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Versions: 00 01 02 03 04 05                                             
IDR Working Group                                              R. Raszuk
Internet-Draft                                             Mirantis Inc.
Intended status: Standards Track                                R. White
Expires: October 28, 2015                                       Ericsson
                                                                 J. Dong
                                                     Huawei Technologies
                                                          April 26, 2015


                       BGP Path Record Attribute
                       draft-raszuk-idr-bgp-pr-03

Abstract

   The BGP protocol contains number of built in mechanisms which records
   information about the routers which have processed a specific piece
   of reachability information critical to insuring only loop free paths
   are chosen by the protocol.  For instance, the AS_PATH, CLUSTER_LIST
   and ORIGINATOR_ID attributes carry information designed to insure
   permanent routing loops are not formed in the path chosen towards a
   particular destination.  However, there are no provisions to record
   other useful information along the path, metadata about the routers
   through which reachability information has passed which can be
   helpful to the operator in order to enhance end to end visibility of
   the BGP control plane.

   In order to solve this problem this document proposes a new single
   BGP attribute designed as an generic and extensible container to
   carry number of new optional information corresponding to the BGP
   speakers given BGP advertisement (or withdraw) message traverses.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [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 http://datatracker.ietf.org/drafts/current/.





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   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 October 28, 2015.

Copyright Notice

   Copyright (c) 2015 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.  Protocol Extensions . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  BGP Path Record Attribute . . . . . . . . . . . . . . . .   3
     2.2.  BGP Per Hop TLV . . . . . . . . . . . . . . . . . . . . .   4
       2.2.1.  Host Name sub-TLV . . . . . . . . . . . . . . . . . .   6
       2.2.2.  Time Stamp sub-TLV  . . . . . . . . . . . . . . . . .   6
       2.2.3.  Next hop record sub-TLV . . . . . . . . . . . . . . .   6
       2.2.4.  Path count sub-TLV  . . . . . . . . . . . . . . . . .   7
       2.2.5.  Origin Validation sub-TLV . . . . . . . . . . . . . .   7
       2.2.6.  Geo-location sub-TLV  . . . . . . . . . . . . . . . .   7
       2.2.7.  BGP System Load sub-TLV . . . . . . . . . . . . . . .   8
   3.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   4.  Deployment considerations . . . . . . . . . . . . . . . . . .   9
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.  Security considerations . . . . . . . . . . . . . . . . . . .  10
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10







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1.  Introduction

   The ability to record various information from the midpoints through
   which given control plane information traverses seems would be a
   useful tool in number of control plane protocols.  For some use cases
   such information is critical and mandatory for correct operation
   while in other use cases this information could be used for further
   processing on or off line.

   Recently there have been two proposals discussing the need to carry
   opaque operational data in BGP Attributes proposed for such purposes.
   As it seems that there can be many more types of such data it will be
   more efficient to define a single TLV based placeholder to carry all
   optional hop parameters along the path given BGP prefix traverses in
   the network.

   To facilitate the transport of information that may be used within a
   BGP network, but is generally opaque to BGP processes, this document
   proposes the definition of new a BGP attribute called the BGP Path
   Record Attribute which can be used to to carry such new optional
   information.  This attribute is formatted to allow the inclusion of
   information of significance only to the local network operator
   (within the autonomous system).

2.  Protocol Extensions

   This document describes a new BGP attribute known as BGP Path Record
   Attribute which includes a new TLV and a number of sub-TLVs which can
   be used to carry new types of information.  Several types of
   information are defined in this document, and several others have
   been defined in other drafts but included here, as well.  The TLV is
   designed for easy extensibility as well as to accomodate the addition
   of information by each BGP speaker through within a path.

   The TLVs are appended by each participating BGP speaker in the order
   in which the BGP speaker handles the data; hence the order of the
   TLVs and sub-TLVs MUST NOT be changed in local storage or when
   transmitted between BGP speakers.

   The sub-TLVs on the other hand allow for very easy definition of new
   types of data which may be required to be carried both within this
   document as well as by new subsequent documents.

2.1.  BGP Path Record Attribute

   The BGP Path Record attribute is a new BGP optional transitive
   attribute.  The attribute type code for the Path Record attribute is
   to be assigned by IANA.  The value field of the Path Record attribute



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   is defined as a set of one or more Path Record TLVs along with their
   sub-TLVs.

2.2.  BGP Per Hop TLV

   The BGP Per Hop TLV is defined as follows:



           0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              TYPE             |            LENGTH             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                         BGP ROUTER ID                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          AS NUMBER                            |
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          |                             FLAGS                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                           sub-TLVs                            ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                     Figure 1: BGP Per Hop Type 1 TLV

   TYPE: Two octets encoding the Path Record TLV Type.  Each distinct
   type of Path record TLV is assigned a unique identifier as noted in
   this draft.  Further identifiers should be assigned through the
   creation of a new IANA registry and be assigned on a "first come
   first served" basis.  Type 1 TLV is called BGP Hop TLV

   LENGTH: Two octets encoding the length in octets of the Path Record
   TLV, excluding the type and length fields.  The Length is encoded as
   an unsigned binary integer.

