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Versions: (RFC 5575) 00

IDR Working Group                                              R. Raszuk
Internet-Draft                                              Bloomberg LP
Intended status: Standards Track                            J. McPherson
Expires: December 26, 2016                                      Verisign
                                                                J. Mauch
                                                             NTT America
                                                               B. Greene
                                                        Juniper Networks
                                                                S. Hares
                                                                  Huawei
                                                           June 24, 2016


               Dissemination of Flow Specification Rules
                   draft-raszuk-idr-rfc5575bis-00.txt

Abstract

   This document defines a Border Gateway Protocol Network Layer
   Reachability Information (BGP NLRI) encoding format that can be used
   to distribute traffic flow specifications.  This allows the routing
   system to propagate information regarding more specific components of
   the traffic aggregate defined by an IP destination prefix (IPv4,
   IPv6), MPLS addresses, L2VPN addresses, and NV03 encapsulation of IP
   addresses.  The information is carried via the BGP, thereby reusing
   protocol algorithms, operational experience, and administrative
   processes such as inter-provider peering agreements.

   This document provides the definition of a BGP NLRI which carries
   traffic flow specification filters, and Extended Community values
   which encode the actions a routing system can take if a packet
   matches the traffic flow filters.  The specification requires that
   the BGP Flow Specification traffic filters follows a string ordering,
   and that the BGP Flow Specification Extended Communities actions are
   processed in a defined order.  This BGP Flow Specification is denoted
   as BGP Flow Specification version 1.

   There are three applications of that encoding format: 1) automation
   of inter-domain coordination of traffic filtering, such as what is
   required in order to mitigate (distributed) denial-of-service
   attacks; 2) enable traffic filtering in the context of a BGP/MPLS VPN
   service, and 3) aid centralized control of traffic in a SDN or NFV
   context.  Some of deployments of these three applications can be
   handled by the strict ordering of the BGP NLRI traffic flow filters,
   and the strict actions encoded in the Extended Community Flow
   Specification actions.  Other deployments (especially SDN/NFV) need
   to be able to allow the user to order the flow specification.
   Another BGP Flow Specification (version 2) is being defined for user-



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   ordered filters, and user-ordered actions encoded in Wide
   Communities.

Status of This Memo

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

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

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

   This Internet-Draft will expire on December 26, 2016.

Copyright Notice

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

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Definitions of Terms Used in This Memo  . . . . . . . . . . .   6
   3.  Flow Specifications . . . . . . . . . . . . . . . . . . . . .   6
   4.  Traffic Filtering . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Support for other AFIs  . . . . . . . . . . . . . . . . .   8
   5.  Dissemination of IPv4 FLow Specification Information  . . . .   8
     5.1.  Length Encoding . . . . . . . . . . . . . . . . . . . . .   9
     5.2.  NLRI Value Encoding . . . . . . . . . . . . . . . . . . .   9
       5.2.1.  Type 1 - Destination Prefix . . . . . . . . . . . . .  12
       5.2.2.  Type 2 - Source Prefix  . . . . . . . . . . . . . . .  13
       5.2.3.  Type 3 - Source Prefix  . . . . . . . . . . . . . . .  13



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       5.2.4.  Type 4 - Port . . . . . . . . . . . . . . . . . . . .  13
       5.2.5.  Type 5 - Destination Port . . . . . . . . . . . . . .  14
       5.2.6.  Type 6 - Destination Port . . . . . . . . . . . . . .  14
       5.2.7.  Type 7 - ICMP type  . . . . . . . . . . . . . . . . .  14
       5.2.8.  Type 8 - ICMP code  . . . . . . . . . . . . . . . . .  14
       5.2.9.  Type 9 - ICMP code  . . . . . . . . . . . . . . . . .  15
       5.2.10. Type 10 - Packet length . . . . . . . . . . . . . . .  15
       5.2.11. Type 11 -  DSCP (Diffserv Code Point) . . . . . . . .  15
       5.2.12. Type 12 - Fragment  . . . . . . . . . . . . . . . . .  16
       5.2.13. Examples of Encodings . . . . . . . . . . . . . . . .  16
     5.3.  Ordering of Traffic Filtering Rules . . . . . . . . . . .  17
     5.4.  Validation Procedure  . . . . . . . . . . . . . . . . . .  18
   6.  Traffic Filtering Actions . . . . . . . . . . . . . . . . . .  20
     6.1.  Traffic Rate in bytes (sub-type 0x06) . . . . . . . . . .  21
     6.2.  Traffic-action (sub-type 0x07)  . . . . . . . . . . . . .  21
     6.3.  IP Redirect (sub-type 0x08) . . . . . . . . . . . . . . .  22
     6.4.  Traffic Marking (sub-type 0x09) . . . . . . . . . . . . .  22
     6.5.  Rules on Traffic Action interference  . . . . . . . . . .  22
   7.  Dissemination of Traffic Filtering in BGP/MPLS VPN Networks .  23
     7.1.  Validation Procedures for BGP/MPLS VPNs . . . . . . . . .  24
     7.2.  Traffic Actions Rules . . . . . . . . . . . . . . . . . .  24
   8.  Limitations of Previous Traffic Filtering Efforts . . . . . .  24
     8.1.  Limitations in Previous DDOS Traffic Filtering Efforts  .  24
     8.2.  Limitations in Previous BGP/MPLS Traffic Monitoring . . .  25
     8.3.  Limitations in BGP Flow Specification for SDN/NFV
           Applications  . . . . . . . . . . . . . . . . . . . . . .  25
   9.  Traffic Monitoring  . . . . . . . . . . . . . . . . . . . . .  25
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  26
     10.1.  AFI/SAFI Definitions . . . . . . . . . . . . . . . . . .  26
     10.2.  Flow Component definitions . . . . . . . . . . . . . . .  26
     10.3.  Extended Community Flow Specification Actions  . . . . .  27
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  28
   12. Contributing authors  . . . . . . . . . . . . . . . . . . . .  28
   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  29
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  29
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  29
     14.2.  Informative References . . . . . . . . . . . . . . . . .  31
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  32

1.  Introduction

   Modern IP routers contain both the capability to forward traffic
   according to IP prefixes as well as to classify, shape, rate limit,
   filter, or redirect packets based on administratively defined
   policies.






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   These traffic policy mechanisms allow the router to define match
   rules that operate on multiple fields of the packet header.  Actions
   such as the ones described above can be associated with each rule.

   The n-tuple consisting of the matching criteria defines an aggregate
   traffic flow specification.  The matching criteria can include
   elements such as source and destination address prefixes, IP
   protocol, and transport protocol port numbers.

   This document defines a general procedure to encode flow
   specification rules for aggregated traffic flows so that they can be
   distributed as a BGP [RFC5575] NLRI.  Additionally, we define the
   required mechanisms to utilize this definition to the problem of
   immediate concern to the authors: intra- and inter-provider
   distribution of traffic filtering rules to filter (distributed)
   denial-of-service (DoS) attacks.

