Support for Adj-RIB-Out in BGP Monitoring Protocol (BMP)
draft-ietf-grow-bmp-adj-rib-out-07

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Replaces draft-evens-grow-bmp-adj-rib-out
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Global Routing Operations                                       T. Evens
Internet-Draft                                              S. Bayraktar
Updates: 7854 (if approved)                                Cisco Systems
Intended status: Standards Track                              P. Lucente
Expires: February 6, 2020                             NTT Communications
                                                                   P. Mi
                                                                 Tencent
                                                               S. Zhuang
                                                                  Huawei
                                                          August 5, 2019

        Support for Adj-RIB-Out in BGP Monitoring Protocol (BMP)
                   draft-ietf-grow-bmp-adj-rib-out-07

Abstract

   The BGP Monitoring Protocol (BMP) defines access to only the Adj-RIB-
   In Routing Information Bases (RIBs).  This document updates the BGP
   Monitoring Protocol (BMP) RFC 7854 by adding access to the Adj-RIB-
   Out RIBs.  It adds a new flag to the peer header to distinguish Adj-
   RIB-In and Adj-RIB-Out.

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
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   This Internet-Draft will expire on February 6, 2020.

Copyright Notice

   Copyright (c) 2019 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

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   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.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Per-Peer Header . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Adj-RIB-Out . . . . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Post-Policy . . . . . . . . . . . . . . . . . . . . . . .   4
     5.2.  Pre-Policy  . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  BMP Messages  . . . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Route Monitoring and Route Mirroring  . . . . . . . . . .   5
     6.2.  Statistics Report . . . . . . . . . . . . . . . . . . . .   5
     6.3.  Peer Down and Up Notifications  . . . . . . . . . . . . .   6
       6.3.1.  Peer Up Information . . . . . . . . . . . . . . . . .   6
   7.  Other Considerations  . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Peer and Update Groups  . . . . . . . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     9.1.  BMP Peer Flags  . . . . . . . . . . . . . . . . . . . . .   8
     9.2.  BMP Statistics Types  . . . . . . . . . . . . . . . . . .   8
     9.3.  Peer Up Information TLV . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   9
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   BGP Monitoring Protocol (BMP) defines monitoring of the received
   (e.g., Adj-RIB-In) Routing Information Bases (RIBs) per peer.  The
   Adj-RIB-In pre-policy conveys to a BMP receiver all RIB data before
   any policy has been applied.  The Adj-RIB-In post-policy conveys to a
   BMP receiver all RIB data after policy filters and/or modifications
   have been applied.  An example of pre-policy versus post-policy is
   when an inbound policy applies attribute modification or filters.
   Pre-policy would contain information prior to the inbound policy
   changes or filters of data.  Post policy would convey the changed
   data or would not contain the filtered data.

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   Monitoring the received updates that the router received before any
   policy has been applied is the primary level of monitoring for most
   use-cases.  Inbound policy validation and auditing is the primary
   use-case for enabling post-policy monitoring.

   In order for a BMP receiver to receive any BGP data, the BMP sender
   (e.g., router) needs to have an established BGP peering session and
   actively be receiving updates for an Adj-RIB-In.

   Being able to only monitor the Adj-RIB-In puts a restriction on what
   data is available to BMP receivers via BMP senders (e.g., routers).
   This is an issue when the receiving end of the BGP peer is not
   enabled for BMP or when it is not accessible for administrative
   reasons.  For example, a service provider advertises prefixes to a
   customer, but the service provider cannot see what it advertises via
   BMP.  Asking the customer to enable BMP and monitoring of the Adj-
   RIB-In is not feasible.

   BGP Monitoring Protocol (BMP) RFC 7854 [RFC7854] only defines Adj-
   RIB-In being sent to BMP receivers.  This document updates the per-
   peer header in section 4.2 of [RFC7854] by adding a new flag to
   distinguish Adj-RIB-In versus Adj-RIB-Out. BMP senders use the new
   flag to send either Adj-RIB-In or Adj-RIB-Out.

   Adding Adj-RIB-Out provides the ability for a BMP sender to send to
   BMP receivers what it advertises to BGP peers, which can be used for
   outbound policy validation and to monitor routes that were
   advertised.

2.  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 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
   appear in all capitals, as shown here.

3.  Definitions

   o  Adj-RIB-Out: As defined in [RFC4271], "The Adj-RIBs-Out contains
      the routes for advertisement to specific peers by means of the
      local speaker's UPDATE messages."

   o  Pre-Policy Adj-RIB-Out: The result before applying the outbound
      policy to an Adj-RIB-Out. This normally would match what is in the
      local RIB.

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   o  Post-Policy Adj-RIB-Out: The result of applying outbound policy to
      an Adj-RIB-Out. This MUST convey to the BMP receiver what is
      actually transmitted to the peer.

4.  Per-Peer Header

   The per-peer header has the same structure and flags as defined in
   section 4.2 of [RFC7854] with the following O flag addition:

                              0 1 2 3 4 5 6 7
                             +-+-+-+-+-+-+-+-+
                             |V|L|A|O| Resv  |
                             +-+-+-+-+-+-+-+-+

   o  The O flag indicates Adj-RIB-In if set to 0 and Adj-RIB-Out if set
      to 1.

