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BGP Flow Specification Version 2 - IP Basic
draft-hares-idr-fsv2-ip-basic-00

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This is an older version of an Internet-Draft whose latest revision state is "Active".
Authors Susan Hares , Donald E. Eastlake 3rd , Chaitanya Yadlapalli , Sven Maduschke
Last updated 2024-04-17
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draft-hares-idr-fsv2-ip-basic-00
IDR Working Group                                               S. Hares
Internet-Draft                                   Hickory Hill Consulting
Intended status: Standards Track                             D. Eastlake
Expires: 19 October 2024                          Futurewei Technologies
                                                           C. Yadlapalli
                                                                     ATT
                                                             S. Maduscke
                                                                 Verizon
                                                           17 April 2024

              BGP Flow Specification Version 2 - IP Basic
                    draft-hares-idr-fsv2-ip-basic-00

Abstract

   BGP flow specification version 1 (FSv1), defined in RFC 8955, RFC
   8956, and RFC 9117 describes the distribution of traffic filter
   policy (traffic filters and actions) distributed via BGP.  During the
   deployment of BGP FSv1 a number of issues were detected, so version 2
   of the BGP flow specification (FSv2) protocol addresses these
   features.  In order to provide a clear demarcation between FSv1 and
   FSv2, a different NLRI encapsulates FSv2.

   IDR requires two implementations prior to standardization.
   Implementers feedback on FSv2 was that the complete FSv2 has the
   contains the correct information, but that breaking FSv2 into a
   progression of documents would be helpful.  The first priority in
   this progression is expanded IP DDOS capabilities.  This document
   contains original FSv2 IP DDOS capabilities in FlowSpec v2 using just
   the extended communities to define actions.

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 https://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 19 October 2024.

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Copyright Notice

   Copyright (c) 2024 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 (https://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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Why Flow Specification v2 . . . . . . . . . . . . . . . .   3
     1.2.  Definitions and Acronyms  . . . . . . . . . . . . . . . .   5
     1.3.  RFC 2119 language . . . . . . . . . . . . . . . . . . . .   6
   2.  Flow Specification Version 2 Primer . . . . . . . . . . . . .   6
     2.1.  Flow Specification v1 (FSv1) Overview . . . . . . . . . .   7
     2.2.  Flow Specification v2 (FSv2) Overview . . . . . . . . . .   9
     2.3.  Flow Specification v2 (FSv2) Series of Specifications . .  12
   3.  FSv2 Filters and Actions  . . . . . . . . . . . . . . . . . .  13
     3.1.  Basic IP Filters  . . . . . . . . . . . . . . . . . . . .  15
       3.1.1.  IP header SubTLV (type=1(0x01)) . . . . . . . . . . .  15
       3.1.2.  FS Filter Error handling (type=250(0xFA)) . . . . . .  23
     3.2.  Encoding of FSV2 Actions for Basic DDOS . . . . . . . . .  24
       3.2.1.  FSV2 Basic DDOS Actions . . . . . . . . . . . . . . .  25
       3.2.2.  Summary of all FSv2 Actions (informative only)  . . .  29
   4.  Validation and Ordering . . . . . . . . . . . . . . . . . . .  30
     4.1.  Validation of FSv2 NLRI . . . . . . . . . . . . . . . . .  30
       4.1.1.  Validation of FS NLRI (FSv1 or FSv2)  . . . . . . . .  31
       4.1.2.  Validation of Flow Specification Actions  . . . . . .  33
       4.1.3.  Error handling and Validation . . . . . . . . . . . .  33
     4.2.  Ordering for Flow Specification v2 (FSv2) . . . . . . . .  34
       4.2.1.  Ordering of FSv2 NLRI Filters . . . . . . . . . . . .  34
       4.2.2.  Ordering of the Actions . . . . . . . . . . . . . . .  36
     4.3.  Ordering of FS filters for BGP Peers support FSv1 and
           FSv2  . . . . . . . . . . . . . . . . . . . . . . . . . .  40
   5.  Scalability and Aspirations for FSv2  . . . . . . . . . . . .  42
   6.  Optional Security Additions . . . . . . . . . . . . . . . . .  43
     6.1.  BGP FSv2 and BGPSEC . . . . . . . . . . . . . . . . . . .  43
     6.2.  BGP FSv2 with ROA . . . . . . . . . . . . . . . . . . . .  44
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  44
     7.1.  Flow Specification V2 SAFIs . . . . . . . . . . . . . . .  44
     7.2.  BGP Capability Code . . . . . . . . . . . . . . . . . . .  45

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     7.3.  Filter IP Component types . . . . . . . . . . . . . . . .  45
     7.4.  FSV2 NLRI TLV Types . . . . . . . . . . . . . . . . . . .  46
     7.5.  Wide Community Assignments  . . . . . . . . . . . . . . .  47
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  48
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  48
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  48
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  51
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  52

1.  Introduction

   Version 2 of BGP flow specification was original defined in
   [I-D.ietf-idr-flowspec-v2] (denoted FSv2).  However, the full FSv2
   specification contains more than initial implementers desired.
   Therefore, the original FSv2 draft will remain a WG draft, but the
   content will be split out into functions that implementers can
   manage.

   This draft provides the FSv2 specification for DDOS for IP filtering
   using Extended communities with the following action features:

   *  Minimal ordering of actions (4 actions)

   *  Failure instructions (continue or stop)

   This flowspecification will be denoted as FSv2-DDOS.  As

   BGP FSv1 as defined in [RFC8955], [RFC8956], and [RFC9117] specified
   2 SAFIs (133, 134) to be used with IPv4 AFI (AFI = 1) and IPv6 AFI
   (AFI=2).

   This document specifies 2 new SAFIs (TBD1, TBD2) for FSv2 to be used
   with 5 AFIs (1, 2, 6, 25, and 31) to allow user-ordered lists of
   traffic match filters for user-ordered traffic match actions encoded
   in Communities (Wide or Extended).

   FSv1 and FSv2 use different AFI/SAFIs to send flow specification
   filters.  Since BGP route selection is performed per AFI/SAFI, this
   approach can be termed “ships in the night” based on AFI/SAFI.

1.1.  Why Flow Specification v2

   Modern IP routers have the capability to forward traffic and to
   classify, shape, rate limit, filter, or redirect packets based on
   administratively defined policies.  These traffic policy mechanisms
   allow the operator to define match rules that operate on multiple
   fields within header of an IP data packet.  The traffic policy allows
   actions to be taken upon a match to be associated with each match

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   rule.  These rules can be more widely defined as “event-condition-
   action” (ECA) rules where the event is always the reception of a
   packet.

   BGP ([RFC4271]) flow specification as defined by [RFC8955],
   [RFC8956], [RFC9117] specifies the distribution of traffic filter
   policy (traffic filters and actions) via BGP to a mesh of BGP peers
   (IBGP and EBGP peers).  The traffic filter policy is applied when
   packets are received on a router with the flow specification function
   turned on.  The flow specification protocol defined in [RFC8955],
   [RFC8956], and [RFC9117] will be called BGP flow specification
   version 1 (BGP FSv1) in this draft.

   Some modern IP routers also include the abilities of firewalls which
   can match on a sequence of packet events based on administrative
   policy.  These firewall capabilities allow for user ordering of match
   rules and user ordering of actions per match.

   Multiple deployed applications currently use BGP FSv1 to distribute
   traffic filter policy.  These applications include: 1) mitigation of
   Denial of Service (DoS), 2) traffic filtering in BGP/MPLS VPNS, and
   3) centralized traffic control for networks utilizing SDN control of
   router firewall functions, 4) classifiers for insertion in an SFC,
   and 5) filters for SRv6 (segment routing v6).

   During the deployment of BGP flow specification v1, the following
   issues were detected:

   *  lack of consistent TLV encoding prevented extension of encodings,

   *  inability to allow user defined order for filtering rules,

   *  inability to order actions to provide deterministic interactions
      or to allow users to define order for actions, and

   *  no clearly defined mechanisms for BGP peers which do not support
      flow specification v1.

   Networks currently cope with some of these issues by limiting the
   type of traffic filter policy sent in BGP.  Current Networks do not
   have a good workaround/solution for applications that receive but do
   not understand FSv1 policies.

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   FSv1 is a critical component of deployed applications.  Therefore,
   this specification defines how FSv2 will interact with BGP peers that
   support either FSv2, FSv1, FSv2 and FSv1,or neither of them.  It is
   expected that a transition to FSv2 will occur over time as new
   applications require FSv2 extensibility and user-defined ordering for
   rules and actions or network operators tire of the restrictions of
   FSv1 such as error handling issues and restricted topologies.

   Section 2 contains the definition of Flow specification, a short
   review of FSv1 and an overview of FSv2.  Section 3 contains the
   encoding rules for FSv2 and user-based encoding sent via BGP.
   Section 4 describes how to validate FSv2 NLRI.  Section 5 discusses
   how to order FSV2 rules.  Section 6 covers combining FSv2 user-
   ordered match rules and FSv1 rules.  Section 6 also discusses how to
   combine user-ordered actions, FSv1 actions, and default actions.
   Sections 7-10 address an alternate security mechanism, considerations
   for IANA, security in deployments, and scalability aspirations.

1.2.  Definitions and Acronyms

      AFI - Address Family Identifier

      AS - Autonomous System

      BGPSEC - secure BGP [RFC8205] updated by [RFC8206]

      BGP Session ephemeral state - state which does not survive the
      loss of BGP peer session.

      Configuration state - state which persist across a reboot of
      software module within a routing system or a reboot of a hardware
      routing device.

      DDOs - Distributed Denial of Service.

      Ephemeral state - state which does not survive the reboot of a
      software module, or a hardware reboot.  Ephemeral state can be
      ephemeral configuration state or operational state.

      FSv1 - Flow Specification version 1 [RFC8955] [RFC8956]

      FSv2 - Flow Specification version 2 (this document)

      NETCONF - The Network Configuration Protocol [RFC6241].

      RESTCONF - The RESTCONF configuration Protocol [RFC8040]

      RIB - Routing Information Base.

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      ROA - Route Origin Authentication [RFC6482]

      RR - Route Reflector.

      SAFI – Subsequent Address Family Identifier

1.3.  RFC 2119 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 BCP 14 [RFC2119]
   [RFC8174] when, and only when, they appear in all capitals as shown
   here.

2.  Flow Specification Version 2 Primer

   A BGP Flow Specification (v1 or v2) is an n-tuple containing one or
   more match criteria that can be applied to IP traffic, traffic
   encapsulated in IP traffic or traffic associated with IP traffic.
   The following are examples of such traffic: IP packet or an IP packet
   inside a L2 packet (Ethernet), an MPLS packet, and SFC flow.

