Network Working Group                                            H. Wang
Internet-Draft                                                    Huawei
Intended status: Standards Track                                 A. Wang
Expires: August 16, 2022                                   China Telecom
                                                               S. Zhuang
                                                                  Huawei
                                                       February 12, 2022


       Destination-IP-Origin-AS Filter for BGP Flow Specification
            draft-wang-idr-flowspec-dip-origin-as-filter-05

Abstract

   BGP Flowspec mechanism (BGP-FS) [RFC8955] [RFC8956] propagates both
   traffic Flow Specifications and Traffic Filtering Actions by making
   use of the BGP NLRI and the BGP Extended Community encoding formats.
   This document specifies a new BGP-FS component type to support AS-
   level filtering.  The match field is the origin AS number of the
   destination IP address that is encoded in the Flowspec NLRI.  This
   function is applied in a single administrative domain.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

Status of This Memo

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

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

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

   This Internet-Draft will expire on August 16, 2022.







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Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions and Acronyms  . . . . . . . . . . . . . . . . . .   3
   3.  The Flow Specification Encoding for Destination-IP-Origin-AS
       Filter  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Use Case  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  IANA  . . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   BGP Flow Specification (BGP-FS) [RFC8955] [RFC8956] defines a new BGP
   NLRI to distribute traffic flow specification rules via BGP
   ([RFC4271]).  BGP-FS policies have a match condition that may be
   n-tuple match in a policy, and an action that modifies the packet and
   forwards/drops the packet.  Via BGP, new filter rules can be sent to
   all BGP peers simultaneously without changing router configuration,
   and the BGP peer can install these routes in the forwarding table.
   BGP-FS defines Network Layer Reachability Information (NLRI) format
   used to distribute traffic flow specification rules.  NLRI (AFI=1,
   SAFI=133) is for IPv4 unicast filtering.  NLRI (AFI=1, SAFI=134) is
   for BGP/MPLS VPN filtering.[I-D.ietf-idr-flowspec-l2vpn][I-D.ietf-
   idr-flowspec-l2vpn] extends the flow-spec rules for layer 2 Ethernet
   packets.

   This document specifies a new BGP-FS component type to support AS-
   level filtering.  The match field is the origin AS number of the




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   destination IP address that is encoded in the Flowspec NLRI.  This
   function is applied in a single administrative domain.

2.  Definitions and Acronyms

   o  FS: Flow Specification

   o  Destination-IP-Origin-AS: The origin AS number of the destination
      IP address

3.  The Flow Specification Encoding for Destination-IP-Origin-AS Filter

   This document proposes a new flow specification component type that
   is encoded in the BGP Flowspec NLRI.  The following new component
   type is defined.

   o  Destination-IP-Origin-AS

   Type TBD1 - Destination-IP-Origin-AS

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

   Contains a set of {operator, value} pairs that are used to match the
   Destination-IP-Origin-AS (i.e. the origin AS number of the
   destination IP address).

   The operator byte is encoded as:

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


   Where:

   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 MUST be
   unset in the Destination-IP-Origin-AS filter.

   len - The length of the value field for this operator given as (1 <<
   len).  This encodes 1 (len=00), 2 (len=01), 4 (len=10), and 8
   (len=11) octets.

   lt - less than comparison between data and value.




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   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 match the
   Destination-IP-Origin-AS filter or a range of Destination-IP-Origin-
   AS filter(e.g. less than AS1 and greater than AS2).

   The value field is encoded as:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +---------------------------------------------------------------+
     ~       Destination-IP-Origin-AS  (4 octets)                    ~
     +---------------------------------------------------------------+

   Per section 10 of [RFC8955] , If a receiving BGP speaker cannot
   support this new Flow Specification component type, it MUST discard
   the NLRI value field that contains such unknown components.  Since
   the NLRI field encoding (Section 4 of [RFC8955]) is defined in the
   form of a 2-tuple <length, NLRI value>, message decoding can skip
   over the unknown NLRI value and continue with subsequent remaining
   NLRI.

4.  Use Case

   This section describes how to use this function in a simple scenario.
   Considering the topology shown in Figure 1.  In AS64597's R1, if the
   ISP AS64597 wants to redirect all packets originating from IP Prefix
   61 to AS64598, first go to R3, then forward them to AS64598", the ISP
   AS64597 can use the traditional method or the method defining in this
   draft.



















