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      DOTS                                                      M. Chen
Internet-Draft                                                    Li. Su
Intended status: Informational                              China Mobile
Expires: September 10, 2020                                March 9, 2020


                  A method for dots server deployment
           draft-chen-dots-server-hierarchical-deployment-02

Abstract

   As DOTS is used for DDoS Mitigation signaling, in practice, there are
   different deployment scenarios for DOTS agents deployment depending
   on the network deployment mode.  This document made an recommandation
   for DOTS Server deployment, include ISP and enterprise deployment
   scenarios.  The goal is to provide some guidance for DOTS agents
   deployment.

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 10, 2020.

Copyright Notice

   Copyright (c) 2020 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
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   include Simplified BSD License text as described in Section 4.e of




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  DOTS server Considerations  . . . . . . . . . . . . . . . . .   3
   4.  DOTS server deployment inside an ISP  . . . . . . . . . . . .   4
     4.1.  DOTS Agents Deployment  . . . . . . . . . . . . . . . . .   4
     4.2.  DOTS Agents interfaces  . . . . . . . . . . . . . . . . .   6
       4.2.1.  Bandwidth consuming attack  . . . . . . . . . . . . .   7
       4.2.2.  Host resource consuming attack  . . . . . . . . . . .   7
   5.  DOTS server deployment between ISPs . . . . . . . . . . . . .   8
   6.  DOTS server deployment for Enterprise . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Acknowledgement . . . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   DDoS Open Threat Signaling (DOTS) is a protocol to standardize real-
   time signaling, threat-handling
   requests[I-D.ietf-dots-signal-channel], when attack target is under
   attack, dots client send mitigation request to dots server for help,
   If the mitigation request contains enough messages of the attack,
   then the mitigator can respond very effectively.

   In the architecture draft[I-D.ietf-dots-architecture], when comes to
   the deployment topic, it says this does not necessarily imply that
   the attack target and the DOTS client have to be co-located in the
   same administrative domain, but it is expected to be a common
   scenario.  Although co-location of DOTS server and mitigator within
   the same domain is expected to be a common deployment model, it is
   assumed that operators may require alternative models.

   In the DOTS server discovery draft[I-D.ietf-dots-server-discovery],
   it is says that a key point in the deployment of DOTS is the ability
   of network operators to be able to configure DOTS clients with the
   correct DOTS server(s) information consistently.

   In the DOTS multihoming draft[I-D.ietf-dots-multihoming], it provides
   deployment recommendations for DOTS client and DOTS gateway, it is
   says when conveying a mitigation request to protect the attack



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   target, the DOTS client among the DOTS servers available Must select
   a DOTS server whose network has assigned the prefixes from which
   target prefixes and target IP addresses are derived.  This implies
   that id no appropriate DOTS server is found, the DOTS client must not
   send the mitigation request to any DOTS server.  So in this document,
   we give some dots server deployment consideration as the title
   suggests we prefer hierarchical deployment.

   This is DOTS server deployment guidance for operators, We've written
   about our experience as an ISP, and we hope that other scenarios will
   contribute as well.

2.  Terminology

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

   The readers should be familiar with the terms defined in
   [I-D.ietf-dots-requirements] [I-D.ietf-dots-use-cases]

   The terminology related to YANG data modules is defined in [RFC7950]

   In addition, this document uses the terms defined below:

   dots svr:  abbreviation of dots server.

   ISP:  Internet service provider.

   Orchestrator:  With the function of DOTS server that can receive
      messages from clients and made decisions for mitigators selection.

   netflow/ipfix collector:  Flow collector used for DDoS attack
      detection.

3.  DOTS server Considerations

   When take dots server deployment into consideration, one thing must
   be involved is mitigator.  So far, how many network devices can play
   the role of mitigator, we make a summerized list as follows:

   o  Router.

   o  Special cleaning equipment, such as flow clean device and clean
      center.

   o  Network security equipment, such as firewall, IPS and WAF.



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   o  Servers that websites can hidden behind them.

   Whether DOTS server can be deployed, the following conditions need to
   be met:

   o  DOTS server and mitigator are in the same administrative domain.

   o  DOTS server can go directly to the mitigator which had best go
      through without any other DOTS agents.

   o  DOTS server has the permissions for scheduling on mitigators.

   o  DOTS server has the ability to know the address of attack target
      belong to which mitigator, if DOTS server hasn't matched attack
      target to mitigators, DOTS server need to configure default
      mitigators.

