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Versions: (draft-vandevelde-idr-flowspec-path-redirect) 00 01

IDR Working Group                                   G. Van de Velde, Ed.
Internet-Draft                                                     Nokia
Intended status: Standards Track                                K. Patel
Expires: September 3, 2017                                        Arrcus
                                                                   Z. Li
                                                     Huawei Technologies
                                                           March 2, 2017


                    Flowspec Indirection-id Redirect
                draft-ietf-idr-flowspec-path-redirect-01

Abstract

   Flowspec is an extension to BGP that allows for the dissemination of
   traffic flow specification rules.  This has many possible
   applications but the primary one for many network operators is the
   distribution of traffic filtering actions for DDoS mitigation.  The
   flow-spec standard RFC5575 [2] defines a redirect-to-VRF action for
   policy-based forwarding but this mechanism is not always sufficient,
   particularly if the redirected traffic needs to be steered into an
   engineered path or into a service plane.

   This document defines a new extended community known as redirect-to-
   indirection-id (32-bit) flowspec action to provide advanced
   redirection capabilities on flowspec clients.  When activated, the
   flowspec extended community is used by a flowspec client to find the
   correct next-hop entry within a localised indirection-id mapping
   table.

   The functionality present in this draft allows a network controller
   to decouple flowspec functionality from the creation and maintainance
   of the network's service plane itself including the setup of tunnels
   and other service constructs that could be managed by other network
   devices.

Requirements Language

   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 [1].

Status of This Memo

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





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Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  indirection-id and indirection-id table . . . . . . . . . . .   3
   3.  Use Case Scenarios  . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Redirection shortest Path tunnel  . . . . . . . . . . . .   4
     3.2.  Redirection to path-engineered tunnels  . . . . . . . . .   5
     3.3.  Redirection to complex dynamically constructed tunnels  .   6
   4.  Redirect to indirection-id Community  . . . . . . . . . . . .   7
   5.  Redirect using localised indirection-id mapping table . . . .   8
   6.  Validation Procedures . . . . . . . . . . . . . . . . . . . .   9
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   9.  Contributor Addresses . . . . . . . . . . . . . . . . . . . .   9
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     11.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Appendix A.  Additional indirection_id types waiting for use-case
                description  . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13



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1.  Introduction

   Flowspec RFC5575 [2] is an extension to BGP that allows for the
   dissemination of traffic flow specification rules.  This has many
   possible applications, however the primary one for many network
   operators is the distribution of traffic filtering actions for DDoS
   mitigation.

   Every flowspec policy route is effectively a rule, consisting of a
   matching part (encoded in the NLRI field) and an action part (encoded
   in one or more BGP extended communities).  The flow-spec standard
   RFC5575 [2] defines widely-used filter actions such as discard and
   rate limit; it also defines a redirect-to-VRF action for policy-based
   forwarding.  Using the redirect-to-VRF action to steer traffic
   towards an alternate destination is useful for DDoS mitigation but
   using this technology can be cumbersome when there is need to steer
   the traffic onto an engineered traffic path.

   This draft proposes a new redirect-to-indirection-id flowspec action
   facilitating an anchor point for policy-based forwarding onto an
   engineered path or into a service plane.  The flowspec client
   consuming and utilizing the new flowspec indirection-id extended-
   community constructs the redirection information based upon
   information found within a localised indirection-id mapping table.
   The localised mapping table is a table construct, sequenced by a
   table key, providing next-hop information.

   The redirect-to-indirection-id flowspec action is encoded in a newly
   defined BGP extended community.  The type of redirection is
   identified as an extended community indirection-id type field.

   This draft defines the indirection-id extended-community and a few
   wellknown indirection-id types.  The specific mechanics to construct
   a localised indirection-id mapping table are out-of-scope of this
   document.

2.  indirection-id and indirection-id table

   An indirection-id is an abstract number (32-bit value) used as
   identifier for a localised indirection decision.  The indirection-id
   will allow a flowspec client to redirect traffic into a service plane
   or consequently onto an engineered traffic path.  For example, when a
   BGP flowspec controller signals a flowspec client the indirection-id
   extended community, then the flowspec client uses the indirection-id
   to make a recursive lookup to find the next-hop information.  The
   indirection-id is used to find the corresponding next-hop information
   within the localised indirection mapping table.




