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Versions: (draft-scudder-bmp) 00 01 02 03 04 05 06

Network Working Group                                         J. Scudder
Internet-Draft                                               R. Fernando
Intended status: Standards Track                        Juniper Networks
Expires: October 10, 2009                                      S. Stuart
                                                                  Google
                                                           April 8, 2009


                        BGP Monitoring Protocol
                         draft-ietf-grow-bmp-01

Status of this Memo

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

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   This Internet-Draft will expire on October 10, 2009.

Copyright Notice

   Copyright (c) 2009 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 in effect on the date of
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   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Abstract

   This document proposes a simple protocol, BMP, which can be used to



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   monitor BGP sessions.  BMP is intended to provide a more convenient
   interface for obtaining route views for research purpose than the
   screen-scraping approach in common use today.  The design goals are
   to keep BMP simple, useful, easily implemented, and minimally
   service-affecting.  BMP is not suitable for use as a routing
   protocol.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  3
   2.  BMP Message Format . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Route Monitoring . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  Stats Reports  . . . . . . . . . . . . . . . . . . . . . .  6
     2.3.  Peer Down Notification . . . . . . . . . . . . . . . . . .  7
   3.  Route Monitoring . . . . . . . . . . . . . . . . . . . . . . .  8
   4.  Stat Reports . . . . . . . . . . . . . . . . . . . . . . . . .  8
   5.  Using BMP  . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10


























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1.  Introduction

   Many researchers wish to have access to the contents of routers' BGP
   RIBs as well as a view of protocol updates that the router is
   receiving.  This monitoring task cannot be realized by standard
   protocol mechanisms.  At present, this data can only be obtained
   through screen-scraping.

   The BMP protocol provides access to the Adj-RIB-In of a peer on an
   ongoing basis and a periodic dump of certain statistics that the
   monitoring station can use for further analysis.  The following are
   the messages provided by BMP.

   o  Route Monitoring (RM): An initial dump of all routes received from
      a peer as well as an ongoing mechanism that sends the incremental
      routes advertised and withdrawn by a peer to the monitoring
      station.

   o  Peer Down Notification (PD): A message sent to indicate that a
      peering session has gone down with information indicating the
      reason for the session disconnect.

   o  Stats Reports (SR): This is an ongoing dump of statistics that can
      be used by the monitoring station as a high level indication of
      the activity going on in the router.

   BMP operates over TCP.  All options are controlled by configuration
   on the monitored router.  Communication is unidirectional, from the
   monitored router to the monitoring station.

   The monitoring station is configured to listen on a particular TCP
   port and the router is configured to establish an active connection
   to that port and to send messages on that TCP connection.  There is
   no initialization or handshaking phase, messages are simply sent as
   soon as the connection is established.

   If the monitoring station intends to restart BMP processing, it
   simply drops the connection.  The router then re-establishes the
   connection and resends the messages.

1.1.  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].






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2.  BMP Message Format

   The following common header appears in all BMP messages.  The rest of
   the data in a BMP message is dependent on the "Message Type" field in
   the common header.

     0 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Version    |    Msg. Type  |   Peer Type   |  Peer Flags   |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Peer Distinguisher (present based on peer type)       |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                 Peer Address (16 bytes)                       |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           Peer AS                             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                         Peer BGP ID                           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Timestamp (seconds)                        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  Timestamp (microseconds)                     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   o  Version (1 byte): Indicates the BMP version.  This is set to '1'
      for all messages defined in this specification.

   o  Message Type (1 byte): This identifies the type of the BMP
      message,

      *  Type = 0: Route Monitoring
      *  Type = 1: Statistics Report
      *  Type = 2: Peer Down Notification

   o  Peer Type (1 byte): These bits identify the type of the peer.
      Currently only two types of peers are identified,

      *  Peer Type = 0: Global Instance Peer
      *  Peer Type = 1: L3 VPN Instance Peer

   o  Peer Flags (1 byte): These flags provide more information about
      the peer.  The flags are defined as follows.


                             0 1 2 3 4 5 6 7 8
                             +-+-+-+-+-+-+-+-+
                             |V|   Reserved  |



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                             +-+-+-+-+-+-+-+-+


      *  The V flag indicates the the Peer address is an IPv6 address.
         For IPv4 peers this is set to 0.
      *  The remaining bits are reserved for future use.

   o  Peer Distinguisher (8 bytes): Routers today can have multiple
      instances (example L3VPNs).  This field is present to distinguish
      peers that belong to one address domain from the other.

