BMP Extension for Path Status sub-TLV
draft-cppy-grow-bmp-path-marking-tlv-04
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
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|
|---|---|---|---|
| Authors | Camilo Cardona , Paolo Lucente , Pierre Francois , Yunan Gu , Thomas Graf | ||
| Last updated | 2020-07-13 | ||
| Replaced by | draft-ietf-grow-bmp-path-marking-tlv | ||
| RFC stream | (None) | ||
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| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
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draft-cppy-grow-bmp-path-marking-tlv-04
Network Working Group C. Cardona
Internet-Draft P. Lucente
Intended status: Standards Track NTT
Expires: January 13, 2021 P. Francois
INSA-Lyon
Y. Gu
Huawei
T. Graf
Swisscom
July 12, 2020
BMP Extension for Path Status sub-TLV
draft-cppy-grow-bmp-path-marking-tlv-04
Abstract
The BGP Monitoring Protocol (BMP) provides an interface for obtaining
BGP Path information. BGP Path Information is conveyed within BMP
Route Monitoring (RM) messages. This document proposes an extension
to BMP to convey the status of a BGP path before and after being
processed by the BGP best-path selection algorithm. This extension
makes use of the Path Information TLV defined in draft-cppy-grow-bmp-
path-info-tlv [I-D.cppy-grow-bmp-path-info-tlv].
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 BCP
14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
appear in all capitals, as shown here.
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 https://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."
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Internet-Draft BMP path status sub-tlv July 2020
This Internet-Draft will expire on January 13, 2021.
Copyright Notice
Copyright (c) 2020 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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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Path Status sub-TLV . . . . . . . . . . . . . . . . . . . . . 3
2.1. IANA-registered Path Status sub-TLV . . . . . . . . . . . 3
2.2. Enterprise-specific Path Status sub-TLV . . . . . . . . . 6
3. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
For a given prefix, multiple paths with different path status, e.g.,
the "best-path", "back-up path" and so on, may co-exist in the BGP
RIB after being processed by the local policy and the BGP decision
process. The path status information is currently not carried in the
BGP Update Message RFC4271 [RFC4271] or in the BMP Update Message
RFC7854 [RFC7854].
External systems can use the path status for various applications.
The path status is commonly checked by operators when performing
troubleshooting. Having such status stored in a centralized system
can enable the development of tools that facilitate this process.
Optimisation systems can include the path status in their process,
and also use the status as a validation source (since it can compare
the calculated state to the actual outcome of the network, such as
primary and backup path). As a final example, path status
information can complement other centralized sources of data, for
example, flow collectors.
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This document defines a so-called Path Status sub-TLV to convey the
BGP path status to the BMP server. The BMP Path Status sub-TLV is
encapsulated within the BMP Path Information TLV carried in the BMP
Route Monitoring (RM) Message draft-cppy-grow-bmp-path-info-tlv
[I-D.cppy-grow-bmp-path-info-tlv].
2. Path Status sub-TLV
As stated in draft-cppy-grow-bmp-path-info-tlv
[I-D.cppy-grow-bmp-path-info-tlv], the order of the sub-TLVs MUST be
in accordance with the prefix order encapsulated in the Update PDU.
This document defines two types of Path Status sub-TLVs: one is IANA-
registered Path Status sub-TLV, and the other is Enterprise-specific
Path Status sub-TLV.
2.1. IANA-registered Path Status sub-TLV
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
+-------------------------------+-------------------------------+
|E| Type (15 bits) | Length (2 octets) |
+-------------------------------+-------------------------------+
| Path Status(4 octets) |
+---------------------------------------------------------------+
| Reason Code(4 octets) |
+---------------------------------------------------------------+
Figure 2:IANA-Registered Encoding of the path status sub-TLV
o E bit: For an IANA-registered sub-TLV, the E bit MUST be set to 0.
o Type = TBD2 (15 Bits): indicates that it is the IANA-registered
Path Status sub-TLV.
o Length (2 Octets): indicates the length of the value field of the
Path Status TLV. The value field further consists of the Path-
Status field and Reason Code field.
o Path Status (4 Octets): indicates the path status of the BGP
Update PDU encapsulated in the RM Message. Currently 9 types of
path status are defined, as shown in Table 1.
o Reason Code (4 Octets): indicates the reasons/explanations of the
path status indicated in the Path Type field. The currently
defined reason codes are shown in Table 2.