   By expanding routing information with flow specifications, the
   routing system can take advantage of the ACL (Access Control List) or
   firewall capabilities in the router's forwarding path.  Flow
   specifications can be seen as more specific routing entries to a
   unicast prefix and are expected to depend upon the existing unicast
   data information.

   A flow specification received from an external autonomous system will
   need to be validated against unicast routing before being accepted.
   If the aggregate traffic flow defined by the unicast destination
   prefix is forwarded to a given BGP peer, then the local system can
   safely install more specific flow rules that may result in different
   forwarding behavior, as requested by this system.

   The key technology components required to address the class of
   problems targeted by this document are:

   1.  Efficient point-to-multipoint distribution of control plane
       information.

   2.  Inter-domain capabilities and routing policy support.

   3.  Tight integration with unicast routing, for verification
       purposes.

   Items 1 and 2 have already been addressed using BGP for other types
   of control plane information.  Close integration with BGP also makes
   it feasible to specify a mechanism to automatically verify flow
   information against unicast routing.  These factors are behind the
   choice of BGP as the carrier of flow specification information.




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   As with previous extensions to BGP, this specification makes it
   possible to add additional information to Internet routers.  These
   are limited in terms of the maximum number of data elements they can
   hold as well as the number of events they are able to process in a
   given unit of time.  The authors believe that, as with previous
   extensions, service providers will be careful to keep information
   levels below the maximum capacity of their devices.

   In many deployments of BGP Flow Specification, the flow specification
   information has replace existing host length route advertisements.

   Experience with previous BGP extensions has also shown that the
   maximum capacity of BGP speakers has been gradually increased
   according to expected loads.  Taking into account Internet unicast
   routing as well as additional applications as they gain popularity.

   From an operational perspective, the utilization of BGP as the
   carrier for this information allows a network service provider to
   reuse both internal route distribution infrastructure (e.g., route
   reflector or confederation design) and existing external
   relationships (e.g., inter-domain BGP sessions to a customer
   network).

   While it is certainly possible to address this problem using other
   mechanisms, this solution has been utilized in deployments because of
   the substantial advantage of being an incremental addition to already
   deployed mechanisms.

   In current deployments, the information distributed by the flow-spec
   extension is originated both manually as well as automatically.  The
   latter by systems that are able to detect malicious flows.  When
   automated systems are used, care should be taken to ensure their
   correctness as well as to limit the number and advertisement rate of
   flow routes.

   This specification defines required protocol extensions to address
   most common applications of IPv4 unicast and VPNv4 unicast filtering.
   The same mechanism can be reused and new match criteria added to
   address similar filtering needs for other BGP address families such
   as:

   o  IPv6 [I-D.ietf-idr-flow-spec-v6],

   o  MAC address for L2VPN [I-D.ietf-idr-flowspec-l2vpn],

   o  NV03 encapsulation [I-D.ietf-idr-flowspec-nvo3],





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   o  and MPLS ([I-D.ietf-idr-flowspec-mpls-match],
      [I-D.ietf-idr-bgp-flowspec-label]).

   These additions to BGP Flow Specification IPv4 are included in a
   separate documents to allow implementers the choice of implementing
   portions of the BGP Flow specification.

2.  Definitions of Terms Used in This Memo

   NLRI -   Network Layer Reachability Information.

   RIB -   Routing Information Base.

   Loc-RIB -   Local RIB.

   AS -   Autonomous System number.

   VRF -   Virtual Routing and Forwarding instance.

   PE -   Provider Edge router

   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 [RFC2119]

3.  Flow Specifications

   A flow specification is an n-tuple consisting of several matching
   criteria that can be applied to IP traffic.  A given IP packet is
   said to match the defined flow if it matches all the specified
   criteria.

   A given flow may be associated with a set of attributes, depending on
   the particular application; such attributes may or may not include
   reachability information (i.e., NEXT_HOP).  Well-known or AS-specific
   community attributes can be used to encode a set of predetermined
   actions.

   A particular application is identified by a specific (Address Family
   Identifier, Subsequent Address Family Identifier (AFI, SAFI)) pair
   [RFC4760] and corresponds to a distinct set of RIBs.  Those RIBs
   should be treated independently from each other in order to assure
   non-interference between distinct applications.

   BGP itself treats the NLRI as an opaque key to an entry in its
   databases.  Entries that are placed in the Loc-RIB are then
   associated with a given set of semantics, which is application
   dependent.  This is consistent with existing BGP applications.  For



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   instance, IP unicast routing (AFI=1, SAFI=1) and IP multicast
   reverse-path information (AFI=1, SAFI=2) are handled by BGP without
   any particular semantics being associated with them until installed
   in the Loc-RIB.

   Standard BGP policy mechanisms, such as UPDATE filtering by NLRI
   prefix and community matching, SHOULD apply to the Flow specification
   defined NLRI-type.  Network operators can also control propagation of
   such routing updates by enabling or disabling the exchange of a
   particular (AFI, SAFI) pair on a given BGP peering session.

4.  Traffic Filtering

   Traffic filtering policies have been traditionally considered to be
   relatively static.  Limitations of the static mechanisms caused this
   mechanism to be designed for the three new applications of traffic
   filtering (prevention of traffic-based, denial-of-service (DOS)
   attacks, traffic filtering in the context of BGP/MPLS VPN service,
   and centralized traffic control for SDN/NFV networks) requires
   coordination among service providers and/or coordination among the AS
   within a service provider.  Section 8 has details on the limitation
   of previous mechanisms and why BGP Flow Specification version 1
   provides a solution for to prevent DOS and aid BGP/MPLS VPN filtering
   rules.

   This flow specification NLRI defined above to convey information
   about traffic filtering rules for traffic that should be discarded or
   handled in manner specified by a set of pre-defined actions (which
   are defined in BGP Extended Communities).  This mechanism is
   primarily designed to allow an upstream autonomous system to perform
   inbound filtering in their ingress routers of traffic that a given
   downstream AS wishes to drop.

   In order to achieve this goal, this draft specifies two application
   specific NLRI identifiers that provide traffic filters, and a set of
   actions encoding in BGP Extended Communities.  The two application
   specific NLRI identifiers are:

   o  IPv4 flow specification identifier (AFI=1, SAFI=133) along with
      specific semantic rules for IPv4 routes, and

   o  BGP NLRI type (AFI=1, SAFI=134) value, which can be used to
      propagate traffic filtering information in a BGP/MPLS VPN
      environment.

   Distribution of the IPv4 Flow specification is described in section
   6, and distibution of BGP/MPLS traffic flow specification is




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   described in section 8.  The traffic filtering actions are described
   in section 7.

4.1.  Support for other AFIs

   Other documents shown in table 5 provide the application identifiers
   for IPv6, L2VPN, NVO3 and MPLS.  However, to provide backward
   compatiblity with [RFC5575] documents adhering to this specification
   do not need to support IPv6, L2VPN, NV03, and MPLS AFI/SAFIs.


