terminate DDoS mitigation service on their
        respective networks (the mechanism by which this process takes
        place is beyond the scope of this document).

   (k)  The DOTS servers transmit a DOTS mitigation status update to the
        CPE or PE Attack Telemetry Detection/Classification Systems
        indicating that DDoS mitigation services have been terminated.

   (l)  The CPE or PE Attack Telemetry Detection/Classification Systems
        transmit a DOTS mitigation termination status acknowledgement to
        the DOTS servers.

A.1.4.  Automatic or Operator-Assisted Targeted Service/ Application
        Request to Upstream Mitigator

   A service or application which is the target of a DDoS attack and
   which has the capability to detect and classify DDoS attacks (i.e,
   Apache mod_security [APACHE], BIND RRL [RRL], etc.) as well as DOTS
   client functionality may be configured so that upon detecting and
   classifying a DDoS attack, it signals one or more DOTS servers in
   order to request upstream DDoS mitigation service initiation.  DDoS
   mitigation service may be terminated either automatically or manually
   via a DOTS mitigation service termination request initiated by the
   service/application when it has been determined that the DDoS attack
   has ended.

   In this use-case, the service/application does not possess inherent
   DDoS attack mitigation capabilities, and is signaling for upstream




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   mitigation assistance.  This can be an inter- or intra-domain use-
   case.

   (a)  A DDoS attack is initiated against online properties of an
        organization which include DOTS-client-capable services or
        applications that are the specific target(s) of the attack.

   (b)  The targeted services or applications utilize their DOTS client
        functionality to send a DOTS mitigation service initiation
        request to one or more DOTS servers residing on the same network
        as the services or applications, one or more upstream transit
        networks, peer networks, or overlay MSSP networks, either
        directly or via intermediate DOTS relays residing upon the
        requesting organization's network, the upstream mitigation
        provider's network, or both.  This DOTS mitigation service
        initiation request may be automatically initiated by the
        targeted services or applications, or may be manually triggered
        by personnel of the requesting organization in response to an
        alert from the targeted services or applications or a system
        which monitors them (the mechanism by which this process takes
        place is beyond the scope of this document).

   (c)  The DOTS servers which receive the DOTS mitigation service
        initiation requests determine that they have been provisioned to
        honor requests from the requesting services or applications, and
        initiate situationally-appropriate DDoS mitigation service on
        their respective networks (the mechanism by which this process
        takes place is beyond the scope of this document).

   (d)  The DOTS servers transmit a DOTS service status message to the
        services or applications indicating that upstream DDoS
        mitigation service has been initiated

   (e)  While DDoS mitigation services are active, the DOTS servers
        regularly transmit DOTS mitigation status updates to the
        requesting services or applications.

   (f)  While DDoS mitigation services are active, the requesting
        services or applications may optionally regularly transmit DOTS
        mitigation efficacy updates to the relevant DOTS servers.

   (g)  When the upstream DDoS mitigators determine that the DDoS attack
        has ceased, they indicate this change in status to their
        respective DOTS servers (the mechanism by which this process
        takes place is beyond the scope of this document).






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   (h)  The DOTS servers transmit a DOTS mitigation status update to the
        requesting services or applications indicating that the DDoS
        attack has ceased.

   (i)  The targeted services or applications transmit a DOTS mitigation
        service termination request to the DOTS servers.  This DOTS
        mitigation service termination request may be automatically
        initiated by the targeted services or applications, or may be
        manually triggered by personnel of the requesting organization
        in response to an alert from a system which monitors them (the
        mechanism by which this process takes place is beyond the scope
        of this document).

   (j)  The DOTS servers terminate DDoS mitigation service on their
        respective networks (the mechanism by which this process takes
        place is beyond the scope of this document).

   (k)  The DOTS servers transmit a DOTS mitigation status update to the
        targeted services or applications indicating that DDoS
        mitigation services have been terminated.

   (l)  The targeted services or applications transmit a DOTS mitigation
        termination status acknowledgement to the DOTS servers.