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+------------+------------------+
| Value | Path type |
+-------------------------------+
| 0x00000000 | Unknown |
| 0x00000001 | Invalid |
| 0x00000002 | Best |
| 0x00000004 | Non-selected |
| 0x00000008 | Primary |
| 0x00000010 | Backup |
| 0x00000020 | Non-installed |
| 0x00000040 | Best-external |
| 0x00000080 | Add-Path |
+------------+------------------+
Table 1: IANA-Registered Path Type
The Path Status field contains a bitmap where each bit encodes a
specific role of the path. Multiple bits may be set when multiple
path status apply to a path.
o The best-path is defined in RFC4271 [RFC4271] and the best-
external path is defined in draft-ietf-idr-best-external
[I-D.ietf-idr-best-external].
o An invalid path is a route that does not enter the BGP decision
process.
o A non-selected path is a route that is not selected in the BGP
decision process. Back-up routes are considered non-selected,
while the best and ECMP routes are not considered as non-selected.
o A primary path is a recursive or non-recursive path whose nexthop
resolution ends with an adjacency draft-ietf-rtgwg-bgp-pic
[I-D.ietf-rtgwg-bgp-pic]. A prefix can have more than one primary
path if multipath is configured draft-lapukhov-bgp-ecmp-
considerations [I-D.lapukhov-bgp-ecmp-considerations]. A best-
path is also considered as a primary path.
o A backup path is also installed in the RIB, but it is not used
until some or all primary paths become unreachable. Backup paths
are used for fast convergence in the event of failures.
o A non-installed path refers to the route that is not installed
into the IP routing table.
o For the advertisement of multiple paths for the same address
prefix without the new paths implicitly replacing any previous
ones, the add-path status is applied RFC7911 [RFC7911].
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+-------------+---------------------------------------------------
| value | reason code |
+----------------------------------------------------------------+
|[0x00000000] |invalid for unknown, |
|[0x00000001] |invalid for super network, |
|[0x00000002] |invalid for dampening, |
|[0x00000003] |invalid for history, |
|[0x00000004] |invalid for policy deny, |
|[0x00000005] |invalid for ROA not validation, |
|[0x00000006] |invalid for interface error, |
|[0x00000007] |invalid for nexthop route unreachable, |
|[0x00000008] |invalid for nexthop tunnel unreachable, |
|[0x0000000f] |invalid for nexthop restrain, |
|[0x00000010] |invalid for relay BGP LSP, |
|[0x00000014] |invalid for being inactive within VPN instance |
|[0x00000015] |invalid for prefix-sid not exist, |
|[0x00000200] |not preferred for peer address, |
|[0x00000300] |not preferred for router ID, |
|[0x00000400] |not preferred for Cluster List, |
|[0x00000500] |not preferred for IGP cost, |
|[0x00000600] |not preferred for peer type, |
|[0x00000700] |not preferred for MED, |
|[0x00000800] |not preferred for origin, |
|[0x00000900] |not preferred for AS-Path, |
|[0x00000a00] |not preferred for route type, |
|[0x00000b00] |not preferred for Local_Pref, |
|[0x00000c00] |not preferred for PreVal, |
|[0x00000f00] |not preferred for not direct route, |
|[0x00001000] |not preferred for nexthop bit error, |
|[0x00001100] |not preferred for received path-id, |
|[0x00001200] |not preferred for validation, |
|[0x00001300] |not preferred for originate IP, |
|[0x00001500] |not preferred for route distinguisher, |
|[0x00001600] |not preferred for route-select delay, |
|[0x00001700] |not preferred for being imported route, |
|[0x00001800] |not preferred for med-plus-igp, |
|[0x00001c00] |not preferred for AIGP, |
|[0x00001d00] |not preferred for nexthop-resolved aigp, |
|[0x00002000] |not preferred for nexthop unreachable, |
|[0x00002100] |not preferred for nexthop IP, |
|[0x00002300] |not preferred for high-priority, |
|[0x00002400] |not preferred for nexthop-priority, |
|[0x00002500] |not preferred for process ID, |
|[0xFFFFFFFF] |no reason code |
-----------------------------------------------------------------+
Table 2: IANA-Registered Reason Code
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2.2. Enterprise-specific Path Status sub-TLV
The E-bit [I-D.lucente-grow-bmp-tlv-ebit] mechanism allows the usage
of vendor-specific TLVs in addition to IANA-registered one. In this
document, both encoding options for the Path Status sub-TLV are
described.
