Internet DRAFT - draft-raszuk-idr-bgp-pr
draft-raszuk-idr-bgp-pr
IDR Working Group R. Raszuk, Ed.
Internet-Draft Bloomberg LP
Intended status: Standards Track R. White
Expires: December 2, 2016 Ericsson
J. Dong
Huawei Technologies
May 31, 2016
BGP Path Record Attribute
draft-raszuk-idr-bgp-pr-05
Abstract
The BGP protocol contains number of built in mechanisms which records
information about the routers which have processed a specific piece
of reachability information critical to insuring only loop free paths
are chosen by the protocol. For instance, the AS_PATH, CLUSTER_LIST
and ORIGINATOR_ID attributes carry information designed to insure
permanent routing loops are not formed in the path chosen towards a
particular destination. However, there are no provisions to record
other useful information along the path, metadata about the routers
through which reachability information has passed which can be
helpful to the operator in order to enhance end to end visibility of
the BGP control plane.
In order to solve this problem this document proposes a new single
BGP attribute designed as an generic and extensible container to
carry number of new optional information corresponding to the BGP
speakers given BGP advertisement (or withdraw) message traverses.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on December 2, 2016.
Copyright Notice
Copyright (c) 2016 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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 3
2.1. BGP Path Record Attribute . . . . . . . . . . . . . . . . 3
2.2. BGP Per Hop TLV . . . . . . . . . . . . . . . . . . . . . 4
2.2.1. Host Name sub-TLV . . . . . . . . . . . . . . . . . . 6
2.2.2. Time Stamp sub-TLV . . . . . . . . . . . . . . . . . 6
2.2.3. Next hop record sub-TLV . . . . . . . . . . . . . . . 6
2.2.4. Path count sub-TLV . . . . . . . . . . . . . . . . . 7
2.2.5. Origin Validation sub-TLV . . . . . . . . . . . . . . 7
2.2.6. Geo-location sub-TLV . . . . . . . . . . . . . . . . 7
2.2.7. BGP System Load sub-TLV . . . . . . . . . . . . . . . 8
3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4. Deployment considerations . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Security considerations . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
The ability to record various information from the midpoints through
which given control plane information traverses seems would be a
useful tool in number of control plane protocols. For some use cases
such information is critical and mandatory for correct operation
while in other use cases this information could be used for further
processing on or off line.
Recently there have been two proposals discussing the need to carry
opaque operational data in BGP Attributes proposed for such purposes.
As it seems that there can be many more types of such data it will be
more efficient to define a single TLV based placeholder to carry all
optional hop parameters along the path given BGP prefix traverses in
the network.
To facilitate the transport of information that may be used within a
BGP network, but is generally opaque to BGP processes, this document
proposes the definition of new a BGP attribute called the BGP Path
Record Attribute which can be used to to carry such new optional
information. This attribute is formatted to allow the inclusion of
information of significance only to the local network operator
(within the autonomous system).
2. Protocol Extensions
This document describes a new BGP attribute known as BGP Path Record
Attribute which includes a new TLV and a number of sub-TLVs which can
be used to carry new types of information. Several types of
information are defined in this document, and several others have
been defined in other drafts but included here, as well. The TLV is
designed for easy extensibility as well as to accomodate the addition
of information by each BGP speaker through within a path.
The TLVs are appended by each participating BGP speaker in the order
in which the BGP speaker handles the data; hence the order of the
TLVs and sub-TLVs MUST NOT be changed in local storage or when
transmitted between BGP speakers.
The sub-TLVs on the other hand allow for very easy definition of new
types of data which may be required to be carried both within this
document as well as by new subsequent documents.
2.1. BGP Path Record Attribute
The BGP Path Record attribute is a new BGP optional transitive
attribute. The attribute type code for the Path Record attribute is
to be assigned by IANA. The value field of the Path Record attribute
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is defined as a set of one or more Path Record TLVs along with their
sub-TLVs.
2.2. BGP Per Hop TLV
The BGP Per Hop TLV is defined as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BGP ROUTER ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS NUMBER |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FLAGS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ sub-TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BGP Per Hop Type 1 TLV
TYPE: Two octets encoding the Path Record TLV Type. Each distinct
type of Path record TLV is assigned a unique identifier as noted in
this draft. Further identifiers should be assigned through the
creation of a new IANA registry and be assigned on a "first come
first served" basis. Type 1 TLV is called BGP Hop TLV
LENGTH: Two octets encoding the length in octets of the Path Record
TLV, excluding the type and length fields. The Length is encoded as
an unsigned binary integer.