A.1.5.  Manual Web Portal Request to Upstream Mitigator

   A Web portal which has DOTS client capabilities has been configured
   in order to allow authorized personnel of organizations which are
   targeted by DDoS attacks to manually request upstream DDoS mitigation
   service initiation from a DOTS server.  When an organization has
   reason to believe that it is under active attack, authorized
   personnel may utilize the Web portal to manually initiate a DOTS
   client mitigation request to one or more DOTS servers.  DDoS
   mitigation service may be terminated manually via a DOTS mitigation
   service termination request through the Web portal when it has been
   determined that the DDoS attack has ended.

   In this use-case, the organization targeted for attack does not
   possess any automated or operator-assisted mechanisms for DDoS attack
   detection, classification, traceback, or mitigation; the existence of
   an attack has been inferred manually, and the organization is
   requesting upstream mitigation assistance.  This can theoretically be
   an inter- or intra-domain use-case, but is more typically an inter-
   domain scenario.

   (a)  A DDoS attack is initiated against online properties of an
        organization have access to a Web portal which incorporates DOTS




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        client functionality and can generate DOTS mitigation service
        requests upon demand.

   (b)  Authorized personnel utilize the Web portal to send a DOTS
        mitigation service initiation request to one or more upstream
        transit networks, peer networks, or overlay MSSP networks,
        either directly or via intermediate DOTS relays residing upon
        the requesting organization's network, the upstream mitigation
        provider's network, or both.  This DOTS mitigation service
        initiation request is manually triggered by personnel of the
        requesting organization when it is judged that the organization
        is under DDoS attack (the mechanism by which this process takes
        place is beyond the scope of this document).

   (c)  The DOTS servers which receive the DOTS mitigation service
        initiation requests determine that they have been provisioned to
        honor requests from the Web portal, and initiate situationally-
        appropriate DDoS mitigation service on their respective networks
        (the mechanism by which this process takes place is beyond the
        scope of this document).

   (d)  The DOTS servers transmit a DOTS service status message to the
        Web portal indicating that upstream DDoS mitigation service has
        been initiated.

   (e)  While DDoS mitigation services are active, the DOTS servers
        regularly transmit DOTS mitigation status updates to the Web
        portal.

   (f)  While DDoS mitigation services are active, the Web portal may
        optionally regularly transmit manually-triggered DOTS mitigation
        efficacy updates to the relevant DOTS servers.

   (g)  When the upstream DDoS mitigators determine that the DDoS attack
        has ceased, they indicate this change in status to their
        respective DOTS servers (the mechanism by which this process
        takes place is beyond the scope of this document).

   (h)  The DOTS servers transmit a DOTS mitigation status update to the
        Web portal indicating that the DDoS attack has ceased.

   (i)  The Web portal transmits a manually-triggered DOTS mitigation
        service termination request to the DOTS servers (the mechanism
        by which this process takes place is beyond the scope of this
        document).

   (j)  The Web portal transmits a manually-triggered DOTS mitigation
        service termination request to the DOTS servers (the mechanism



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        by which this process takes place is beyond the scope of this
        document).

   (k)  The DOTS servers transmit a DOTS mitigation status update to the
        Web portal indicating that DDoS mitigation services have been
        terminated.

   (l)  The Web portal transmits a DOTS mitigation termination status
        acknowledgement to the DOTS servers.

A.1.6.  Manual Mobile Device Application Request to Upstream Mitigator

   An application for mobile devices such as smartphones and tablets
   which incorporates DOTS client capabilities has been made available
   to authorized personnel of an organization.  When the organization
   has reason to believe that it is under active DDoS attack, authorized
   personnel may utilize the mobile device application to manually
   initiate a DOTS client mitigation request to one or more DOTS servers
   in order to initiate upstream DDoS mitigation services.  DDoS
   mitigation service may be terminated manually via a DOTS mitigation
   service termination request initiated through the mobile device
   application when it has been determined that the DDoS attack has
   ended.

   This use-case is similar to the one described in Appendix A.1.5; the
   difference is that a mobile application provided by the DDoS
   mitigation service provider is used to request upstream attack
   mitigation assistance.  This can theoretically be an inter- or intra-
   domain use-case, but is more typically an inter-domain scenario.

