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BGP Dissemination of Flow Specification Rules for Tunneled Traffic
draft-ietf-idr-flowspec-nvo3-07

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This is an older version of an Internet-Draft whose latest revision state is "Active".
Authors Donald E. Eastlake 3rd , Hao Weiguo , Shunwan Zhuang , Zhenbin Li , Rong Gu
Last updated 2019-11-04 (Latest revision 2019-07-08)
Replaces draft-hao-idr-flowspec-nvo3
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draft-ietf-idr-flowspec-nvo3-07
INTERNET-DRAFT                                               D. Eastlake
Intended Status: Proposed Standard                Futurewei Technologies
                                                                  W. Hao
                                                               S. Zhuang
                                                                   Z. Li
                                                     Huawei Technologies
                                                                   R. Gu
                                                             China Mobil
Expires: May 3, 2020                                    November 4, 2019

                          BGP Dissemination of
             Flow Specification Rules for Tunneled Traffic
                    draft-ietf-idr-flowspec-nvo3-07

Abstract
   This draft specifies a Border Gateway Protocol Network Layer
   Reachability Information (BGP NLRI) encoding format for flow
   specifications (RFC 5575bis) that can match on a variety of tunneled
   traffic. In addition, flow specification components are specified for
   certain tunneling header fields.

Status of This Document

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

   Distribution of this document is unlimited. Comments should be sent
   to the authors or the IDR Working Group mailing list <idr@ietf.org>.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
   Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

D. Eastlake, et al                                              [Page 1]
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Table of Contents

      1. Introduction............................................3
      1.1 Terminology............................................3

      2. Tunneled Traffic Flow Specification NLRI................5
      2.1 SAFI Code Point........................................6
      2.2 Component Code Points..................................6
      2.3 Specific Tunnel Types..................................8
      2.3.1 VXLAN................................................8
      2.3.2 VXLAN-GPE............................................8
      2.3.3 NVGRE................................................9
      2.3.4 L2TPv3...............................................9
      2.3.5 GRE.................................................10
      2.3.6 IP-in-IP............................................10
      2.4 Tunneled Traffic Actions..............................11

      3. Order of Traffic Filtering Rules.......................12
      4. Flow Spec Validation...................................13

      5. Security Considerations................................13
      6. IANA Considerations....................................13

      Normative References......................................14
      Informative References....................................15

      Acknowledgments...........................................16
      Authors' Addresses........................................16

D. Eastlake, et al                                              [Page 2]
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1. Introduction

   BGP Flow-spec [RFC5575bis] is an extension to BGP that supports the
   dissemination of traffic flow specification rules.  It uses the BGP
   control plane to simplify the distribution of Access Control Lists
   (ACLs) and allows new filter rules to be injected to all BGP peers
   simultaneously without changing router configuration. A typical
   application of BGP Flow-spec is to automate the distribution of
   traffic filter lists to routers for Distributed Denial of Service
   (DDOS) mitigation.

   BGP Flow-spec defines a BGP Network Layer Reachability Information
   (NLRI) format used to distribute traffic flow specification rules.
   AFI=1/SAFI=133 is for IPv4 unicast filtering. AFI=1/SAFI=134 is for
   IPv4 BGP/MPLS VPN filtering. [FlowSpecV6] and [Layer2- FlowSpec]
   extend the flow-spec rules for IPv6 and layer 2 Ethernet packets
   respectively. All these previous flow specifications match only a
   single level of IP/Ethernet information fields such as
   source/destination IP prefix, protocol type, source/destination MAC,
   ports, EtherType and the like.

   In the cloud computing era, multi-tenancy has become a core
   requirement for data centers. It is increasingly common to see
   tunneled traffic with a field to distinguish tenants. An example is
   the Network Virtualization Over Layer 3 (NVO3 [RFC8014]) overlay
   technology that can satisfy multi-tenancy key requirements. VXLAN
   [RFC7348] and NVGRE [RFC7637] are two typical NVO3 encapsulations.
   Other encapsulations such as IP-in-IP or GRE may be encountered.
   Because these tunnel / overlay technologies involving an additional
   level of encapsulation, flow specification that can match on the
   inner header as well as the outer header are needed.