BGP ROUTER ID (4 octets): 4 octet BGP router ID assigned to a given
BGP speaker processing prefix with path containing BGP Path Record
Attribute.
AS NUMBER (4 octets): 4 octet AS number or zero padded 2 octet AS
number of the autonomous system BGP Hop belongs to.
FLAGS: Number of boolean flags describing BGP Hop basic
characteristics. The following flags are defined for BGP Hop TLV:
Bit 0:
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NH - Next Hop - Values: 0 - next hop not set; 1 - next hop set
Bit 1:
RR - Route Reflector - Values: 0 - not a route reflector; 1 -
route reflector
Bit 2:
RS - Route Server - Values: 0 - not route server; 1 - route
server
Bit 3:
B - Beacon prefix - Values: 0 - not a special beacon prefix; 1
- special beacon prefix
Bits 4-31:
Reserved for future use
sub-TLVs: Variable length sub-TLVs describing various information
pertaining to the TLV they are nested under. The general format of a
sub-TLV is illustrated below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | LENGTH |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ VALUE ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: sub-TLV format
TYPE (2 octets): The sub-TLV type used to differentiate information
types carried in the context of given TLV.
LENGTH (2 octets): The length in octets of the sub-TLV, excluding the
type and length fields. The Length is encoded as an unsigned binary
integer.
VALUE: Variable length field described in the context of each sub-
TLV.
The following optional sub-TLVs are proposed in this document to be
carried under BGP Hop TLV:
o Type 1 - Host Name sub-TLV
o Type 2 - Time Stamp sub-TLV
o Type 3 - Next Hop record sub-TLV
o Type 4 - Path Count sub-TLV
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o Type 5 - Origin Validation sub-TLV
o Type 6 - Geo-location sub-TLV
o Type 7 - BGP System Load sub-TLV
2.2.1. Host Name sub-TLV
Type:
1
Length:
Length of sub-TLV in octets.
Value:
UTF-8 encoded BGP speaker hostname.
Description:
Useful for enhance display in number of direct or indirect show
commands and operational logs.
2.2.2. Time Stamp sub-TLV
Type:
2
Length:
10 octets
Value:
8 octets - BGP UPDATE message receive timestamp,
1 octet - flags; Bit 0 - T flag (synchronized to external
clock) Bits 1-7 - reserved.
1 octet - Sync type as described in [RFC5905],
Description:
For full details of this sub-TLV use case and architecture are
described in separate document:
[I-D.litkowski-idr-bgp-timestamp]
2.2.3. Next hop record sub-TLV
Type:
3
Length:
5 octets or 17 octets
Flags:
Bit 0: Set if next hop is third party next hop Bits 1-7:
Reserved
Value:
IPv4 or IPv6 address of the next hop changed by current BGP Hop
Description:
For full details of this sub-TLV use case and architecture are
described in separate document:
[I-D.zhang-idr-nexthop-path-record]
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2.2.4. Path count sub-TLV
Type:
4
Length:
2 octets
Value:
Integer indicating number of paths present for a given prefix
in BGP speaker.
Description:
Enables easy visibility in validation of expected propagation
model for multiple paths of given prefix. Can validate
effectiveness of various BGP mechanisms (best-external, bgp
diverse path, bgp add-paths etc ...) (TBD .. should we include
how many paths are marked as stale ?)
2.2.5. Origin Validation sub-TLV
Type:
5
Length:
10 octets
Value:
8 octets - Last time BGP Origin Validation database has been
updated.
1 octet - flags; Bit 0 - T flag (synchronized to external
clock) Bits 1-7 - reserved.
1 octet - Sync type as described in [RFC5905],
Description:
Allows to easily detect issues associated with possible lack of
synchronization of Origin Validation local database.
2.2.6. Geo-location sub-TLV
Type:
6
Length:
16 octets
Value:
Proposed encoding follows IETF consensus for representation of
coordinate based location.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LatUnc | Latitude +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lat (cont'd) | LongUnc | Longitude +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Longitude (cont'd) | AType | AltUnc | Altitude +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Altitude (cont'd) |Ver| Res |Datum|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Geo-location encoding format
Description:
Allows to map BGP control plane hops taken by BGP
advertisements to two or three dimensional geo location
coordinates of participating BGP speakers. Encoding details
are described in [RFC6225] (DHCP geo-location options
document).