   (a)  A DDoS attack is initiated against online properties of an
        organization have access to a Web portal which incorporates DOTS
        client functionality and can generate DOTS mitigation service
        requests upon demand.

   (b)  Authorized personnel utilize the mobile application to send a
        DOTS mitigation service initiation request to one or more DOTS
        servers residing on the same network as the targeted Internet
        properties, one or more upstream transit networks, peer
        networks, or overlay MSSP networks, either directly or via
        intermediate DOTS relays residing upon the requesting
        organization's network, the upstream mitigation provider's
        network, or both.  This DOTS mitigation service initiation
        request is manually triggered by personnel of the requesting
        organization when it is judged that the organization is under
        DDoS attack (the mechanism by which this process takes place is
        beyond the scope of this document).




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   (c)  The DOTS servers which receive the DOTS mitigation service
        initiation requests determine that they have been provisioned to
        honor requests from the mobile application, and initiate
        situationally-appropriate DDoS mitigation service on their
        respective networks (the mechanism by which this process takes
        place is beyond the scope of this document).

   (d)  The DOTS servers transmit a DOTS service status message to the
        mobile application indicating that upstream DDoS mitigation
        service has been initiated.

   (e)  While DDoS mitigation services are active, the DOTS servers
        regularly transmit DOTS mitigation status updates to the mobile
        application.

   (f)  While DDoS mitigation services are active, the mobile
        application may optionally regularly transmit manually-triggered
        DOTS mitigation efficacy updates to the relevant DOTS servers.

   (g)  When the upstream DDoS mitigators determine that the DDoS attack
        has ceased, they indicate this change in status to their
        respective DOTS servers (the mechanism by which this process
        takes place is beyond the scope of this document).

   (h)  The DOTS servers transmit a DOTS mitigation status update to the
        mobile application indicating that the DDoS attack has ceased.

   (i)  The mobile application transmits a manually-triggered DOTS
        mitigation service termination request to the DOTS servers (the
        mechanism by which this process takes place is beyond the scope
        of this document).

   (j)  The DOTS servers terminate DDoS mitigation service on their
        respective networks (the mechanism by which this process takes
        place is beyond the scope of this document).

   (k)  The DOTS servers transmit a DOTS mitigation status update to the
        mobile application indicating that DDoS mitigation services have
        been terminated.

   (l)  The mobile application transmits a DOTS mitigation termination
        status acknowledgement to the DOTS servers.









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A.1.7.  Unsuccessful Automatic or Operator-Assisted CPE or PE Mitigators
        Request Upstream DDoS Mitigation Services

   One or more CPE or PE mitigators with DOTS client capabilities may be
   configured to signal to one or more DOTS servers in order to request
   upstream DDoS mitigation service initiation during an attack when
   DDoS attack volumes and/or attack characteristics exceed the
   capabilities of such CPE mitigators.  DDoS mitigation service may be
   terminated either automatically or manually via a DOTS mitigation
   service termination request initiated by the mitigator when it has
   been determined that the DDoS attack has ended.

   This can theoretically be an inter- or intra-domain use-case, but is
   more typically an inter-domain scenario.

   (a)  A DDoS attack is initiated against online properties of an
        organization which has deployed DOTS-client-capable DDoS
        mitigators.

   (b)  CPE or PE DDoS mitigators detect, classify, and begin mitigating
        the DDoS attack.

   (c)  CPE or PE DDoS mitigators determine that their capacity and/or
        capability to mitigate the DDoS attack is insufficient, and
        utilize their DOTS client functionality to send a DOTS
        mitigation service initiation request to one or more DOTS
        servers residing on one or more upstream transit networks, peer
        networks, or overlay MSSP networks.  This DOTS mitigation
        service initiation request may be automatically initiated by the
        CPE or PE DDoS mitigators, or may be manually triggered by
        personnel of the requesting organization in response to an alert
        from the mitigators (the mechanism by which this process takes
        place is beyond the scope of this document).

