--- 1/draft-ietf-grow-large-communities-usage-00.txt 2016-12-07 15:13:12.599180109 -0800 +++ 2/draft-ietf-grow-large-communities-usage-01.txt 2016-12-07 15:13:12.623180710 -0800 @@ -1,19 +1,19 @@ -GROW J. Snijders +Global Routing Operations J. Snijders Internet-Draft NTT Intended status: Informational M. Schmidt Expires: June 10, 2017 i3D.net December 7, 2016 Usage of Large BGP Communities - draft-ietf-grow-large-communities-usage-00 + draft-ietf-grow-large-communities-usage-01 Abstract Examples and inspiration for operators on how to use Large BGP Communities. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this @@ -63,28 +63,28 @@ 3.1.2. An UNSD region function . . . . . . . . . . . . . . . 5 3.2. Relation . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. Combining Informational Communities . . . . . . . . . . . 6 4. Examples of Action Communities . . . . . . . . . . . . . . . 6 4.1. Selective NO_EXPORT . . . . . . . . . . . . . . . . . . . 6 4.1.1. Peer ASN Based Selective NO_EXPORT . . . . . . . . . 6 4.1.2. Location Based Selective NO_EXPORT . . . . . . . . . 7 4.2. 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 - 4.3. Region-Specific LOCAL_PREFERENCE . . . . . . . . . . . . 8 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 8.1. Normative References . . . . . . . . . . . . . . . . . . 9 - 8.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 + 4.3. Location based manipulation of LOCAL_PREF . . . . . . . . 8 + 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 10 + 8.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 11 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction Large BGP Communities [I-D.ietf-idr-large-community] provide a mechanism to signal opaque information between Autonomous Systems. This document presents a set of examples on how Large BGP Communities could be implemented by an operator to achieve various goals. This document draws from experience in Operational Communities such as NANOG [1] and NLNOG [2]. @@ -244,34 +244,34 @@ Multiple Informational Communities can be tagged on a route, for example: a route learned in the Netherlands from a customer can contain both 64497:1:528 and 64497:2:150 and 64497:3:1. 4. Examples of Action Communities 4.1. Selective NO_EXPORT As part of the commercial agreement between AS 64497 and AS 64498, AS 64497 might offer AS 64498 certain BGP Traffic Engineering features - such as selectively not exporting routes learned from 64498 to - certain EBGP neighbors of AS 64497. + such as selectively not export routes learned from 64498 to certain + EBGP neighbors of AS 64497. 4.1.1. Peer ASN Based Selective NO_EXPORT AS 64497 might assign function identifier 4 to allow preventing propagation of routes to the ASN listed in the second Local Data field. +---------------------+---------------------------------+ | Large BGP Community | Meaning | +---------------------+---------------------------------+ | 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 | +---------------------+---------------------------------+ Example documentation for AS 64497 offering Action Communties to limit propagation of routes based on the Peer ASN described in the third field. Table 4: Action: Peer ASN NO_EXPORT 4.1.2. Location Based Selective NO_EXPORT @@ -323,74 +323,146 @@ trigger prepending of the AS_PATH only when propagating the route to a certain Peer ASN. Table 6: Action: Prepend to Peer ASN 4.2.2. Location Based Selective AS_PATH Prepending AS 64497 might assign function identifier 7 to allow prepending of the AS_PATH on propagation of routes to on any EBGP neighbor's 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 | | Community | | +------------------+------------------------------------------------+ | 64497:7:528 | Prepend once to EBGP neighbors in the | | | Netherlands | | 64497:7:392 | Prepend once to EBGP neighbors in Japan | | 64497:7:840 | Prepend once to EBGP neighbors in United | | | States of America | +------------------+------------------------------------------------+ Example documentation for AS 64497 offering Action Communties to trigger prepending of the AS_PATH only when propagating the route to a certain geographical 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 Network operators should note the recommendations in Section 11 of BGP Operations and Security [RFC7454]. 6. IANA Considerations None. 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 8.1. Normative References [I-D.ietf-idr-large-community] - Heitz, J., Snijders, J., Patel, K., Bagdonas, I., Simpson, - A., and N. Hilliard, "Large BGP Communities", draft-ietf- - idr-large-community-06 (work in progress), October 2016. + Heitz, J., Snijders, J., Patel, K., Bagdonas, I., and N. + Hilliard, "BGP Large Communities", draft-ietf-idr-large- + community-11 (work in progress), December 2016. [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . + [RFC4264] Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264, + DOI 10.17487/RFC4264, November 2005, + . + [RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454, February 2015, . 8.2. URIs [1] http://nanog.net [2] http://nlnog.net