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
+-------------------------------+-------------------------------+
|E| Type (15 bits) | Length (2 octets) |
+-------------------------------+-------------------------------+
| PEN number (4 octets) |
+---------------------------------------------------------------+
| Path Status(4 octets) |
+---------------------------------------------------------------+
| Reason Code(variable) |
+---------------------------------------------------------------+
Figure 3: Enterprise-specific encoding of Path Status sub-TLV
o E bit: For an Enterprise-specific sub-TLV, the E bit MUST be set
to 1.
o Type = 1 (15 Bits): indicates that it's the Enterprise-specific
Path Status sub-TLV.
o Length (2 Octets): indicates the length of the value field of the
Path Status sub-TLV. The value field further consists of the
Path-Status field and Reason Code field.
o PEN Number (4 octets): indicates the IANA enterprise number IANA-
PEN.
o Path Status (4 Octets): indicates the enterprise-specific path
status.
o Reason Code (Variable): indicates the reasons/explanations of the
path status indicated in the Path Type field.
3. Acknowledgments
We would like to thank Jeff Haas for his valuable comments.
4. IANA Considerations
This document requests that IANA assign the following new parameters
to the BMP parameters name space.
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Type = TBD1 (15 Bits): indicates that it is the IANA-registered Path
Status sub-TLV.
5. Security Considerations
It is not believed that this document adds any additional security
considerations.
6. Normative References
[I-D.cppy-grow-bmp-path-info-tlv]
Cardona, C., Lucente, P., Francois, P., Gu, Y., and T.
Graf, "BMP Extension for Path Information TLV", draft-
cppy-grow-bmp-path-info-tlv-00 (work in progress), July
2020.
[I-D.ietf-grow-bmp-tlv]
Lucente, P., Gu, Y., and H. Smit, "TLV support for BMP
Route Monitoring and Peer Down Messages", draft-ietf-grow-
bmp-tlv-02 (work in progress), March 2020.
[I-D.ietf-idr-best-external]
Marques, P., Fernando, R., Chen, E., Mohapatra, P., and H.
Gredler, "Advertisement of the best external route in
BGP", draft-ietf-idr-best-external-05 (work in progress),
January 2012.
[I-D.ietf-rtgwg-bgp-pic]
Bashandy, A., Filsfils, C., and P. Mohapatra, "BGP Prefix
Independent Convergence", draft-ietf-rtgwg-bgp-pic-11
(work in progress), February 2020.
[I-D.lapukhov-bgp-ecmp-considerations]
Lapukhov, P. and J. Tantsura, "Equal-Cost Multipath
Considerations for BGP", draft-lapukhov-bgp-ecmp-
considerations-04 (work in progress), May 2020.
[I-D.lucente-grow-bmp-tlv-ebit]
Lucente, P. and Y. Gu, "Support for Enterprise-specific
TLVs in the BGP Monitoring Protocol", draft-lucente-grow-
bmp-tlv-ebit-01 (work in progress), May 2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271,
DOI 10.17487/RFC4271, January 2006,
<https://www.rfc-editor.org/info/rfc4271>.
[RFC7854] Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
Monitoring Protocol (BMP)", RFC 7854,
DOI 10.17487/RFC7854, June 2016,
<https://www.rfc-editor.org/info/rfc7854>.
[RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder,
"Advertisement of Multiple Paths in BGP", RFC 7911,
DOI 10.17487/RFC7911, July 2016,
<https://www.rfc-editor.org/info/rfc7911>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses
Camilo Cardona
NTT
164-168, Carrer de Numancia
Barcelona 08029
Spain
Email: camilo@ntt.net
Paolo Lucente
NTT
Siriusdreef 70-72
Hoofddorp, WT 2132
Netherlands
Email: paolo@ntt.net
Pierre Francois
INSA-Lyon
Lyon
France
Email: Pierre.Francois@insa-lyon.fr
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Yunan Gu
Huawei
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: guyunan@huawei.com
Thomas Graf
Swisscom
Binzring 17
Zurich 8045
Switzerland
Email: thomas.graf@swisscom.com
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