      If the peer is a "Global Instance Peer", this field is zero
      filled.  If the peer is a "L3VPN Instance Peer", it is set to the
      route distinguisher of the particular L3VPN instance that the peer
      belongs to.

   o  Peer Address: The remote IP address associated with the TCP
      session over which the encapsulated PDU was received.  It is 4
      bytes long if an IPv4 address is carried in this field (with most
      significant bytes zero filled) and 16 bytes long if an IPv6
      address is carried in this field.

   o  Peer AS: The Autonomous System number of the peer from which the
      encapsulated PDU was received.  If a 16 bit AS number is stored in
      this field [RFC4893], it should be padded with zeroes in the most
      significant bits.

   o  Peer BGP ID: The BGP Identifier of the peer from which the
      encapsulated PDU was received.

   o  Timestamp: The time when the encapsulated PDU was received,
      expressed in seconds and microseconds since midnight (zero hour),
      January 1, 1970 (UTC).  If zero, the time is unavailable.

2.1.  Route Monitoring

   Route Monitoring messages are used for initial synchronization of
   ADJ-RIB-In.  They are also used for ongoing monitoring of received
   advertisements and withdraws.  This is discussed in more detail in
   subsequent sections.

   Following the common BMP header is a BGP PDU.  The length of the PDU
   can be determined by parsing it in the normal fashion as specified in
   [RFC4271].







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2.2.  Stats Reports

   These messages contain information that could be used by the
   monitoring station to observe interesting events that occur on the
   router.  'Stats Report' messages have a message type of '3'.

   The transmission of the SR messages could be timer triggered or event
   driven (for example, when a significant event occurs or a threshold
   is reached).  This specification does not impose any timing
   restrictions on when and on what event these reports have to be
   transmitted.  It is left to the implementation to determine
   transmission timings.  This document only specifies the form and
   content of SR messages.

   Following the common BMP header is a 4-byte field that indicates the
   number of counters in the stats message where each counter is encoded
   as a TLV.


     0 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Stats Count                            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Each counter is encoded as follows,


     0 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Stat Type             |          Stat Len             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Stat Data                              |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   o  Stat Type (2 bytes): Defines the type of the statistic carried in
      the "Stat Data" field.

   o  Stat Len (2 bytes): Defines the length of the "Stat Data" Field.

   This specification defines the following statistics.  All statistics
   are 4-byte quantities and the stats data are counters.

   o  Stat Type = 0: Number of prefixes rejected by inbound policy.

   o  Stat Type = 1: Number of (known) duplicate prefix advertisements.





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   o  Stat Type = 2: Number of (known) duplicate withdraws.

   o  Stat Type = 3: Number of updates invalidated due to CLUSTER_LIST
      loop.

   o  Stat Type = 4: Number of updates invalidated due to AS_PATH loop.

   Note that the current specification only specifies 4-byte counters as
   "Stat Data".  This does not preclude future versions from
   incorporating more complex TLV-type "Stat Data" (for example, one
   which can carry prefix specific data).  SR messages are optional.
   However if an SR message is transmitted, this specification requires
   at least one statistic to be carried in it.

2.3.  Peer Down Notification

   This message is used to indicate that a peering session was
   terminated.  The type of this message is 4.

     0 1 2 3 4 5 6 7 8
     +-+-+-+-+-+-+-+-+
     |    Reason     | 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |       Notification Message (present if Reason = 1 or 3)       |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Reason indicates why the session was closed.  Defined values are:

   o  Reason 1: The local system closed the session.  Following the
      Reason is a BGP PDU containing a BGP NOTIFICATION message that
      would have been sent to the peer.  The length of the PDU can be
      determined by parsing it in the normal fashion as specified in
      [RFC4271].

   o  Reason 2: The local system closed the session.  No notification
      message was sent.

   o  Reason 3: The remote system closed the session with a notification
      message.  Following the Reason is a BGP PDU containing the BGP
      NOTIFICATION message as received from the peer.  The length of the
      PDU can be determined by parsing it in the normal fashion as
      specified in [RFC4271].

   o  Reason 4: The remote system closed the session without a
      notification message.





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3.  Route Monitoring

   After the BMP session is up, Route Monitoring messages are used to
   provide a snapshot of the Adj-RIB-In of a particular peer.  It does
   so by sending all routes stored in the Adj-RIB-In of that peer using
   standard BGP Update messages.  There is no requirement on the
   ordering of messages in the peer dump.

   Depending on the implementation or configuration, it may only be
   possible to send the Loc-RIB (post-policy routes) instead of the Adj-
   RIB-In.  This is because it is possible that a BGP implementation may
   not store, for example, routes which have been filtered out by
   policy.  If this is the case, the implementation may send the Loc-RIB
   path that pertains to a particular peer in the route monitor message.