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   The indirection-id table is localised on the router.  The
   indirection-id table is constructed out of table keys, each mapped to
   localised redirection information.  Each table key is composed by the
   combining indirection-id type and an indirection-id 32-bit value.
   Each entry in the indirection-table key maps to sufficient
   information (parameters regarding encapsulation, egress-interface,
   QoS, etc...) to successfully redirect traffic according flowspec
   controller expectations.

3.  Use Case Scenarios

   This section describes use-case scenarios when deploying redirect-to-
   indirection-id.

3.1.  Redirection shortest Path tunnel

   Example: Indirection-ID community types to be used:

   o  0 (localised ID): When the intent is to use a localised
      Indirection-id table on the flowspec client

   o  1 (Node ID): When the intent is to use a Segment Routing based
      Indirection-id table on the flowspec client

   Description:

   The first use-case describes an example where a single flowspec route
   (i.e. flowspec_route#1) is sent by a flowspec controller to many BGP
   flowspec clients.  This single flowspec route will instruct all
   Flowspec clients to redirect matching dataflows onto a shortest-path
   tunnel pointing towards a single IP destination address.

   For this first use-case scenario, each flowspec client receives a
   flowspec route (flowspec_route#1) which has the redirect-to-
   indirection-id extended community attached.  The extended redirect-
   to-indirection-id community contains the table key consisting out of
   the indirection-id type and indirection-id 32-bit value.  The table
   key is used on the flowspec client to map to the corresponding next-
   hop information within the local indirection-id table.  The finite
   result of this operation is a remote tunnel end-point IP address
   together with accordingly sufficient tunnel encapsulation information
   to forward and encapsulate the data-packet accordingly.

   Requirements:

   For redirect to shortest path tunnel it is required that the tunnel
   MUST be operational and allow packets to be exchanged between tunnel
   head- and tail-end.



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3.2.  Redirection to path-engineered tunnels

   Example: Indirection-ID community types to be used:

   o  0 (localised ID): When the intent is to use a localised
      Indirection-id table on the flowspec client

   o  6 (Binding Segment ID): When the intent is to use a Segment
      Routing based Indirection-id table on the flowspec client

   Description:

   The second use-case describes an example where a flowspec controler
   injects a single flowspec route which gets distributed to many BGP
   flowspec clients.  This single flowspec route intends to instruct all
   Flowspec clients to redirect corresponding dataflows onto a path
   engineered tunnel.  It is expected that each of the path engineered
   tunnels is instantiated by out-of-band mechanisms.  Each used path
   engineered tunnel has a unque table key identifier. consequently, the
   table key uniquely identifies exactly -one- path engineered tunnel.

   In this use-case example, the flowspec controller sends a flowspec
   route to each of the flowspec clients and this flowspec route has a
   redirect-to-indirection-id extended community attached.  The
   redirect-to-indirection-id extended community embeds table key
   information and hence provides sufficient information to select the
   corresponding path-engineered tunnel to redirect the packet according
   the flowspec controller expectations.

   Segment Routing Example:

   A concrete embodiment of a Segment Routing use-case example is found
   in networks where path engineered tunnels are created by a Segment
   Routing MPLS label stack.  In such a deployment, the indirection-id
   provides an anchorpoint reference to a Segment Routing Binding SID.
   However, the indirection-id type provides a pointer to the Binding
   SID semantics to be used.  The Binding SID is a segment identifier
   value (as per segment routing definitions in [I-D.draft-ietf-spring-
   segment-routing] [6]) used to associate an explicit path.  The
   Binding SID and corresponding path engineered tunnel can for example
   be setup by a controller using BGP as specified in [I-D.sreekantiah-
   idr-segment-routing-te] [5] or by using PCEP as detailed in draft-
   ietf-pce-segment-routing [7].  To conclude, when a BGP speaker at
   some point in time receives a flow-spec route with an extended
   'redirect-to-indirection-id' community, it installs a traffic
   filtering rule that matches particular packets and redirects them
   onto an explicit path associated with the corresponding Binding SID.




