Network Working Group                                         J. Scudder
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                             R. Fernando
Expires: June 2, 2012 April 25, 2013                                    Cisco Systems
                                                               S. Stuart
                                                                  Google
                                                       November 30, 2011
                                                        October 22, 2012

                        BGP Monitoring Protocol
                         draft-ietf-grow-bmp-06
                         draft-ietf-grow-bmp-07

Abstract

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

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/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   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 June 2, 2012. April 25, 2013.

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  5  4
   2.  Lifecycle  Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Overview of a BMP Session Operation  . . . . . . . . . . . . . . . . . .  4
     3.1.  BMP Messages . . . . . . . . . . . . . . . . . . . . . . .  4
     3.2.  Connection Establishment and Termination . . . . . . . . .  5
   3.
     3.3.  Lifecycle of a BMP Session . . . . . . . . . . . . . . . .  6
   4.  BMP Message Format . . . . . . . . . . . . . . . . . . . . . .  5
     3.1.  7
     4.1.  Common Header  . . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  7
     4.2.  Per-Peer Header  . . . . . . . . . . . . . . . . . . . . .  6
     3.3.  7
     4.3.  Initiation Message . . . . . . . . . . . . . . . . . . . .  8
     3.4.  9
     4.4.  Termination Message  . . . . . . . . . . . . . . . . . . . 10
     4.5.  Route Monitoring . . . . . . . . . . . . . . . . . . . . .  9
     3.5. 11
     4.6.  Stats Reports  . . . . . . . . . . . . . . . . . . . . . .  9
     3.6. 11
     4.7.  Peer Down Notification . . . . . . . . . . . . . . . . . . 10
     3.7. 13
     4.8.  Peer Up Notification . . . . . . . . . . . . . . . . . . . 11
   4. 14
   5.  Route Monitoring . . . . . . . . . . . . . . . . . . . . . . . 12
   5. 15
   6.  Stat Reports . . . . . . . . . . . . . . . . . . . . . . . . . 13
   6. 17
   7.  Other Considerations . . . . . . . . . . . . . . . . . . . . . 13
   7. 17
   8.  Using BMP  . . . . . . . . . . . . . . . . . . . . . . . . . . 14
   8. 17
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   9.  Security Considerations 17
     9.1.  BMP Message Types  . . . . . . . . . . . . . . . . . . . 15
   10. Acknowledgements . 18
     9.2.  BMP Statistics Types . . . . . . . . . . . . . . . . . . . 18
     9.3.  BMP Initiation Message TLVs  . . . . 15
   11. References . . . . . . . . . . . 18
     9.4.  BMP Termination Message TLVs . . . . . . . . . . . . . . . 15
     11.1. Normative References 19
     9.5.  BMP Termination Message Reason Codes . . . . . . . . . . . 19
   10. Security Considerations  . . . . . . . . . . 15
     11.2. Informative . . . . . . . . . 19
   11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   12. References . . . . . . . . . . . . . . . . . . 16
   Appendix A.  Changes Between BMP Versions 1 and 2 . . . . . . . . 16
   Appendix B.  Changes Between BMP Versions 2 and 3 20
     12.1. Normative References . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . 20
     12.2. Informative References . . . . . . . . . . . . . 16

1.  Introduction . . . . . 20
   Appendix A.  Changes Between BMP Versions 1 and 2  . . . . . . . . 21
   Appendix B.  Changes Between BMP Versions 2 and 3  . . . . . . . . 21
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21

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,  Prior to introduction of BMP, this data can could
   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.  From a high level,
   BMP can be thought of as the result of multiplexing together the
   messages received on the various monitored BGP sessions.

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].

2.  Definitions

   o  Adj-RIB-In: As defined in [RFC4271], "The Adj-RIBs-In contains
      unprocessed routing information that has been advertised to the
      local BGP speaker by its peers."  This is also referred to as the
      pre-policy Adj-RIB-In in this document.

   o  Post-Policy Adj-RIB-In: The result of applying inbound policy to
      an Adj-RIB-In, but prior to the application of route selection to
      form the Loc-RIB.