   A given Flow Specification NLRI may be associated with a set of path
   attributes depending on the particular application, and attributes
   within that set may or may not include reachability information
   (e.g., NEXT_HOP).  FSv1 and FSv2-DDOS use only the Extended Community
   to encode a set of pre-determined actions.  The full FSv2 uses either
   Extended Communities or Wide Communities to encode actions.

   A particular application is identified by a specific AFI/SAFI
   (Address Family Identifier/Subsequent Address Family Identifier) and
   corresponds to a distinct set of RIBs.  Those RIBs should be treated
   independently of each other in order to assure noninterference
   between distinct applications.

   BGP processing treats the NLRI as a key to entries in AFI/SAFI BGP
   databases.  Entries that are placed in the Loc-RIB are then
   associated with a given set of semantics which are application
   dependent.  Standard BGP mechanisms such as update filtering by NLRI
   or by attributes such as AS_PATH or large communities apply to the
   BGP Flow Specification defined NLRI-types.

   Network operators can control the propagation of BGP routes by
   enabling or disabling the exchange of routes for a particular AFI/
   SAFI pair on a particular peering session.  As such, the Flow
   Specification may be distributed to only a portion of the BGP
   infrastructure.

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2.1.  Flow Specification v1 (FSv1) Overview

   The FSv1 NLRI defined in [RFC8955] and [RFC8956] include 13 match
   conditions encoded for the following AFI/SAFIs:

   *  IPv4 traffic: AFI:1, SAFI:133

   *  IPv6 Traffic: AFI:2, SAFI:133

   *  BGP/MPLS IPv4 VPN: AFI:1, SAFI: 134

   *  BGP/MPLS IPv6 VPN: AFI:2, SAFI: 134

   If one considers the reception of the packet as an event, then BGP
   FSv1 describes a set of Event-MatchCondition-Action (ECA) policies
   where:

   *  event is the reception of a packet,

   *  condition stands for “match conditions” defined in the BGP NLRI as
      an n-tuple of component filters, and

   *  the action is either: the default condition (accept traffic), or a
      set of actions (1 or more) defined in Extended BGP Community
      values [RFC4360].

   The flow specification conditions and actions combine to make up FSv1
   specification rules.  Each FSv1 NLRI must have a type 1 component
   (destination prefix).  Extended Communities with FSv1 actions can be
   attached to a single NLRI or multiple NLRIs in a BGP message

   Within an AFI/SAFI pair, FSv1 rules are ordered based on the
   components in the packet (types 1-13) ordered from left-most to
   right-most and within the component types by value of the component.
   Rules are inserted in the rule list by component-based order where an
   FSv1 rule with existing component type has higher precedence than one
   missing a specific component type,

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   Since FSv1 specifications ([RFC8955], [RFC8956], and [RFC9117])
   specify that the FSv1 NLRI MUST have a destination prefix (as
   component type 1) embedded in the flow specification, the FSv1 rules
   with destination components are ordered by IP Prefix comparison rules
   for IPv4 ([RFC8955]) and IPv6 ([RFC8956]).  [RFC8955] specifies that
   more specific prefixes (aka longest match) have higher precedence
   than that of less specific prefixes and that for prefixes of the same
   length the lower IP number is selected (lowest IP value).  [RFC8955]
   specifies that if the offsets within component 1 are the same, then
   the longest match and lowest IP comparison rules from [RFC8955]
   apply.  If the offsets are different, then the lower offset has
   precedence.

   These rules provide a set of FSv1 rules ordered by IP Destination
   Prefix by longest match and lowest IP address.  [RFC8955] also states
   that the requirement for a destination prefix component “MAY be
   relaxed by explicit configuration” Since the rule insertions are
   based on comparing component types between two rules in order, this
   means the rules without destination prefixes are inserted after all
   rules which contain destination prefix component.

   The actions specified in FSv1 are:

   *  accept packet (default),

   *  traffic flow limitation by bytes (0x6),

   *  traffic-action (0x7),

   *  redirect traffic (0x8),

   *  mark traffic (0x9), and

   *  traffic flow limitation by packets (12, 0xC)

   Figure 1 shows a diagram of the FSv1 logical data structures with 5
   rules.  If FSv1 rules have destination prefix components (type=1) and
   FSv1 rule 5 does not have a destination prefix, then FSv1 rule 5 will
   be inserted in the policy after rules 1-4.

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        +--------------------------------------+
        | Flow Specification (FS)              |
        |  Policy                              |
        +--------------------------------------+
            ^               ^              ^
            |               |              |
            |               |              |
   +--------^----+  +-------^-------+     +-------------+
   |   FS Rule 1 |  |   FS Rule 2   | ... |  FS rule 5  |
   +-------------+  +---------------+     +-------------+
                       :          :
                       :          :
                    ...:          :........
                    :                     :
          +---------V---------+      +----V-------------+
          |  Rule Condition   |      |   Rule Action    |
          |  in BGP NLRIs     |      | in BGP extended  |
          | AFIs: 1 and 2     |      | Communities      |
          | SAFI 133, 134     |      |                  |
          +-------------------+      +------------------+
              :     :    :                 :      :    :
         .....:     .    :.....       .....:      .    :.....
         :          :         :       :           :         :
    +----V---+  +---V----+ +--V---+ +-V------+ +--V-----++--V---+
    |  Match |  | match  | |match | | Action | | action ||action|
    |Operator|  |Variable| |Value | |Operator| |variable|| Value|
    |*1      |  |        | |      | |(subtype| |        ||      |
    +--------+  +--------+ +------+ +--------+ +--------++------+

      *1 match operator may be complex.

      Figure 2-1: BGP Flow Specification v1 Policy

2.2.  Flow Specification v2 (FSv2) Overview

   Flow Specification v2 allows the user to order the flow specification
   rules and the actions associated with a rule.  Each FSv2 rule may
   have one or more match conditions and one or more associated actions.
   The IDR WG draft [I-D.ietf-idr-flowspec-v2] contains the complete
   solution for FSv2.  However, this complete solution makes
   implementation of these features a large task so, please see the next
   section on how the complete solution is broken into a series of
   solutions.  This section describres the complete solution.

   This FSv2 specification supports the components and actions for the
   following:

   *  IPv4 (AFI=1, SAFI=TBD1) [defined in FSv2-DDOS],

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   *  IPv6 (AFI=2, SAFI=TBD2) [defined in FSv2-DDOS],

   *  L2 (AFI=6, SAFI=TDB1) [defined in FSv2-L2],

   *  BGP/MPLS IPv4 VPN: (AFI=1, SAFI=TBD2),

   *  BGP/MPLS IPv6 VPN: (AFI=2, SAFI=TBD2),

   *  BGP/MPLS L2VPN (AFI=25, SAFI=TDB2) [defined in FSv2-L2],

   *  SFC: (AFI=31, SAFI=TBD1) [defined in FSv2-SFC], and

   *  SFC VPN (AFI=31, SAFI=TBD2) [defined in FSv2-SFC].

   The FSv2 specification for tunnel traffic is outside the scope of
   this specification.  The FSv1 specification for tunneled traffic is
   in [I-D.ietf-idr-flowspec-nvo3].  The FSv2 tunnel traffic will be
   defined in [FSv2-Tunnel].

   FSv2 operates in the ships-in-the night model with FSv1 so network
   operators can manipulate which the distribution of FSv2 and FSv1
   using configuration parameters.  Since the lack of deterministic
   ordering was an FSv1 problem, this specification provides rules and
   protocol features to keep filters in a deterministic order between
   FSv1 and FSv2.

   The basic principles regarding ordering of flow specification filter
   rules are:

      1) Rule-0 (zero) is defined to be 0/0 with the “permit-all”
      action.

      2) FSv2 rules are ordered based on user-specified order.

      -  The user-specified order is carried in the FSv2 NLRI and a
         numerical lower value takes precedence over a numerically
         higher value.  For rules received with the same order value,
         the FSv1 rules apply (order by component type and then by value
         of the components).

      3) FSv2 rules are added starting with Rule 1 and FSv1 rules are
      added after FSv2 rules

      -  For example, BGP Peer A has FSv2 data base with 10 FSv2 rules
         (1-10).  FSv1 user number is configured to start at 301 so 10
         FSv1 rules are added at 301-310.

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      4) An FSv2 peer may receive BGP NLRI routes from a FSv1 peer or a
      BGP peer that does not support FSv1 or FSv2.  The capabilities
      sent by a BGP peer indicate whether the AFI/SAFI can be received
      (FSv1 NLRI or FSv2 NLRI).

      5) Associate a chain of actions to rules based on user-defined
      action number (1-n).  (optional)

      -  If no actions are associated with a filter rule, the default is
         to drop traffic the filter rules match

      -  An action chain of 1-n actions can be associated with a set of
         filter rules can via Extended Communities or Wide Communities.
         Only Wide Communities can associate a user-defined order for
         the actions.  Extended Community actions occur after actions
         with a user specified order (see section 5.2 for details).

   Figure 2-2 provides a logical diagram of the FSv2 structure

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          +--------------------------------+
          |          Rule Group            |
          +--------------------------------+
            ^          ^                  ^
            |          |---------         |
            |                   |         ------
            |                   |               |
   +--------^-------+   +-------^-----+     +---^-----+
   |      Rule1     |   |     Rule2   | ... |  Rule-n |
   +----------------+   +-------------+     +---------+
                         :  :   :    :
       :.................:  :   :    :
       :          |.........:   :    :
    +--V--+    +--V--+          :    :
    | name|    |order| .........:    :.....
    +-----+    +-----+ :                  :
                       :                  :
      +----------------V----+  +-----V----------------+
      |Rule Match condition |  | Rule Action          |
      +---------------------+  +----------------------+
       :      :     :    :       :      :   :   :   |
    +--V--+   :     :    :    +--V---+  :   :   :   V
    | Rule|   :     :    :    |action|  :   :   :  +-----------+
    | name|   :     :    :    |order |  :   :   :  |action name|
    +-----+   :     :    :    +------+  :   :   :  +-----------+
              :     :    :              :   :   :.............
              :     :    :              :   :                :
         .....:     .    :.....       ..:   :......          :
         :          :         :       :           :          :
    +----V---+  +---V----+ +--V---+ +-V------+ +--V-----+ +--V---+
    |  Match |  | match  | |match | | Action | | action | |action|
    |Operator|  |variable| |Value | |Operator| |Variable| | Value|
    +--------+  +--------+ +------+ +--------+ +--------+ +------+

      Figure 2-2: BGP FSv2 Data storage

2.3.  Flow Specification v2 (FSv2) Series of Specifications

   The full FSV2 information is contained in [I-D.ietf-idr-flowspec-v2]

   Feedback from the implementers indicate that the Flow Specification
   v2 needs to broken into drafts based on the use cases the technology
   supports.  These include IPv4/IPv6 DDOS, IPv4/IPv6 filters beyond
   DDOS, BGP/MPLS IPv4 VPN, BGP/MPLS IPv6 VPN, BGP/MPLS L2VPN, Segment
   routing (SRMPLS, SRv6), SFC, SFC VPN, and tunnel.