   In summary, the Flow specifications should be able to include inner
   nested header information as well as fields specific to the type of
   tunneling in use such as virtual network / tenant ID. This draft
   specifies methods for accomplishing this using SAFI=TBD1 and a new
   NLRI encoding.

1.1 Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

D. Eastlake, et al                                              [Page 3]
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   The reader is assumed to be familiar with BGP terminology. The
   following terms and acronyms are used in this document with the
   meaning indicated:

   ACL - Access Control List

   DDOS - Distributed Denial of Service (Attack)

   DSCP - Differentiated Services Code Point

   GRE - Generic Router Encapsulation [RFC2890]

   L2TPv3 - Layer Two Tunneling Protocol - Version 3 [RFC3931]

   NLRI - Network Layer Reachability Information

   NVGRE - Network Virtualization Using Generic Routing Encapsulation
      [RFC7637]

   NVO3 - Network Virtual Overlay Layer 3 [RFC8014]

   VN - virtual network

   VXLAN - Virtual eXtensible Local Area Network [RFC7348]

D. Eastlake, et al                                              [Page 4]
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2. Tunneled Traffic Flow Specification NLRI

   The Flow-spec rules in [RFC5575bis], [FlowSpecV6], and [FlowSpecL2]
   can only recognize flows based on one level of header in a data
   packet. To enable flow specification of tunneled traffic, a new SAFI
   (TBD1) and NLRI encoding are introduced. This encoding, shown in
   Figure 1, enables flow specification of more than one layer of header
   when needed.

         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
         | Length                          2 bytes       |
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
         | Tunnel Type                     2 bytes       |
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
       Flags:
         +--+--+--+--+--+--+--+--+
         | D| I| Reserved        |         1 byte
         +--+--+--+--+--+--+--+--+
       Optional Routing Discriminator:
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
         |                                               |
         +                                               +
         |                                               |
         + Routing Discriminator           8 bytes       +
         |                                               |
         +                                               +
         |                                               |
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
       Outer Flow-spec:
         +--+--+--+--+--+--+--+--+
         | Outer Flowspec Length :         1 or 2 bytes
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
         | Outer Flowspec                  variable      :
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
       Optional Inner Flow-spec:
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
         | Inner AFI                       2 bytes       |
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
         | Inner Flowspec Length :         1 or 2 bytes
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
         | Inner Flowspec                  variable      :
         +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

                    Figure 1. Tunneled Traffic Flow-spec NLRI

   Length - The NLRI Length encoded as an unsigned integer including the
         Tunnel Type.

   Tunnel Type - The type of tunnel using a value from the IANA BGP
         Tunnel Encapsulation Attribute Tunnel Types registry.

D. Eastlake, et al                                              [Page 5]
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   Flags: D bit - Indicates the presence of the Routing Discriminator
         (see below).

   Flags: I bit - Indicates the presence of an inner AFI and Flow-spec.

   Flags: Reserved - Six bits that MUST be sent as zero and ignored on
         receipt.

   Routing Discriminator - If the outer layer 3 address belongs to a
         BGP/MPLS VPN, the routing discriminator can be included to
         support traffic filtering within that VPN. Because NVO3 outer
         layer addresses normally belong to a public network, a Route
         Distinguisher field is normally not needed for NVO3.

   Outer Flowspec / Length - The flow specification for the outer
         header. The length is encoded as provided in Section 4.1 of
         [RFC5575bis]. The AFI for the outer flowspec is that AFI at the
         beginning of the BGP multiprotocol MP_REACH_NLRI or
         MP_UNREACH_NLRI containing the tunneled traffic flow
         specification NLRI.

