idr Z. Zhang Internet-Draft J. Haas Updates: 4684 (if approved) Juniper Networks Intended status: Standards Track July 12, 2020 Expires: January 13, 2021 Route Target Constrain Extension draft-zzhang-idr-bgp-rt-constrains-extension-00 Abstract This document specifies the extensions to Route Target Constrain mechanism so that it works with various types of Route Targets of arbitrary lengths. 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 [RFC2119] [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." 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 Provisions Relating to IETF Documents Zhang & Haas Expires January 13, 2021 [Page 1] Internet-Draft rtc-extension July 2020 (https://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 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Specification . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 6.2. Informative References . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction The importation and propagation of BGP routes can be controled using Route Targets [RFC4364] and Route Target Constrains [RFC4684]. A Route Target (RT) could be an 8-octet BGP Extended Community (EC) or a 20-octet IPv6 Address Sepcfic EC, though the RT Constrain mechanism specified in [RFC4684] was designed for the 8-octet RTs only. [I-D.ietf-idr-bgp-ipv6-rt-constrain] extends the mechanism to handle IPv6 Address Specific RTs by allowing the NLRI prefix to be of 0 to 24 octets (vs. 0 to 12 octets as in [RFC4684]): +-------------------------------+ | origin as (4 octets) | +-------------------------------+ | route target (8 or 20 octets)| ~ ~ | | +-------------------------------+ There is a limitation with the approach in [I-D.ietf-idr-bgp-ipv6-rt- constrain] - when the prefix is not more than 12 octets, there is no way to determine if the route target part is a partial IPv6 Address Sepcific RT or a full/partial AS or IPv4 Address Specific RT. Zhang & Haas Expires January 13, 2021 [Page 2] Internet-Draft rtc-extension July 2020 Additional types of RTs of arbitrary lengths could also be defined, e.g. [I-D.zzhang-idr-bitmask-route-target]. To extend the RT Constrain mechanisms in a generic way so that any forseeable types of RTs can be used, this document proposes the extensions specified in the following section. While the extended mechnism specified in this document can be used for existing RTs including IPv6 Address Specific RTs, it is not the intention of this document to replace or obsolete the mechansim defined in [I-D.ietf-idr-bgp-ipv6-rt-constrain], given its current status and potential existing implementations and deployments. An operator may choose either way as long as there is no ambiguity. 2. Specification To advertise Route Target Membership with various types of RTs, a new NLRI encoding with a new SAFI "Extended Route Target constrains" is used as following: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Origin AS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Path Attr Type | Route Target ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Route Target (continued, variable length ) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The one-octet "Path Attr Type" indicates the category of Route Target that follows it, using the type of BGP Path Attribute for the RT. For example, the "Path Attr Type" is 16 (Extended Community) for regular RTs, 25 (IPv6 Address Specific Extended Community) for IPv6 Address Specific RTs, or 34 (BGP Community Container Attribute) for any RT defined as a BGP Community Container (e.g. [I-D.zzhang-idr- bitmask-route-target]). Similar to [RFC4684], except for the default route target, which is encoded as a zero-length prefix, the minimum prefix length is 40 bits - the Origin AS field and the Path Attr Type field cannot be interpreted as a prefix. Route targets MAY then be expressed as prefixes, where, for instance, a prefix would encompass all regular or IPv6 Address Specific RTs assigned by a given Global Administrator. Semantics of adverising Route Target Membership for other types of RTs as prefixes MUST be defined with the specfication of those types of RTs. Zhang & Haas Expires January 13, 2021 [Page 3] Internet-Draft rtc-extension July 2020 3. Security Considerations This document does not change security aspects as discussed in [RFC4684]. 4. IANA Considerations This document requests IANA to assign a new SAFI "Extended Route Target constrains". 5. Acknowledgements The authors thank John Scudder for his comments and suggestions. 6. References 6.1. 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, . [RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, R., Patel, K., and J. Guichard, "Constrained Route Distribution for Border Gateway Protocol/MultiProtocol Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684, November 2006, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 6.2. Informative References [I-D.ietf-idr-wide-bgp-communities] Raszuk, R., Haas, J., Lange, A., Decraene, B., Amante, S., and P. Jakma, "BGP Community Container Attribute", draft- ietf-idr-wide-bgp-communities-05 (work in progress), July 2018. [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, . Zhang & Haas Expires January 13, 2021 [Page 4] Internet-Draft rtc-extension July 2020 Authors' Addresses Zhaohui Zhang Juniper Networks EMail: zzhang@juniper.net Jeffrey Haas Juniper Networks EMail: jhaas@juniper.net Zhang & Haas Expires January 13, 2021 [Page 5]