draft-ietf-grow-large-communities-usage-00.txt   draft-ietf-grow-large-communities-usage-01.txt 
GROW J. Snijders Global Routing Operations J. Snijders
Internet-Draft NTT Internet-Draft NTT
Intended status: Informational M. Schmidt Intended status: Informational M. Schmidt
Expires: June 10, 2017 i3D.net Expires: June 10, 2017 i3D.net
December 7, 2016 December 7, 2016
Usage of Large BGP Communities Usage of Large BGP Communities
draft-ietf-grow-large-communities-usage-00 draft-ietf-grow-large-communities-usage-01
Abstract Abstract
Examples and inspiration for operators on how to use Large BGP Examples and inspiration for operators on how to use Large BGP
Communities. Communities.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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3.1.2. An UNSD region function . . . . . . . . . . . . . . . 5 3.1.2. An UNSD region function . . . . . . . . . . . . . . . 5
3.2. Relation . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Relation . . . . . . . . . . . . . . . . . . . . . . . . 5
3.3. Combining Informational Communities . . . . . . . . . . . 6 3.3. Combining Informational Communities . . . . . . . . . . . 6
4. Examples of Action Communities . . . . . . . . . . . . . . . 6 4. Examples of Action Communities . . . . . . . . . . . . . . . 6
4.1. Selective NO_EXPORT . . . . . . . . . . . . . . . . . . . 6 4.1. Selective NO_EXPORT . . . . . . . . . . . . . . . . . . . 6
4.1.1. Peer ASN Based Selective NO_EXPORT . . . . . . . . . 6 4.1.1. Peer ASN Based Selective NO_EXPORT . . . . . . . . . 6
4.1.2. Location Based Selective NO_EXPORT . . . . . . . . . 7 4.1.2. Location Based Selective NO_EXPORT . . . . . . . . . 7
4.2. Selective AS_PATH Prepending . . . . . . . . . . . . . . 7 4.2. Selective AS_PATH Prepending . . . . . . . . . . . . . . 7
4.2.1. Peer ASN Based Selective AS_PATH Prepending . . . . . 7 4.2.1. Peer ASN Based Selective AS_PATH Prepending . . . . . 7
4.2.2. Location Based Selective AS_PATH Prepending . . . . . 8 4.2.2. Location Based Selective AS_PATH Prepending . . . . . 8
4.3. Region-Specific LOCAL_PREFERENCE . . . . . . . . . . . . 8 4.3. Location based manipulation of LOCAL_PREF . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 9 8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
Large BGP Communities [I-D.ietf-idr-large-community] provide a Large BGP Communities [I-D.ietf-idr-large-community] provide a
mechanism to signal opaque information between Autonomous Systems. mechanism to signal opaque information between Autonomous Systems.
This document presents a set of examples on how Large BGP Communities This document presents a set of examples on how Large BGP Communities
could be implemented by an operator to achieve various goals. This could be implemented by an operator to achieve various goals. This
document draws from experience in Operational Communities such as document draws from experience in Operational Communities such as
NANOG [1] and NLNOG [2]. NANOG [1] and NLNOG [2].
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Multiple Informational Communities can be tagged on a route, for Multiple Informational Communities can be tagged on a route, for
example: a route learned in the Netherlands from a customer can example: a route learned in the Netherlands from a customer can
contain both 64497:1:528 and 64497:2:150 and 64497:3:1. contain both 64497:1:528 and 64497:2:150 and 64497:3:1.
4. Examples of Action Communities 4. Examples of Action Communities
4.1. Selective NO_EXPORT 4.1. Selective NO_EXPORT
As part of the commercial agreement between AS 64497 and AS 64498, AS As part of the commercial agreement between AS 64497 and AS 64498, AS
64497 might offer AS 64498 certain BGP Traffic Engineering features 64497 might offer AS 64498 certain BGP Traffic Engineering features
such as selectively not exporting routes learned from 64498 to such as selectively not export routes learned from 64498 to certain
certain EBGP neighbors of AS 64497. EBGP neighbors of AS 64497.
4.1.1. Peer ASN Based Selective NO_EXPORT 4.1.1. Peer ASN Based Selective NO_EXPORT
AS 64497 might assign function identifier 4 to allow preventing AS 64497 might assign function identifier 4 to allow preventing
propagation of routes to the ASN listed in the second Local Data propagation of routes to the ASN listed in the second Local Data
field. field.
+---------------------+---------------------------------+ +---------------------+---------------------------------+
| Large BGP Community | Meaning | | Large BGP Community | Meaning |
+---------------------+---------------------------------+ +---------------------+---------------------------------+
| 64497:4:2914 | Do not export route to AS 2914 | | 64497:4:2914 | Do not export route to AS 2914 |
| 64497:4:7018 | Do not export route to AS 3356 | | 64497:4:7018 | Do not export route to AS 7018 |
| 64497:4:65551 | Do not export route to AS 65551 | | 64497:4:65551 | Do not export route to AS 65551 |
+---------------------+---------------------------------+ +---------------------+---------------------------------+
Example documentation for AS 64497 offering Action Communties to Example documentation for AS 64497 offering Action Communties to
limit propagation of routes based on the Peer ASN described in the limit propagation of routes based on the Peer ASN described in the
third field. third field.
Table 4: Action: Peer ASN NO_EXPORT Table 4: Action: Peer ASN NO_EXPORT
4.1.2. Location Based Selective NO_EXPORT 4.1.2. Location Based Selective NO_EXPORT
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trigger prepending of the AS_PATH only when propagating the route to trigger prepending of the AS_PATH only when propagating the route to
a certain Peer ASN. a certain Peer ASN.