   Inner AFI - Depending on the Tunnel Type, there may be an inner AFI
         that indicates the address family for the inner flow
         specification. There is no need for a SAFI as it is
         automatically TBD1, the SAFI for a tunneled traffic flow
         specification.

   Inner Flowspec / Length - Depending on the Tunnel Type, there may be
         an inner flow specification for the header level encapsulated
         within the outer header. The length is encoded as provided in
         Section 4.1 of [RFC5575bis].

2.1 SAFI Code Point

   Use of the tunneled traffic flow specification NLRI format is
   indicated by SAFI=TBD1. This is used in conjunction with the AFI for
   the outer layer 3 header, that is AFI=1 for IPv4 and AFI=2 for IPv6.

2.2 Component Code Points

   For flow specification based on certain tunnel header fields, the
   component types below are added. These are associated with the Tunnel
   Type and MAY appear in the outer flow specification or, if it is
   present, in the inner flow specification.

D. Eastlake, et al                                              [Page 6]
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      Type TBD2 - VN ID
      Encoding: <type (1 octet), length (1 octet), [op, value]+>.

         Defines a list of {operation, value} pairs used to match the
         24-bit VN ID that is used as the tenant identification in some
         tunneling headers. For VXLAN encapsulation, the VN ID is the
         VNI. For NVGRE encapsulation, the VN ID is the VSID. op is
         encoded as specified in Section 4.2.3 of [RFC5575bis]. Values
         are encoded as 1- to 3-byte quantities.

      Type TBD3 - Flow ID
      Encoding: <type (1 octet), length (1 octet), [op, value]+>

         Defines a list of {operation, value} pairs used to match 8-bit
         Flow ID fields which are currently only useful for NVGRE
         encapsulation. op is encoded as specified in Section 4.2.3 of
         [RFC5575bis]. Values are encoded as 1-byte quantity.

      Type TBD4 - Session
      Encoding: <type (1 octet), length (1 octet), [op, value]+>

         Defines a list of {operation, value} pairs used to match a
         32-bit Session field. This field is called Key in GRE [RFC2890]
         encapsulation and Session ID in L2TPv3 encapsulation. op is
         encoded as specified in Section 4.2.3 of [RFC5575bis]. Values
         are encoded as a 1, 2, or 4 byte quantity.

      Type TBD5 - Cookie
      Encoding: <type (1 octet), length (1 octet), [op, value]+>

         Defines a list of {operation, value} pairs used to match a
         variable length Cookie field. This is only useful in L2TPv3
         encapsulation. op is encoded as specified in Section 4.2.3 of
         [RFC5575bis]. Values are encoded as a 1, 2, 4, or 8 byte
         quantity. If the Cookie does not fit exactly into the value
         length, it is left justified, that is, padded with following
         bytes the MUST be sent as zero and ignored on receipt.

      Type TBD6 - VXLAN-GPE Flags
      Encoding: <type (1 octet), length (1 octet), [op, bitmask]+>

         Defines a list of {operation, value} pairs used to match
         against the VSLAN-GPE flags field. op is encoded as in Section
         4.2.9 of [RFC5575bis]. bitmask is encoded as 1 byte.

D. Eastlake, et al                                              [Page 7]
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2.3 Specific Tunnel Types

   The following subsections describe how to handle flow specification
   for several specific tunnel types.

2.3.1 VXLAN

   The headers on a VXLAN [RFC7348] data packet are an outer Ethernet
   header, an outer IP header, a UDP header, the VXLAN header, and an
   inner Ethernet header. This inner Ethernet header is frequently, but
   not always, followed by an inner IP header. If the tunnel type is
   VXLAN, the I flag MUST be set.

   The version (IPv4 or IPv6) of the outer IP header is indicated by the
   AFI at the beginning of the multiprotocol MP_REACH_NLRI or
   MP_UNREACH_NLRI containing the tunneled traffic flow specification
   NLRI.  The outer flowspec is used to filter the outer headers and the
   UDP header.