   BGP ROUTER ID (4 octets): 4 octet BGP router ID assigned to a given
   BGP speaker processing prefix with path containing BGP Path Record
   Attribute.

   AS NUMBER (4 octets): 4 octet AS number or zero padded 2 octet AS
   number of the autonomous system BGP Hop belongs to.

   FLAGS: Number of boolean flags describing BGP Hop basic
   characteristics.  The following flags are defined for BGP Hop TLV:

   Bit 0:



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         NH - Next Hop - Values: 0 - next hop not set; 1 - next hop set
   Bit 1:
         RR - Route Reflector - Values: 0 - not a route reflector; 1 -
         route reflector
   Bit 2:
         RS - Route Server - Values: 0 - not route server; 1 - route
         server
   Bit 3:
         B - Beacon prefix - Values: 0 - not a special beacon prefix; 1
         - special beacon prefix
   Bits 4-31:
         Reserved for future use

   sub-TLVs: Variable length sub-TLVs describing various information
   pertaining to the TLV they are nested under.  The general format of a
   sub-TLV is illustrated below:



           0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              TYPE             |            LENGTH             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      ~                             VALUE                             ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



                         Figure 2: sub-TLV format

   TYPE (2 octets): The sub-TLV type used to differentiate information
   types carried in the context of given TLV.

   LENGTH (2 octets): The length in octets of the sub-TLV, excluding the
   type and length fields.  The Length is encoded as an unsigned binary
   integer.

   VALUE: Variable length field described in the context of each sub-
   TLV.

   The following optional sub-TLVs are proposed in this document to be
   carried under BGP Hop TLV:

   o  Type 1 - Host Name sub-TLV
   o  Type 2 - Time Stamp sub-TLV
   o  Type 3 - Next Hop record sub-TLV
   o  Type 4 - Path Count sub-TLV



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   o  Type 5 - Origin Validation sub-TLV
   o  Type 6 - Geo-location sub-TLV
   o  Type 7 - BGP System Load sub-TLV

2.2.1.  Host Name sub-TLV

   Type:
         1
   Length:
         Length of sub-TLV in octets.
   Value:
         UTF-8 encoded BGP speaker hostname.
   Description:
         Useful for enhance display in number of direct or indirect show
         commands and operational logs.

2.2.2.  Time Stamp sub-TLV

   Type:
         2
   Length:
         10 octets
   Value:
         8 octets - BGP UPDATE message receive timestamp,
         1 octet - flags; Bit 0 - T flag (synchronized to external
         clock) Bits 1-7 - reserved.
         1 octet - Sync type as described in [RFC5905],
   Description:
         For full details of this sub-TLV use case and architecture are
         described in separate document:
         [I-D.litkowski-idr-bgp-timestamp]

2.2.3.  Next hop record sub-TLV

   Type:
         3
   Length:
         5 octets or 17 octets
   Flags:
         Bit 0: Set if next hop is third party next hop Bits 1-7:
         Reserved
   Value:
         IPv4 or IPv6 address of the next hop changed by current BGP Hop
   Description:
         For full details of this sub-TLV use case and architecture are
         described in separate document:
         [I-D.zhang-idr-nexthop-path-record]




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2.2.4.  Path count sub-TLV

   Type:
         4
   Length:
         2 octets
   Value:
         Integer indicating number of paths present for a given prefix
         in BGP speaker.
   Description:
         Enables easy visibility in validation of expected propagation
         model for multiple paths of given prefix.  Can validate
         effectiveness of various BGP mechanisms (best-external, bgp
         diverse path, bgp add-paths etc ...) (TBD .. should we include
         how many paths are marked as stale ?)

2.2.5.  Origin Validation sub-TLV

   Type:
         5
   Length:
         10 octets
   Value:
         8 octets - Last time BGP Origin Validation database has been
         updated.
         1 octet - flags; Bit 0 - T flag (synchronized to external
         clock) Bits 1-7 - reserved.
         1 octet - Sync type as described in [RFC5905],
   Description:
         Allows to easily detect issues associated with possible lack of
         synchronization of Origin Validation local database.

2.2.6.  Geo-location sub-TLV

   Type:
         6
   Length:
         16 octets
   Value:
         Proposed encoding follows IETF consensus for representation of
         coordinate based location.