   The following is the list of planned drafts:

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   FSv2 IP DDOS (FSv2 IP DDOS):  The first draft will support IP filter
      functions (Type 1) and Extended Community actions supported by
      [RFC8955] and [RFC8956] with additions to provide the following:

      *  user ordering of IP filters

      *  new filter for filtering of unknown FSv2 types and filters
         (type = 250)

      *  no support for user ordering of actions

      *  a new action (Action Chain Operation) for handling failures
         when multiple actions are associated with a set of filters.

      This draft provides the basic functions all other FSv2 drafts will
      extend.

   FSv2 IP Extensions (FSv2 IP DDOS Extra):  This draft provides
      extensions for proposed filters for IP FSv2.

   FSv2 Non-IP (FSv2 Non-IP):  This draft provides Non-IP Filters
      filters for BGP/MPLS IPv4 VPNS, BGP/MPLS IPv6 VPNs, Segment
      Routing (SRMPLS and SRV6).

   FSv2 L2VPN:  [I-D.ietf-idr-flowspec-l2vpn] provides user ordered
      filters for L2VPNs.

   FSv2 Additional Extended Community Actions (FSv2 EC Actions Extra)
   :  This draft provides additional Flow Specification Actions that can
      be implemented safely with action chain failures, but without user
      ordering.

   FSv2 Wide Community Actions in Type 1 (FSv2 Wide Action T1):  This
      draft provides the Wide Community actions in the Type 1 format of
      Wide communities.

   FSv2 Wide Community Actions in Type 2 (FSv2 Wide Action T2):  This
      draft provides Wide Community actions in the type 2 format of Wide
      communities.

3.  FSv2 Filters and Actions

   The BGP FSv2 uses an NRLI with the format for AFIs for IPv4 (AFI =
   1), IPv6 (AFI = 2), L2 (AFI = 6), L2VPN (AFI=25), and SFC (AFI=31)
   with SAFIs TBD1 and TBD2 to support transmission of the flow
   specification which supports user ordering of traffic filters and
   actions for IP traffic and IP VPN traffic.

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   This NLRI information is encoded using MP_REACH_NLRI and
   MP_UNREACH_NLRI attributes defined in [RFC4760].  When advertising
   FSv2 NLRI, the length of the Next-Hop Network Address MUST be set to
   0.  Upon reception, the Network Address in the Next-Hop field MUST be
   ignored.

   Implementations wishing to exchange flow specification rules MUST use
   BGP's Capability Advertisement facility to exchange the Multiprotocol
   Extension Capability Code (Code 1) as defined in [RFC4760], and
   indicate a capability for FSv1, FSv2 (Code TBD3), or both.

   The AFI/SAFI NLRI for BGP Flow Specification version 2 (FSv2) has the
   format:

    +-------------------------------+
    |length (2 octets)              |
    +-------------------------------+
    | Sub-TLVs (variable)           |
    | +===========================+ |
    | | order (4 octets)          | |
    | +---------------------------+ |
    | | identifier (4 octets)     | |
    | +---------------------------+ |
    | | type (2 octets)           | |
    | +---------------------------+ |
    | | length-Subtlv (2 octets)  | |
    | +---------------------------+ |
    | | value (variable)          | |
    | +===========================+ |
    +-------------------------------+

    Figure 3-1: FSv2 format

   where:

   *  length: length of field including all SubTLVs in octets.

      -  The combined lengths of any FSv2 NLRI in the MP_REACH_NLRI or
         MP_UNREACH_NLRI.  The BGP NLRI length must be less than the
         packet size minus the other fields (BGP header, BGP Path
         Attributes, and NLRI).

   *  order: flow-specification global rule order number (4 octets).

   *  identifier: identifier for the rule (used for NM/Logging) (4
      octets)

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   *  type: contains a type for FSv2 TLV format of the NRLI (2 octets)
      which can be:

      -  0 - reserved,

      -  1 - IP Traffic Rules

      -  2 - Extended IP rules

      -  3- L2 traffic rules

      -  4- SFC Traffic rules

      -  5- SFC VPN Traffic rules

      -  6 - BGP/MPLS VPN IP Traffic Rules

      -  7 - BGP/MPLS VPN L2 Traffic Rules

      -  8 - Tunneled traffic

   *  length-Subtlv: is the length of the value part of the Sub-TLV,

   *  value: value depends on the subTLV (see sections below).

   The FSv2 Basic DDOS function must recognize that the defined types
   are valid even if the implementation does not support anything except

3.1.  Basic IP Filters

3.1.1.  IP header SubTLV (type=1(0x01))

   The format of the IP header TLV value field is shown in figure 3-2.
   The IP header for the VPN case is specified in section 3.5.

       +-------------------------------+
       | +--------------------------+  |
       | | (subTLVs)+               |  |
       | +==========================+  |
       +-------------------------------+

         Figure 3-2 - IP Header TLV

   Where: Each SubTLV has the format:

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       +-------------------------------+
       |  SubTLV type (1 octet)        |
       +-------------------------------+
       |  length (1 octet)             |
       + ------------------------------+
       |  value (variable)             |
       +-------------------------------+
        Figure 3-3 – IP header SubTLV format

   Where:

      SubTLV type: component values are defined in the “Flow
      Specification Component types” registry for IPv4 and IPv6 by
      [RFC8955], [RFC8956], and [I-D.ietf-idr-flowspec-srv6]

      length: length of SubTLV (varies depending on SubTLV type).

      value: dependent on the subTLV

      -  For descriptions of value portions for components 1-13 see
         [RFC8955] and [RFC8956].  For component 14 see
         [I-D.ietf-idr-flowspec-srv6].

   Many of the components use the operators [numeric_op] and
   [bitmask_op] defined in [RFC8955]

   The list of valid SubTLV types appears in Table 2.

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   Table 2 IP SubTLV Types for IP Filters
           DDOS support
   SubTLV
   -type     Definition
   ======    ============
      1 -    IP Destination prefix
      2 -    IP Source prefix
      3 –    IPv4 Protocol /
             IPv6 Upper Layer Protocol
      4 –    Port
      5 –    Destination Port
      6 –    Source Port
      7 –    ICMPv4 type / ICMPv6 type
      8 –    ICMPv4 code / ICPv6 code
      9 –    TCP Flags
     10 –    Packet length
     11 –    DSCP
     12 –    Fragment
     13 –    Flow Label
     14 -    TTL
     15-63   reserved for IP Extensions
             (standards action)

   Table 2b IP SubTLV types for non-IP Filters
   SubTLV   IP SubTLV types
   -type    Definition
   ======   ===========
     64      Parts of SID
     65      MPLS LAbel Match-1
     66      MPLS Label Match-2
     67-127  Match reserved for Non-IP
     128-191 reserved (standards action)
     192-249 FCFS
     250-    FSv2 Filter Error handling
    251-255  Reserved

   Ordering within the TLV in FSv2: The transmission of SubTLVs within a
   flow specification rule MUST be sent ascending order by SubTLV type.
   If the SubTLV types are the same, then the value fields are compared
   using mechanisms defined in [RFC8955] and [RFC8956] and MUST be in
   ascending order.  NLRIs having TLVs which do not follow the above
   ordering rules MUST be considered as malformed by a BGP FSv2
   propagator.  This rule prevents any ambiguities that arise from the
   multiple copies of the same NLRI from multiple BGP FSv2 propagators.
   A BGP implementation SHOULD treat such malformed NLRIs as "Treat-as-
   withdraw" [RFC7606].

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   See [RFC8955], [RFC8956], and [I-D.ietf-idr-flowspec-srv6]. for
   specific details.

3.1.1.1.  IP Destination Prefix (type = 1)

   IPv4 Name: IP Destination Prefix (reference: [RFC8955])

   IPv6 Name: IPv6 Destination Prefix (reference: [RFC8956])

   IPv4 length: Prefix length in bits

   IPv4 value: IPv4 Prefix (variable length)

   IPv6 length: length of value

   IPv6 value: [offset (1 octet)] [pattern (variable)]
   [padding(variable)]

   If IPv6 length = 0 and offset = 0, then component matches every
   address.  Otherwise, length must be offset "less than" length "less
   than" 129 or component is malformed.

3.1.1.2.  IP Source Prefix (type = 2)

   IPv4 Name: IP Source Prefix (reference: [RFC8955])

   IPv6 Name: IPv6 Source Prefix (reference: [RFC8956])

   IPv4 length: Prefix length in bits

   IPv4 value: Source IPv4 Prefix (variable length)

   IPv6 length: length of value

   IPv6 value: [offset (1 octet)] [pattern
   (variable)][padding(variable)]

   If IPv6 length = 0 and offset = 0, then component matches every
   address.  Otherwise, length must be offset < length < 129 or
   component is malformed.

3.1.1.3.  IP Protocol (type = 3)

   IPv4 Name: IP Protocol IP Source Prefix (reference: [RFC8955])

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   IPv6 Name: IPv6 Upper-Layer Protocol: (reference: [RFC8956])

   IPv4 length: variable

   IPv4 value: [numeric_op, value]+

   IPv6 length: variable

   IPv6 value: [numeric_op, value}+

   where the value following each numeric_op is a single octet.

3.1.1.4.  Port (type = 4)

   IPv4/IPv6 Name: Port (reference: [RFC8955]), [RFC8956])

   Filter defines: a set of port values to match either destination port
   or source port.

   IPv4 length: variable

   IPv4 value: [numeric_op, value]+

   IPv6 length: variable

   IPv6 value: [numeric_op, value]+

   where the value following each numeric_op is a single octet.