         Table 5 - AFI/SAFI values vs. application
   +---+----+-----------+-----------------------------------+---+
   |AFI|SAFI|Application| Document                          |Req|
   +---+----+-----------+-----------------------------------+---+
   |  1| 133| DDOS      | this document                     |Yes|
   |  1| 134| BGP/MPLS  | this document                     | No|
   +---+----------------+-----------------------------------+---+
   |  2| 133| DDOS      |draft-ietf-idr-flow-spec-v6        | No|
   |  2| 134| BGP/MPLS  |draft-ietf-idr-flow-spec-v6        | No|
   +---+----+-----------+-----------------------------------+---+
   | 25| 133| DDOS      |draft-ietf-idr-flowspec-l2vpn      | No|
   | 25| 134| BGP/MPLS  |draft-ietf-idr-flowspec-l2vpn      | No|
   +---+----+-----------+-----------------------------------+---+
   |TBD| 133| DDOS      |draft-ietf-idr-flowspec-mpls-label | No|
   |TBD| 134| BGP/MPLS  |draft-ietf-idr-flowspec-mpls-label | No|
   +---+----+-----------+-----------------------------------+---+
   |TBD| 133| DDOS      |draft-ietf-idr-flowspec-nv03       | No|
   |TBD| 134| BGP/MPLS  |draft-ietf-idr-flowspec-nv03       | No|
   +---+----+-----------+-----------------------------------+---+

5.  Dissemination of IPv4 FLow Specification Information

   We define a "Flow Specification" NLRI type that may include several
   components such as destination prefix, source prefix, protocol,
   ports, and others (see Tables 1-4 below).  This NLRI is treated as an
   opaque bit string prefix by BGP.  Each bit string identifies a key to
   a database entry with which a set of attributes can be associated.

   This NLRI information is encoded using MP_REACH_NLRI and
   MP_UNREACH_NLRI attributes as defined in [RFC4760].  Whenever the
   corresponding application does not require Next-Hop information, this
   shall be encoded as a 0-octet length Next Hop in the MP_REACH_NLRI
   attribute and ignored on receipt.

   The NLRI field of the MP_REACH_NLRI and MP_UNREACH_NLRI is encoded as
   a 1- or 2-octet NLRI length field followed by a variable-length NLRI
   value.  The NLRI length is expressed in octets.



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       +------------------------------+
       |    length (0xnn or 0xfn nn)  |
       +------------------------------+
       |    NLRI value  (variable)    |
       +------------------------------+

               Figure 1: Flow-spec NLRI for IPv4

   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].  The
   (AFI, SAFI) pair carried in the Multiprotocol Extension Capability
   MUST be the same as the one used to identify a particular application
   that uses this NLRI-type.

5.1.  Length Encoding

   o  If the NLRI length value is smaller than 240 (0xf0 hex), the
      length field can be encoded as a single octet.

   o  Otherwise, it is encoded as an extended-length 2-octet value in
      which the most significant nibble of the first byte is all ones.

   In figure 1 above, values less-than 240 are encoded using two hex
   digits (0xnn).  Values above 240 are encoded using 3 hex digits
   (0xfnnn).  The highest value that can be represented with this
   encoding is 4095.  The value 241 is encoded as 0xf0f1.

5.2.  NLRI Value Encoding

   The Flow specification NLRI-type consists of several optional
   subcomponents.  A specific packet is considered to match the flow
   specification when it matches the intersection (AND) of all the
   components present in the specification.  The encoding of each of the
   NLRI components begins with a type field as listed in Table 1-4.
   Sections 4.2.1 to 4.2.12 contain the specific encodings for the IPv4
   IP layer and transport layer headings.  Additional filters encodiings
   are described in the following documents.

   o  IPv4 Header - this document,

   o  IPv6 Header - [I-D.ietf-idr-flow-spec-v6],

   o  MPLS label - [I-D.ietf-idr-flowspec-mpls-match],

   o  MAC Addresses - [I-D.ietf-idr-flowspec-l2vpn], and

   o  NV03 encapsulations - [I-D.ietf-idr-flowspec-nvo3].



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   o  Vendor Specific Flow Specifications (First Come First Served)
      specifications - range is defined in this document.

   Flow specification components must follow strict type ordering by
   increasing numerical order.  A given component type may or may not be
   present in the specification, but if present, it MUST precede any
   component of higher numeric type value.

   If a given component type within a prefix in unknown, the prefix in
   question cannot be used for traffic filtering purposes by the
   receiver.  Since a flow specification has the semantics of a logical
   AND of all components, if a component is FALSE, by definition it
   cannot be applied.  However, for the purposes of BGP route
   propagation, this prefix should still be transmitted since BGP route
   distribution is independent on NLRI semantics.

   The <type, value< encoding is chosen in order to allow for future
   extensibility.

































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      Table 1 - NLRI Types (IP values)
   +----+-------------------------+---------------------------+---+
   |Type| NLRI component          | Document                  |Req|
   +----+-------------------------+---------------------------+---+
   |  1 | IPv4 Destination Prefix |this document              |Yes|
   |    | IPv6 Destination Prefix |draft-ietf-idr-flow-spec-v6| No|
   +----+-------------------------+---------------------------+---+
   |  2 | IPv4 Source Prefix      |this document              | No|
   |    | IPv6 Source Prefix      |draft-ietf-idr-flow-spec-v6| No|
   +----+-------------------------+---------------------------+---+
   |  3 | IPv4 Protocol           |this document              | No|
   |    | IPv6 Next Header        |draft-ietf-idr-flow-spec-v6| No|
   +----+-------------------------+---------------------------+---+
   |  4 | Transport Port          |this document              | No|
   |    | (TCP/UDP source or      |                           |   |
   |    | destination port        |                           |   |
   +----+-------------------------+---------------------------+---+
   |  5 | Destination Port        |this document              | No|
   |    | (TCP or UDP)            |                           |   |
   +----+-------------------------+---------------------------+---+
   |  6 | Source Port (TCP/UDP)   |this document              | No|
   +----+-------------------------+---------------------------+---+
   |  7 | ICMP type               |this document              | No|
   +----+-------------------------+---------------------------+---+
   |  8 | ICMP Code               |this document              | No|
   +----+-------------------------+---------------------------+---+
   |  9 | TCP flags               |this document              | No|
   +----+-------------------------+---------------------------+---+
   | 10 | IP Packet length        |this document              | No|
   +----+-------------------------+---------------------------+---+
   | 11 | DSCP                    |this document              | No|
   +----+-------------------------+---------------------------+---+
   | 12 | IPv4 Fragment           |this document              | No|
   |    | IPv6 Fragment           |draft-ietf-idr-flow-spec-v6| No|
   +----+-------------------------+---------------------------+---+

