BGP Monitoring Protocol
draft-ietf-grow-bmp-08
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (grow WG) | |
|---|---|---|---|
| Authors | John Scudder , Rex Fernando , Stephen Stuart | ||
| Last updated | 2015-05-22 | ||
| Replaces | draft-scudder-bmp | ||
| Stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-grow-bmp-08
Network Working Group J. Scudder
Internet-Draft Juniper Networks
Intended status: Standards Track R. Fernando
Expires: November 23, 2015 Cisco Systems
S. Stuart
Google
May 22, 2015
BGP Monitoring Protocol
draft-ietf-grow-bmp-08
Abstract
This document defines a 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 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.
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
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 November 23, 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
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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.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Overview of BMP Operation . . . . . . . . . . . . . . . . . . 4
3.1. BMP Messages . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Connection Establishment and Termination . . . . . . . . 4
3.3. Lifecycle of a BMP Session . . . . . . . . . . . . . . . 5
4. BMP Message Format . . . . . . . . . . . . . . . . . . . . . 6
4.1. Common Header . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Per-Peer Header . . . . . . . . . . . . . . . . . . . . . 7
4.3. Initiation Message . . . . . . . . . . . . . . . . . . . 9
4.4. Information TLV . . . . . . . . . . . . . . . . . . . . . 9
4.5. Termination Message . . . . . . . . . . . . . . . . . . . 10
4.6. Route Monitoring . . . . . . . . . . . . . . . . . . . . 11
4.7. Route Mirroring . . . . . . . . . . . . . . . . . . . . . 11
4.8. Stats Reports . . . . . . . . . . . . . . . . . . . . . . 12
4.9. Peer Down Notification . . . . . . . . . . . . . . . . . 14
4.10. Peer Up Notification . . . . . . . . . . . . . . . . . . 15
5. Route Monitoring . . . . . . . . . . . . . . . . . . . . . . 17
6. Route Mirroring . . . . . . . . . . . . . . . . . . . . . . . 18
7. Stat Reports . . . . . . . . . . . . . . . . . . . . . . . . 18
8. Other Considerations . . . . . . . . . . . . . . . . . . . . 18
8.1. Multiple Instances . . . . . . . . . . . . . . . . . . . 18
8.2. Locally-Originated Routes . . . . . . . . . . . . . . . . 19
9. Using BMP . . . . . . . . . . . . . . . . . . . . . . . . . . 19
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
10.1. BMP Message Types . . . . . . . . . . . . . . . . . . . 20
10.2. BMP Statistics Types . . . . . . . . . . . . . . . . . . 20
10.3. BMP Initiation Message TLVs . . . . . . . . . . . . . . 20
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10.4. BMP Termination Message TLVs . . . . . . . . . . . . . . 21
10.5. BMP Termination Message Reason Codes . . . . . . . . . . 21
10.6. BMP Peer Down Reason Codes . . . . . . . . . . . . . . . 21
10.7. Route Mirroring TLVs . . . . . . . . . . . . . . . . . . 22
10.8. BMP Route Mirroring Information Codes . . . . . . . . . 22
11. Security Considerations . . . . . . . . . . . . . . . . . . . 22
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 23
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
13.1. Normative References . . . . . . . . . . . . . . . . . . 23
13.2. Informative References . . . . . . . . . . . . . . . . . 23
Appendix A. Changes Between BMP Versions 1 and 2 . . . . . . . . 24
Appendix B. Changes Between BMP Versions 2 and 3 . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
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. Prior to introduction of BMP, this data 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", "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.
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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): 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.
o Route Mirroring: a means for the monitored router to send verbatim
duplicates of messages as received. Can be used to exactly mirror
a monitored BGP session. Can also be used to report malformed BGP
PDUs.
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 (for example by
half-closing the TCP session or setting its window size to zero) or
it MAY silently discard any data sent by the monitoring station.
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The router may be monitored by one or more monitoring stations. With
respect to each (router, monitoring station) pair, one party is
active with respect to TCP session establishment, and the other party
is passive. Which party is active and which is passive is controlled
by configuration.
The passive party is configured to listen on a particular TCP port
and the active party is configured to establish a connection to that
port. If the active party is unable to connect to the 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 is 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, optionally with a Termination message.
3.3. Lifecycle of a BMP Session
A router is configured to speak BMP with one or more monitoring
stations. It MAY be configured to send 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 (pre-policy, post-policy or both, see Section 5) encapsulated
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in Route Monitoring messages. Once it has sent all the routes for a
given peer, it MUST send a End-of-RIB message for that peer; when
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 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. The router MAY send a Termination message prior to
closing the session.