3.  Overview of BMP Operation

3.1.  BMP Messages

   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 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.

   o  Peer Up Notification (PU): A message sent to indicate that a
      peering session has come up.  The message includes information
      regarding the data exchanged between the peers in their OPEN
      messages as well as information about the peering TCP session
      itself.  In addition to being sent whenever a peer transitions to
      ESTABLISHED state, a Peer Up Notification is sent for each peer
      that is in ESTABLISHED state when the BMP session itself comes up.

   o  Initiation: A means for the monitored router to inform the
      monitoring station of its vendor, software version, and so on.

   o  Termination: A means for the monitored router to inform the
      monitoring station of why it is closing a BMP session.

3.2.  Connection Establishment and Termination

   BMP operates over TCP.  All options are controlled by configuration
   on the monitored router.  No message is ever sent from the monitoring
   station to the monitored router.  The monitored router MAY take steps
   to prevent the monitoring station from sending data (e.g. (for example by half-
   closing
   half-closing the TCP session or setting its window size to zero) or
   it MAY silently discard any data erroneously sent by the monitoring station.

   The router may be monitored by one or more monitoring station stations.  With
   respect to each (router, monitoring station) pair, one party is configured
   active with respect to listen on a particular TCP
   port session establishment, and the router other party
   is passive.  Which party is configured to establish an active connection
   to that port and which is passive is controlled
   by configuration.

   The passive party is configured to send messages listen on that a particular TCP connection.  There is
   no initialization or handshaking phase, messages are simply sent as
   soon as port
   and the connection active party is established. configured to establish a connection to that
   port.  If the router active party is unable to connect to the monitoring station, passive party,
   it periodically retries the connection.  Retries MUST be subject to
   some variety of backoff.  Exponential backoff with a default initial
   backoff of 30 seconds and a maximum of 720 seconds is suggested.

   The router MAY restrict the set of IP addresses from which it will
   accept connections.  It SHOULD restrict the number of simultaneous
   connections it will permit from a given IP address.  The default
   value for this restriction SHOULD be 1, though an implementation MAY
   permit this restriction to be disabled in configuration.  The router
   MUST also restrict the rate at which sessions may be established.  A
   suggested default retry period is 30 seconds. an establishment rate of 2 sessions per minute.

   A router (or management station) MAY implement logic to detect
   redundant connections, as might occur if both parties are configured
   to be active, and MAY elect to terminate redundant connections.  A
   Termination reason code is defined for this purpose.

   Once a connection is established, the router sends messages over it.
   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].

2. connection, optionally with a Termination message.

3.3.  Lifecycle of a BMP Session

   A BMP session begins when a router running BMP successfully opens a
   TCP session (the "BMP session") to the monitoring station it is configured to talk to. speak BMP with one more monitoring
   stations.  It MAY first be configured to send an Initiation message.  It
   subsequently sends a Peer Up monitoring information for
   only a subset of its BGP peers.  Otherwise, all BGP peers are assumed
   to be monitored.

   A BMP session begins when the active party (either router or
   management station, as determined by configuration) successfully
   opens a TCP session (the "BMP session").  Once the session is up, the
   router begins to send BMP messages.  It MUST begin by sending an
   Initiation message.  It subsequently sends a Peer Up message over the
   BMP session for each of its monitored BGP peers which are in
   Established state.  It follows by sending the contents of its Adj-RIBs-In (or Loc-RIB, Adj-
   RIBs-In (pre-policy, post-policy or both, see Section 4) 5) encapsulated
   in Route Monitoring messages.  Once it has sent all the routes for a
   given peer, it sends an End-of-RIB message for that peer; when End-of-RIB End-
   of-RIB has been sent for each monitored peer, the initial table dump
   has completed.  (A monitoring station that wishes only to gather a
   table dump could close the connection once it has gathered an End-
   of-RIB End-of-
   RIB or Peer Down message corresponding to each Peer Up message.)

   Following the initial table dump, the router sends incremental
   updates encapsulated in Route Monitoring messages.  It MAY
   periodically send Stats Reports or even new Initiation messages,
   according to configuration.  If any new monitored BGP peers become
   Established, corresponding Peer Up messages are sent.  If any BGP
   peers for which Peer Up messages were sent transition out of the
   Established state, corresponding Peer Down messages are sent.

   A BMP session ends when the TCP session that carries it is closed for
   any reason.

3.  The router MAY send a Termination message prior to
   closing the session.

4.  BMP Message Format

3.1.