      Table 2 - NLRI Types (L2VPN values)
   +----+-----------------+----------------------------------+---+
   |Type| NLRI component  | Document                         |Req|
   +----+-----------------+----------------------------------+---+
   |TBD1| MPLS Label      |draft-ietf-idr-flowspec-mpls-match| No|
   |    | on label stack  |                                  |   |
   +----+-----------------+----------------------------------+---+
   |TBD2| MPLS EXP bits   |draft-ietf-idr-flowspec-mpls-match| No|
   |    | on top of label |                                  |   |
   |    | stack           |                                  |   |
   +----+-----------------+----------------------------------+---+




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      Table 3 - NLRI Types (L2VPN values)
   +----+--------------------+-----------------------------+---+
   |Type| NLRI component     | Document                    |Req|
   +----+--------------------+-----------------------------+---+
   | 13 | Ethernet type      |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 14 | Flow Label         |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 15 | Source MAC         |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 16 | Destination MAC    |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 17 | DSAP in LLC        |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 18 | SSAP in LLC        |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 19 | LLC control field  |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 20 | SNAP               |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 21 | VLAN ID            |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 22 | VLAN COS           |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 23 | Inner VLAN ID      |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+
   | 24 | Inner VLAN COS     |draft-ietf-idr-flowspec-l2vpn| No|
   +----+--------------------+-----------------------------+---+

  Table 4 - NV03 Encapsulations
 +----+--------------------+-----------------------------+---+
 |Type| NLRI component     | Document                    |Req|
 +----+--------------------+-----------------------------+---+
 |TBD3| Delimiter type     |draft-ietf-idr-flowspec-nv03 | No|
 |    | (VXLAN or NVGRE)   |                             |   |
 +----+--------------------+-----------------------------+---+
 |TBD4| VNID               |draft-ietf-idr-flowspec-nv03 | No|
 +----+--------------------+-----------------------------+---+
 |TBD5| Flow ID (NVGRE)    |draft-ietf-idr-flowspec-nv03 | No|
 +----+--------------------+-----------------------------+---+                                  |

5.2.1.  Type 1 - Destination Prefix

      Encoding: <type (1 octet), prefix length (1 octet), prefix>

      Defines: the destination prefix to match.  Prefixes are encoded as
      in BGP UPDATE messages, a length in bits is followed by enough
      octets to contain the prefix information.



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5.2.2.  Type 2 - Source Prefix

      Encoding: <type (1 octet), prefix-length (1 octet), prefix>

      Defines the source prefix to match.

5.2.3.  Type 3 - Source Prefix

      Encoding:<type (1 octet), [op, value]+>

      Contains a set of {operator, value} pairs that are used to match
      the IP protocol value byte in IP packets.

      The operator byte is encoded as:

     0   1   2   3   4   5   6   7
   +---+---+---+---+---+---+---+---+
   | e | a |  len  | 0 |lt |gt |eq |
   +---+---+---+---+---+---+---+---+

        Numerical operator

      e - end-of-list bit.  Set in the last {op, value} pair in the
      list.

      a - AND bit.  If unset, the previous term is logically ORed with
      the current one.  If set, the operation is a logical AND.  It
      should be unset in the first operator byte of a sequence.  The AND
      operator has higher priority than OR for the purposes of
      evaluating logical expressions.

      len - length of the value field for this operand is given as (1 <<
      len).

      lt - less than comparison between data and value.

      gt - greater than comparison between data and value.

      eq -equality between data and value

   The bits lt, gt, and eq can be combined to produce "less or equal",
   "greater or equal", and inequality values

5.2.4.  Type 4 - Port

      Encoding:<type (1 octet), [op, value]+>





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      Defines a list of {operation, value} pairs that matches source OR
      destination TCP/UDP ports.  This list is encoded using the numeric
      operand format defined above.  Values are encoded as 1- or 2-byte
      quantities.

      Port, source port, and destination port components evaluate to
      FALSE if the IP protocol field of the packet has a value other
      than TCP or UDP, if the packet is fragmented and this is not the
      first fragment, or if the system in unable to locate the transport
      header.  Different implementations may or may not be able to
      decode the transport header in the presence of IP options or
      Encapsulating Security Payload (ESP) NULL [RFC4303] encryption.

5.2.5.  Type 5 - Destination Port

      Encoding:<type (1 octet), [op, value]+>

      Defines a list of {operation, value} pairs used to match the
      destination port of a TCP or UDP packet.  Values are encoded as 1-
      or 2-byte quantities

5.2.6.  Type 6 - Destination Port

      Encoding:<type (1 octet), [op, value]+>

      Defines a list of {operation, value} pairs used to match the
      source port of a TCP or UDP packet.  Values are encoded as 1- or
      2-byte quantities

5.2.7.  Type 7 - ICMP type

      Encoding:<type (1 octet), [op, value]+>

      Defines a list of {operation, value} pairs used to match the type
      field of an ICMP packet.  Values are encoded using a single byte.

      The ICMP type and code specifiers evaluate to FALSE whenever the
      protocol value is not ICMP.

5.2.8.  Type 8 - ICMP code

      Encoding:<type (1 octet), [op, value]+>

      Defines a list of {operation, value} pairs used to match the code
      field of an ICMP packet.  Values are encoded using a single byte.






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5.2.9.  Type 9 - ICMP code

      Encoding:<type (1 octet), [op, bitmask]+>

      Bitmask values can be encoded as a 1- or 2-byte bitmask.  When a
      single byte is specified, it matches byte 13 of the TCP header
      [RFC0793], which contains bits 8 though 15 of the 4th 32-bit word.
      When a 2-byte encoding is used, it matches bytes 12 and 13 of the
      TCP header with the data offset field having a "don't care" value.

      As with port specifiers, this component evaluates to FALSE for
      packets that are not TCP packets.

      This type uses the bitmask operand format, which differs from the
      numeric operator format in the lower nibble.

    0   1   2   3   4   5   6   7
   +---+---+---+---+---+---+---+---+
   | e | a |  len  | 0 | 0 |not| m |
   +---+---+---+---+---+---+---+---+

      Bitmask format

   e, a, len - Most significant nibble:  (end-of-list bit, AND bit, and
      length field), as defined for in the numeric operator format.

   not - NOT bit.  If set, logical negation of operation.

   m -   Match bit.  If set, this is a bitwise match operation defined
      as "(data AND value) == value"; if unset, (data AND value)
      evaluates to TRUE if any of the bits in the value mask are set in
      the data

5.2.10.  Type 10 - Packet length

      Encoding:<type (1 octet), [op, bitmask]+>

      Defines match on the total IP packet length (excluding Layer 2 but
      including IP header).  Values are encoded using 1- or 2-byte
      quantities.

5.2.11.  Type 11 - DSCP (Diffserv Code Point)

      Encoding:<type (1 octet), [op, value]+>

      Defines a list of {operation, value} pairs used to match the 6-bit
      DSCP field [RFC2474].  Values are encoded using a single byte,




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      where the two most significant bits are zero and the six least
      significant bits contain the DSCP value.