   Note-1: (from FSV1) In the presence of the port component
   (destination or source port), only a TCP (port 6) or UDP (port 17)
   packet can match the entire flow specification.  If the packet is
   fragmented and this is not the first fragment, then the system may
   not be able to find the header.  At this point, the FSv2 filter may
   fail to detect the correct flow.  Similarly, if other IP options or
   the encapsulating security payload (ESP) is present, then the node
   may not be able to describe the transport header and the FSv2 filter
   may fail to detect the flow.

   The restriction in note-1 comes from the inheritance of the FSv1
   filter component for port.  If better resolution is desired, a new
   FSv2 filter should be defined.

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   Note-2: FSv2 component only matches the first upper layer protocol
   value.

3.1.1.5.  Destination Port (type = 5)

   IPv4/IPv6 Name: Destination Port (reference: [RFC8955]), [RFC8956])

   Filter defines: a list of match filters for destination port for TCP
   or UDP within a received packet

   Length: variable

   Component Value format: [numeric_op, value]+

3.1.1.6.  Source Port (type = 6)

   IPv4/IPv6 Name: Source Port (reference: [RFC8955]), [RFC8956])

   Filter defines: a list of match filters for source port for TCP or
   UDP within a received packet

   IPv4/IPv6 length: variable

   IPv4/Ipv6 value: [numeric_op, value]+

3.1.1.7.  ICMP Type (type = 7)

   IPv4: ICMP Type (reference: [RFC8955])

   Filter defines: Defines: a list of match criteria for ICMPv4 type

   IPv6: ICMPv6 Type (reference: [RFC8956])

   Filter defines: a list of match criteria for ICMPv6 type.

   IPv4/IPv6 length: variable

   IPv4/IPv6 value: [numeric_op, value]+

3.1.1.8.  ICMP Code (type = 8)

   IPv4: ICMP Type (reference: [RFC8955])

   Filter defines: a list of match criteria for ICMPv4 code.

   IPv6: ICMPv6 Type (reference: [RFC8956])

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   Filter defines: a list of match criteria for ICMPv6 code.

   IPv4/IPv6 length: variable

   IPv4/IPv6 value: [numeric_op, value]+

3.1.1.9.  TCP Flags (type = 9)

   IPv4/IPv6: TCP Flags Code (reference: [RFC8955])

   Filter defines: a list of match criteria for TCP Control bits

   IPv4/IPv6 length: variable

   IPv4/IPv6 value: [bitmask_op, value]+

   Note: a 2 octets bitmask match is always used for TCP-Flags

3.1.1.10.  Packet length (type = 10 (0x0A))

   IPv4/IPv6: Packet Length (reference: [RFC8955], [RFC8956])

   Filter defines: a list of match criteria for length of packet
   (excluding L2 header but including IP header).

   IPv4/IPv6 length: variable

   IPv4/IPv6 value: [numeric_op, value]+

   Note:[RFC8955] uses either 1 or 2 octet values.

3.1.1.11.  DSCP (Differentiaed Services Code Point)(type = 11 (0x0B))

   IPv4/IPv6: DSCP Code (reference: [RFC8955], [RFC8956])

   Filter defines: a list of match criteria for DSCP code values to
   match the 6-bit DSCP field.

   IPv4/IPv6 length: variable

   IPv4/IPv6 value: [numeric_op, value]+

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   Note: This component uses the Numeric Operator (numeric_op) described
   in [RFC8955] in section 4.2.1.1.  Type 11 component values MUST be
   encoded as single octet (numeric_op len=00).

   The six least significant bits contain the DSCP value.  All other
   bits SHOULD be treated as 0.

3.1.1.12.  Fragment (type = 12 (0x0C))

   IPv4/IPv6: Fragment (reference: [RFC8955], [RFC8956])

   Filter defines: a list of match criteria for specific IP fragments.

   Length: variable

   Component Value format: [bitmask_op, value]+

   Bitmask values are:

         0    1   2   3   4   5   6  7
       +---+---+---+---+---+---+---+---+
       | 0 | 0 | 0 | 0 |LF |FF |IsF| DF|
       +---+---+---+---+---+---+---+---+
                    Figure 3-4

   Where:

      DF (don’t fragment): match If IP header flags bit 1 (DF) is 1.

      IsF(is a fragment other than first: match if IP header fragment
      offset is not 0.

      FF (First Fragment): Match if [RFC0791] IP Header Fragment offset
      is zero and Flags Bit-2 (MF) is 1.

      LF (last Fragment): Match if [RFC7091] IP header Fragment is not 0
      And Flags bit-2 (MF) is 0

      0: MUST be sent in NLRI encoding as 0, and MUST be ignored during
      reception.

3.1.1.13.  Flow Label(type = 13 (0xOD))

   IPv4/IPv6: Fragment (reference: [RFC8956])

   Filter defines: a list of match criteria for 20-bit Flow Label in the
   IPv6 header field.

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   Length: variable

   Component Value format: [numeric_op, value]+

3.1.1.14.  TTL (type=14 (0x0E))

   TTL: Defines matches for 8-bit TTL field in IP header

   Encoding: <[numeric_op, value]+>

   where: value is a 1 octet value for TTL.

   ordering: by full value of number_op concatenated with value

   conflict: none

   reference: draft-bergeon-flowspec-ttl-match-00.txt

3.1.2.  FS Filter Error handling (type=250(0xFA))

   Editor note: This filters FSv2 information.  Is it useful?  If not,
   it can be moved to the non-IP section.

   Type Filter Error handling(0xFA)  Function: This function suggests additional for unknown types
         and missing fields in the FSv2 NLRI

         reference: none

         Encoding: <type(1 octet), length(1 octet), T-Err (1 octet),
         (M-Err (1 octet)

         It contains a set of {operator, value} pairs that are used for
         the matching filter.

         T-Err - specifies handling of unknown type.  The values for
         this type are:

            Disable AFI/SAFI

            Treat as withdrawl

            Ignore MPREACH_NLRI attribute

            Ignore filter component (Sub-TLV)

         M-Error - specifies the handling of a missing field with values
         of: (TBD).

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          0   1   2   3   4   5   6   7   8       9      10  11  12  13  14  15
    +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
    |            T-Err              |  M-error                      |
    +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
                 Figure 3-8b

3.2.  Encoding of FSV2 Actions for Basic DDOS

   The long-term goal of the FSv2 actions is to allow user ordering of
   the flow specification actions.  Only Wide Communities provide enough
   structured space for user ordering of actions.  The IDR WG draft
   [I-D.ietf-idr-flowspec-v2] contains the long-term plan for FSv2
   filters with actions.  To provide an easy migration between FSv1 and
   FSv2, a sequence of drafts will break allow adding of additional
   actions to the basic IP DDOS actions in the Extended Community.

   The Basic IP DDOS FSv2 will support existing IPv4 from [RFC8955], and
   existing IPv6 actions from [RFC8956] and one additional feature for
   action chain ordering (ACO).

   An action chain for FSv2 Extended Community actions is defined as a
   series of Extended Communities which are attached to a set of
   filters.

   The action chain ordering (ACO)action provides a set of flags that
   define a clear action if failure occurs.  One of the issues with FSv1
   is the lack of a clear definition on what happens if multiple actions
   interact.  The existance of the Action chain ordering action enforces
   that the actions will have a deterministic outcome during failures.

   The AC-Failure types are:

   *  0x00 – default – stop on failure

   *  0x01 – continue on failure (best effort on actions)

   *  0x02 – conditional stop on failure (depends on AC-Failure-value/
      policy)

   *  0x03 – rollback do all or nothing (depends on AC-Failure-value/
      policy)

   Editors note: The following options for encoding ACO exist.

   Option 1:  redefine bits in Traffic Action subtype

   Option 2:  create a new Extended Community

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3.2.1.  FSV2 Basic DDOS Actions

3.2.1.1.  Encoding FSv2 Actions in IPv4 Extended Communities

   The Extended Community encodes the Flow Specification actions in the
   Extended Community format as generic transitive extended communities
   per [RFC4360] per [RFC8955], [RFC9117], and [RFC9184].

   The format of the these actions can be:

   Generic Transitive Extended Community (0x80):  where the Sub-Types
      are defined in the Generic Transitive Extended Community Sub-Types
      registry.

   Generic Transitive Extended Community Part 2(0x81):  where the Sub-
      Types are defined in the Generic Transitive Extended Community
      Part 2 Sub-Types registry.

   Transitive Four-Octet AS-Specific Extended Communit(0x82):  where the
      Sub-Types defined in the Generic Transitive Extended Community
      Part 3 Sub-Types registry.

   Generic Transitive Extended Community Part 3 (0x83):  where the Sub-
      Types defined in the Transitive Opaque Extended Community Sub-
      Types" registry.

     0                   1                   2                   3
     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 high    |  Type low(*)  |                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+          Value (6 octets)     |
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3-9

                                   Table x-x

   IPv4 Extended Communities (Type 0x80) 2 byte AS,
   Value   Description                    Name  Reference
   =====   =======================        ===== ==========
   0x01    Flow Spec Action Chain         ACO   [This document]
   0x06    Flow spec traffic-rate-byte    TRB   [RFC8955]
   0x07    Flow spec traffic-action       TAIS  [RFC8955]
   0x08    Flow spec rt-redirect          RDIP  [RFC8955]
           AS-2 octet format
   0x09    Flow spec traffic-remarking        TM    [RFC8955]
   0x0C    Flow Spec Traffic-rate-packets TRP   [RFC8955]

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                                   Table x-x

   IPv4 Extended Communities FSv2 action (Type 0x81)
   Value   Description                    Name  Reference
   =====   =======================        ===== ==========
   0x08    Flow spec rt-redirect          RDIP  [RFC8955]
           IPv4 octet format                        [this document]

                                   Table x-x
   IPv4 Extended Communities (Type 0x82)
   Value   Description                  Name  Reference
   =====   =======================      ====  ==========
   0x08    Flow spec rt-redirect        RDIP  [RFC8955]
           AS-4 octet format

3.2.1.2.  Encoding FSv2 Actions in IPv6 Extended Community

   The IPv6 Extended Community encodes the Flow Specification actions in
   the Extended Community format [RFC5701] per [RFC8956], [RFC9117], and
   [RFC9184] in the transitive opaque format.

     0                   1                   2                   3
     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     |   Global Administrator        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
    |         Global Administrator (cont.)                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Global Administrator (cont.)                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Global Administrator (cont.)                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Global Administrator (cont.)  |   Local Administrator         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  figure 3-10

   The 20 octets of value are given in the following format:

   Type = 0x00 (transitive)
   Sub-Type = see table x-x

   Global Administrator: IPv6 address assigned by Internet Registry
   Local Administrator:  2 bytes of

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   Table x-x

   IPv6 Extended Communities (Type 1)
   Value   Description                  Name   Reference
   =====   =======================      =====  ==========
   0x01    Flow Spec Action Chain       ACO    [This document]
   0x0C    Flow Spec redirect-v6-flag   RD6F   [ID-redirect-IP]
   0x0D    Flow Spec rt-redirect        RD6    [RFC8956]
           IPv6 format

3.2.1.3.  New Actions for FSv2 DDOS

   There are two options for encoding the Action chain.