4. BMP Message Format
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
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* Type = 1: Statistics Report
* Type = 2: Peer Down Notification
* Type = 3: Peer Up Notification
* Type = 4: Initiation Message
* 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|A| 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 L flag, if set to 1, indicates that the message reflects
the post-policy Adj-RIB-In (i.e., its path attributes reflect
the application of inbound policy). It is set to 0 if the
message reflects the pre-policy Adj-RIB-In. Locally-sourced
routes also carry an L flag of 1. See Section 5 for further
detail. This flag has no significance when used with route
mirroring messages (Section 4.7).
* The A flag, if set to 1, indicates that the message is
formatted using the legacy two-byte AS_PATH format. If set to
0, the message is formatted using the four-byte AS_PATH format
[RFC6793]. A BMP speaker MAY choose to propagate the AS_PATH
information as received from its peer, or it MAY choose to
reformat all AS_PATH information into four-byte format
regardless of how it was received from the peer. In the latter
case, AS4_PATH or AS4_AGGREGATOR path attributes SHOULD NOT be
sent in the BMP UPDATE message. This flag has no significance
when used with route mirroring messages (Section 4.7).
* 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 [RFC6793], 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
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unavailable. Precision of the timestamp is implementation-
dependent.
4.3. Initiation Message
The initiation message provides a means for the 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 Information TLVs (Section 4.4) containing information
about the monitored router. The sysDescr and sysName Information
TLVs MUST be sent, any others are optional. The string TLV MAY be
included multiple times.
4.4. Information TLV
The Information TLV is used by the Initiation (Section 4.3) and Peer
Up (Section 4.10) messages.
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. Note that
there is no requirement to terminate the string with a null (or
any other particular) character -- the length field gives its
termination. If multiple strings are included, their ordering
MUST be preserved when they are reported.
* 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.
* 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.
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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.
4.5. 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 MUST
close the TCP session after receiving a termination message.
The termination message consists of the common BMP header followed by
one or more TLVs containing information about the 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 REQUIRED. Defined reasons are:
+ Reason = 0: Session administratively closed. The session
might be re-initiated.
+ Reason = 1: Unspecified reason.
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+ 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.
+ Reason = 4: Session permanently administratively closed,
will not be re-initiated. Collector should reduce
(potentially to zero) the rate at which it attempts
reconnection to the monitored router.
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.
4.6. Route Monitoring
Route Monitoring messages are used for initial synchronization of
ADJ-RIBs-In. They are also used for ongoing monitoring of received
advertisements and withdraws. Route monitoring messages are state-
compressed. This is all discussed in more detail in Section 5.
Following the common BMP header and per-peer header is a BGP Update
PDU.
4.7. Route Mirroring
Route Mirroring messages are used for verbatim duplication of
messages as received. A possible use for mirroring is exact
mirroring of one or more monitored BGP sessions, without state
compression. Another possible use is mirroring of messages that have
been treated-as-withdraw [I-D.ietf-idr-error-handling], for debugging
purposes. Mirrored messages may be sampled, or may provide complete
fidelity. The Messages Lost Information code is provided to allow
this to be communicated. Section 6 provides more detail.
Following the common BMP header and per-peer header is a set of TLVs
that contain information about a message or set of messages. Each
TLV comprises a two-byte type code, a two-byte length field, and a
variable-length value. Inclusion of any given TLV is OPTIONAL,
however at least one TLV SHOULD be included, otherwise what's the
point of sending the message? Defined TLVs are as follows:
o Type = 0: BGP Message. A BGP PDU. This PDU may or may not be an
Update message. If the BGP Message TLV occurs in the Route
Mirroring message, it MUST occur last in the list of TLVs.
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o Type = 1: Information. A two-byte code that provides information
about the mirrored message or message stream. Defined codes are:
* Code = 0: Errored PDU. The contained message was found to have
some error that made it unusable, causing it to be treated-as-
withdraw [I-D.ietf-idr-error-handling]. A BGP Message TLV MUST
also occur in the TLV list.
* Code = 1: Messages Lost. One or more messages may have been
lost. This could occur, for example, if an implementation runs
out of available buffer space to queue mirroring messages.
4.8. Stats Reports
These messages contain information that could be used by the
monitoring station to observe interesting events that occur on the
router.
Transmission of 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 |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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. A BMP
implementation MUST ignore unrecognized stat types on receipt, and
likewise MUST ignore unexpected data in the 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.