4.  DOTS server deployment inside an ISP

4.1.  DOTS Agents Deployment

   From the internal structure of ISP, the whole network can divide into
   backbone and metropolitan area networks logically.  There are two
   most important routers: backbone router, man(metropolitan area
   network) router.  It's worth noting that there are usually Internet
   Data Centers(IDC), high bandwidth demand customers(such as online
   game companies) and VIP customer centers(such as financial clients)
   distributed in metropolitan area networks.  When a ddos attack
   occurs, it must be one of the three cases as follows, and the
   corresponding mitigator will responsible for mitigation.

   o  DDoS attacks occur inside the LAN or the attack source inside
      metropolitan area network launched an attack against the target in
      local area network, the lan network detected the attack, dots
      server3 will receive mitigation request, and mitigator3 will act
      as the first responsible mitigator.

   o  DDoS attacks occur inside the MAN or the attack source inside
      backbone network launched an attack against the target in
      metropolitan area network, the man network detected the attack,
      dots server2 will receive mitigation request, then mitigator2 will
      act as the first responsible mitigator.

   o  DDoS attacks from other ISPs, the backbone network detected the
      attack, dots server1 will receive mitigation request, then
      mitigator1 will act as the first responsible mitigator.





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   If attacks on the same attack target are found both in adjacent
   areas, there are two strategies for the mitigators' selection, then
   found the best mitigation node for different scenes.

   o  Near Attack Source Mitigation(NASM), NASM means that the
      mitigation is performed closest to the source of the attack, this
      usually happens at the entrance to the edge of the network.  This
      approach can block attack flow at the source and protect network
      bandwidth maximumly, but requires the ability to operate the
      entire network.  This principle is more suitable for large-traffic
      attack mitigation.

   o  Near Attack Target Mitigation(NATM), NATM means that the
      mitigation is performed closest to the attack target, This is the
      easiest and most direct way, but it will cause the attack flow
      long-distance transmission, occupy the bandwidth along the link,
      more likely to cause link congestion.  This principle is more
      suitable for low-traffic attack mitigation.

   According to the NATM, the lower network mitigator will act as the
   first responsible mitigator. for example, dots server1 and dots
   server2 both received the mitigation request from attack target by
   dots client, mitigator2 will responsible for ddos
   disposition(priority ranking: mitigator3, mitigator2, mitigator1),
   but according to the NASM the priority will be reverse.

   Normally, The lower network the target in, the easier it is to alert.
   Because the higher network the attack target in, the greater the
   bandwidth of the pipeline.  As shown in the following figure,
   Orchestrator take on the role for scheduling.  Because the importance
   of the orchestrator, it is suggested to consider bakeup mechanisms or
   heartbeat technology to ensure continuity and security.

   How does DOTS client can find DOTS servers, we can reference the DOTS
   server discovery draft[I-D.ietf-dots-server-discovery], Static
   configuration or dynamic discovery depends on the actual scenario and
   the size of the network.














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   +----------+
   |other ISPs|
   +----------+
         |
   +-----------+
   |dots client|
   ======|==========================
         |    Backbone Network
   +---------------+     +----------+
   |backbone router|-----|mitigator1|
   +---------------+     +----------+
      |dots svr1|
      +---------+
   ........|........................
           |      MAN
     +----------+       +----------+
     |man router|-------|mitigator2|
     +----------+       +----------+
     |dots svr2|
     +---------+
   .......|........................
          |       LAN
   +----------+      +----------+
   |IDC router|------|mitigator3|
   +----------+      +----------+
   |dots svr3|
   +------------+
   |Orchestrator|
   +------------+
         |
   +-----------+    +--------------+   +-------------+
   |dots client|----|flow collector|---|attack target|
   +-----------+    +--------------+   +-------------+

   *MAN is for metropolitan area network
   *LAN is for local area network
   *flow collector is for netflow/ipfix collector


            Figure 1: hierarchical deployment for DOTS servers

4.2.  DOTS Agents interfaces

   In the dots use case draft[I-D.ietf-dots-use-cases], it is says the
   orchestrator analyses the various information it receives from DDoS
   telemetry system, and initiates one or multiple DDoS mitigation
   strategies.  In the telemetry draft, all the telemetry informations
   are contained and some parameters can be used to make decisions.



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   This section made a discussion on which attributes could be used in
   orchestrator for scheduling.

   We suggest orchestrator has three capabilities and reuse the method
   of registration and notification in signal channel to know all the
   related mitigators capability and residue capability:

   1.Can get the neflow/ipfix collector's telemetry informations.

   2.Can get the capabilities of each mitigator, it means the initial
   capacity, this means that with each addition of mitigator there needs
   to be a protocol that can push this information to orchestrator, we
   recommend using DOTS signal channel to transfer initial capacity.

   3.When mitigation finished, mitigator can inform orchestrator that
   mitigation is finished and capacity has been released, also we
   recommend using DOTS signal channel to transfer.

4.2.1.  Bandwidth consuming attack

   The following parameters will be required by orchestrator:

   o  top-talker

   o  source-prefix

   o  total-traffic

   o  total-attack-traffic

   o  total-pipe-capability

   The recommended approach here is to redirect traffic and flow
   cleaning.

4.2.2.  Host resource consuming attack

   The following parameters will be required by orchestrator:

   o  top-talker

   o  source-prefix

   The recommended approach here is to use router for disposition.