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         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
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |  LatUnc   |                  Latitude                         +
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Lat (cont'd)  |  LongUnc  |               Longitude           +
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Longitude (cont'd)         | AType |   AltUnc  |  Altitude +
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |               Altitude (cont'd)               |Ver| Res |Datum|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                  Figure 3: Geo-location encoding format
   Description:
         Allows to map BGP control plane hops taken by BGP
         advertisements to two or three dimensional geo location
         coordinates of participating BGP speakers.  Encoding details
         are described in [RFC6225] (DHCP geo-location options
         document).

2.2.7.  BGP System Load sub-TLV

   Type:
         7
   Length:
         2 octets
   Value:
         1 octet - avg last 15 min of CPU utilization in percent by BGP
         process/thread
         1 octet - avg last 15 min of BGP process memory use to total
         available memory use in percent
   Description:
         Used as indicator of possible CPU or memory problems of any
         given participating BGP speaker along the BGP control plane
         path.  To prevent unnecessary churn implementation should only
         append it upon BGP update generation as well as inserted value
         should be an avrage over configurable time (default: 15 sec).

3.  Operation

   The proposed new BGP Path Record attribute is an opaque entity for
   BGP operation and as such there is no requirement for any direct
   modification to BGP operation or BGP state machine based on the
   information it contains.  It is expected that such feedback loop will
   be performed by operator either by automated or manual process.





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   Operator should be able to allow or deny origination of BGP Path
   Record attribute or insertion of any TLV or sub-TLV into BGP UPDATE
   message.  It is however recommended that given BGP implementation
   adds available sub-TLVs to BGP Hop TLV when particular prefix has
   been received with BGP Path Record Attribute already containing such
   sub-TLVs.

   BGP policy should be enhanced to allow for easy filtering of BGP Path
   Record attribute both on egress as well as ingress eBGP sessions.

   BGP Path Record attribute can be used within any AFI/SAFI.

4.  Deployment considerations

   It needs to be recognized that some sub-TLVs of BGP Hop TLV of BGP
   Path Record attribute can break update packing.  Therefor it is
   strongly recommended that sub-TLVs type 2, 4, 7 as defined above are
   to be used only for specific beacon prefixes injected into BGP
   control plane by operator and flagged with the "B" bit within the
   originating BGP Hop TLV.

   Beacon prefixes due to the store-and-forward nature of P2MP BGP
   distribution for information correctness should be carefully injected
   and withdrawn from entire network before subsequent injection is to
   take place again.

5.  IANA Considerations

   This document defines a new BGP attribute known as a BGP Path Record
   Attribute.  The code point for a new BGP Path Record attribute has to
   be assigned by IANA from the BGP Path Attributes registry.

   This document requests IANA to define and maintain a new registry
   named: "BGP Path Record Attribute TLV types".  The reserved pool of
   0x0000-0xFFFF has been defined for its allocations.  The allocations
   policy is on a first come first served basis.  The recommended
   allocation of 0x0001 is to be allocated for BGP Hop TLV.

   This document requests IANA to define and maintain a new registry
   named: "BGP Hop sub-TLV types".  The reserved pool of 0x0000-0xFFFF
   has been defined for its allocations.  The allocations policy is on a
   first come first served basis.  The recommended allocation of first 7
   sub-TLVs are indicated in section 2.2 titled: BGP Hop TLV.








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6.  Security considerations

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

7.  Acknowledgements

   Authors would like to acknowledge Stephane Litkowski for his valuable
   input, review and comments.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4223]  Savola, P., "Reclassification of RFC 1863 to Historic",
              RFC 4223, October 2005.

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

8.2.  Informative References

   [I-D.litkowski-idr-bgp-timestamp]
              Litkowski, S., Patel, K., and J. Haas, "Timestamp support
              for BGP paths", draft-litkowski-idr-bgp-timestamp-00 (work
              in progress), July 2014.

   [I-D.zhang-idr-nexthop-path-record]
              Li, Z., Zhang, L., and S. Hares, "NEXTHOP_PATH_RECORD
              ATTIBUTE for BGP", draft-zhang-idr-nexthop-path-record-00
              (work in progress), July 2014.

   [RFC5905]  Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network
              Time Protocol Version 4: Protocol and Algorithms
              Specification", RFC 5905, June 2010.

   [RFC6225]  Polk, J., Linsner, M., Thomson, M., and B. Aboba, "Dynamic
              Host Configuration Protocol Options for Coordinate-Based
              Location Configuration Information", RFC 6225, July 2011.

Authors' Addresses







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   Robert Raszuk
   Mirantis Inc.
   615 National Ave. #100
   Mt View, CA  94043
   USA

   Email: robert@raszuk.net


   Russ White
   Ericsson
   Oak Island, NC  28465
   USA

   Email: russw@riw.us


   Jie Dong
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Rd.
   Beijing  100095
   China

   Email: jie.dong@huawei.com



























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