4.1.  Common Header

   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    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Message Length                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   Msg. Type   |
     +---------------+

   o  Version (1 byte): Indicates the BMP version.  This is set to '3'
      for all messages defined in this specification.  Version 0 is
      reserved and MUST NOT be sent.

   o  Message Length (4 bytes): Length of the message in bytes
      (including headers, data and encapsulated messages, if any).

   o  Message Type (1 byte): This identifies the type of the BMP
      message.  A BMP implementation MUST ignore unrecognized message
      types upon receipt.

      *  Type = 0: Route Monitoring
      *  Type = 1: Statistics Report
      *  Type = 2: Peer Down Notification
      *  Type = 3: Peer Up Notification
      *  Type = 4: Initiation Message

3.2.
      *  Type = 5: Termination Message

4.2.  Per-Peer Header

   The per-peer header follows the common header for most 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   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  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|L| Reserved  |
                             +-+-+-+-+-+-+-+-+

      *  The V flag indicates the the Peer address is an IPv6 address.
         For IPv4 peers this is set to 0.
      *  The L flag, if set to 1, indicates that the message reflects
         the Loc-RIB post-policy Adj-RIB-In (i.e., it reflects the application
         of inbound policy).  It is set to 0 if the message reflects the
         pre-policy Adj-RIB-In.  See Section 4 5 for further detail.
      *  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 routes were received
      (one may also think of this as the time when they were installed
      in the Adj-RIB-In), 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.

3.3.

4.3.  Initiation Message

   The initiation message provides a means for the monitored router to
   inform monitored router to
   inform the monitoring station of its vendor, software version, and so
   on.  An initiation message MUST be sent as the first message after
   the TCP session comes up.  An initiation message MAY be sent at any
   point thereafter, if warranted by a change on the monitored router.

   The initiation message consists of the common BMP header followed by
   two or more TLVs containing information about the monitored router,
   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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Information Type     |       Information Length      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                 Information (variable)                        |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   o  Information Type (2 bytes): Type of information provided.  Defined
      types are:

      *  Type = 0: String.  The Information field contains a free-form
         UTF-8 string whose length is given by the "Information Length"
         field.  The value is administratively assigned.  Inclusion of
         this TLV is optional.  Multiple String TLVs MAY be included in
         the message.

      *  Type = 1: sysDescr.  The Information field contains an ASCII
         string whose value MUST be set to be equal to the value of the
         sysDescr MIB-II [RFC1213] object.  Inclusion of this TLV is
         mandatory.

      *  Type = 2: sysName.  The Information field contains a ASCII
         string whose value MUST be set to be equal to the value of the
         sysName MIB-II [RFC1213] object.  Inclusion of this TLV is
         mandatory.

   o  Information Length (2 bytes): The length of the following
      Information field, in bytes.

   o  Information (variable): Information about the monitored router,
      according to the type.

4.4.  Termination Message

   The termination message provides a way for a monitored router to
   indicate why it is terminating a session.  Although use of this
   message is RECOMMENDED, a monitoring station must always be prepared
   for the session to terminate with no message.  Once the router has
   sent a termination message, it MUST close the TCP session without
   sending any further messages.  Likewise, the monitoring station of its vendor, software version, and so
   on.  The initiation message is OPTIONAL.  When used, an initiation
   message MUST be sent as the first message after
   close the TCP session comes
   up.  An initiation message MAY be sent at any point thereafter, if
   warranted by after receiving a change on the monitored router. termination message.

   The initiation termination message consists of the common BMP header followed by
   one or more TLVs containing information about the monitored router, reason for the
   termination, 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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Information Type     |       Information Length      |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                 Information (variable)                        |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   o  Information Type (2 bytes): Type of information provided.  Defined
      types are:

      *  Type = 0: String.  The Information field contains a free-form
         UTF-8 string whose length is given by the "Information Length"
         field.  Inclusion of this TLV is optional.  It MAY be used to
         provide further detail for any of the defined reasons.
         Multiple String TLVs MAY be included in the message.

      *  Type = 1: Reason.  The Information field contains a two-byte
         code indicating the reason the connection was terminated.  Some
         reasons may have further TLVs associated with them.  Inclusion
         of this TLV is not optional.  Defined reasons are:

         +  Reason = 0: Session administratively closed.