Table 6: Action: Prepend to Peer ASN Table 6: Action: Prepend to Peer ASN
4.2.2. Location Based Selective AS_PATH Prepending 4.2.2. Location Based Selective AS_PATH Prepending
AS 64497 might assign function identifier 7 to allow prepending of AS 64497 might assign function identifier 7 to allow prepending of
the AS_PATH on propagation of routes to on any EBGP neighbor's the AS_PATH on propagation of routes to on any EBGP neighbor's
interconnection in the geographical entity listed in the second Local interconnection in the geographical entity listed in the second Local
Data field. This example follows the ISO 3166-1 numeric encoding. Data field. This example follows the ISO 3166-1 numeric regions
codes in the Local Data 2 field.
+------------------+------------------------------------------------+ +------------------+------------------------------------------------+
| Large BGP | Meaning | | Large BGP | Meaning |
| Community | | | Community | |
+------------------+------------------------------------------------+ +------------------+------------------------------------------------+
| 64497:7:528 | Prepend once to EBGP neighbors in the | | 64497:7:528 | Prepend once to EBGP neighbors in the |
| | Netherlands | | | Netherlands |
| 64497:7:392 | Prepend once to EBGP neighbors in Japan | | 64497:7:392 | Prepend once to EBGP neighbors in Japan |
| 64497:7:840 | Prepend once to EBGP neighbors in United | | 64497:7:840 | Prepend once to EBGP neighbors in United |
| | States of America | | | States of America |
+------------------+------------------------------------------------+ +------------------+------------------------------------------------+
Example documentation for AS 64497 offering Action Communties to Example documentation for AS 64497 offering Action Communties to
trigger prepending of the AS_PATH only when propagating the route to trigger prepending of the AS_PATH only when propagating the route to
a certain geographical region. a certain geographical region.
Table 7: Action: Prepend in Region Table 7: Action: Prepend in Region
4.3. Region-Specific LOCAL_PREFERENCE 4.3. Location based manipulation of LOCAL_PREF
To be filled in. In some cases, it can be desirable for an autonomous system to allow
adjacent Autonomous Systems to directly influence the degree of
preference associated with a route, usually expressed within the
LOCAL_PREF attribute.
Furthermore, in the case of large networks spanning significant
geography, it is often also useful to be able to extend this
capability and scope its effect to a geographic region. This is a
more powerful mechanism than AS_PATH prepending, but since degree of
preference determines BGP route selection and thus onward
advertisement, it can also be self-limiting in its scope.
Since the LOCAL_PREF attribute which influences degree of preference
is locally significant within each autonomous system, it is not
usually practical or useful to compare LOCAL_PREF attribute values
between autonomous systems. Instead it can be useful to classify the
major types of route likely to exist within an autonomous system's
routing hierarchy and provide an ability to set one's route to that
preference:
o A qualified customer route. Usually the highest preference.
o A peer, or network-share, route. A co-operating network provider
engaged in a partnership for customer coverage ("peering").
o A last resort, or backup route.
It is entirely possible that some providers may have more classes of
route preference but it is possible to codify both the route
preference class and the regional scope within the Local Data fields
of the Large Community attribute.
For example, AS64497 might establish the following function
identifiers to set route preference class, which could allow pairing
with a location or peer-based operand to determine scope.
+----------+-----------------------------------------------+
| Function | Preference Class |
+----------+-----------------------------------------------+
| 10 | Qualified customer route. Highest preference. |
| 15 | Peering partner. Median preference. |
| 19 | Route of last resort. Lowest preference. |
+----------+-----------------------------------------------+
Table 8: Action: Preference Function Identifiers
Once established, these route preference setting functions can be
linked with a scoping operand such as per-peer or per-location based
identifiers in order to provide AS64497's customers with a
comprehensive and rich toolset to influence route preference.
+--------------------+----------------------------------------------+
| Large BGP | Meaning |
| Community | |
+--------------------+----------------------------------------------+
| 64497:15:528 | Set as peer route in Netherlands |
| 64497:19:840 | Set as backup route in United States of |
| | America |
+--------------------+----------------------------------------------+
Table 9: Action: Regional Preference Communities
Since the degree of preference influences BGP best path selection
(which in turn influences onward route propagation) Operators should
take special care with a traffic engineering tool such as location
based local preference influence (BGP Wedgies [RFC4264]).
5. Security Considerations 5. Security Considerations
Network operators should note the recommendations in Section 11 of Network operators should note the recommendations in Section 11 of
BGP Operations and Security [RFC7454]. BGP Operations and Security [RFC7454].
6. IANA Considerations 6. IANA Considerations
None. None.
7. Acknowledgements 7. Acknowledgements
Thanks to ... The authors would like to gratefully acknowledge the insightful
comments, contributions, critique and support from John Heasley, Adam
Chappell and Jonathan Stewart.
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-idr-large-community] [I-D.ietf-idr-large-community]
Heitz, J., Snijders, J., Patel, K., Bagdonas, I., Simpson, Heitz, J., Snijders, J., Patel, K., Bagdonas, I., and N.
A., and N. Hilliard, "Large BGP Communities", draft-ietf- Hilliard, "BGP Large Communities", draft-ietf-idr-large-
idr-large-community-06 (work in progress), October 2016. community-11 (work in progress), December 2016.
[RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities
Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
<http://www.rfc-editor.org/info/rfc1997>. <http://www.rfc-editor.org/info/rfc1997>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264,
DOI 10.17487/RFC4264, November 2005,
<http://www.rfc-editor.org/info/rfc4264>.
[RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations [RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454, and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
February 2015, <http://www.rfc-editor.org/info/rfc7454>. February 2015, <http://www.rfc-editor.org/info/rfc7454>.
8.2. URIs 8.2. URIs
[1] http://nanog.net [1] http://nanog.net
[2] http://nlnog.net [2] http://nlnog.net
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