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   The encoding of the Binding SID within the redirect-to-indirection-id
   extended community is specified in section 4.

   Requirements:

   For redirect to path engineered tunnels it is required that the
   engineered tunnel MUST be active and allow packets to be exchanged
   between tunnel head- and tail-end.

3.3.  Redirection to complex dynamically constructed tunnels

   Example: Indirection-ID community types to be used:

   o  0 (localised ID) with TID: When the intent is to use a localised
      Indirection-id table, then TID (Table-ID) field could be used to
      sequence multiple redirect-to-indirection-id actions together to
      construct a more complex path engineered tunnel.  The order of
      sequencing the redirection information may be identified by using
      the TID field.

   Description:

   A third use-case describes the application and redirection towards
   complex dynamically constructed tunnels.  For this use-case a BGP
   flowspec controller injects a flowspec route with multiple 'redirect-
   to-indirection-id' communities attached.  A recipient flowspec client
   may use the Table-ID (TID) field embedded within each 'redirect-to-
   indirection-id' community to sequence the redirect information.  The
   complex dynamically constructed tunnel is the product of
   concatenating the available redirect information (i.e.  MPLS Segment
   Routing Labels).

   Segment Routing Example:

   i.e. a classic Segment Routing example using complex tunnels is found
   in DDoS mitigation and traffic offload.  Suspicious traffic (e.g.
   dirty traffic flows) may be steered into a Segment Routing Central
   Egress Path Engineered tunnel [4].  For this particular complex
   dynamic redirect tunnel embodiment, a first redirect-to-indirection-
   id (i.e.  TID=0) is used to redirect traffic into a tunnel towards a
   particlar egress router, while a second redirect-to-indirection-id
   (i.e.  TID=1) is used to steer traffic beyond the particular egress
   router towards a pre-identified interface/peer.

   For this DDoS use-case, in its simplest embodiment, the flowspec
   client must dynamically append 2 MPLS labels.  A first MPLS label
   (the outer label) to steer the original packet to the egress node
   (and hence using a shortest path tunnel), while a second MPLS label



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   (matching redirect-to-indirection-id with TID=1), the inner label, to
   steer on the egress router the original packet to a pre-defined
   interface/peer.  The basic data-plane principles are documented by
   [4].

   Requirements:

   To achieve redirection towards complex dynamically constructed
   tunnels, for each flowspec route, multiple indirection-ids, each
   using a unique Tunnel ID may imposed upon a given flowspec policy
   rule.  It is required that there is synchronisation established
   between the data- and control-plane of all relevant devices involved.
   Each complex dynamically constructed tunnel MUST be operational and
   allow packets to be exchanged between tunnel head- and tail-end
   before it should be used to redirect traffic.

4.  Redirect to indirection-id Community

   This document defines a new BGP extended community known as a
   Redirect-to-indirection-id extended community.  This extended
   community is a new transitive extended community with the Type and
   the Sub-Type field to be assigned by IANA.  The format of this
   extended community is show in Figure 1.


      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type          | Sub-Type      | Flags(1 octet)| Indirection ID|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Generalized indirection_id                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                                 Figure 1

   The meaning of the extended community fields are as follows:

   Type: 1 octet to be assigned by IANA.

   Sub-Type: 1 octet to be assigned by IANA.

   Flags: 1 octet field.  Following Flags are defined.








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                              0             1
                              0 1 2 3 4 5 6 7
                             +-+-+-+-+-+-+-+-+
                             | RES |  TID  |C|
                             +-+-+-+-+-+-+-+-+


                                 Figure 2

   The least-significant Flag bit is defined as the 'C' (or copy) bit.
   When the 'C' bit is set the redirection applies to copies of the
   matching packets and not to the original traffic stream.

   The 'TID' field identifies a 4 bit Table-id field.  This field is
   used to provide the flowspec client an indication how and where to
   sequence the received indirection-ids to redirecting traffic.  TID
   value 0 indicates that Table-id field is NOT set and SHOULD be
   ignored.

   All bits other than the 'C' and 'TID' bits MUST be set to 0 by the
   originating BGP speaker and ignored by receiving BGP speakers.