3.2.1.3.1.  Option 1: Action Chain operation IPv4 Extended (ACO)(1,
            0x01)

      0                   1                   2                   3
     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 high    |  Type low(01) |AC-failure-type|  AC-Failure   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          AC-Failure-value (cont.)                             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   SubTLV: 0x01

   Length: 6 octets

   Value:

      AC-dependence - 1 octet byte of flag regarding dependency

      AC-failure-type – 1 octet byte that determines the action on
      failure

      AC-failure-value – variable depending on AC-failure-type.

   Actions may succeed or fail and an Action chain must deal with it.
   The default value stored for an action chain that does not have this
   action chain is “stop on failure”.

   where:

      AC-Failure types are:

      -  0x00 – default – stop on failure

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      -  0x01 – continue on failure (best effort on actions)

      -  0x02 – conditional stop on failure – depending on AC-Failure-
         value

      -  0x03 – rollback – do all or nothing - depending in AC-Failure-
         value

      AC-Failure values: TBD

   Interactions with other actions: Interactions with all other Actions

   Ordering within Action type: By AC-Failure type

3.2.1.3.2.  Option 2: Action Chain operation encoded in IPv4 Traffic
            Action (0x07)

      0                   1                   2                   3
     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 high    |  Type low(07) |traffic action field  (zero)   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          AC-Failure-value (cont.)                   | ACO |S|T|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Where
    ACO - is the Action Chain failure types (0x00 to 0x03)
          00 - stop on failure
              01 - continue on failure
              02 - conditional stop on failure (by policy)
              03 - rollback on failure (with policy)
    S - Sample flag
    T - Terminal action

3.2.1.4.  Interactions between FSv2 DDOS actions

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    Table 5 – All FSv2 IPv4 Action types for IP DDOS

    Action  Name  Description             May Interacts
    ======  ====  ======================  ===============
      01    ACO   Action Chain Operation  none
      06    TRB   Traffic Rate limited    TRP
                   by Bytes
      07    TA    Traffic Action          none
                  (terminal/sample/ACO)
      08    RDIP  Redirect IPv4           none
      09    TM    Mark DSCP value         none
      12    TRP   Traffic Rate limited    TRB
                   by Packets

             Figure 3-15

    Table 5 – All FSv2 IPv6 Action types for IP DDOS

    Action  Name  Description             May Interacts
    ======  ====  ======================  ===============
      01    ACO   Action Chain Operation  none
      06    TRB   Traffic Rate limited    TRP
                   by Bytes
      07    TA    Traffic Action          none
                  (terminal/sample/ACO)
      08    RDIP  Redirect IPv4           none
      09    TM    Mark DSCP value         none
      12    TRP   Traffic Rate limited    TRB
                   by Packets

             Figure 3-15

3.2.2.  Summary of all FSv2 Actions (informative only)

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    Table 4  All IP Actions in Extended Communities
    Action   Name Description
    ======   ===========
      00     reserved
      01     ACO:  action chain operation
      02     reserved
      03     TAIS: traffic actions per interface group
      04     LkBW: Link bandwidth
             (draft-ietf-idr-linkbandwidth-07) [non-transitive]
                     [juniper link bandwidth] [transitive]

      06     TRB:  traffic rate limited by bytes
      07     TA: traffic action (terminal/sample)
      08     RDIP: Redirect IPv4
      09     TM: mark DSCP value
      10     TBA (to be assigned)
      11     TBA (to be assigned)
      12     TRP: traffic rate limited by packets
      13     TISFC: SFC Classifier
      14     RDIID: redirect to Indirection-id (move from 0x00)

      31     TISFC: SFC classifier II (this document)
      32     MPLSLA: MPLS label action
      33     VLAN: VLAN-Action (0x16)[draft-ietf-idr-flowspec-l2vpn-17]
      34     TPID: TPID-Action (0x17)[draft-ietf-idr-flowspec-l2vpn-17]
      24-254 TBA (to be assigned)
      255    reserved

             Figure 3-15

     IPv6 Extended Communities (Type 1)
   Value   Description                  Name   Reference
   =====   =======================      =====  ==========
   0x01    Flow Spec Action Chain       ACO    [This document]
   0x0C    Flow Spec redirect-v6-flag   RD6F   [ID-redirect-IP]
   0x0D    Flow Spec rt-redirect        RD6    [RFC8956]
           IPv6 format

4.  Validation and Ordering

4.1.  Validation of FSv2 NLRI

   The validation of FSv2 NLRI adheres to the combination of rules for
   general BGP FSv1 NLRI found in [RFC8955], [RFC8956], [RFC9117], and
   the specific additions made for SFC NLRI [RFC9015], and L2VPN NLRI
   [I-D.ietf-idr-flowspec-l2vpn].

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   To provide clarity, the full validation process for flow
   specification routes (FSv1 or FSv2) is described in this section
   rather than simply referring to the relevant portions of these RFCs.
   Validation only occurs after BGP UPDATE message reception and the
   FSv2 NLRI and the path attributes relating to FSv2 (Extended
   community and Wide Community) have been determined to be well-formed.
   Any MALFORMED FSv2 NRLI is handled as a “TREAT as WITHDRAW”
   [RFC7606].

4.1.1.  Validation of FS NLRI (FSv1 or FSv2)

   Flow specifications received from a BGP peer that are accepted in the
   respective Adj-RIB-In are used as input to the route selection
   process.  Although the forwarding attributes of the two routes for
   tbe same prefix may be the same, BGP is still required to perform its
   path selection algorithm in order to select the correct set of
   attributes to advertise.

   The first step of the BGP Route selection procedure (section 9.1.2 of
   [RFC4271] is to exclude from the selection procedure routes that are
   considered unfeasible.  In the context of IP routing information,
   this is used to validate that the NEXT_HOP Attribute of a given route
   is resolvable.

   The concept can be extended in the case of the Flow Specification
   NLRI to allow other validation procedures.

   The FSv2 validation process validates the FSv2 NLRI with following
   unicast routes received over the same AFI (1 or 2) but different
   SAFIs:

   *  Flow specification routes (FSv1 or FSv2) received over SAFI=133
      will be validated against SAFI=1,

   *  Flow Specification routes (FSv1 or FSv2) received over SAFI=134
      will be validated against SAFI=128, and

   *  Flow Specification routes (FSv1 or FSv2) [AFI =1, 2] received over
      SAFI=77 will be validated using only the Outer Flow Spec against
      SAFI = 133.

   The FSv2 validates L2 FSv2 NLRI with the following L2 routes received
   over the same AFI (25), but a different SAFI:

   *  Flow specification routes (FSv1 or FSv2)received over SAFI=135 are
      validated against SAFI=128.

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   In the absence of explicit configuration, a Flow specification NLRI
   (FSv1 or FSv2) MUST be validated such that it is considered feasible
   if and only if all of the conditions are true:

      a) A destination prefix component is embedded in the Flow
      Specification,

      b) One of the following conditions holds true:

      -  1.  The originator of the Flow Specification matches the
         originator of the best-math unicast route for the destination
         prefix embedded in the flow specification (this is the unicast
         route with the longest possible prefix length covering the
         destination prefix embedded in the flow specification).

      -  2.  The AS_PATH attribute of the flow specification is empty or
         contains only an AS_CONFED_SEQUENCE segment [RFC5065].

         o  2a.This condition should be enabled by default.

         o  2b.This condition may be disabled by explicit configuration
            on a BGP Speaker,

         o  2c.As an extension to this rule, a given non-empty AS_PATH
            (besides AS_CONFED_SEQUENCE segments) MAY be permitted by
            policy].

      c) There are no “more-specific” unicast routes when compared with
      the flow destination prefix that have been received from a
      different neighbor AS than the best-match unicast route, which has
      been determined in rule b.

   However, part of rule a may be relaxed by explicit configuration,
   permitting Flow Specifications that include no destination prefix
   component.  If such is the case, rules b and c are moot and MUST be
   disregarded.

   By “originator” of a BGP route, we mean either the address of the
   originator in the ORIGINATOR_ID Attribute [RFC4456] or the source
   address of the BGP peer, if this path attribute is not present.

   A BGP implementation MUST enforce that the AS in the left-most
   position of the AS_PATH attribute of a Flow Specification Route (FSv1
   or FSv2) received via the Exterior Border Gateway Protocol (eBGP)
   matches the AS in the left-most position of the AS_PATH attribute of
   the best-match unicast route for the destination prefix embedded in
   the Flow Specification (FSv1 or FSv2) NLRI.

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   The best-match unicast route may change over time independently of
   the Flow Specification NLRI (FSv1 or FSv2).  Therefore, a
   revalidation of the Flow Specification MUST be performed whenever
   unicast routes change.  Revalidation is defined as retesting rules a
   to c as described above.

4.1.2.  Validation of Flow Specification Actions

   Flow Specifications may be mapped to actions using Extended
   Communities or a Wide Communities.  The FSv2 actions in Extended
   Communities and Wide communities can be associated with large number
   of NLRIs.

   The ordering of precedence for these actions in the case when the
   user-defined order is the same follows the precedence of the FSv2
   NLRI action TLV values (lowest to highest).  User-defined order is
   the same when the order value for action is the same.  All Extended
   Community actions MUST be translated to the user-defined order data
   format for internal comparison.  By default, all Extended Community
   actions SHOULD be translated to a single value.

   Actions may conflict, duplicate, or complement other actions.  An
   example of conflict is the packet rate limiting by byte and by
   packet.  An example of a duplicate is the request to copy or sample a
   packet under one of the redirect functions (RDIPv4, RDIPv6, RDIID, )
   Each FSv2 actions in this document defines the potential conflicts or
   duplications.  Specifications for new FSv2 actions outside of this
   specification MUST specify interactions or conflicts with any FSv2
   actions (that appear in this specification or subsequent
   specifications).

   Well-formed syntactically correct actions should be linked to a
   filtering rule in the order the actions should be taken.  If one
   action in the ordered list fails, the default procedure is for the
   action process for this rule to stop and flag the error via system
   management.  By explicit configuration, the action processing may
   continue after errors.

