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Versions: (draft-vandevelde-idr-flowspec-path-redirect) 00 01 02

IDR Working Group                                   G. Van de Velde, Ed.
Internet-Draft                                                     Nokia
Intended status: Standards Track                                K. Patel
Expires: March 3, 2018                                            Arrcus
                                                                   Z. Li
                                                     Huawei Technologies
                                                         August 30, 2017


                    Flowspec Indirection-id Redirect
                draft-ietf-idr-flowspec-path-redirect-02

Abstract

   This document defines a new extended community known as flowspec
   redirect-to-indirection-id.  This extended community triggers
   advanced redirection capabilities to flowspec clients.  When
   activated, this flowspec extended community is used by a flowspec
   client to find the correct next-hop information within a localised
   indirection-id mapping table.

   The functionality detailed in this document allows a network
   controller to decouple the BGP flowspec redirection instruction from
   the actual redirection path selected.

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.

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

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 March 3, 2018.




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Copyright Notice

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   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   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 . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   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 onto an
   explicite path.

   Every flowspec policy route is effectively a rule, consisting of a
   matching part (encoded in the NLRI field) and an action part (encoded



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   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 explicitely defined traffic path.

   This draft proposes a new redirect-to-indirection-id flowspec action
   making use of a 32-bit indirection-id within a new extended
   community.  Each indirection-id serves as anchor point, for policy-
   based forwarding onto an explicite path on a flowspec client.

   A flowspec based indirection service plane can be create when a
   single 32-bit flowspec indirection-id maps towards a pool of
   explicite paths.

2.  indirection-id and indirection-id table

   The indirection-id is a 32-bit unsigned number, used as anchor point
   on a flowspec client.  The indirection-id is on a flowspec client the
   lookup key-value within a localised list of potential indirection
   paths.  The indirection-id will allow the flowspec client to steer
   traffic to a particular path or into an indirection service plane by
   doing a recursive key-value lookup.

   The indirection-id table is the table containing an ordered list of
   indirection-id key-values, ordered by indirection-id type; where each
   key-value maps towards a particular path or set of paths.  The
   indirection-id type MAY provide additional context about the
   indirection-id 32-bit value.  The flowspec client MUST use the
   indirection-id as key-value within the indirection-id type
   corresponding indirection-id table to locate the explicite path and
   corresponding next-hop information.

   The configuration of the indirection-id table on a flowspec client
   MAY happen out-of-band from BGP flowspec and is a localised construct
   on each router.  For some use-case scenarios the indirection-id type
   provides additional (maybe even fully sufficient) context towards a
   flowspec client to deduct automatic, without explicite out-of-band
   configuration, the indirection-id table.  For example, when the
   indirection-id refers to a segment routing node-id [6], then
   indirection-id type can provide the flowspec client the awareness
   that the indirection-id is a segment routing node-id.  For this
   example the indirection-id type allows the flowspec clients to do a
   recursive lookup using traditional segment routing technology.





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   To summarise, each indirection-id key-value entry in the indirection-
   table maps recursively to sufficient next-hop information (parameters
   regarding encapsulation, egress-interface, QoS, etc...) to
   successfully indirect 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

   Description:

   The first use-case describes an example where a single flowspec route
   is sent from a BGP flowspec controller to many BGP flowspec clients.
   This BGP flowspec route carries the redirect-to-indirection-id to all
   flowspec clients to redirect matching dataflows onto a shortest-path
   tunnel pointing towards a single remote destination.

   For this first use-case scenario, each flowspec client receives
   flowspec routes.  The flowspec routes have the extended redirect-to-
   indirection-id community attached.  Each redirect-to-indirection-id
   community embeds two relevant components: (1) 32-bit indirection-id
   key-value and (2) indirection-id type.  The indirection-id type is
   used to identify the corresponding indirection-id table, and the
   actual 32-bit indirection-id key-value is used within the
   indirection-id table to locate the corresponding next-hop
   information.  The finite result of this operation is sufficient
   tunnel encapsulation information to forward and encapsulate the data-
   packet accordingly to a remote tunnel end-point.

   Requirements:

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

   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.  This requires out-
      of-band configuration of the indirection-id table

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



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3.2.  Redirection to path-engineered tunnels

   Description:

   The second use-case describes an example where a single flowspec
   route is sent from a BGP flowspec controller to many BGP flowspec
   clients.  This BGP flowspec route carries the redirect-to-
   indirection-id extended community to all flowspec clients with
   instructions to redirect matching dataflows onto a path engineered
   tunnel.  It is expected that each of the path engineered tunnels is
   instantiated by out-of-band configuration and can be uniquely
   identified by the combination of (1) indirection-id 32-bit key-value
   and (2) indirection-id type.

   For this second use-case scenario, each flowspec client receives
   flowspec routes.  The flowspec routes have the extended redirect-to-
   indirection-id community attached.  Each redirect-to-indirection-id
   community embeds two relevant components similar as explained in
   previous use-case.  However the finite result of this operation is
   sufficient tunnel encapsulation information to forward and
   encapsulate the data-packet accordingly to a remote tunnel end-point
   using a path engineered tunnel construction.

   Segment Routing Example:

   For this example the indirection-id type informs the flowspec client
   that the indirection-id 32-bit key-value references a Segment Routing
   Binding SID.  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.  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
   unidirectional exchanged between tunnel head- and tail-end.

   Example: Indirection-ID community types to be used:



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   o  0 (localised ID): When the intent is to use a localised
      Indirection-id table on the flowspec client.  This requires out-
      of-band configuration of the indirection-id table.

   o  6 (Binding Segment ID): When the intent is to use a Segment
      Routing based Indirection-id table on the flowspec client.  This
      requires out-of-band configuration of the Binding Segment IDs.

3.3.  Redirection to complex dynamically constructed tunnels

   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 two 'redirect-to-
   indirection-id' communities attached, each tagged with a different
   Table-ID (TID).  A flowspec client may use the Table-ID (TID) to
   sequence the flowspec redirect information.  A common use-case
   scenario would for example be the dynamic construction of Segment
   Routing Central Egress Path Engineered tunnel [4] or next-next-hop
   tunnels.

   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 complex dynamic redirect
   tunnel construction, 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 Segment Routing labels.  A
   first MPLS Segment Routing label (the outer label) to steer the
   packet to the egress node (and hence use a shortest path tunnel),
   while a second MPLS label (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 are pushed upon a given flowspec policy



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   rule.  It is required that there is synchronisation established
   between the data-plane and control-plane of all relevant devices
   involved.  Each complex dynamically constructed tunnel MUST be
   operational and allow packets to be unidirectional exchanged between
   tunnel head- and tail-end before it can be used to redirect traffic.

   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 the TID (Table-ID) MUST be used to
      sequence multiple redirect-to-indirection-id actions to construct
      a more complex path engineered tunnel.  The order of sequencing
      the redirection information MUST be identified by using the TID
      field.

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.  On a flowspec client the indirection-id with lowest TID
   MUST be processed first for a flowspec route.

   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]
           6        Tunnel ID (Tunnel Binding 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,
              <https://www.rfc-editor.org/info/rfc5575>.

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.





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   [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.

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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