   The inner flowspec is used on the Inner Ethernet header [FlowSpecL2].
   If the inner AFI is 25, then whether or not an IP header follows the
   inner Ethernet header is ignored and the inner flowspec SHOULD NOT
   contain and IPv4 or IPv6 flowspec components.  If the inner AFI is 1
   or 2, to match the flowspec the Inner Ethernet header must be
   followed by an IPv4 or IPv6 header, respectively, and the inner
   flowspec is also used to filter that inner IP header.

   A component filtering on the VXLAN header VN ID (VNI) can appear in
   either the outer or inner flowspec. The inner MAC/IP address is
   associated with a VN ID. In the NVO3 terminating into a VPN scenario,
   if multiple access VN IDs map to one VPN instance, one shared VN ID
   can be carried in the Flow-Spec rule to enforce the rule on the
   entire VPN instance and the shared VN ID and VPN correspondence
   should be configured on each VPN PE beforehand. In this case, the
   function of the layer 3 VN ID is the same as a Route Discriminator:
   it acts as the identification of the VPN instance.

2.3.2 VXLAN-GPE

   VXLAN-GPE [GPE] is similar to VXLAN and the VXLAN-GPE header is the
   same size as the VXLAN header but has been extended from the VXLAN
   header by specifying a number of bits that are reserved in the VXLAN
   header. In particular, a number of additional flag bits are specified
   and a Next Protocol field is added that is valid if the P flag bit is
   set.  These flags bits can be tested using the VXLAN-GPE Flags
   component defined above. VXLAN and VXLAN-GPE are distinguished by the

D. Eastlake, et al                                              [Page 8]
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   port number in the UDP header the precedes the VXLAN or VXLAN-GPE
   headers.

   If the VXLAN-GPE header P flag is zero, then the header is followed
   by the same sequence as for VXLAN and the same flow-spec choices
   apply (see Section 2.3.1).

   If the VXLAN-GPE header P flag is one and that header's next protocol
   field is 1, then the VXLAN-GPE header is followed by an IPv4 header.
   The inner AFI/flowspec match only if the inner AFI is 1 and the inner
   flowspec matches.

   If the VXLAN-GPE header P flag is one and that header's next protocol
   field is 2, then the VXLAN-GPE header is followed by an IPv6 header.
   The inner AFI/flowspec match only if the inner AFI is 2 and the inner
   flowspec matches.

2.3.3 NVGRE

   NVGRE [RFC7637] is very similar to VXLAN except that the UDP header
   and VXLAN header immediately after the outer IP header are replaced
   by a GRE (Generic Router Encapsulation) header. The GRE header as
   used in NVGRE has no Checksum or Reserved1 field as shown in
   [RFC2890] but there are Virtual Subnet ID and FlowID fields in place
   of what is labeled in [RFC2890] as the Key field. Processing and
   restrictions for NVGRE are as in Section 2.3.1 eliminating references
   to a UDP header and replacing references to the VXLAN header and its
   VN ID with references to the GRE header and its VN ID (VSID) and Flow
   ID.

2.3.4 L2TPv3

   The headers on an L2TPv3 [RFC3931] packets are an outer Ethernet
   header, an outer IP header, the L2TPv3 header, an inner Ethernet
   header, and possibly an inner IP header if indicated by the inner
   Ethernet header EtherType. The outer flowspec operates on the outer
   headers that precede the GRE header. The version of IP is specified
   by the outer AFI at the beginning of the MP_REACH_NLRI or
   MP_UNREACH_NLRI.

   The L2TPv3 header consists of a 32-bit Session ID followed by a
   variable length Cookie (maximum length 8 bytes). The Session ID and
   Cookie can be filtered for by using the Session and Cookie flowspec
   components. To filter on Cookie or even be able to bypass Cookie and
   parse the remainder of the L2TPv3 packet, the node implementing
   flowspec needs to know the length and/or value of the Cookie fields

D. Eastlake, et al                                              [Page 9]
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   of interest. This is negotiated at L2TPv3 session establishment and
   it is out of scope for this document how the node would learn this
   information. Of course, if flowspec is being used for DDOS mitigation
   and the Cookie has a fixed length and/or value in the DDOS traffic,
   this could be learned by inspecting that traffic.

