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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: The MVPN PEs that act as customer RPs or have one or more MSDP sessions in a VPN (or the global table in case of GTM) are treated as an MSDP mesh group for that VPN (or the global table). In the rest of the document, it is referred to as the PE mesh group. It MUST not include other MSDP speakers, and is integrated into the rest of MSDP infrastructure for the VPN (or the global table) following normal MSDP rules and practices. 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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC2119' is defined on line 227, but no explicit reference was found in the text ** Downref: Normative reference to an Experimental RFC: RFC 3618 Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 BESS Z. Zhang 3 Internet-Draft L. Giuliano 4 Updates: 6514 (if approved) Juniper Networks 5 Intended status: Standards Track March 22, 2018 6 Expires: September 23, 2018 8 MVPN and MSDP SA Interoperation 9 draft-ietf-bess-mvpn-msdp-sa-interoperation-00 11 Abstract 13 This document specifies the procedures for interoperation between 14 MVPN Source Active routes and customer MSDP Source Active routes, 15 which is useful for MVPN provider networks offering services to 16 customers with an existing MSDP infrastructure. Without the 17 procedures described in this document, VPN-specific MSDP sessions are 18 required among the PEs that are customer MSDP peers. 20 Requirements Language 22 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 23 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 24 document are to be interpreted as described in RFC2119. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on September 23, 2018. 43 Copyright Notice 45 Copyright (c) 2018 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 2 61 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2.1. MVPN RPT-SPT Mode . . . . . . . . . . . . . . . . . . . . 4 63 3. Specification . . . . . . . . . . . . . . . . . . . . . . . . 4 64 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 65 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 66 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 67 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 68 6.2. Informative References . . . . . . . . . . . . . . . . . 6 69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 71 1. Terminologies 73 Familiarity with MVPN and MSDP protocols and procedures is assumed. 74 Some terminologies are listed below for convenience. 76 o ASM: Any source multicast. 78 o SPT: Source-specific Shortest-path Tree. 80 o C-S: A multicast source address, identifying a multicast source 81 located at a VPN customer site. 83 o C-G: A multicast group address used by a VPN customer. 85 o C-RP: A multicast Rendezvous Point for a VPN customer. 87 o EC: Extended Community. 89 2. Introduction 91 Section "14. Supporting PIM-SM without Inter-Site Shared C-Trees" of 92 [RFC6514] specifies the procedures for MVPN PEs to discover (C-S,C-G) 93 via MVPN Source Active A-D routes and then send (C-S,C-G) C-multicast 94 routes towards the ingress PEs, to establish SPTs for customer ASM 95 flows for which they have downstream receivers. (C-*,C-G) 96 C-multicast routes are not sent among the PEs so inter-site shared 97 C-Trees are not used and the method is generally referred to as "spt- 98 only" mode. 100 With this mode, the MVPN Source Active routes are functionally 101 similar to MSDP Source-Active messages [RFC3618]. One or more of the 102 PEs, say PE1, either act as a C-RP and learn of (C-S,C-G) via PIM 103 Register messages, or have MSDP sessions with some MSDP peers and 104 learn (C-S,C-G) via MSDP SA messages. In either case, PE1 will then 105 originate MVPN SA routes for other PEs to learn the (C-S,C-G). 107 [RFC6514] only specifies that a PE receiving the MVPN SA routes, say 108 PE2, will advertise (C-S,C-G) C-multicast routes if it has 109 corresponding (C-*,C-G) state learnt from its CE. PE2 may also have 110 MSDP sessions with other C-RPs at its site, but [RFC6514] does not 111 specify that it advertise MSDP SA messages to those MSDP peers for 112 the (C-S,C-G) that it learns via MVPN SA routes. PE2 would need to 113 have an MSDP session with PE1 (that advertised the MVPN SA messages) 114 to learn the sources via MSDP SA messages, for it to advertise the 115 MSDP SA to its local peers. To make things worse, unless blocked by 116 policy control, PE2 would in turn advertise MVPN SA routes because of 117 those MSDP SA messages that it receives from PE1, which are redundant 118 and unnecessary. Also notice that the PE1-PE2 MSDP session is VPN- 119 specific, while the BGP sessions over which the MVPN routes are 120 advertised are not. 122 If a PE does advertise MSDP SA messages based on received MVPN SA 123 routes, the VPN-specific MSDP sessions are no longer needed. 124 Additionally, this MVPN/MSDP SA interoperation has the following 125 inherent benefits for a BGP based solution. 127 o MSDP SA refreshes are replaced with BGP hard state. 129 o Route Reflectors can be used instead of having peer-to-peer 130 sessions. 132 o VPN extranet mechanisms can be used to propagate (C-S,C-G) 133 information across VPNs with flexible policy control. 