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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.
o Stat Type = 9: Number of routes in per-AFI/SAFI Adj-RIB-In. The
value is structured as: AFI (2 bytes), SAFI (1 byte), followed by
a 64-bit Gauge.
o Stat Type = 10: Number of routes in per-AFI/SAFI Loc-RIB. The
value is structured as: AFI (2 bytes), SAFI (1 byte), followed by
a 64-bit Gauge.
o Stat Type = 11: (32-bit Counter) Number of updates subjected to
treat-as-withdraw treatment [I-D.ietf-idr-error-handling].
o Stat Type = 12: (32-bit Counter) Number of prefixes subjected to
treat-as-withdraw treatment [I-D.ietf-idr-error-handling].
o Stat Type = 13: (32-bit Counter) Number of duplicate update
messages received.
Note that although the current specification only specifies 4-byte
counters and 8-byte gauges 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, at least one
statistic MUST be carried in it.
4.9. Peer Down Notification
This message is used to indicate that a peering session was
terminated.
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:
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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]).
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.
o Reason 5: Information for this peer will no longer be sent to the
monitoring station for configuration reasons. This does not,
strictly speaking, indicate that the peer has gone down, but it
does indicate that the monitoring station will not receive updates
for the peer.
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.
4.10. 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:
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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 |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Information (variable) |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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, or zero if no TCP session actually exists (see
Section 8.2).
o Remote Port: The remote port number associated with the peering
TCP session, or zero if no TCP session actually exists (see
Section 8.2). (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.
o Information: Information about the peer, using the Information TLV
(Section 4.4) format. Only the string type is defined in this
context; it may be repeated. Inclusion of the Information field
is OPTIONAL. Its presence or absence can be inferred by
inspection of the Message Length in the common header.
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5. Route Monitoring
In BMP's normal operating mode, after the BMP session is up, Route
Monitoring messages are used to provide a snapshot of the Adj-RIB-In
of each monitored peer. This is done by sending all routes stored in
the Adj-RIB-In of those peers using standard BGP Update messages,
encapsulated in Route Monitoring messages. There is no requirement
on the ordering of messages in the peer dumps. When the initial dump
is 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). See also Section 9.
A BMP speaker may send pre-policy routes, post-policy routes, or
both. The selection may be due to implementation constraints (it is
possible that a BGP implementation may not store, for example, routes
which have been filtered out by policy). Pre-policy routes MUST have
their L flag clear in the BMP header (see Section 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.
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. 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 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
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the router generate the final state of that prefix to the monitoring
station. This is sometimes known as "state compression". 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.
6. Route Mirroring
Route Mirroring messages are provided for two primary reasons: First,
to enable an implementation to operate in a mode where it provides a
full-fidelity view of all messages received from its peers, without
state compression. As we note in Section 5, BMP's normal operational
mode cannot provide this. Implementors are strongly cautioned that
without state compression, an implementation could require unbounded
storage to buffer messages queued to be mirrored. This requirement,
and concomitant performance implications, means that this mode of
operation is unlikely to be suitable for implementation in
conventional routers, and its use is NOT RECOMMENDED except in cases
where implementors have carefully considered the tradeoffs.
The second application for Route Mirroring is for error reporting and
diagnosis. When [I-D.ietf-idr-error-handling] is in use, a router
can process BGP messages that are determined to contain errors,
without resetting the BGP session. Such messages MAY be mirrored.
The buffering used for such mirroring SHOULD be limited. If an
errored message is unable to be mirrored due to buffer exhaustion, a
message with the "Messages Lost" code SHOULD be sent to indicate
this. (This implies that a buffer should be reserved for this use.)
7. 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.
8. Other Considerations
8.1. Multiple Instances
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
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supports multiple BGP instances it should also support multiple BMP
instances (one per BGP instance).
8.2. Locally-Originated Routes
Some consideration is required for routes that are originated into
BGP by the local router, whether as a result of redistribution from a
another protocol or for some other reason.
Such routes can be modeled as having been sent by the router to
itself, placing the router's own address in the Peer Address field of
the header. It is RECOMMENDED that when doing so the router should
use the same address it has used as its local address for the BMP
session. Since in this case no transport session actually exists the
Local and Remote Port fields of the Peer Up message MUST be set to
zero. Clearly the OPEN Message fields of the Peer Up message will
equally not have been physically transmitted, but should represent
the relevant capabilities of the local router.
Also recall that the L flag is used to indicate locally-sourced
routes, see Section 4.2.
9. 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.
10. IANA Considerations
IANA is requested to create the following registries.
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10.1. BMP Message Types
This document defines five message types for transferring BGP
messages between cooperating systems (Section 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
o Type 6: Mirroring
Type values 7 through 128 MUST be assigned using the "Standards
Action" policy, and values 129 through 255 using the "Specification
Required" policy defined in [RFC5226].