   Implementations MAY wish to log the actions taken by FS actions (FSv1
   or FSv2).

4.1.3.  Error handling and Validation

   The following two error handling rules must be followed by all BGP
   speakers which support FSv2:

   *  FSv2 NLRI having TLVs which do not have the correct lengths or
      syntax must be considered MALFORMED.

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   *  FSv2 NLRIs having TLVs which do not follow the above ordering
      rules described in section 4.1 MUST be considered as malformed by
      a BGP FSv2 propagator.

   The above two rules prevent any ambiguity that arises from the
   multiple copies of the same NLRI from multiple BGP FSv2 propagators.

   A BGP implementation SHOULD treat such malformed NLRIs as ‘Treat-as-
   withdraw’ [RFC7606]

   An implementation for a BGP speaker supporting both FSv1 and FSv2
   MUST support the error handling for both FSv1 and FSv2.

4.2.  Ordering for Flow Specification v2 (FSv2)

   Flow Specification v2 allows the user to order flow specification
   rules and the actions associated with a rule.  Each FSv2 rule has one
   or more match conditions and one or more actions associated with that
   match condition.

   This section describes how to order FSv2 filters received from a peer
   prior to transmission to another peer.  The same ordering should be
   used for the ordering of forwarding filtering installed based on only
   FSv2 filters.

   Section 7.0 describes how a BGP peer that supports FSv1 and FSv2
   should order the flow specification filters during the installation
   of these flow specification filters into FIBs or firewall engines in
   routers.

   The BGP distribution of FSv1 NLRI and FSv2 NLRI and their associated
   path attributes for actions (Wide Communities and Extended
   Communities) is “ships-in-the-night” forwarding of different AFI/SAFI
   information.  This recommended ordering provides for deterministic
   ordering of filters sent by the BGP distribution.

4.2.1.  Ordering of FSv2 NLRI Filters

   The basic principles regarding ordering of rules are simple:

      1) Rule-0 (zero) is defined to be 0/0 with the “permit-all” action

      -  BGP peers which do not support flow specification permit
         traffic for routes received.  Rule-0 is defined to be “permit-
         all” for 0/0 which is the normal case for filtering for routes
         received by BGP.

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      -  By configuration option, the “permit-all” may be set to “deny-
         all” if traffic rules on routers used as BGP must have a
         “route” AND a firewall filter to allow traffic flow.

      2) FSv2 rules are ordered based on the user-defined order numbers
      specified in the FSv2 NLRI (rules 1-n).

      3) If multiple FSv2 NLRI have the same user-defined order, then
      the filters are ordered by type of FSv2 NRLI filters (see Table 1,
      section 4) with lowest numerical number have the best precedence.

      -  For the same user-defined order and the same value for the FSv2
         filters type, then the filters are ordered by FSv2 the
         component type for that FSv2 filter type (see Tables 3-6) with
         the lowest number having the best precedence.

      -  For the same user-defined order, the same value of FSv2 Filter
         Type, and the same value for the component type, then the
         filters are ordered by value within the component type.  Each
         component type defines value ordering.

      -  For component types inherited from the FSv1 component types,
         there are the following two types of comparisons:

         o  FSv1 component value comparison for the IP prefix values,
            compares the length of the two prefixes.  If the length is
            different, the longer prefix has precedence.  If the length
            is the same, the lower IP number has precedence.

         o  For all other FSv1 component types, unless specified, the
            component data is compared using the memcmp() function
            defined by [ISO_IEC_9899].  For strings with the same
            length, the lowest string memcmp() value has precedence.
            For strings of different lengths, the common prefix is
            compared.  If the common string prefix is not equal, then
            the string with the lowest string prefix has higher
            precedence.  If the common prefix is equal, the longest
            string is considered to have higher precedence

   Notes:

   *  Since the user can define rules that re-order these value
      comparisons, this order is arbitrary and set to provide a
      deterministic default.

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4.2.2.  Ordering of the Actions

   The FSv2 specification allows for actions to be associated by:

      a) a Wide Community path attribute, or

      b) an Extended Community path attribute.

   Actions may be ordered by user-defined action order number from 1-n
   (where n is 2**16-2 and the value 2**16-1 is reserved.

   Byy default, extended community actions are associated with default
   order number 32768 [0x8000] or a specific configured value for the
   FSv2 domain.

   Action user-order number zero is defined to have an Action type of
   “Set Action Chain operation” (ACO) (value 0x01) that defines the
   default action chain process.  For details on “set action chain
   operation” see section 3.2.1 or section 5.2.1 below.

   If the user-defined action number for two actions are the same, then
   the actions are ordered by FSv2 action types (see Table 3 for a list
   of action types).  If the user-defined action number and the FSv2
   action types are the same, then the order must be defined by the FSv2
   action.

4.2.2.1.  Action Chain Operation (ACO)

   The “Action Chain Operation” (ACO) changes the way the actions after
   the current action in an action chain are handled after a failure.
   If no action chain operations are set, then the default action of
   “stop upon failure” (value 0x00) will be used for the chain.

4.2.2.1.1.  Example 1 - Default ACO

   Use Case 1: Rate limit to 600 packets per second

   Description: The provider will support 600 packets per second All
   Packets sampled for reporting purposes and packet streams over 600
   packets per second will be dropped.

   Suppose BGP Peer A has a

   *  a Wide Community action with user-defined order 10 with Traffic
      Sampling

   *  a Wide Community action with user-defined order 11 from AS 2020
      that limits packet-based rate limit of 600 packets per second.

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   *  an Extended Community from AS 2020 that does limits packet-based
      rate limit of 50 packets per second.

   The FSv2 data base would store the following action chain:

   *  at user-defined action order 10

      -  A user action of type 7 (traffic action) with values of
         Sampling and logging.

   *  at user-defined action order 11

      -  a user action type of 12 (packet-based rate limit) with values
         of AS 2020 and float value for 600 packets per second (pps)

   *  at user-defined action order 32768 (0x8000) with type 12 and
      values of A user action of type 12 with values of AS 2020 and
      float value of 50 packets/second.

   Normal action:

      The match on the traffic would cause a sample of the traffic
      (probably with packet rate saved in logging) followed by a rate
      limit to 600 pps.  The Extended community action would further
      limit the rate to 50 packets per second.

   When does the action chain stop?

      The default process for the action chain is to stop on failure.
      If there is no failure, then all three actions would occur.  This
      is probably not what the user wants.

      If there is failure at action 10 (sample and log), then there
      would be no rate limiting per packet (actions 11 and action
      32768).

      If there is failure at action 11 (rate limit to packet 600), then
      there would be no rate limiting per packet (action 32768).

   The different options for Action chain ordering (ACO) have been
   worked on with NETCONF/RESTCONF configuration and actions.

4.2.2.1.2.  Example 2: Redirect traffic over limit to processing via SFC

   Use case 2: Redirect traffic over limit to processing via SFC.

   Description: The normal function is for traffic over the limit to be
   forwarded for offline processing and reporting to a customer.

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   Suppose we have the following 4 actions defined for a match:

   *  Sent Redirect to indirection ID (0x01) with user-defined match 2
      attached in wide community,

   *  Traffic rate limit by bytes (0x07) with user-defined match 1
      attached in wide community,

   *  Traffic sample (0x07) sent in extended community, and

   *  SF classifier Info (0x0E) sent in extended community.

   These 4 filters rate limit a potential DDoS attack by: a) redirect
   the packet to indirection ID (for slower speed processing), sample to
   local hardware, and forward the attack traffic via a SFC to a data
   collection box.

   The FSv2 action list for the match would look like this

      Action 0: Operation of action chain (0x01) (stop upon failure)

      Action 1: Traffic Rate limit by byte (0x07)

      Action 2: Redirect to Redirection ID (0x0F)

      Action 32768 (0x8000) Traffic Action (0x07) Sample

      Action 32768 (0x8000) SFC Classifier: (0xE)

   If the redirect to a redirection ID fails, then Traffic Sample and
   sending the data to an SFC classifier for forwarding via SFC will not
   happen.  The traffic is limited, but not redirect away from the
   network and a sample sent to DDOS processing via a SFC classifier.

   Suppose the following 5 actions were defined for a FSV2 filter:

   *  Set Action Chain Operation (ACO) (0x01) to continue on failure
      (ox01) at user-order 2 attached in wide community,

   *  redirect to indirection ID (0x0F) at user-order 2 attached in wide
      community,

   *  traffic rate limit by bytes (0x07)with user-order 1 attached in
      wide community,

   *  Traffic sample (0x07) attached via extended community, and

   *  SFC classifier Info (0x0E) attached in extended community.

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   The FSv2 action list for the match would look like this:

      Action 00: Operation of action chain (0x01) (stop upon failure)

      Action 01:Traffic Rate limit by byte (0x07)

      Action 02:Set Action Chain Operation (ACO) (0x01) (continue on
      failure)

      Action 02: Redirect to Redirection ID (0F)

      Action 32768 (0x8000): Traffic Action (0x07) Sample

      Action 32768 (0x8000): SFC classifier (0x0E) forward via SFC [to
      DDoS classifier]

   If the redirect to a redirection ID fails, the action chain will
   continue on to sample the data and enact SFC classifier actions.

4.2.2.2.  Summary of FSv2 ordering

   Operators should use user-defined ordering to clearly specify the
   actions desired upon a match.  The FSv2 actions default ordering is
   specified to provide deterministic order for actions which have the
   same user-defined order and same type.

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   FS Action                          Value Order
   (lowest value to highest)          (lowest to highest)
   ================================   ==============================
   0x01: ACO: Action chain operation  Failure flag
   0x02: TAIS:Traffic actions per     AS, then Group-ID, then Action ID
          Interface group

   0x03-0x05 to be assigned           TBD
   0x06: TRB: Traffic rate limit      AS, then float value
         by bytes
   0x07: TA: Traffic Action           traffic action value
   0x08: RDIP: Redirect to IP             AS, then IP Address, then ID
   0x09: TM: Traffic Marking          DSCP value (lowest to highest)
   0x0A: AL2: Associated L2 Info.     TBD
   0x0B: AET: Associated E-tree Info. TBD
   0x0C: TRP: Traffic Rate limit      AS, then float value
            by bytes
   0x0D: RDIPv6: Traffic
           Redirect to IPv6           AS, IPv6 value, then local Admin
   0x0E: TISFC: Traffic insertion
        to SFC                        SPI, then SI, the SFT
   0xOF: Redirect to
             Indirection-ID           ID-type, then Generalized-ID

   0x10: MPLSLA: MPLS Label stack     order, action, label, Exp
   0x16 – VLAN action                 rewrite-actions, VALN1, VLAN2,
                                      PCP-DE1, PCP-DE2
   0x17 – TPID action                 rewrite actions, TP-ID-1, TP-ID-2

                    Figure 6-1

4.3.  Ordering of FS filters for BGP Peers support FSv1 and FSv2

   FSv2 allows the user to order flow specification rules and the
   actions associated with a rule.  Each FSv2 rule has one or more match
   conditions and one or more actions associated with each rule.