5.2.12.  Type 12 - Fragment

      Encoding:<type (1 octet), [op, bitmask]+>

      Uses bitmask operand format defined above in section 5.2.9.



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

      Bitmask values:

         Bit 7 - Don't fragment (DF)

         Bit 6 - Is a fragment (IsF)

         Bit 5 - First fragment (FF)

         Bit 4 - Last fragment (LF)

5.2.13.  Examples of Encodings

   An example of a flow specification encoding for: "all packets to
   10.0.1/24 and TCP port 25".

      +------------------+----------+----------+
      | destination      | proto    | port     |
      +------------------+----------+----------+
      | 0x01 18 0a 00 01 | 03 81 06 | 04 81 19 |
      +------------------+----------+----------+

   Decode for protocol:

      +-------+----------+------------------------------+
      | Value |          |                              |
      +-------+----------+------------------------------+
      |  0x03 | type     |                              |
      |  0x81 | operator | end-of-list, value size=1, = |
      |  0x06 | value    |                              |
      +-------+----------+------------------------------+





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   An example of a flow specification encoding for: "all packets to
   10.0.1/24 from 192/8 and port {range [137, 139] or 8080}".

      +------------------+----------+-------------------------+
      | destination      | source   | port                    |
      +------------------+----------+-------------------------+
      | 0x01 18 0a 01 01 | 02 08 c0 | 04 03 89 45 8b 91 1f 90 |
      +------------------+----------+-------------------------+

   Decode for port:

      +--------+----------+------------------------------+
      |  Value |          |                              |
      +--------+----------+------------------------------+
      |   0x04 | type     |                              |
      |   0x03 | operator | size=1, >=                   |
      |   0x89 | value    | 137                          |
      |   0x45 | operator | "AND", value size=1, <=      |
      |   0x8b | value    | 139                          |
      |   0x91 | operator | end-of-list, value-size=2, = |
      | 0x1f90 | value    | 8080                         |
      +--------+----------+------------------------------+


   This constitutes an NLRI with an NLRI length of 16 octets.

5.3.  Ordering of Traffic Filtering Rules

   With traffic filtering rules, more than one rule may match a
   particular traffic flow.  Thus, it is necessary to define the order
   at which rules get matched and applied to a particular traffic flow.
   This ordering function must be such that it must not depend on the
   arrival order of the flow specification's rules and must be constant
   in the network.

   The relative order of two flow specification rules is determined by
   comparing their respective components.  The algorithm starts by
   comparing the left-most components of the rules.  If the types
   differ, the rule with lowest numeric type value has higher precedence
   (and thus will match before) than the rule that doesn't contain that
   component type.  If the component types are the same, then a type-
   specific comparison is performed.

   For IP prefix values (IP destination and source prefix) precedence is
   given to the lowest IP value of the common prefix length; if the
   common prefix is equal, then the most specific prefix has precedence.





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   For all other component types, unless otherwise specified, the
   comparison is performed by comparing the component data as a binary
   string using the memcmp() function as defined by the ISO C standard.
   For strings of different lengths, the common prefix is compared.  If
   equal, the longest string is considered to have higher precedence
   than the shorter one.

   Pseudocode:

   flow_rule_cmp (a, b)
   {
       comp1 = next_component(a);
       comp2 = next_component(b);
       while (comp1 || comp2) {
           // component_type returns infinity on end-of-list
           if (component_type(comp1) < component_type(comp2)) {
               return A_HAS_PRECEDENCE;
           }
           if (component_type(comp1) > component_type(comp2)) {
               return B_HAS_PRECEDENCE;
           }

           if (component_type(comp1) == IP_DESTINATION || IP_SOURCE) {
               common = MIN(prefix_length(comp1), prefix_length(comp2));
               cmp = prefix_compare(comp1, comp2, common);
               // not equal, lowest value has precedence
               // equal, longest match has precedence
           } else {
               common =
                  MIN(component_length(comp1), component_length(comp2));
               cmp = memcmp(data(comp1), data(comp2), common);
               // not equal, lowest value has precedence
               // equal, longest string has precedence
           }
       }

       return EQUAL;
   }


5.4.  Validation Procedure

   Flow specifications received from a BGP peer and that are accepted in
   the respective Adj-RIB-In are used as input to the route selection
   process.  Although the forwarding attributes of two routes for the
   same flow specification 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.



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   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 non-feasible.  In the context of IP routing information,
   this step is used to validate that the NEXT_HOP attribute of a given
   route is resolvable.

   The concept can be extended, in the case of flow specification NLRI,
   to allow other validation procedures.

   A flow specification NLRI must be validated such that it is
   considered feasible if and only if:

      a) The originator of the flow specification matches the originator
      of the best-match unicast route for the destination prefix
      embedded in the flow specification.

      b) There are no more specific unicast routes, 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).

   By originator of a BGP route, we mean either the BGP originator path
   attribute, as used by route reflection, or the transport address of
   the BGP peer, if this path attribute is not present.

   The underlying concept is that the neighboring AS that advertises the
   best unicast route for a destination is allowed to advertise flow-
   spec information that conveys a more or equally specific destination
   prefix.  Thus, as long as there are no more specific unicast routes,
   received from a different neighboring AS, which would be affected by
   that filtering rule.

   The neighboring AS is the immediate destination of the traffic
   described by the flow specification.  If it requests these flows to
   be dropped, that request can be honored without concern that it
   represents a denial of service in itself.  Supposedly, the traffic is
   being dropped by the downstream autonomous system, and there is no
   added value in carrying the traffic to it.

   BGP implementations MUST also enforce that the AS_PATH attribute of a
   route received via the External Border Gateway Protocol (eBGP)
   contains the neighboring AS in the left-most position of the AS_PATH
   attribute.  While this rule is optional in the BGP specification, it
   becomes necessary to enforce it for security reasons.







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6.  Traffic Filtering Actions

   This specification defines a minimum set of filtering actions that it
   standardizes as BGP extended community values [RFC4360].  This is not
   meant to be an inclusive list of all the possible actions, but only a
   subset that can be interpreted consistently across the network.
   Additional actions can be defined as either requiring standards or as
   vendor specific.

   Implementations SHOULD provide mechanisms that map an arbitrary BGP
   community value (normal or extended) to filtering actions that
   require different mappings in different systems in the network.  For
   instance, providing packets with a worse-than-best-effort, per-hop
   behavior is a functionality that is likely to be implemented
   differently in different systems and for which no standard behavior
   is currently known.  Rather than attempting to define it here, this
   can be accomplished by mapping a user-defined community value to
   platform-/network-specific behavior via user configuration.

   The default action for a traffic filtering flow specification is to
   accept IP traffic that matches that particular rule.

   This document defines the following extended communities values shown
   in table X in the form 0x8xnn where nn indicates the sub-type.