   If the implementation is able to provide information about when
   routes were received, it MAY provide such information in the BMP
   timestamp field.  Otherwise, the BMP timestamp field MUST be set to
   zero, indicating that time is not available.

   Ongoing monitoring is accomplished by propagating route changes in
   BGP UPDATE PDUs and forwarding those PDUs to the monitoring station,
   again using RM messages.  When a change occurs to a route, such as an
   attribute change, the router must update the monitor with the new
   attribute.  When a route is withdrawn by a peer, a corresponding
   withdraw is sent to the monitor.  Multiple changed routes MAY be
   grouped into a single BGP UPDATE PDU when feasible, exactly as in the
   standard BGP protocol.

   It's important to note that RM messages are not real time replicated
   messages received from a peer.  While the router should attempt to
   generate updates as soon as they are received there is a finite time
   that could elapse between reception of an update and the generation
   an RM message and its transmission to the monitoring station.  If
   there are state changes in the interim for that prefix, it is
   acceptable that the router generate the final state of that prefix to
   the monitoring station.  The actual PDU generated and transmitted to
   the station might also differ from the exact PDU received from the
   peer, for example due to differences between how different
   implementations format path attributes.


4.  Stat Reports

   As outlined above, SR messages are used to monitor specific events
   and counters on the monitored router.  One type of monitoring could
   be to find out if there are an undue number of route advertisements
   and withdraws happening (churn) on the monitored router.  Another



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   metric is to evaluate the number of looped AS-Paths on the router.

   While this document proposes a small set of counters to begin with,
   the authors envision this list may grow in the future with new
   applications that require BMP style monitoring.


5.  Using BMP

   Once the BMP session is established route monitoring starts dumping
   the current snapshot as well as incremental changes simultaneously.

   It is fine to have these operations occur concurrently.  If the
   initial dump visits a route and subsequently a withdraw is received,
   this will be forwarded to the monitoring station which would have to
   correlate and reflect the deletion of that route in its internal
   state.  This is an operation a monitoring station would need to
   support regardless.

   If the router receives a withdraw for a prefix even before the peer
   dump procedure visits that prefix, then the router would clean up
   that route from its internal state and will not forward it to the
   monitoring station.  In this case, the monitoring station may receive
   a bogus withdraw which it can safely ignore.


6.  IANA Considerations

   This document defines three message types for transferring BGP
   messages between cooperating systems (Section 2):

   o  Type 0: Route Monitor
   o  Type 1: Statistics Report
   o  Type 2: Peer Down Notification

   Type values 3 through 255 MUST be assigned using the "IETF Consensus"
   policy defined in [RFC5226].

   This document defines five statistics types for statistics reporting
   (Section 2.2):

   o  Stat Type = 0: Number of prefixes rejected by inbound policy.
   o  Stat Type = 1: Number of (known) duplicate prefix advertisements.
   o  Stat Type = 2: Number of (known) duplicate withdraws.
   o  Stat Type = 3: Number of updates invalidated due to CLUSTER_LIST
      loop.





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   o  Stat Type = 4: Number of updates invalidated due to AS_PATH loop.

   Stat Type values 5 through 32767 MUST be assigned using the "IETF
   Consensus" policy, and values 32768 through 65535 using the "First
   Come First Served" policy, defined in [RFC5226].


7.  Security Considerations

   This document defines a mechanism to obtain a full dump or provide
   continuous monitoring of a BGP speaker's local BGP table, including
   received BGP messages.  This capability could allow an outside party
   to obtain information not otherwise obtainable.

   Implementations of this protocol MUST require manual configuration of
   the monitored and monitoring devices.

   Users of this protocol MAY use some type of secure transmission
   mechanism, such as IPSec [RFC4303], to transmit this data.


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.

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

   [RFC4893]  Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
              Number Space", RFC 4893, May 2007.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

8.2.  Informative References

   [RFC4303]  Kent, S., "IP Encapsulating Security Payload (ESP)",
              RFC 4303, December 2005.









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Authors' Addresses

   John Scudder
   Juniper Networks
   1194 N. Mathilda Ave
   Sunnyvale, CA  94089
   USA

   Email: jgs@juniper.net


   Rex Fernando
   Juniper Networks
   1194 N. Mathilda Ave
   Sunnyvale, CA  94089
   USA

   Email: rex@juniper.net


   Stephen Stuart
   Google
   1600 Amphitheatre Parkway
   Mountain View, CA  94043
   USA

   Email: sstuart@google.com
























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