         +  Reason = 1: Unspecified reason.

         +  Reason = 2: Out of resources.  The router has exhausted
            resources available for the BMP session.

         +  Reason = 3: Redundant connection.  The router has determined
            that this connection is redundant with another one.

   o  Information Length (2 bytes): The length of the following
      Information field, in bytes.

   o  Information (variable): Information about the monitored router,
      according to the type.

3.4.

4.5.  Route Monitoring

   Route Monitoring messages are used for initial synchronization of
   ADJ-RIB-In.
   ADJ-RIBs-In.  They are also used for ongoing monitoring of received
   advertisements and withdraws.  This is discussed in more detail in
   subsequent sections.
   Section 5.

   Following the common BMP header and per-peer header is a BGP Update
   PDU.

3.5.

4.6.  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

   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 --
   however, configuration control should be provided of the timer and/or
   threshold values.  This document only specifies the form and content
   of SR messages.

   Following the common BMP header and per-peer 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.  A BMP
   implementation MUST ignore unrecognized stat types on receipt, and
   likewise MUST ignore unexpected data in the Stat Data field. Stat Data field.

   Stats are either counters or gauges, defined as follows after the
   examples of [RFC1155] Section 3.2.3.3 and [RFC2856] Section 4
   respectively:

   32-bit Counter: A non-negative integer which monotonically increases
   until it reaches a maximum value, when it wraps around and starts
   increasing again from zero.  It has a maximum value of 2^32-1
   (4294967295 decimal).

   64-bit Gauge: non-negative integer, which may increase or decrease,
   but shall never exceed a maximum value, nor fall below a minimum
   value.  The maximum value can not be greater than 2^64-1
   (18446744073709551615 decimal), and the minimum value can not be
   smaller than 0.  The value has its maximum value whenever the
   information being modeled is greater than or equal to its maximum
   value, and has its minimum value whenever the information being
   modeled is smaller than or equal to its minimum value.  If the
   information being modeled subsequently decreases below (increases
   above) the maximum (minimum) value, the 64-bit Gauge also decreases
   (increases).

   o  Stat Type = 0: (32-bit Counter) Number of prefixes rejected by
      inbound policy.

   o  Stat Type = 1: (32-bit Counter) Number of (known) duplicate prefix
      advertisements.

   o  Stat Type = 2: (32-bit Counter) Number of (known) duplicate
      withdraws.

   o  Stat Type = 3: (32-bit Counter) Number of updates invalidated due
      to CLUSTER_LIST loop.

   o  Stat Type = 4: (32-bit Counter) Number of updates invalidated due
      to AS_PATH loop.

   o  Stat Type = 5: (32-bit Counter) Number of updates invalidated due
      to ORIGINATOR_ID.

   o  Stat Type = 6: (32-bit Counter) Number of updates invalidated due
      to AS_CONFED loop.

   o  Stat Type = 7: (64-bit Gauge) Number of routes in Adj-RIBs-In.

   o  Stat Type = 8: (64-bit Gauge) Number of routes in Loc-RIB.

   Note that although the current specification only specifies 4-byte
   counters and 8-byte gauges as "Stat Data".  This 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 MUST be carried in it.

3.6.

4.7.  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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |            Data (present if Reason = 1, 2 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.

   o  Reason 2: The local system closed the session.  No notification
      message was sent.  Following the reason code is a two-byte field
      containing the code corresponding to the FSM Event which caused
      the system to close the session (see Section 8.1 of [RFC4271]).
      Zero is
      Two bytes both set to zero are used to indicate that no relevant
      Event code is defined.

   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.

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

3.7.

   A Peer Down message implicitly withdraws all routes that had been
   associated with the peer in question.  A BMP implementation MAY omit
   sending explicit withdraws for such routes.

4.8.  Peer Up Notification

   The Peer Up message is used to indicate that a peering session has
   come up (i.e., has transitioned into ESTABLISHED state).  Following
   the common BMP header and per-peer header is the following:

     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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                 Local Address (16 bytes)                      |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Local Port            |        Remote Port            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                    Sent OPEN Message                          |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                  Received OPEN Message                        |
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   o  Local Address: The local IP address associated with the peering
      TCP session.  It is 4 bytes long if an IPv4 address is carried in
      this field, as determined by the V flag (with most significant
      bytes zero filled) and 16 bytes long if an IPv6 address is carried
      in this field.

   o  Local Port: The local port number associated with the peering TCP
      session.

   o  Remote Port: The remote port number associated with the peering
      TCP session.  (Note that the remote address can be found in the
      Peer Address field of the fixed header.)

   o  Sent OPEN Message: The full OPEN message transmitted by the
      monitored router to its peer.

   o  Received OPEN Message: The full OPEN message received by the
      monitored router from its peer.