    Table 5 - Traffic Action Extended Communities
              Defined in this document

    +--------+-----------------------+---------------------------+
    | type   | extended community    | encoding                  |
    +--------+-----------------------+---------------------------+
    | 0x8006 | traffic-rate in bytes | 2-byte ASN, 4-byte float  |
    | 0x8007 | traffic-action        | bitmask                   |
    | 0x8008 | redirect IPv4 AS-2byte| 2-octet ASN, 4-octet value|
    | 0x8108 | redirect IPv4 address | 4-octet IPv4 Address,     |
    |        |                       |  2-octet Value            |
    | 0x8208 | redirect IPv4 AS-4byte| 4-octet AS, 2-octet Value |
    | 0x8009 | traffic-marking       | DSCP value                |
    +--------+-----------------------+---------------------------+


   Encodings for these extended communities are described below.

   Some traffic action communities may interfere with each other.
   Section x.x of this specification provides rules for handling
   interference between specific types of traffic actions, and error
   handling based on [RFC7606] in section.  Each definition of a traffic



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   action MUST specify any interface with any other traffic actions, any
   impact on flow specification process, and error handling per
   [RFC7606].

   The traffic actions are processed in ascending order of the sub-type
   found in the BGP Extended Communities.

6.1.  Traffic Rate in bytes (sub-type 0x06)

   The traffic-rate extended community is a non- transitive extended
   community across the autonomous-system boundary and uses following
   extended community encoding:

   The first two octets carry the 2-octet id, which can be assigned from
   a 2-byte AS number.  When a 4-byte AS number is locally present, the
   2 least significant bytes of such an AS number can be used.  This
   value is purely informational and should not be interpreted by the
   implementation.

   The remaining 4 octets carry the maximum rate information in IEEE
   floating point [IEEE.754.1985] format, units being bytes per second.
   A traffic-rate of 0 should result on all traffic for the particular
   flow to be discarded.

   Interfers with: Traffic Rate in packets.  Process traffic rate in
   bytes (sub-type 0x06) action before traffic rate action (sub-type
   TBD).

6.2.  Traffic-action (sub-type 0x07)

   The traffic-action extended community consists of 6 bytes of which
   only the 2 least significant bits of the 6th byte (from left to
   right) are currently defined.

        40  41  42  43  44  45  46  47
       +---+---+---+---+---+---+---+---+
       |        reserved       | S | T |
       +---+---+---+---+---+---+---+---+

   where S and T are defined as:

   o  T: Terminal Action (bit 47): When this bit is set, the traffic
      filtering engine will apply any subsequent filtering rules (as
      defined by the ordering procedure).  If not set, the evaluation of
      the traffic filter stops when this rule is applied.

   o  S:Sample (bit 46): Enables traffic sampling and logging for this
      flow specification.



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   Interfers with: No other BGP Flow Specification traffic action in
   this document.

6.3.  IP Redirect (sub-type 0x08)

   The redirect extended community allows the traffic to be redirected
   to a VRF routing instance that lists the specified route-target in
   its import policy.  If several local instances match this criteria,
   the choice between them is a local matter (for example, the instance
   with the lowest Route Distinguisher value can be elected).  This
   extended community uses the same encoding as the Route Target
   extended community [RFC4360].

   It should be noted that the low-order nibble of the Redirect's Type
   field corresponds to the Route Target Extended Community format field
   (Type).  (See Sections 3.1, 3.2, and 4 of [RFC4360] plus Section 2 of
   [RFC5668].)  The low-order octet (Sub-Type) of the Redirect Extended
   Community remains 0x08 for all three encodings of the BGP Extended
   Communities (AS 2-byte, AS 4-byte, and IPv4 address).

   Interfers with: All other redirect functions.  All redirect functions
   are mutually exclusive.  If this redirect function exists, then no
   other redirect functions can be processed.

6.4.  Traffic Marking (sub-type 0x09)

   The traffic marking extended community instructs a system to modify
   the DSCP bits of a transiting IP packet to the corresponding value.
   This extended community is encoded as a sequence of 5 zero bytes
   followed by the DSCP value encoded in the 6 least significant bits of
   6th byte.

   Interfers with: No other action in this document.

6.5.  Rules on Traffic Action interference

   The following traffic Actions may interfere with each other:

   o  redirect actions,

   o  traffic rate actions, and

   o  encapsulation actions.

   This specification has the following rules regaarding multiple
   traffic actions to prevent the interference:





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   1.  All redirect actions are mutually exclusive.  Presence of more
       than one results in no redirect.

   2.  If multiple rate actions are present, these are applied in
       ascending order of the sub-type.

   3.  Some actions are unique, and may operate independently.  For
       example, an MPLS push/pop action is unique.

   4.  Each additional flow specification Action must specify:

       *  whether it is a redirect or rate action,

       *  whether the action is unique or if it interfers with other
          actions,

       *  If the action interfers with other actions, the handling must
          be specified if both the action and other interfering actions
          exist are associated with a Flow specification NLRI.

7.  Dissemination of Traffic Filtering in BGP/MPLS VPN Networks

   Provider-based Layer 3 VPN networks, such as the ones using a BGP/
   MPLS IP VPN [RFC4364] control plane, have different traffic filtering
   requirements than Internet service providers.  This document proposes
   an additional BGP NLRI type (AFI=1, SAFI=134) value, which can be
   used to propagate traffic filtering information in a BGP/MPLS VPN
   environment.

   The NLRI format for this address family consists of a fixed-length
   Route Distinguisher field (8 bytes) followed by a flow specification,
   following the encoding defined above in section x of this document.
   The NLRI length field shall include both the 8 bytes of the Route
   Distinguisher as well as the subsequent flow specification.

       +------------------------------+
       | length (0xnn or 0xfn nn)     |
       +------------------------------+
       | Route Distinguisher (8 bytes)|
       +------------------------------+
       |    NLRI value  (variable)    |
       +------------------------------+

            Figure 2: Flow-spec NLRI for MPLS

   Propagation of this NLRI is controlled by matching Route Target
   extended communities associated with the BGP path advertisement with




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   the VRF import policy, using the same mechanism as described in "BGP/
   MPLS IP VPNs" [RFC4364].

   Flow specification rules received via this NLRI apply only to traffic
   that belongs to the VRF(s) in which it is imported.  By default,
   traffic received from a remote PE is switched via an MPLS forwarding
   decision and is not subject to filtering.

   Contrary to the behavior specified for the non-VPN NLRI, flow rules
   are accepted by default, when received from remote PE routers.

7.1.  Validation Procedures for BGP/MPLS VPNs

   The validation procedures are the same as for IPv4.

7.2.  Traffic Actions Rules

   The traffic action rules are the same as for IPv4.

8.  Limitations of Previous Traffic Filtering Efforts

8.1.  Limitations in Previous DDOS Traffic Filtering Efforts

   The popularity of traffic-based, denial-of-service (DoS) attacks,
   which often requires the network operator to be able to use traffic
   filters for detection and mitigation, brings with it requirements
   that are not fully satisfied by existing tools.

   Increasingly, DoS mitigation requires coordination among several
   service providers in order to be able to identify traffic source(s)
   and because the volumes of traffic may be such that they will
   otherwise significantly affect the performance of the network.