2.2.7. BGP System Load sub-TLV
Type:
7
Length:
2 octets
Value:
1 octet - avg last 15 min of CPU utilization in percent by BGP
process/thread
1 octet - avg last 15 min of BGP process memory use to total
available memory use in percent
Description:
Used as indicator of possible CPU or memory problems of any
given participating BGP speaker along the BGP control plane
path. To prevent unnecessary churn implementation should only
append it upon BGP update generation as well as inserted value
should be an avrage over configurable time (default: 15 sec).
3. Operation
The proposed new BGP Path Record attribute is an opaque entity for
BGP operation and as such there is no requirement for any direct
modification to BGP operation or BGP state machine based on the
information it contains. It is expected that such feedback loop will
be performed by operator either by automated or manual process.
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Operator should be able to allow or deny origination of BGP Path
Record attribute or insertion of any TLV or sub-TLV into BGP UPDATE
message. It is however recommended that given BGP implementation
adds available sub-TLVs to BGP Hop TLV when particular prefix has
been received with BGP Path Record Attribute already containing such
sub-TLVs.
BGP policy should be enhanced to allow for easy filtering of BGP Path
Record attribute both on egress as well as ingress eBGP sessions.
BGP Path Record attribute can be used within any AFI/SAFI.
4. Deployment considerations
It needs to be recognized that some sub-TLVs of BGP Hop TLV of BGP
Path Record attribute can break update packing. Therefor it is
strongly recommended that sub-TLVs type 2, 4, 7 as defined above are
to be used only for specific beacon prefixes injected into BGP
control plane by operator and flagged with the "B" bit within the
originating BGP Hop TLV.
Beacon prefixes due to the store-and-forward nature of P2MP BGP
distribution for information correctness should be carefully injected
and withdrawn from entire network before subsequent injection is to
take place again.
5. IANA Considerations
This document defines a new BGP attribute known as a BGP Path Record
Attribute. The code point for a new BGP Path Record attribute has to
be assigned by IANA from the BGP Path Attributes registry.
This document requests IANA to define and maintain a new registry
named: "BGP Path Record Attribute TLV types". The reserved pool of
0x0000-0xFFFF has been defined for its allocations. The allocations
policy is on a first come first served basis. The recommended
allocation of 0x0001 is to be allocated for BGP Hop TLV.
This document requests IANA to define and maintain a new registry
named: "BGP Hop sub-TLV types". The reserved pool of 0x0000-0xFFFF
has been defined for its allocations. The allocations policy is on a
first come first served basis. The recommended allocation of first 7
sub-TLVs are indicated in section 2.2 titled: BGP Hop TLV.
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6. Security considerations
No new security issues are introduced to the BGP protocol by this
specification.
7. Acknowledgements
Authors would like to acknowledge Stephane Litkowski for his valuable
input, review and comments.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4223] Savola, P., "Reclassification of RFC 1863 to Historic",
RFC 4223, DOI 10.17487/RFC4223, October 2005,
<http://www.rfc-editor.org/info/rfc4223>.
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.
8.2. Informative References
[I-D.litkowski-idr-bgp-timestamp]
Litkowski, S., Patel, K., and J. Haas, "Timestamp support
for BGP paths", draft-litkowski-idr-bgp-timestamp-00 (work
in progress), July 2014.
[I-D.zhang-idr-nexthop-path-record]
Li, Z., Zhang, L., and S. Hares, "NEXTHOP_PATH_RECORD
ATTIBUTE for BGP", draft-zhang-idr-nexthop-path-record-00
(work in progress), July 2014.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<http://www.rfc-editor.org/info/rfc5905>.
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[RFC6225] Polk, J., Linsner, M., Thomson, M., and B. Aboba, Ed.,
"Dynamic Host Configuration Protocol Options for
Coordinate-Based Location Configuration Information",
RFC 6225, DOI 10.17487/RFC6225, July 2011,
<http://www.rfc-editor.org/info/rfc6225>.
Authors' Addresses
Robert Raszuk (editor)
Bloomberg LP
731 Lexington Ave
New York City, NY 10022
USA
Email: robert@raszuk.net
Russ White
Ericsson
Oak Island, NC 28465
USA
Email: russw@riw.us
Jie Dong
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: jie.dong@huawei.com
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