   Indirection ID: 1 octet value.  This draft defines following
   indirection_id Types:

      0 - Localised ID (The flowspec client uses the received
      indirection-id to lookup the redirection information in the
      localised indirection-id table.)

      1 - Node ID (The flowspec client uses the received indirection-id
      as a Segment Routing Node ID to redirect traffic towards)

      6 - Binding Segment ID (The flowspec client uses the received
      indirection-id as a Segment Routing Binding Segment ID to redirect
      traffic towards) [I-D.draft-ietf-spring-segment-routing] [6]

5.  Redirect using localised indirection-id mapping table

   When a BGP flowspec client receives a flowspec policy route with a
   'redirect to indirection-id' extended community attached and the
   route represents the best BGP path, it will install a flowspec
   traffic filtering rule matching the IP tupples described by the
   flowpsec NLRI field and consequently redirects the flow (C=0) or
   copies the flow (C=1) using the information identified by the
   'redirect-to-indirection-id' community.






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6.  Validation Procedures

   The validation check described in RFC5575 [2] and revised in [3]
   SHOULD be applied by default to received flow-spec routes with a
   'redirect to indirection-id' extended community.  This means that a
   flow-spec route with a destination prefix subcomponent SHOULD NOT be
   accepted from an EBGP peer unless that peer also advertised the best
   path for the matching unicast route.

   While it MUST NOT happen, and is seen as invallid combination, it is
   possible from a semenatics perspective to have multiple clashing
   redirect actions defined within a single flowspec rule.  For best and
   consistant RFC5575 flowspec redirect behavior the redirect as
   documented by RFC5575 MUST not be broken, and hence when a clash
   occurs, then RFC5575 based redirect SHOULD take priority.
   Additionally, if the 'redirect to indirection-id' does not result in
   a valid redirection, then the flowspec rule must be processed as if
   the 'redirect to indirection-id' community was not attached to the
   flowspec route and MUST provide an indication within the BGP routing
   table that the respective 'redirect to indirection-id' resulted in an
   invalid redirection action.

7.  Security Considerations

   A system using 'redirect-to-indirection-id' extended community can
   cause during the redirect mitigation of a DDoS attack result in
   overflow of traffic received by the mitigation infrastructure.

8.  Acknowledgements

   This document received valuable comments and input from IDR working
   group including Adam Simpson, Mustapha Aissaoui, Jan Mertens, Robert
   Raszuk, Jeff Haas, Susan Hares and Lucy Yong.

9.  Contributor Addresses

   Below is a list of other contributing authors in alphabetical order:














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   Arjun Sreekantiah
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: asreekan@cisco.com

   Nan Wu
   Huawei Technologies
   Huawei Bld., No. 156 Beiquing Rd
   Beijing  100095
   China

   Email: eric.wu@huawei.com

   Shunwan Zhuang
   Huawei Technologies
   Huawei Bld., No. 156 Beiquing Rd
   Beijing  100095
   China

   Email: zhuangshunwan@huawei.com

   Wim Henderickx
   Nokia
   Antwerp
   BE

   Email: wim.henderickx@nokia.com




                                 Figure 3

10.  IANA Considerations

   This document requests a new type and sub-type for the Redirect to
   indirection-id Extended community from the "Transitive Extended
   community" registry.  The Type name shall be "Redirect to
   indirection-id Extended Community" and the Sub-type name shall be
   'Flow-spec Redirect to 32-bit Path-id'.

   In addition, this document requests IANA to create a new registry for
   Redirect to indirection-id Extended Community INDIRECTION-IDs as
   follows:




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   Under "Transitive Extended Community:"

   Registry: "Redirect Extended Community indirection_id"

   Reference: [RFC-To-Be]

   Registration Procedure(s): First Come, First Served

   Registry: "Redirect Extended Community indirection_id"


           Value    Code                              Reference

           0        Localised ID                      [RFC-To-Be]
           1        Node ID                           [RFC-To-Be]
           2        Agency ID                         [RFC-To-Be]
           3        AS (Autonomous System) ID         [RFC-To-Be]
           4        Anycast ID                        [RFC-To-Be]
           5        Multicast ID                      [RFC-To-Be]
           6        Tunnel ID (Tunnel Binding ID )    [RFC-To-Be]
           7        VPN ID                            [RFC-To-Be]
           8        OAM ID                            [RFC-To-Be]
           9        ECMP (Equal Cost Multi-Path) ID   [RFC-To-Be]
           10       QoS ID                            [RFC-To-Be]
           11       Bandwidth-Guarantee ID            [RFC-To-Be]
           12       Security ID                       [RFC-To-Be]
           13       Multi-Topology ID                 [RFC-To-Be]


                                 Figure 4

11.  References

11.1.  Normative References

   [1]        Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997,
              <http://xml.resource.org/public/rfc/html/rfc2119.html>.