   The existing flags are defined in section 4.2 of [RFC7854] and the
   remaining bits are reserved for future use.  They MUST be transmitted
   as 0 and their values MUST be ignored on receipt.

   When the O flag is set to 1, the following fields in the Per-Peer
   Header are redefined:

   o  Peer Address: The remote IP address associated with the TCP
      session over which the encapsulated PDU is sent.

   o  Peer AS: The Autonomous System number of the peer to which the
      encapsulated PDU is sent.

   o  Peer BGP ID: The BGP Identifier of the peer to which the
      encapsulated PDU is sent.

   o  Timestamp: The time when the encapsulated routes were advertised
      (one may also think of this as the time when they were installed
      in the Adj-RIB-Out), expressed in seconds and microseconds since
      midnight (zero hour), January 1, 1970 (UTC).  If zero, the time is
      unavailable.  Precision of the timestamp is implementation-
      dependent.

5.  Adj-RIB-Out

5.1.  Post-Policy

   The primary use-case in monitoring Adj-RIB-Out is to monitor the
   updates transmitted to a BGP peer after outbound policy has been
   applied.  These updates reflect the result after modifications and
   filters have been applied (e.g., Adj-RIB-Out Post-Policy).  Some

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   attributes are set when the BGP message is transmitted, such as next-
   hop.  Adj-RIB-Out Post-Policy MUST convey to the BMP receiver what is
   actually transmitted to the peer.

   The L flag MUST be set to 1 to indicate post-policy.

5.2.  Pre-Policy

   Similarly to Adj-RIB-In policy validation, pre-policy Adj-RIB-Out can
   be used to validate and audit outbound policies.  For example, a
   comparison between pre-policy and post-policy can be used to validate
   the outbound policy.

   Depending on BGP peering session type (IBGP, IBGP route reflector
   client, EBGP, BGP confederations, Route Server Client) the candidate
   routes that make up the Pre-Policy Adj-RIB-Out do not contain all
   local-rib routes.  Pre-Policy Adj-RIB-Out conveys only routes that
   are available based on the peering type.  Post-Policy represents the
   filtered/changed routes from the available routes.

   Some attributes are set only during transmission of the BGP message,
   i.e., Post-Policy.  It is common that next-hop may be null, loopback,
   or similar during pre-policy phase.  All mandatory attributes, such
   as next-hop, MUST be either ZERO or have an empty length if they are
   unknown at the Pre-Policy phase completion.  The BMP receiver will
   treat zero or empty mandatory attributes as self-originated.

   The L flag MUST be set to 0 to indicate pre-policy.

6.  BMP Messages

   Many BMP messages have a per-peer header but some are not applicable
   to Adj-RIB-In or Adj-RIB-Out monitoring, such as peer up and down
   notifications.  Unless otherwise defined, the O flag should be set to
   0 in the per-peer header in BMP messages.

6.1.  Route Monitoring and Route Mirroring

   The O flag MUST be set accordingly to indicate if the route monitor
   or route mirroring message conveys Adj-RIB-In or Adj-RIB-Out.

6.2.  Statistics Report

   The Statistics report message has a Stat Type field to indicate the
   statistic carried in the Stat Data field.  Statistics report messages
   are not specific to Adj-RIB-In or Adj-RIB-Out and MUST have the O
   flag set to zero.  The O flag SHOULD be ignored by the BMP receiver.

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   The following new statistic types are added:

   o  Stat Type = 14: (64-bit Gauge) Number of routes in Adj-RIBs-Out
      Pre-Policy.

   o  Stat Type = 15: (64-bit Gauge) Number of routes in Adj-RIBs-Out
      Post-Policy.

   o  Stat Type = 16: Number of routes in per-AFI/SAFI Adj-RIB-Out Pre-
      Policy.  The value is structured as: 2-byte Address Family
      Identifier (AFI), 1-byte Subsequent Address Family Identifier
      (SAFI), followed by a 64-bit Gauge.

   o  Stat Type = 17: Number of routes in per-AFI/SAFI Adj-RIB-Out Post-
      Policy.  The value is structured as: 2-byte Address Family
      Identifier (AFI), 1-byte Subsequent Address Family Identifier
      (SAFI), followed by a 64-bit Gauge.

6.3.  Peer Down and Up Notifications

   Peer Up and Down notifications convey BGP peering session state to
   BMP receivers.  The state is independent of whether or not route
   monitoring or route mirroring messages will be sent for Adj-RIB-In,
   Adj-RIB-Out, or both.  BMP receiver implementations SHOULD ignore the
   O flag in Peer Up and Down notifications.

6.3.1.  Peer Up Information

   The following Peer Up message Information TLV type is added:

   o  Type = 4: Admin Label.  The Information field contains a free-form
      UTF-8 string whose byte length is given by the Information Length
      field.  The value is administratively assigned.  There is no
      requirement to terminate the string with null or any other
      character.

      Multiple admin labels can be included in the Peer Up notification.
      When multiple admin labels are included the BMP receiver MUST
      preserve their order.