   If the I flag bit is zero, then no filtering is done on data beyond
   the L2TPv3 header. If the I flag is one, indicating the presence of
   an inner flowspec, and the node implementing flowspec does not know
   the length of the L2TPv3 header Cookie, the match fails. If that node
   does know the length of that Cookie, the inner flowspec if matched
   against the headers at the beginning of that data using the inner
   AFI. If the inner AFI is 1 or 2, then an inner IP header is required
   and filtering can be done on the Ethernet header immediately after
   the L2TPv3 header and the following IPv4 or IPv6 headers
   respectively. If the inner AFI is 25, filtering SHOULD only be done
   on the inner Ethernet header [FlowSpecL2].

2.3.5 GRE

   Generic Router Encapsulation (GRE [RFC2890]) is a common type of
   encapsulation. The outer flowspec operates on the outer headers that
   precede the GRE header. The version of IP is specified by the outer
   AFI at the beginning of the MP_REACH_NLRI or MP_UNREACH_NLRI.

   If the I flag bit is zero, no filtering is done on data after the GRE
   header. If the I flag bit is one, then there is an inner AFI and
   flowspec and the Protocol Type field of the GRE header must match the
   inner AFI as follows for the flowspec to match:

       GRE Protocol Type    Inner AFI
      -------------------  -----------
       0x0800  (IPv4)             1
       0x86DD  (IPv6)             2
       0x6558                    25

   With the I flag a one and the inner AFI and GRE Protocol Type fields
   match, the inner flowspec is used to filter the inner Ethernet header
   (AFI=25) or the inner IP and Ethernet headers (AFI=1 or 2).

2.3.6 IP-in-IP

   IP-in-IP encapsulation is shown when the outer IP header indicates an
   inner IP IPv4 or IPv6 header by the value of the outer IP header's
   Protocol (IPv4) or Next Protocol (IPv6) field. If the Tunnel Type is
   IP-in-IP, the I flag MUST be set.

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   The version of the outer IP header (IPv4 or IPv6) matched is
   indicated by the AFI at the beginning of the MP_REACH_NLRI or
   MP_UNREACH_NLRI.  The version of the inner IP header is indicated by
   the inner AFI. The outer flowspec applies to the outer IP header and
   the inner flowspec applies to the inner IP header.

2.4 Tunneled Traffic Actions

   The previously specified traffic filtering actions are used for
   tunneled traffic [RFC5575bis] [FlowSpecL2]. For Traffic Marking in
   NVO3, only the DSCP in the outer header can be modified.

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3. Order of Traffic Filtering Rules

   In comparing an applicable tunneled traffic flow specification with a
   non-tunneled flow specification, the tunneled specification has
   precedence.

   If comparing two tunneled traffic flow specifications, if both are
   applicable, the tunnel types will be the same. If only one has a
   Routing Discriminator, it has precedence. If both have a Routing
   Discriminator, those discriminators are compared as unsigned integers
   and the one with the smaller magnitude Routing Discriminator has
   precedence.

   If neither has a Routing Discriminator or they have equal Routing
   Discriminators, the order of precedence is determined by comparing
   the outer flowspec.

   If the outer flowspecs are equal and the tunnel type calls for an
   inner flowspec, then the precedence is determined by comparing inner
   AFI as an unsigned integer with the inner AFI having the smaller
   magnitude having precedence.

   If the inner AFIs are equal, precedence is determined by comparing
   the inner flow specifications.

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4. Flow Spec Validation

   Flow-specs received over AFI=1/SAFI=TBD1 or AFI=2/SFAI=TBD1 are
   validated, using only the outer Flow-spec, against routing
   reachability received over AFI=1/SAFI=133 and AFI=2/SAFI=133
   respectively, as modified by [FlowSpecOID].