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5.  DOTS server deployment between ISPs

   Because of global connectivity, the coexistence of different
   operators is very common, coordination between operators across
   networks is very important.  Interdomain attacks occur frequently, We
   recommend deploying the DOTS server at the access point.

   o  DDoS attack from one of other ISPs, for example, ISP A received
      DDoS attack from ISP B or ISP C, then dots server C or dots server
      B will receive the mitigation request.

   o  DDoS attacks from two or more of other ISPs,for example, ISP A and
      ISP B both start ddos attack to ISP C, then dots server A and dots
      server B will both receive mitigation request from dots client C.

   +-------------+        +-------------+
   |    ISP A    |        |    ISP B    |
   | +---------+ |        | +---------+ |
   | |dots svrA| |        | |dots svrB| |
   +-------------+        +-------------+
                       |                           |
                       +-------+===========+-------+
                   |dots client|
                   +===========+
                       |
                       |
                +-------------+
                | |dots svrC| |
                | +---------+ |
                |    ISP C    |
                +-------------+


          Figure 2: DOTS Server Deployment between different ISPs

   It is obvious from the figure 2 that there is a super DOTS client in
   the middle, this also means that there will be corresponding netflow/
   ipfix collector on the link between different ISPs, the final
   location of the DOTS client according to the actual network topology.
   When an DDoS attack occurs, depending on the direction of the attack,
   the corresponding server is required for mitigation, DOTS server can
   use call home to find the source of the DDoS
   attacks[I-D.ietf-dots-signal-call-home]








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6.  DOTS server deployment for Enterprise

   In addition to operators taking advantage of the pipeline to make a
   contribution to DDoS attack mitigation, there are also enterprise-
   level DDoS attack mitigation solutions.  It's usually a cloud service
   and a large number of distributed nodes are deployed to protect their
   customers from DDoS attack, customers' websites can be hidden behind
   the nodes, usually the internet game companies and the live streaming
   company will choose this way.

               +-------------+
               |    ISP      |
               | +---------+ |
               | |dots svr | |
               +-------------+
                      |
                      |
               +-------------+
               | Anti-D Node |
               +-------------+
                |dots client|
                +-----------+
                      |
                      |
               +-------------+
               |attack target|
               +-------------+

         *Anti-D is for Anti-DDoS

          Figure 3: DOTS Server Deployment for Enterprise and ISP

   When enterprise-level anti-DDos nodes are unable to mitigate the DDoS
   attack, they can trigger DOTS client which integrated in the Anti-D
   Node to send mitigation request to ISP's DOTS server.

7.  Security Considerations

   TBD

8.  IANA Considerations

   TBD








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9.  Acknowledgement

   TBD

10.  References

10.1.  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,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

10.2.  Informative References

   [I-D.ietf-dots-architecture]
              Mortensen, A., Reddy.K, T., Andreasen, F., Teague, N., and
              R. Compton, "Distributed-Denial-of-Service Open Threat
              Signaling (DOTS) Architecture", draft-ietf-dots-
              architecture-15 (work in progress), March 2020.

   [I-D.ietf-dots-multihoming]
              Boucadair, M., Reddy.K, T., and W. Pan, "Multi-homing
              Deployment Considerations for Distributed-Denial-of-
              Service Open Threat Signaling (DOTS)", draft-ietf-dots-
              multihoming-03 (work in progress), January 2020.

   [I-D.ietf-dots-requirements]
              Mortensen, A., K, R., and R. Moskowitz, "Distributed
              Denial of Service (DDoS) Open Threat Signaling
              Requirements", draft-ietf-dots-requirements-22 (work in
              progress), March 2019.

   [I-D.ietf-dots-server-discovery]
              Boucadair, M. and T. Reddy.K, "Distributed-Denial-of-
              Service Open Threat Signaling (DOTS) Agent Discovery",
              draft-ietf-dots-server-discovery-10 (work in progress),
              February 2020.

   [I-D.ietf-dots-signal-call-home]
              Reddy.K, T., Boucadair, M., and J. Shallow, "Distributed
              Denial-of-Service Open Threat Signaling (DOTS) Signal
              Channel Call Home", draft-ietf-dots-signal-call-home-07
              (work in progress), November 2019.



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   [I-D.ietf-dots-signal-channel]
              Reddy.K, T., Boucadair, M., Patil, P., Mortensen, A., and
              N. Teague, "Distributed Denial-of-Service Open Threat
              Signaling (DOTS) Signal Channel Specification", draft-
              ietf-dots-signal-channel-41 (work in progress), January
              2020.

   [I-D.ietf-dots-use-cases]
              Dobbins, R., Migault, D., Moskowitz, R., Teague, N., Xia,
              L., and K. Nishizuka, "Use cases for DDoS Open Threat
              Signaling", draft-ietf-dots-use-cases-20 (work in
              progress), September 2019.

Authors' Addresses

   Meiling Chen
   China Mobile

               32, Xuanwumen West


               BeiJing
             ,
               BeiJing

               100053


               China


   Email:
             chenmeiling@chinamobile.com


















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   Li Su
   China Mobile

               32, Xuanwumen West


               BeiJing

               100053


               China


   Email:
             suli@chinamobile.com



































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