   Several techniques are currently used to control traffic filtering of
   DoS attacks.  Among those, one of the most common is to inject
   unicast route advertisements corresponding to a destination prefix
   being attacked.  One variant of this technique marks such route
   advertisements with a community that gets translated into a discard
   Next-Hop by the receiving router.  Other variants attract traffic to
   a particular node that serves as a deterministic drop point.

   Using unicast routing advertisements to distribute traffic filtering
   information has the advantage of using the existing infrastructure
   and inter-AS communication channels.  This can allow, for instance, a
   service provider to accept filtering requests from customers for
   address space they own.





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   There are several drawbacks, however.  An issue that is immediately
   apparent is the granularity of filtering control: only destination
   prefixes may be specified.  Another area of concern is the fact that
   filtering information is intermingled with routing information.

   The mechanism defined in this document is designed to address these
   limitations.  We use the flow specification NLRI defined above to
   convey information about traffic filtering rules for traffic that
   should be discarded.

8.2.  Limitations in Previous BGP/MPLS Traffic Monitoring

   Provider-based Layer 3 VPN networks, such as the ones using a BGP/
   MPLS IP VPN [RFC4364] control plane, have different traffic filtering
   requirements than Internet service providers.

   In these environments, the VPN customer network often has traffic
   filtering capabilities towards their external network connections
   (e.g., firewall facing public network connection).  Less common is
   the presence of traffic filtering capabilities between different VPN
   attachment sites.  In an any-to-any connectivity model, which is the
   default, this means that site-to-site traffic is unfiltered.

   In circumstances where a security threat does get propagated inside
   the VPN customer network, there may not be readily available
   mechanisms to provide mitigation via traffic filter.

   The BGP Flow Specification version 1 addresses these limitations.

8.3.  Limitations in BGP Flow Specification for SDN/NFV Applications

   The SDN/NFV applications which use centralized control of network
   traffic via dynamic distribution of traffic filters can utilize the
   BGP Flow Specification version 1 described in this draft with a fixed
   order to traffic filter matches.  However, for control of large
   amounts of data a user-defined order to traffic matches and actions
   may be required.

9.  Traffic Monitoring

   Traffic filtering applications require monitoring and traffic
   statistics facilities.  While this is an implementation-specific
   choice, implementations SHOULD provide:

   o  A mechanism to log the packet header of filtered traffic.

   o  A mechanism to count the number of matches for a given flow
      specification rule.



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10.  IANA Considerations

   This section complies with [RFC7153]

10.1.  AFI/SAFI Definitions

   For the purpose of this work, IANA has allocated values for two
   SAFIs: SAFI 133 for IPv4 dissemination of flow specification rules
   and SAFI 134 for VPNv4 dissemination of flow specification rules.

10.2.  Flow Component definitions

   A flow specification consists of a sequence of flow components, which
   are identified by a an 8-bit component type.  Types must be assigned
   and interpreted uniquely.  The current specification defines types 1
   though 12, with the value 0 being reserved.

   IANA created and maintains a new registry entitled: "Flow Spec
   Component Types".  The following component types have been
   registered:

      Type 1 - Destination Prefix

      Type 2 - Source Prefix

      Type 3 - IP Protocol

      Type 4 - Port

      Type 5 - Destination port

      Type 6 - Source port

      Type 7 - ICMP type

      Type 8 - ICMP code

      Type 9 - TCP flags

      Type 10 - Packet length

      Type 11 - DSCP

      Type 12 - Fragment

   In order to manage the limited number space and accommodate several
   usages, the following policies defined by RFC 5226 [RFC5226] are
   used:



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      +--------------+-------------------------------+
      | Range        | Policy                        |
      +--------------+-------------------------------+
      | 0            | Invalid value                 |
      | [1 .. 12]    | Defined by this specification |
      | [13 .. 127]  | Specification Required        |
      | [128 .. 255] | First Come First Served       |
      +--------------+-------------------------------+

   The specification of a particular "flow component type" must clearly
   identify what the criteria used to match packets forwarded by the
   router is.  This criteria should be meaningful across router hops and
   not depend on values that change hop-by-hop such as TTL or Layer 2
   encapsulation.

   The "traffic-action" extended community defined in this document has
   46 unused bits, which can be used to convey additional meaning.  IANA
   created and maintains a new registry entitled: "Traffic Action
   Fields".  These values should be assigned via IETF Review rules only.
   The following traffic-action fields have been allocated:

      47 Terminal Action

      46 Sample

      0-45 Unassigned

10.3.  Extended Community Flow Specification Actions

   The Extended Community FLow Specification Action types consists of
   two parts: BGP Transitive Extended Community types and a set of sub-
   types.

   IANA has updated the following "BGP Transitive Extended Community
   Types" registries to contain the values listed below:

   0x80 -   Generic Transitive Experimental Use Extended Community Part
      1 (Sub-Types are defined in the "Generic Transitive Experimental
      Extended Community Part 1 Sub-Types" Registry)

   0x81 -   Generic Transitive Experimental Use Extended Community Part
      2 (Sub-Types are defined in the "Generic Transitive Experimental
      Extended Community Part 2 Sub-Types" Registry)

   0x82 -   Generic Transitive Experimental Use Extended Community Part
      3 (Sub-Types are defined in the "Generic Transitive Experimental
      Use Extended Community Part 3 Sub-Types" Registry)




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        RANGE              REGISTRATION PROCEDURE
        0x00-0xbf          First Come First Served
        0xc0-0xff          IETF Review

        SUB-TYPE VALUE     NAME                    REFERENCE
        0x00-0x05          unassigned
        0x06               traffic-rate            [this document]
        0x07               traffic-action          [this document]
        0x08               Flow spec redirect IPv4 [RFC5575] [RFC7674]
                                                       [this document]
        0x09               traffic-marking         [this document]
        0x10-0xff          Unassigned              [this document]

11.  Security Considerations

   Inter-provider routing is based on a web of trust.  Neighboring
   autonomous systems are trusted to advertise valid reachability
   information.  If this trust model is violated, a neighboring
   autonomous system may cause a denial-of-service attack by advertising
   reachability information for a given prefix for which it does not
   provide service.

   As long as traffic filtering rules are restricted to match the
   corresponding unicast routing paths for the relevant prefixes, the
   security characteristics of this proposal are equivalent to the
   existing security properties of BGP unicast routing.

   Where it is not the case, this would open the door to further denial-
   of-service attacks.

   Enabling firewall-like capabilities in routers without centralized
   management could make certain failures harder to diagnose.  For
   example, it is possible to allow TCP packets to pass between a pair
   of addresses but not ICMP packets.  It is also possible to permit
   packets smaller than 900 or greater than 1000 bytes to pass between a
   pair of addresses, but not packets whose length is in the range 900-
   1000.  Such behavior may be confusing and these capabilities should
   be used with care whether manually configured or coordinated through
   the protocol extensions described in this document.