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                            +---------+
                            | BGP FS  |
                            | Server  |
                            +----|----+
                                 |
                                 |
                                 /
                                /
                   ************/************  IP Prefix 81
                   *          /            *  IP Prefix 82
     IP Prefix 61  *         / AS64597     *  IP Prefix 83
                   *        /              *  IP Prefix 84
      +-------+    *  +---+/        +---+  *   +-------+
      +AS64596+-------+ R1+---------+ R2|------+AS64598+
      +-------+    *  +-+-+\        +---+  */  +-------+
                   *        \         |\   /
                   *         \        | \ /*  IP Prefix 91
                   *          \       |  /\*  IP Prefix 92
                   *           \      | /  \  IP Prefix 93
                   *            \     |/   *\ IP Prefix 94
                   *             \  +-+-+  * \ +-------+
                   *              \-+ R3+------+AS64599+
                   *                +---+  *   +-------+
                   *                       *
                   *************************
     Figure 1: Redirect the traffic using Flowspec


   Using the traditional method, the ISP AS64597 needs to setup multiple
   "Destination Prefix + Source Prefix" rules in Router R1 as following:

       +--------------+--------------+-------------------------+
       | Destination  | Source Prefix| Redirect to IP Nexthop  |
       | Prefix       |              |                         |
       +--------------+--------------+-------------------------+
       | IP Prefix 81 | IP Prefix 61 |       R3                |
       +--------------+--------------+-------------------------+
       | IP Prefix 82 | IP Prefix 61 |       R3                |
       +--------------+--------------+-------------------------+
       | IP Prefix 83 | IP Prefix 61 |       R3                |
       +--------------+--------------+-------------------------+
       | IP Prefix 84 | IP Prefix 61 |       R3                |
       +--------------+--------------+-------------------------+
       |                  More...                              |
       +--------------+--------------+-------------------------+

     Figure 2: Using the traditional method to redirect the traffic




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   Using the method defining in this draft, the ISP AS64597 needs to
   setup only one "Destination Origin AS + Source Prefix" rule in Router
   R1 as following:

   +--------------+--------------+-------------------------+
   | Destination  | Source Prefix| Redirect to IP Nexthop  |
   | IP Origin AS |              |                         |
   +--------------+--------------+-------------------------+
   |  64598       | IP Prefix 61 |       R3                |
   +--------------+--------------+-------------------------+

   Figure 3: Using the AS-level filtering method to redirect the traffic


   Obviously, the new method defining in this draft saves a lot of entry
   spaces on the control plane and forwarding plane, and it would
   greatly simplify the operation of the control plane, and the more
   destination prefixes an AS has, the more obvious the benefit.

5.  Security Considerations

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

6.  IANA

   IANA is requested to a new entry in "Flow Spec component types
   registry" with the following values:

      +----------------------------------------------------------+
      |   Type  | RFC or Draft |    Description                  |
      +----------------------------------------------------------+
      |   TBD1  |  This Draft  |    Destination-IP-Origin-AS     |
      +----------------------------------------------------------+


7.  Contributors

   TBD

8.  Acknowledgments

   The authors would like to acknowledge the review and inputs from Gang
   Yan, Zhenbin Li, Rainbow Wu, Jie Dong and Ziqing Cao.







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9.  References

   [I-D.ietf-idr-flowspec-l2vpn]
              Hao, W., Eastlake, D. E., Litkowski, S., and S. Zhuang,
              "BGP Dissemination of L2 Flow Specification Rules", draft-
              ietf-idr-flowspec-l2vpn-18 (work in progress), October
              2021.

   [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>.

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

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

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

Authors' Addresses

   Haibo Wang
   Huawei
   156 Beiqing Road
   Beijing  100095
   P.R. China

   Email: rainsword.wang@huawei.com


   Aijun Wang
   China Telecom
   Beiqijia Town, Changping District
   Beijing  102209
   P.R. China

   Email: wangaj3@chinatelecom.cn





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   Shunwan Zhuang
   Huawei
   156 Beiqing Road
   Beijing  100095
   P.R. China

   Email: zhuangshunwan@huawei.com












































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