   [2]        Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
              and D. McPherson, "Dissemination of Flow Specification
              Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009,
              <http://www.rfc-editor.org/info/rfc5575>.








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11.2.  Informative References

   [3]        Uttaro, J., Filsfils, C., Alcaide, J., and P. Mohapatra,
              "Revised Validation Procedure for BGP Flow
              Specifications", January 2014.

   [4]        Filsfils, C., Previdi, S., Aries, E., Ginsburg, D., and D.
              Afanasiev, "Segment Routing Centralized Egress Peer
              Engineering", October 2015.

   [5]        Sreekantiah, A., Filsfils, C., Previdi, S., Sivabalan, S.,
              Mattes, P., and S. Lin, "Segment Routing Traffic
              Engineering Policy using BGP", October 2015.

   [6]        Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
              Shakir, R., Bashandy, A., Horneffer, M., Henderickx, W.,
              Tantsura, J., Crabbe, E., Milojevic, I., and S. Ytti,
              "Segment Routing Architecture", December 2015.

   [7]        Sivabalan, S., Medved, M., Filsfils, C., Litkowski, S.,
              Raszuk, R., Bashandy, A., Lopez, V., Tantsura, J.,
              Henderickx, W., Hardwick, J., Milojevic, I., and S. Ytti,
              "PCEP Extensions for Segment Routing", December 2015.

Appendix A.  Additional indirection_id types waiting for use-case
             description

   This section is a placeholder and collection of potential additional
   indirection_id types.  The current use-cases do not require these
   particular indirection types, however at later stage when use-cases
   are identified they may be added to the body of teh draft.

   2 - Agency ID (The flowspec client uses the received indirection-id
   as a Segment Routing Agency ID to redirect traffic towards)

   3 - AS (Autonomous System) ID (The flowspec client uses the received
   indirection-id as a Segment Routing Autonomous System ID to redirect
   traffic towards)

   4 - Anycast ID (The flowspec client uses the received indirection-id
   as a Segment Routing Anycast ID to redirect traffic towards)

   5 - Multicast ID (The flowspec client uses the received indirection-
   id as a Segment Routing Multicast ID to redirect traffic towards)

   7 - VPN ID (The flowspec client uses the received indirection-id as a
   Segment Routing VPN ID to redirect traffic towards)




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   8 - OAM ID (The flowspec client uses the received indirection-id as a
   Segment Routing OAM ID to redirect traffic towards)

   9 - ECMP (Equal Cost Multi-Path) ID (The flowspec client uses the
   received indirection-id as a Segment Routing PeerSet ID to redirect
   traffic towards)

   10 - QoS ID (The flowspec client uses the received indirection-id as
   a Segment Routing QoS ID to redirect traffic towards)

   11 - Bandwidth-Guarantee ID (The flowspec client uses the received
   indirection-id as a Segment Routing Bandwidth-Guarantee ID to
   redirect traffic towards)

   12 - Security ID (The flowspec client uses the received indirection-
   id as a Segment Routing Security ID to redirect traffic towards)

   13 - Multi-Topology ID (The flowspec client uses the received
   indirection-id as a Segment Routing Multi-Topology ID to redirect
   traffic towards)

Authors' Addresses

   Gunter Van de Velde (editor)
   Nokia
   Antwerp
   BE

   Email: gunter.van_de_velde@nokia.com


   Keyur Patel
   Arrcus
   USA

   Email: keyur@arrcus.com


   Zhenbin Li
   Huawei Technologies
   Huawei Bld., No. 156 Beiquing Rd
   Beijing  100095
   China

   Email: lizhenbin@huawei.com






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