135 While MSDP Source Active routes contain the source, group and RP 136 address of a given multicast flow, MVPN Source Active routes only 137 contain the source and group. MSDP requires the RP address 138 information in order to perform peer-RPF. Therefore, this document 139 describes how to convey the RP address information into the MVPN 140 Source Active route using an Extended Community so this information 141 can be shared with an existing MSDP infrastructure. 143 The procedures apply to Global Table Multicast (GTM) [RFC7716] as 144 well. 146 2.1. MVPN RPT-SPT Mode 148 For comparison, another method of supporting customer ASM is 149 generally referred to "rpt-spt" mode. Section "13. Switching from a 150 Shared C-Tree to a Source C-Tree" of [RFC6514] specifies the MVPN SA 151 procedures for that mode, but those SA routes are replacement for 152 PIM-ASM assert and (s,g,rpt) prune mechanisms, not for source 153 discovery purpose. MVPN/MSDP SA interoperation for the "rpt-spt" 154 mode is outside of the scope of this document. In the rest of the 155 document, the "spt-only" mode is assumed. 157 3. Specification 159 The MVPN PEs that act as customer RPs or have one or more MSDP 160 sessions in a VPN (or the global table in case of GTM) are treated as 161 an MSDP mesh group for that VPN (or the global table). In the rest 162 of the document, it is referred to as the PE mesh group. It MUST not 163 include other MSDP speakers, and is integrated into the rest of MSDP 164 infrastructure for the VPN (or the global table) following normal 165 MSDP rules and practices. 167 When an MVPN PE advertises an MVPN SA route following procedures in 168 [RFC6514] for the "spt-only" mode, it SHOULD attach an "MVPN SA RP- 169 address Extended Community". This is a Transitive IPv4-Address- 170 Specific Extended Community. The Local Administrative field is set 171 to zero and the Global Administrative field is set to an RP address 172 determined as the following: 174 o If the (C-S,C-G) is learnt as result of PIM Register mechanism, 175 the local RP address for the C-G is used. 177 o If the (C-S,C-G) is learnt as result of incoming MSDP SA messages, 178 the RP address in the selected MSDP SA message is used. 180 In addition to procedures in [RFC6514], an MVPN PE may be provisioned 181 to generate MSDP SA messages from received MVPN SA routes, with or 182 without fine policy control. If a received MVPN SA route is to 183 trigger MSDP SA message, it is treated as if a corresponding MSDP SA 184 message was received from within the PE mesh group and normal MSDP 185 procedure is followed (e.g. an MSDP SA message is advertised to other 186 MSDP peers outside the PE mesh group). The (S,G) information comes 187 from the (C-S,C-G) encoding in the MVPN SA NLRI and the RP address 188 comes from the "MVPN SA RP-address EC" mentioned above. If the 189 received MVPN SA route does not have the EC (this could be from a 190 legacy PE that does not have the capability to attach the EC), the 191 local RP address for the C-G is used. In that case, it is possible 192 that receiving PE's RP for the C-G is actually the MSDP peer to which 193 the generated MSDP message is advertised, causing the peer to discard 194 it due to RPF failure. To get around that problem the peer SHOULD 195 use local policy to accept the MSDP SA message. 197 An MVPN PE MAY treat only the best MVPN SA route selected by BGP 198 route selection process (instead of all MVPN SA routes) for a given 199 (C-S,C-G) as a received MSDP SA message (and advertise corresponding 200 MSDP message). In that case, if the selected best MVPN SA route does 201 not have the "MVPN SA RP-address EC" but another route for the same 202 (C-S, C-G) does, then the best route with the EC SHOULD be chosen. 203 As a result, when/if the best MVPN SA route with the EC changes, a 204 new MSDP SA message is advertised if the RP address determined 205 according to the newly selected MVPN SA route is different from 206 before. The previously advertised MSDP SA message with the older RP 207 address will be timed out. 209 4. IANA Considerations 211 This document introduces a new Transitive IPv4 Address Specific 212 Extended Community "MVPN SA RP-address Extended Community". An IANA 213 request will be submitted for a subcode of 0x20 (pending approval and 214 subject to change) in the Transitive IPv4-Address-Specific Extended 215 Community Sub-Types registry. 217 5. Acknowledgements 219 The authors thank Eric Rosen and Vinod Kumar for their review, 220 comments, questions and suggestions for this document. The authors 221 also thank Yajun Liu for her review and comments. 223 6. References 225 6.1. Normative References 227 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 228 Requirement Levels", BCP 14, RFC 2119, 229 DOI 10.17487/RFC2119, March 1997, 230 . 232 [RFC3618] Fenner, B., Ed. and D. Meyer, Ed., "Multicast Source 233 Discovery Protocol (MSDP)", RFC 3618, 234 DOI 10.17487/RFC3618, October 2003, 235 . 237 [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 238 Encodings and Procedures for Multicast in MPLS/BGP IP 239 VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012, 240 . 242 6.2. Informative References 244 [RFC7716] Zhang, J., Giuliano, L., Rosen, E., Ed., Subramanian, K., 245 and D. Pacella, "Global Table Multicast with BGP Multicast 246 VPN (BGP-MVPN) Procedures", RFC 7716, 247 DOI 10.17487/RFC7716, December 2015, 248 . 250 Authors' Addresses 252 Zhaohui Zhang 253 Juniper Networks 255 EMail: zzhang@juniper.net 257 Lenny Giuliano 258 Juniper Networks 260 EMail: lenny@juniper.net