4.

5.  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 each monitored peer.  This is
   done by sending all routes stored in the Adj-RIB-In of that peer those peers
   using standard BGP Update messages, encapsulated in Route Monitoring
   messages.  There is no requirement on the ordering of messages in the
   peer dump. dumps.  When the initial peer dump is
   completed, completed for a given peer,
   this MUST be indicated by sending an End-of-RIB marker for that peer
   (as specified in Section 2 of [RFC4724], plus the BMP encapsulation
   header).

   Depending on the implementation  See also Section 8.

   A BMP speaker may send pre-policy routes, post-policy routes, or configuration, it
   both.  The selection may only be
   possible due to send the Loc-RIB (post-policy routes) instead of the Adj-
   RIB-In.  This is because it implementation constraints (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.
   Such paths policy).  Pre-policy routes MUST have the
   their L flag set clear in the BMP header (see Section 3). 4), post-policy
   routes MUST have their L flag set.  When an implementation chooses to
   send both pre- and post-policy routes, it is effectively multiplexing
   two update streams onto the BMP session.  The streams are
   distinguished by their L flags.

   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.

   AS Numbers in the BMP UPDATE message MUST be sent as 4-octet
   quantities, as described in [RFC4893].  This affects the AS_PATH and
   AGGREGATOR path attributes.  AS4_PATH or AS4_AGGREGATOR path
   attributes MUST NOT be sent in a BMP UPDATE message, as it makes no
   sense to do so.

   Ongoing monitoring is accomplished by propagating route changes in
   BGP UPDATE 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.  As discussed above, it MAY generate either an update with
   the L flag clear, with it set, or two updates, one with the L flag
   clear and the other with the L flag set.  When a route is withdrawn
   by a peer, a corresponding withdraw is sent to the monitor.  The
   withdraw MUST have its L flag set to correspond to that of any
   previous announcement; if the route in question was previously
   announced with L flag both clear and set, the withdraw MUST similarly
   be sent twice, with L flag clear and set.  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.

5.

6.  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
   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.

6.

7.  Other Considerations

   Some routers may support multiple instances of the BGP protocol, for
   example as "logical routers" or through some other facility.  The BMP
   protocol relates to a single instance of BGP; thus, if a router
   supports multiple BGP instances it should also support multiple BMP
   instances (one per BMP BGP instance).

7.

8.  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.

8.

9.  IANA Considerations

   IANA is requested to create the following registries.

9.1.  BMP Message Types

   This document defines five message types for transferring BGP
   messages between cooperating systems (Section 3): 4):

   o  Type 0: Route Monitor
   o  Type 1: Statistics Report
   o  Type 2: Peer Down Notification
   o  Type 3: Peer Up Notification
   o  Type 4: Initiation
   o  Type 5: Termination

   Type values 5 6 through 128 MUST be assigned using the "Standards
   Action" policy, and values 129 through 255 using the "Specification
   Required" policy defined in [RFC5226].

9.2.  BMP Statistics Types

   This document defines five nine statistics types for statistics reporting
   (Section 3.5): 4.6):

   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.
   o  Stat Type = 4: Number of updates invalidated due to AS_PATH loop.
   o  Stat Type = 5: Number of updates invalidated due to ORIGINATOR_ID.
   o  Stat Type = 6: Number of updates invalidated due to AS_CONFED
      loop. a loop found
      in AS_CONFED_SEQUENCE or AS_CONFED_SET.
   o  Stat Type = 7: Number of routes in Adj-RIBs-In.
   o  Stat Type = 8: Number of routes in Loc-RIB.

   Stat Type values 7 9 through 32767 MUST be assigned using the
   "Standards Action" policy, and values 32768 through 65535 using the
   "Specification Required" policy, defined in [RFC5226].