5. Security Considerations

   No new security issues are introduced to the BGP protocol by this
   specification.

6. IANA Considerations

   IANA is requested to assign a new SAFI as follows:

      Value  Description                                 Reference
      ----- ------------------------------------------  ---------------
       TBD1  Tunneled traffic flow specification rules  [This document]

   IANA is requested to assign two new values in the "Flow Spec
   Component Types" registry as follows:

      Type    Name            Reference
      ----   --------------   ---------
      TBD2   VN ID            [this document]
      TBD3   Flow ID          [this document]
      TBD4   Session          [this document]
      TBD5   Cookie           [this document]
      TBD6   VXLAN-GPE Flags  [this document]

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Normative References

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

   [RFC2890] - Dommety, G., "Key and Sequence Number Extensions to GRE",
         RFC 2890, DOI 10.17487/RFC2890, September 2000,
         <https://www.rfc-editor.org/info/rfc2890>.

   [RFC3931] - Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed.,
         "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931,
         DOI 10.17487/RFC3931, March 2005, <https://www.rfc-
         editor.org/info/rfc3931>.

   [RFC7348] - Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
         L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
         eXtensible Local Area Network (VXLAN): A Framework for
         Overlaying Virtualized Layer 2 Networks over Layer 3 Networks",
         RFC 7348, DOI 10.17487/RFC7348, August 2014, <https://www.rfc-
         editor.org/info/rfc7348>.

   [RFC7637] - Garg, P., Ed., and Y. Wang, Ed., "NVGRE: Network
         Virtualization Using Generic Routing Encapsulation", RFC 7637,
         DOI 10.17487/RFC7637, September 2015, <https://www.rfc-
         editor.org/info/rfc7637>.

   [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>.

   [FlowSpecL2] - W. Hao, etc, "Dissemination of Flow Specification
         Rules for L2 VPN", draft-ietf-idr-flowspec-l2vpn, work in
         progress.

   [FlowSpecOID] - J. Uttaro, J. Alcaide, C. Filsfils, D. Smith, P.
         Mohapatra, "Revised Validation Procedure for BGP Flow
         Specifications", draft-ietf-idr-bgp-flowspec-oid, work in
         progress.

   [FlowSpecV6] - R. Raszuk, etc, "Dissemination of Flow Specification
         Rules for IPv6", draft-ietf-idr-flow-spec-v6, work in progress.

   [RFC5575bis] - Hares, S., Loibl, C., Raszuk, R., McPherson, D.,
         Bacher, M., "Dissemination of Flow Specification Rules", draft-
         ietf-idr-rfc5575bis-17, Work in progress, January 2019.

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Informative References

   [RFC8014] - Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
         Narten, "An Architecture for Data-Center Network Virtualization
         over Layer 3 (NVO3)", RFC 8014, DOI 10.17487/RFC8014, December
         2016, <https://www.rfc-editor.org/info/rfc8014>.

   [GPE] - P. Quinn, etc, "Generic Protocol Extension for VXLAN", draft-
         ietf-nvo3-vxlan-gpe, work in progress.

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Acknowledgments

   The authors wish to acknowledge the important contributions of Jeff
   Haas, Susan Hares, Qiandeng Liang, Nan Wu, Yizhou Li, Robert Raszuk,
   and Lucy Yong.

Authors' Addresses

      Donald Eastlake
      Futurewei Technologies
      2386 Panoramic Circle
      Apopka, FL 32703 USA

      Tel: +1-508-333-2270
      Email: d3e3e3@gmail.com

      Weiguo Hao
      Huawei Technologies
      101 Software Avenue,
      Nanjing 210012 China

      Email: haoweiguo@huawei.com

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

      Email: zhuangshunwan@huawei.com

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

      Email: lizhenbin@huawei.com

      Rong Gu
      China Mobile

      Email: gurong_cmcc@outlook.com

D. Eastlake, et al                                             [Page 16]
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D. Eastlake, et al                                             [Page 17]