   (d)  The DOTS servers which receive the DOTS mitigation service
        initiation requests determine that they have been configured to
        honor requests from the requesting CPE or PE mitigators, and
        attempt to initiate situationally-appropriate DDoS mitigation
        service on their respective networks (the mechanism by which
        this process takes place is beyond the scope of this document).

   (e)  The DDoS mitigators on the upstream network report back to the
        DOTS servers that they are unable to initiate DDoS mitigation
        service for the requesting organization due to mitigation
        capacity constraints, bandwidth constraints, functionality
        constraints, hardware casualties, or other impediments (the
        mechanism by which this process takes place is beyond the scope
        of this document).



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   (f)  The DOTS servers transmit a DOTS service status message to the
        requesting CPE or PE mitigators indicating that upstream DDoS
        mitigation service cannot be initiated as requested.

   (g)  The CPE or PE mitigators may optionally regularly re-transmit
        DOTS mitigation status request messages to the relevant DOTS
        servers until acknowledgement that mitigation services have been
        initiated.

   (h)  The CPE or PE mitigators may optionally transmit a DOTS
        mitigation service initiation request to DOTS servers associated
        with a configured fallback upstream DDoS mitigation service.
        Multiple fallback DDoS mitigation services may optionally be
        configured.

   (i)  The process describe above cyclically continues until the DDoS
        mitigation service request is fulfilled; the CPE or PE
        mitigators determine that the DDoS attack volume has decreased
        to a level and/or complexity which they themselves can
        successfully mitigate; the DDoS attack has ceased; or manual
        intervention by personnel of the requesting organization has
        taken place.

A.2.  Ancillary Use Cases

A.2.1.  Auto-registration of DOTS clients with DOTS servers

   An additional benefit of DOTS is that by utilizing agreed-upon
   authentication mechanisms, DOTS clients can automatically register
   for DDoS mitigation service with one or more upstream DOTS servers.
   The details of such registration are beyond the scope of this
   document.

A.2.2.  Auto-provisioning of DDoS countermeasures

   The largely manual tasks associated with provisioning effective,
   situationally-appropriate DDoS countermeasures is a significant
   barrier to providing/obtaining DDoS mitigation services for both
   mitigation providers and mitigation recipients.  Due to the 'self-
   descriptive' nature of DOTS registration messages and mitigation
   requests, the implementation and deployment of DOTS has the potential
   to automate countermeasure selection and configuration for DDoS
   mitigators.  The details of such provisioning are beyond the scope of
   this document.

   This can theoretically be an inter- or intra-domain use-case, but is
   more typically an inter-domain scenario.




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A.2.3.  Informational DDoS attack notification to interested and
        authorized third parties

   In addition to its primary role of providing a standardized,
   programmatic approach to the automated and/or operator-assisted
   request of DDoS mitigation services and providing status updates of
   those mitigations to requesters, DOTS may be utilized to notify
   security researchers, law enforcement agencies, regulatory bodies,
   etc. of DDoS attacks against attack targets, assuming that
   organizations making use of DOTS choose to share such third-party
   notifications, in keeping with all applicable laws, regulations,
   privacy and confidentiality considerations, and contractual
   agreements between DOTS users and said third parties.

   This is an inter-domain scenario.

Authors' Addresses

   Roland Dobbins (editor)
   Arbor Networks
   30 Raffles Place
   Level 17 Chevron House
   Singapore 048622
   Singapore

   Email: rdobbins@arbor.net


   Stefan Fouant
   Corero Network Security

   Email: Stefan.Fouant@corero.com


   Daniel Migault
   Ericsson
   8400 boulevard Decarie
   Montreal, QC  H4P 2N2
   Canada

   Phone: +1 514-452-2160
   Email: daniel.migault@ericsson.com









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   Robert Moskowitz
   HTT Consulting
   Oak Park, MI  48237
   USA

   Email: rgm@labs.htt-consult.com


   Nik Teague
   Verisign Inc
   12061 Bluemont Way
   Reston, VA  20190
   USA

   Phone: +44 791 763 5384
   Email: nteague@verisign.com


   Liang Xia
   Huawei
   No. 101, Software Avenue, Yuhuatai District
   Nanjing
   China

   Email: Frank.xialiang@huawei.com


























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