9.3.  BMP Initiation Message TLVs

   This document defines one type three types for information carried in the
   Initiation message (Section 3.3): 4.3):

   o  Type = 0: String.
   o  Type = 1: sysDescr.
   o  Type = 2: sysName.

   Information type values 1 3 through 32767 MUST be assigned using the
   "Standards Action" policy, and values 32768 through 65535 using the
   "Specification Required" policy, defined in [RFC5226].

9.

9.4.  BMP Termination Message TLVs

   This document defines two types for information carried in the
   Termination message (Section 4.4):

   o  Type = 0: String.
   o  Type = 1: Reason.

   Information type values 2 through 32767 MUST be assigned using the
   "Standards Action" policy, and values 32768 through 65535 using the
   "Specification Required" policy, defined in [RFC5226].

9.5.  BMP Termination Message Reason Codes

   This document defines four types for information carried in the
   Termination message (Section 4.4) Reason code,:

   o  Type = 0: Administratively closed.
   o  Type = 1: Unspecified reason.
   o  Type = 2: Out of resources.
   o  Type = 3: Redundant connection.

   Information type values 4 through 32767 MUST be assigned using the
   "Standards Action" policy, and values 32768 through 65535 using the
   "Specification Required" policy, defined in [RFC5226].

10.  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 transport
   mechanism, such as IPSec [RFC4303], [RFC4303] or TCP-AO [RFC5925], in order to transmit this data.

10.
   provide mutual authentication, data integrity and transport
   protection.

   Unless a transport that provides mutual authentication is used, an
   attacker could masquerade as the monitored router and trick a
   monitoring station into accepting false information.

11.  Acknowledgements

   Thanks to Tim Evens, John ji Ioannidis, Mack McBride, Danny
   McPherson, Dimitri Papadimitriou, Erik Romijn, and the members of the
   GROW working group for their comments.

11.

12.  References

11.1.

12.1.  Normative References

   [RFC1213]  McCloghrie, K. and M. Rose, "Management Information Base
              for Network Management of TCP/IP-based internets:MIB-II",
              STD 17, RFC 1213, March 1991.

   [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.

   [RFC4724]  Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y.
              Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724,
              January 2007.

   [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.

11.2.

12.2.  Informative References

   [RFC1155]  Rose, M. and K. McCloghrie, "Structure and identification
              of management information for TCP/IP-based internets",
              STD 16, RFC 1155, May 1990.

   [RFC2856]  Bierman, A., McCloghrie, K., and R. Presuhn, "Textual
              Conventions for Additional High Capacity Data Types",
              RFC 2856, June 2000.

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

   [RFC5925]  Touch, J., Mankin, A., and R. Bonica, "The TCP
              Authentication Option", RFC 5925, June 2010.

Appendix A.  Changes Between BMP Versions 1 and 2

   o  Added Peer Up Message
   o  Added L flag
   o  Editorial changes

Appendix B.  Changes Between BMP Versions 2 and 3

   o  Added a 16-bit 32-bit length field to the fixed header.
   o  Clarified error handling.
   o  Added new stat types types: 5 and (number of updates invalidated due to
      ORIGINATOR_ID), 6 (number of updates invalidated due to
      ORIGINATOR_ID
      AS_CONFED_SEQUENCE/AS_CONFED_SET), 7 (number of routes in
      Adj-RIB-In) and 8 (number of routes in Loc-RIB).
   o  Defined counters and AS_CONFED, respectively). gauges for use with stat types.
   o  For peer down messages, the relevant FSM event is to be sent in
      type 2 messages.
   o  Added local address and local and remote ports to the peer up
      message.
   o  Require End-of-RIB marker after initial dump.
   o  Added Initiation message with string content.
   o  Permit multiplexing pre- and post-policy feeds onto a single BMP
      session.
   o  Changed assignment policy for IANA registries.
   o  Editorial  Changed "Loc-RIB" references to refer to "Post-Policy Adj-RIB-In",
      plus other editorial changes.
   o  Introduced option for monitoring station to be active party in
      initiating connection.
   o  Introduced Termination message.

Authors' Addresses

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

   Email: jgs@juniper.net
   Rex Fernando
   Cisco Systems
   170 W. Tasman Dr.
   San Jose, CA  95134
   USA

   Email: rex@cisco.com

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

   Email: sstuart@google.com