12.  Contributing authors

   Pedro Marques and Nischal Sheth were authors on [RFC5575], and
   therefore are contributing authors on this document.







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13.  Acknowledgements

   The authors would like to thank Yakov Rekhter, Dennis Ferguson, Chris
   Morrow, Charlie Kaufman, and David Smith for their comments for the
   comments on the original [RFC5575].  Chaitanya Kodeboyina helped
   design the flow validation procedure; and Steven Lin and Jim Washburn
   ironed out all the details necessary to produce a working
   implementation in the original [RFC5575].

   Additional acknowledgements for this document will be included here.

14.  References

14.1.  Normative References

   [RFC0793]  Postel, J., "Transmission Control Protocol", STD 7,
              RFC 793, DOI 10.17487/RFC0793, September 1981,
              <http://www.rfc-editor.org/info/rfc793>.

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

   [RFC2474]  Nichols, K., Blake, S., Baker, F., and D. Black,
              "Definition of the Differentiated Services Field (DS
              Field) in the IPv4 and IPv6 Headers", RFC 2474,
              DOI 10.17487/RFC2474, December 1998,
              <http://www.rfc-editor.org/info/rfc2474>.

   [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,
              <http://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, <http://www.rfc-editor.org/info/rfc4360>.

   [RFC4364]  Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
              Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February
              2006, <http://www.rfc-editor.org/info/rfc4364>.

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




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   [RFC4761]  Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private
              LAN Service (VPLS) Using BGP for Auto-Discovery and
              Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007,
              <http://www.rfc-editor.org/info/rfc4761>.

   [RFC4762]  Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
              LAN Service (VPLS) Using Label Distribution Protocol (LDP)
              Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
              <http://www.rfc-editor.org/info/rfc4762>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

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

   [RFC5668]  Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS
              Specific BGP Extended Community", RFC 5668,
              DOI 10.17487/RFC5668, October 2009,
              <http://www.rfc-editor.org/info/rfc5668>.

   [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,
              <http://www.rfc-editor.org/info/rfc6241>.

   [RFC6482]  Lepinski, M., Kent, S., and D. Kong, "A Profile for Route
              Origin Authorizations (ROAs)", RFC 6482,
              DOI 10.17487/RFC6482, February 2012,
              <http://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, <http://www.rfc-editor.org/info/rfc7153>.

   [RFC7223]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
              <http://www.rfc-editor.org/info/rfc7223>.

   [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,
              <http://www.rfc-editor.org/info/rfc7606>.




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   [RFC7674]  Haas, J., Ed., "Clarification of the Flowspec Redirect
              Extended Community", RFC 7674, DOI 10.17487/RFC7674,
              October 2015, <http://www.rfc-editor.org/info/rfc7674>.

14.2.  Informative References

   [I-D.ietf-idr-bgp-flowspec-label]
              liangqiandeng, l., Hares, S., You, J., Raszuk, R., and d.
              danma@cisco.com, "Carrying Label Information for BGP
              FlowSpec", draft-ietf-idr-bgp-flowspec-label-00 (work in
              progress), June 2016.

   [I-D.ietf-idr-bgp-flowspec-oid]
              Uttaro, J., Filsfils, C., Smith, D., Alcaide, J., and P.
              Mohapatra, "Revised Validation Procedure for BGP Flow
              Specifications", draft-ietf-idr-bgp-flowspec-oid-03 (work
              in progress), March 2016.

   [I-D.ietf-idr-flow-spec-v6]
              McPherson, D., Raszuk, R., Pithawala, B.,
              akarch@cisco.com, a., and S. Hares, "Dissemination of Flow
              Specification Rules for IPv6", draft-ietf-idr-flow-spec-
              v6-07 (work in progress), March 2016.

   [I-D.ietf-idr-flowspec-interfaceset]
              Litkowski, S., Simpson, A., Patel, K., and J. Haas,
              "Applying BGP flowspec rules on a specific interface set",
              draft-ietf-idr-flowspec-interfaceset-01 (work in
              progress), June 2016.

   [I-D.ietf-idr-flowspec-l2vpn]
              Weiguo, H., liangqiandeng, l., Litkowski, S., and S.
              Zhuang, "Dissemination of Flow Specification Rules for L2
              VPN", draft-ietf-idr-flowspec-l2vpn-04 (work in progress),
              May 2016.

   [I-D.ietf-idr-flowspec-mpls-match]
              Yong, L., Hares, S., liangqiandeng, l., and J. You, "BGP
              Flow Specification Filter for MPLS Label", draft-ietf-idr-
              flowspec-mpls-match-00 (work in progress), May 2016.

   [I-D.ietf-idr-flowspec-nvo3]
              Weiguo, H., Zhuang, S., Li, Z., and R. Gu, "Dissemination
              of Flow Specification Rules for NVO3", draft-ietf-idr-
              flowspec-nvo3-00 (work in progress), May 2016.






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   [I-D.ietf-idr-flowspec-packet-rate]
              Eddy, W., Dailey, J., and G. Clark, "BGP Flow
              Specification Packet-Rate Action", draft-ietf-idr-
              flowspec-packet-rate-00 (work in progress), June 2016.

   [I-D.ietf-idr-wide-bgp-communities]
              Raszuk, R., Haas, J., Lange, A., Amante, S., Decraene, B.,
              Jakma, P., and R. Steenbergen, "Wide BGP Communities
              Attribute", draft-ietf-idr-wide-bgp-communities-02 (work
              in progress), May 2016.

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, DOI 10.17487/RFC4303, December 2005,
              <http://www.rfc-editor.org/info/rfc4303>.

   [RFC6074]  Rosen, E., Davie, B., Radoaca, V., and W. Luo,
              "Provisioning, Auto-Discovery, and Signaling in Layer 2
              Virtual Private Networks (L2VPNs)", RFC 6074,
              DOI 10.17487/RFC6074, January 2011,
              <http://www.rfc-editor.org/info/rfc6074>.

   [RFC6483]  Huston, G. and G. Michaelson, "Validation of Route
              Origination Using the Resource Certificate Public Key
              Infrastructure (PKI) and Route Origin Authorizations
              (ROAs)", RFC 6483, DOI 10.17487/RFC6483, February 2012,
              <http://www.rfc-editor.org/info/rfc6483>.

Authors' Addresses

   Robert Raszuk
   Bloomberg LP
   731 Lexington Ave
   New York City, NY  10022
   USA

   Email: robert@raszuk.net


   Danny McPherson
   Verisign
   US

   Email: dmcpherson@verisign.com








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   Jared Mauch
   NTT America
   101 Park Ave
   41st Floor
   New York, NY  10178
   US

   Email: jmauch@us.ntt.net


   Barry Greene
   Juniper Networks
   1194 N. Mathilda Ave.
   Sunnyvale, CA   94089
   US

   Email: bgreene@juniper.net


   Susan Hares
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   USA

   Email: shares@ndzh.com

























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