10.2. BMP Statistics Types
This document defines nine statistics types for statistics reporting
(Section 4.8):
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 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.
o Stat Type = 9: Number of routes in per-AFI/SAFI Adj-RIB-In.
o Stat Type = 10: Number of routes in per-AFI/SAFI Loc-RIB.
o Stat Type = 11: Number of updates subjected to treat-as-withdraw.
o Stat Type = 12: Number of prefixes subjected to treat-as-withdraw.
o Stat Type = 13: Number of duplicate update messages received.
Stat Type values 14 through 32767 MUST be assigned using the
"Standards Action" policy, and values 32768 through 65535 using the
"Specification Required" policy, defined in [RFC5226].
10.3. BMP Initiation Message TLVs
This document defines three types for information carried in the
Initiation message (Section 4.3):
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o Type = 0: String.
o Type = 1: sysDescr.
o Type = 2: sysName.
Information type values 3 through 32767 MUST be assigned using the
"Standards Action" policy, and values 32768 through 65535 using the
"Specification Required" policy, defined in [RFC5226].
10.4. BMP Termination Message TLVs
This document defines two types for information carried in the
Termination message (Section 4.5):
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].
10.5. BMP Termination Message Reason Codes
This document defines four types for information carried in the
Termination message (Section 4.5) Reason code,:
o Type = 0: Administratively closed.
o Type = 1: Unspecified reason.
o Type = 2: Out of resources.
o Type = 3: Redundant connection.
o Type = 4: Permanently administratively closed.
Information type values 5 through 32767 MUST be assigned using the
"Standards Action" policy, and values 32768 through 65535 using the
"Specification Required" policy, defined in [RFC5226].
10.6. BMP Peer Down Reason Codes
This document defines five types for information carried in the Peer
Down Notification (Section 4.9) Reason code:
o Type = 1: Local system closed, NOTIFICATION PDU follows.
o Type = 2: Local system closed, FSM Event follows.
o Type = 3: Remote system closed, NOTIFICATION PDU follows.
o Type = 4: Remote system closed, no data.
o Type = 5: Peer de-configured.
Information type values 6 through 32767 MUST be assigned using the
"Standards Action" policy, and values 32768 through 65535 using the
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"Specification Required" policy, defined in [RFC5226]. Value 0 is
reserved.
10.7. Route Mirroring TLVs
This document defines two types for information carried in the Route
Mirroring message (Section 4.7):
o Type = 0: BGP Message.
o Type = 1: Information.
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].
10.8. BMP Route Mirroring Information Codes
This document defines two types for information carried in the Route
Mirroring Information (Section 4.7) code:
o Type = 0: Errored PDU.
o Type = 1: Messages Lost.
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]. Value 0 is
reserved.
11. 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 transport
mechanism, such as IPSec [RFC4303] or TCP-AO [RFC5925], in order to
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.
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12. Acknowledgements
Thanks to Michael Axelrod, Tim Evens, Pierre Francois, John ji
Ioannidis, Mack McBride, Danny McPherson, David Meyer, Dimitri
Papadimitriou, Robert Raszuk, Erik Romijn, and the members of the
GROW working group for their comments.
13. References
13.1. Normative References
[I-D.ietf-idr-error-handling]
Chen, E., Scudder, J., Mohapatra, P., and K. Patel,
"Revised Error Handling for BGP UPDATE Messages", draft-
ietf-idr-error-handling-19 (work in progress), April 2015.
[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.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793, December
2012.
13.2. 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.
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[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 32-bit length field to the fixed header.
o Clarified error handling.
o Added new stat types: 5 (number of updates invalidated due to
ORIGINATOR_ID), 6 (number of updates invalidated due to
AS_CONFED_SEQUENCE/AS_CONFED_SET), 7 (number of routes in Adj-RIB-
In), 8 (number of routes in Loc-RIB), 9 (number of routes in Adj-
RIB-In, per AFI/SAFI), 10 (numer of routes in Loc-RIB, per AFI/
SAFI), 11 (number of updates subjected to treat-as-withdraw
treatment), 12 (number of prefixes subjected to treat-as-withdraw
treatment), and 13 (number of duplicate update messages received).
o Defined counters and gauges for use with stat types.
o For peer down messages, the relevant FSM event is to be sent in
type 2 messages. Added type 5 to indicate peer is no longer
monitored.
o Added local address and local and remote ports to the peer up
message. Also optional descriptive string.
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 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.
o Added "route mirroring" mode.
o Added "A" flag to identify AS Path format in use.
Authors' Addresses
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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
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