   FSv1 and FSv2 filters are sent as different AFI/SAFI pairs so FSv1
   and FSv2 operate as ships-in-the-night.  Some BGP peers in an AS may
   support both FSv1 and FSv2.  Other BGP peers may support FSv1 or
   FSv2.  Some BGP will not support FSv1 or FSV2.  A coherent flow
   specification technology must have consistent best practices for
   ordering the FSv1 and FSv2 filter rules.

   One simple rule captures the best practice: Order the FSv1 filters
   after the FSv2 filter by placing the FSv1 filters after the FSv2
   filters.

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   To operationally make this work, all flow specification filters
   should be included the same data base with the FSv1 filters being
   assigned a user- defined order beyond the normal size of FSv2 user-
   ordered values.  A few examples, may help to illustrate this best
   practice.

   Example 1: User ordered numbering - Suppose you might have 1,000
   rules for the FSv2 filters.  Assign all the FSv1 user defined rules
   to 1,001 (or better yet 2,000).  The FSv1 rules will be ordered by
   the components and component values.

   Example 2: Storage of actions - All FSv1 actions are defined ordered
   actions in FSv2.  Translate your FSv1 actions into FSv2 ordered
   actions for storing in a common FSv1-FSv2 flow specification data
   base.

   Example 3: Mixed Flow Specification Support -

      Suppose an FSv2 peer (BGP Peer A) has the capability to send
      either FSv1 or FSv2.  BGP Peer A peers with BGP Peers B, C, D and
      E.

      BGP Peer B can only send FSv1 routes (NLRI + Extended Community).
      BGP Peer C can send FSv2 routes (NLRI + path attributes (wide
      community or extended community or none)).  BGP Peer D cannot send
      any FS routes.  BGP E can send FSv2 and FSv1 routes

      BGP Peer A sends FSv1 routes in its databases to BGP B.  Since the
      FSv2 NLRI cannot be sent to the FSv1 peer, only the FSv1 NLRI is
      sent.  BGP Peer A sends to BGP C the FSv2 routes in its database
      (configured or received).

      BGP peer A would not send the FSv1 NLRI or FSv2 NLRI to BGP Peer
      D.  The BGP Peer D does not support for these NLRI.

      BGP Peer A sends the NLRI for both FSv1 and FSv2 to BGP Peer E.

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         +---------+                       +---------+
         |    A    |=======================|    C    |
         |FSv1+FSv2|.                   . .|  FSv2   |
         +---------+ .                 .   +---------+
          ||  |   \   .               .      .     ||
          ||  |    \   . . . . . . . . .     .     ||
          ||  |     \               .   .    .     ||
          ||  |      \-----\      .      .   .     ||
          ||  |             \    .        .  .     ||
         +---------+       +------+       +-----+  ||
         |    E    |-------|  B   |. . . .|  D  |  ||
         |FSv1+FSv2|       | FSv1 |       |no FS|  ||
         +---------+       +------+       +-----+  ||
           ||     .                         .      ||
           ||     . . . . . . . . . . . . . .      ||
           ||                                      ||
           |========================================|

           Double line = FSv2
           Single line = FSv1
           Dotted line = BGP peering with no FlowSpec

            Figure 6-2: FSv1 and FVs2 Peering

5.  Scalability and Aspirations for FSv2

   Operational issues drive the deployment of BGP flow specification as
   a quick and scalable way to distribute filters.  The early operations
   accepted the fact validation of the distribution of filter needed to
   be done outside of the BGP distribution mechanism.  Other mechanisms
   (NETCONF/RESTCONF or PCEP) have reply-request protocols.

   These features within BGP have not changed.  BGP still does not have
   an action-reply feature.

   NETCONF/RESTCONF latest enhancements provide action/response features
   which scale.  The combination of a quick distribution of filters via
   BGP and a long-term action in NETCONF/RESTCONF that ask for reporting
   of the installation of FSv2 filters may provide the best scalability.

   The combination of NETCONF/RESTCONF network management protocols and
   BGP focuses each protocol on the strengths of scalability.

   FSv2 will be deployed in webs of BGP peers which have some BGP peers
   passing FSv1, some BGP peers passing FSv2, some BGP peers passing
   FSv1 and FSv2, and some BGP peers not passing any routes.

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   The TLV encoding and deterministic behaviors of FSv2 will not
   deprecate the need for careful design of the distribution of flow
   specification filters in this mixed environment.  The needs of
   networks for flow specification are different depending on the
   network topology and the deployment technology for BGP peers sending
   flow specification.

   Suppose we have a centralized RR connected to DDoS processing sending
   out flow specification to a second tier of RR who distribute the
   information to targeted nodes.  This type of distribution has one set
   of needs for FSv2 and the transition from FSv1 to FSv2

   Suppose we have Data Center with a 3-tier backbone trying to
   distribute DDoS or other filters from the spine to combinational
   nodes, to the leaf BGP nodes.  The BGP peers may use RR or normal BGP
   distribution.  This deployment has another set of needs for FSv2 and
   the transition from FSv1 to FSV2.

   Suppose we have a corporate network with a few AS sending DDoS
   filters using basic BGP from a variety of sites.  Perhaps the
   corporate network will be satisfied with FSv1 for a long time.

   These examples are given to indicate that BGP FSv2, like so many BGP
   protocols, needs to be carefully tuned to aid the mitigation services
   within the network.  This protocol suite starts the migration toward
   better tools using FSv2, but it does not end it.  With FSv2 TLVs and
   deterministic actions, new operational mechanisms can start to be
   understood and utilized.

   This FSv2 specification is merely the start of a revolution of work –
   not the end.

6.  Optional Security Additions

   This section discusses the optional BGP Security additions for BGP-FS
   v2 relating to BGPSEC [RFC8205] and ROA [RFC6482].

6.1.  BGP FSv2 and BGPSEC

   Flow specification v1 ([RFC8955] and [RFC8956]) do not comment on how
   BGP Flow specifications to be passed BGPSEC [RFC8205] BGP Flow
   Specification v2 can be passed in BGPSEC, but it is not required.

   FSv1 and FSv2 may be sent via BGPSEC.

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6.2.  BGP FSv2 with ROA

   BGP FSv2 can utilize ROAs in the validation.  If BGP FSv2 is used
   with BGPSEC and ROA, the first thing is to validate the route within
   BGPSEC and second to utilize BGP ROA to validate the route origin.

   The BGP-FS peers using both ROA and BGP-FS validation determine that
   a BGP Flow specification is valid if and only if one of the following
   cases:

   *  If the BGP Flow Specification NLRI has a IPv4 or IPv6 address in
      destination address match filter and the following is true:

      -  A BGP ROA has been received to validate the originator, and

      -  The route is the best-match unicast route for the destination
         prefix embedded in the match filter; or

   *  If a BGP ROA has not been received that matches the IPv4 or IPv6
      destination address in the destination filter, the match filter
      must abide by the [RFC8955] and [RFC8956] validation rules as
      follows:

      -  The originator match of the flow specification matches the
         originator of the best-match unicast route for the destination
         prefix filter embedded in the flow specification", and

      -  No more specific unicast routes exist when compared with the
         flow destination prefix that have been received from a
         different neighboring AS than the best-match unicast route,
         which has been determined in step A.

   The best match is defined to be the longest-match NLRI with the
   highest preference.

7.  IANA Considerations

   This section complies with [RFC7153].

7.1.  Flow Specification V2 SAFIs

   IANA is requested to assign two SAFI Values in the registry at
   https://www.iana.org/assignments/safi-namespace from the Standard
   Action Range as follows:

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         Value   Description      Reference
        -----   -------------    ---------------
         TBD1   BGP FSv2        [this document]
         TBD2   BGP FSv2 VPN    [this document]

7.2.  BGP Capability Code

   IANA is requested to assign a Capability Code from the registry at
   https://www.iana.org/assignments/capability-codes/ from the IETF
   Review range as follows:

      Value   Description            Reference       Controller
      -----  ---------------------  ---------------  ----------
       TBD3  Flow Specification V2  [this document]  IETF

7.3.  Filter IP Component types

   IANA is requested to indicate [this draft] as a reference on the
   following assignments in the Flow Specification Component Types
   Registry:

   Value  Description         Reference
   -----  ------------------- ------------------------
    1     Destination filter  [RFC8955][RFC8956][this document]
    2     Source Prefix       [RFC8955][RFC8956][this document]
    3     IP Protocol         [RFC8955][RFC8956][this document]
    4     Port                [RFC8955][RFC8956][this document]
    5     Destination Port    [RFC8955][RFC8956][this document]
    6     Source Port         [RFC8955][RFC8956][this document]
    7     ICMP Type [v4 or v6][RFC8955][RFC8956][this document]
    8     ICMP Code [v4 or v6][RFC8955][RFC8956][this document]
    9     TCP Flags [v4]      [RFC8955][RFC8956][this document]
    10    Packet Length       [RFC8955][RFC8956][this document]
    11    DSCP marking        [RFC8955][RFC8956][this document]
    12    Fragment            [RFC8955][RFC8956][this document]
    13    Flow Label          [RFC8956][this document]
    14    TTL                 [this document]
    15    Partial SID         [draft-ietf-idr-flowspec-srv6]
                              [this document]
    16    MPLS Label Match 1  [this document]
                              [draft-ietf-idr-flowspec-mpls-match]
    17    MPLS Label Match 2  [this document]
                              [draft-ietf-idr-flowspec-mpls-match]

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7.4.  FSV2 NLRI TLV Types

   IANA is requested to create the following two new registries on a new
   "Flow Specification v2 TLV Types” web page.

      Name: BGP FSv2 TLV types
      Reference: [this document]
      Registration Procedures: 0x01-0x3FFF Standards Action.