      The TLV is optional.

7.  Other Considerations

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7.1.  Peer and Update Groups

   Peer and update groups are used to group updates shared by many
   peers.  This is a level of efficiency in implementations, not a true
   representation of what is conveyed to a peer in either Pre-Policy or
   Post-Policy.

   One of the use-cases to monitor Adj-RIB-Out Post-Policy is to
   validate and continually ensure the egress updates match what is
   expected.  For example, wholesale peers should never have routes with
   community X:Y sent to them.  In this use-case, there may be hundreds
   of wholesale peers but a single peer could have represented the
   group.

   From a BMP perspective, this should be simple to include a group name
   in the Peer Up, but it is more complex than that.  BGP
   implementations have evolved to provide comprehensive and structured
   policy grouping, such as session, AFI/SAFI, and template-based based
   group policy inheritances.

   This level of structure and inheritance of polices does not provide a
   simple peer group name or ID, such as wholesale peer.

   Instead of requiring a group name to be used, a new administrative
   label informational TLV (Section 6.3.1) is added to the Peer Up
   message.  These labels have administrative scope relevance.  For
   example, labels "type=wholesale" and "region=west" could be used to
   monitor expected policies.

   Configuration and assignment of labels to peers is BGP implementation
   specific.

8.  Security Considerations

   The same considerations as in section 11 of [RFC7854] apply to this
   document.  Implementations of this protocol SHOULD require to
   establish sessions with authorized and trusted monitoring devices.
   It is also believed that this document does not add any additional
   security considerations.

9.  IANA Considerations

   This document requests that IANA assign the following new parameters
   to the BMP parameters name space [1].

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9.1.  BMP Peer Flags

   This document defines the following per-peer header flags
   (Section 4):

   o  Flag 3 as O flag: The O flag indicates Adj-RIB-In if set to 0 and
      Adj-RIB-Out if set to 1.

9.2.  BMP Statistics Types

   This document defines four statistic types for statistics reporting
   (Section 6.2):

   o  Stat Type = 14: (64-bit Gauge) Number of routes in Adj-RIBs-Out
      Pre-Policy.

   o  Stat Type = 15: (64-bit Gauge) Number of routes in Adj-RIBs-Out
      Post-Policy.

   o  Stat Type = 16: Number of routes in per-AFI/SAFI Adj-RIB-Out Pre-
      Policy.  The value is structured as: 2-byte Address Family
      Identifier (AFI), 1-byte Subsequent Address Family Identifier
      (SAFI), followed by a 64-bit Gauge.

   o  Stat Type = 17: Number of routes in per-AFI/SAFI Adj-RIB-Out Post-
      Policy.  The value is structured as: 2-byte Address Family
      Identifier (AFI), 1-byte Subsequent Address Family Identifier
      (SAFI), followed by a 64-bit Gauge.

9.3.  Peer Up Information TLV

   This document defines the following BMP Peer Up Information TLV types
   (Section 6.3.1):

   o  Type = 4: Admin Label.  The Information field contains a free-form
      UTF-8 string whose byte length is given by the Information Length
      field.  The value is administratively assigned.  There is no
      requirement to terminate the string with null or any other
      character.

      Multiple admin labels can be included in the Peer Up notification.
      When multiple admin labels are included the BMP receiver MUST
      preserve their order.

      The TLV is optional.

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10.  References

10.1.  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>.

   [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>.

   [RFC7854]  Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
              Monitoring Protocol (BMP)", RFC 7854,
              DOI 10.17487/RFC7854, June 2016,
              <https://www.rfc-editor.org/info/rfc7854>.

   [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>.

10.2.  URIs

   [1] https://www.iana.org/assignments/bmp-parameters/bmp-
       parameters.xhtml

Acknowledgements

   The authors would like to thank John Scudder and Mukul Srivastava for
   their valuable input.

Contributors

   Manish Bhardwaj
   Cisco Systems
   3700 Cisco Way
   San Jose, CA 95134
   USA

   Email: manbhard@cisco.com

   Xianyuzheng
   Tencent
   Tencent Building, Kejizhongyi Avenue,
   Hi-techPark, Nanshan District,Shenzhen 518057, P.R.China

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   Weiguo
   Tencent
   Tencent Building, Kejizhongyi Avenue,
   Hi-techPark, Nanshan District,Shenzhen 518057, P.R.China

   Shugang cheng
   H3C

Authors' Addresses

   Tim Evens
   Cisco Systems
   2901 Third Avenue, Suite 600
   Seattle, WA  98121
   USA

   Email: tievens@cisco.com

   Serpil Bayraktar
   Cisco Systems
   3700 Cisco Way
   San Jose, CA  95134
   USA

   Email: serpil@cisco.com

   Paolo Lucente
   NTT Communications
   Siriusdreef 70-72
   Hoofddorp, WT  2132
   NL

   Email: paolo@ntt.net

   Penghui Mi
   Tencent
   Tengyun Building,Tower A ,No. 397 Tianlin Road
   Shanghai  200233
   China

   Email: kevinmi@tencent.com

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

   Email: zhuangshunwan@huawei.com

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