       Type          Use                     Reference
      -----          ---------------         ---------------
       0x00          Reserved                [this document]
       0x01          IP traffic rules        [this document]
       0x02          FSv2 Actions            [this document]
       0x03          L2 traffic rules        [this document]
       0x04          tunnel traffic rules    [this document]
       0x05          SFC AFI filter rules    [this document]
       0x06          BGP/MPLS VPN IP
                      traffic rules          [this document]
       0x07          BGP/MPLS VPN L2
                       traffic rules         [this document]
       0x08-0x3FFF   Unassigned              [this document]
       0x4000-0x7FFF Vendor specific         [this document]
       0x8000-0xFFFF Reserved                [this document]

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      Name: BGP FSv2 Action types
      Reference: [this document]
      Registration Procedure: 0x01-0x3FFF Standards Action.

       Type     Use                           Reference
      -----  ---------------                 ---------------
      0x00   Reserved                        [this document]
      0x01   ACO: Action Chain Operation     [this document]
      0x02   TAIS: Traffic actions per
             interface group                 [this document]
      0x03   Unassigned                      [this document]
      0x04   Unassigned                      [this document]
      0x05   Unassigned                      [this document]
      0x06   TRB: traffic rate
              limited by bytes                [this document]
      0x07   TA: Traffic action
             (terminal/sample)               [this document]
      0x08   RDIPv4: redirect IPv4           [this document]
      0x09   TM: traffic marking (DSCP)      [this document]
      0x0A   AL2: associate L2 Information   [this document]
      0x0B   AET: associate E-Tree
              information                    [this document]
      0x0C   TRP: traffic rate
              limited by packets             [this document]
      0x0D   RDIPv6: Redirect to IPv6        [this document]
      0x0E   TISFC: Traffic insertion
              to SFC                         [this document]
      0x0F   RDIID: Redirect
              to indirection-iD              [this document]
      0x10   MPLS Label Action               [this document]
      0x11   unassigned                      [this document]
      0x12   unassigned                      [this document]
      0x13   unassigned                      [this document]
      0x14   unassigned                      [this document]
      0x15   unassigned                      [this document]
      0x16   VLAN action                     [this document]
      0x17   TIPD action                     [this document]
      0x18-
      0x3ff  Unassigned                      [this document]
      0x4000-
      0x7fff Vendor assigned                 [this document]
      0x8000-
      0xFFFF Reserved                        [this document]

7.5.  Wide Community Assignments

   IANA is requested to assign values in the BGP Community Container
   Atom Type Registry

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      Name                    Type value
      -----                   -----------
      FSv2 action atom        TBD5

   IANA is requested to assign values from the Registered Type 1 BGP
   Wide Community Types:

      Name                    type Value
      ------                  -----------
      FSv2 Actions            TBD4

8.  Security Considerations

   The use of ROA improves on [RFC8955] by checking to see of the route
   origination.  This check can improve the validation sequence for a
   multiple-AS environment.

   >The use of BGPSEC [RFC8205] to secure the packet can increase
   security of BGP flow specification information sent in the packet.

   The use of the reduced validation within an AS [RFC9117] can provide
   adequate validation for distribution of flow specification within a
   single autonomous system for prevention of DDoS.

   Distribution of flow filters may provide insight into traffic being
   sent within an AS, but this information should be composite
   information that does not reveal the traffic patterns of individuals.

9.  References

9.1.  Normative References

   [I-D.ietf-idr-bgp-flowspec-label]
              liangqiandeng, Hares, S., You, J., Raszuk, R., and D. Ma,
              "Carrying Label Information for BGP FlowSpec", Work in
              Progress, Internet-Draft, draft-ietf-idr-bgp-flowspec-
              label-02, 20 October 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
              flowspec-label-02>.

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   [I-D.ietf-idr-flowspec-interfaceset]
              Litkowski, S., Simpson, A., Patel, K., Haas, J., and L.
              Yong, "Applying BGP flowspec rules on a specific interface
              set", Work in Progress, Internet-Draft, draft-ietf-idr-
              flowspec-interfaceset-05, 18 November 2019,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              flowspec-interfaceset-05>.

   [I-D.ietf-idr-flowspec-l2vpn]
              Weiguo, H., Eastlake, D. E., Litkowski, S., and S. Zhuang,
              "BGP Dissemination of L2 Flow Specification Rules", Work
              in Progress, Internet-Draft, draft-ietf-idr-flowspec-
              l2vpn-23, 15 April 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              flowspec-l2vpn-23>.

   [I-D.ietf-idr-flowspec-mpls-match]
              Yong, L., Hares, S., liangqiandeng, and J. You, "BGP Flow
              Specification Filter for MPLS Label", Work in Progress,
              Internet-Draft, draft-ietf-idr-flowspec-mpls-match-02, 20
              October 2022, <https://datatracker.ietf.org/doc/html/
              draft-ietf-idr-flowspec-mpls-match-02>.

   [I-D.ietf-idr-flowspec-nvo3]
              Eastlake, D. E., Weiguo, H., Zhuang, S., Li, Z., and R.
              Gu, "BGP Dissemination of Flow Specification Rules for
              Tunneled Traffic", Work in Progress, Internet-Draft,
              draft-ietf-idr-flowspec-nvo3-19, 26 December 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              flowspec-nvo3-19>.

   [I-D.ietf-idr-flowspec-path-redirect]
              Van de Velde, G., Patel, K., and Z. Li, "Flowspec
              Indirection-id Redirect", Work in Progress, Internet-
              Draft, draft-ietf-idr-flowspec-path-redirect-12, 24
              November 2022, <https://datatracker.ietf.org/doc/html/
              draft-ietf-idr-flowspec-path-redirect-12>.

   [I-D.ietf-idr-flowspec-srv6]
              Li, Z., Li, L., Chen, H., Loibl, C., Mishra, G. S., Fan,
              Y., Zhu, Y., Liu, L., and X. Liu, "BGP Flow Specification
              for SRv6", Work in Progress, Internet-Draft, draft-ietf-
              idr-flowspec-srv6-05, 29 March 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              flowspec-srv6-05>.

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   [I-D.ietf-idr-wide-bgp-communities]
              Raszuk, R., Haas, J., Lange, A., Decraene, B., Amante, S.,
              and P. Jakma, "BGP Community Container Attribute", Work in
              Progress, Internet-Draft, draft-ietf-idr-wide-bgp-
              communities-11, 9 March 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
              wide-bgp-communities-11>.

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,
              <https://www.rfc-editor.org/info/rfc791>.

   [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>.

   [RFC3032]  Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y.,
              Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack
              Encoding", RFC 3032, DOI 10.17487/RFC3032, January 2001,
              <https://www.rfc-editor.org/info/rfc3032>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.

   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
              February 2006, <https://www.rfc-editor.org/info/rfc4360>.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              DOI 10.17487/RFC4760, January 2007,
              <https://www.rfc-editor.org/info/rfc4760>.

   [RFC5065]  Traina, P., McPherson, D., and J. Scudder, "Autonomous
              System Confederations for BGP", RFC 5065,
              DOI 10.17487/RFC5065, August 2007,
              <https://www.rfc-editor.org/info/rfc5065>.

   [RFC5701]  Rekhter, Y., "IPv6 Address Specific BGP Extended Community
              Attribute", RFC 5701, DOI 10.17487/RFC5701, November 2009,
              <https://www.rfc-editor.org/info/rfc5701>.

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   [RFC6482]  Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
              Origin Authorizations (ROAs)", RFC 6482,
              DOI 10.17487/RFC6482, February 2012,
              <https://www.rfc-editor.org/info/rfc6482>.

   [RFC7153]  Rosen, E. and Y. Rekhter, "IANA Registries for BGP
              Extended Communities", RFC 7153, DOI 10.17487/RFC7153,
              March 2014, <https://www.rfc-editor.org/info/rfc7153>.

   [RFC7606]  Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K.
              Patel, "Revised Error Handling for BGP UPDATE Messages",
              RFC 7606, DOI 10.17487/RFC7606, August 2015,
              <https://www.rfc-editor.org/info/rfc7606>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8955]  Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
              Bacher, "Dissemination of Flow Specification Rules",
              RFC 8955, DOI 10.17487/RFC8955, December 2020,
              <https://www.rfc-editor.org/info/rfc8955>.

   [RFC8956]  Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
              "Dissemination of Flow Specification Rules for IPv6",
              RFC 8956, DOI 10.17487/RFC8956, December 2020,
              <https://www.rfc-editor.org/info/rfc8956>.

   [RFC9015]  Farrel, A., Drake, J., Rosen, E., Uttaro, J., and L.
              Jalil, "BGP Control Plane for the Network Service Header
              in Service Function Chaining", RFC 9015,
              DOI 10.17487/RFC9015, June 2021,
              <https://www.rfc-editor.org/info/rfc9015>.

   [RFC9117]  Uttaro, J., Alcaide, J., Filsfils, C., Smith, D., and P.
              Mohapatra, "Revised Validation Procedure for BGP Flow
              Specifications", RFC 9117, DOI 10.17487/RFC9117, August
              2021, <https://www.rfc-editor.org/info/rfc9117>.

   [RFC9184]  Loibl, C., "BGP Extended Community Registries Update",
              RFC 9184, DOI 10.17487/RFC9184, January 2022,
              <https://www.rfc-editor.org/info/rfc9184>.

9.2.  Informative References

   [I-D.ietf-idr-flowspec-v2]
              Hares, S., Eastlake, D. E., Yadlapalli, C., and S.
              Maduschke, "BGP Flow Specification Version 2", Work in

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              Progress, Internet-Draft, draft-ietf-idr-flowspec-v2-03,
              23 October 2023, <https://datatracker.ietf.org/doc/html/
              draft-ietf-idr-flowspec-v2-03>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.

   [RFC8205]  Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol
              Specification", RFC 8205, DOI 10.17487/RFC8205, September
              2017, <https://www.rfc-editor.org/info/rfc8205>.

   [RFC8206]  George, W. and S. Murphy, "BGPsec Considerations for
              Autonomous System (AS) Migration", RFC 8206,
              DOI 10.17487/RFC8206, September 2017,
              <https://www.rfc-editor.org/info/rfc8206>.

Authors' Addresses

   Susan Hares
   Hickory Hill Consulting
   7453 Hickory Hill
   Saline, MI 48176
   United States of America
   Phone: +1-734-604-0332
   Email: shares@ndzh.com

   Donald Eastlake
   Futurewei Technologies
   2386 Panoramic Circle
   Apopka, FL 32703
   United States of America
   Phone: +1-508-333-2270
   Email: d3e3e3@gmail.com

   Chaitanya Yadlapalli
   ATT
   United States of America
   Email: cy098d@att.com

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   Sven Maduschke
   Verizon
   Germany
   Email: sven.maduschke@de.verizon.com

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