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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Z. Zhang 3 Internet-Draft Juniper Networks 4 Intended status: Informational S. Esale 5 Expires: January 30, 2020 Juniper Networks, Inc. 6 July 29, 2019 8 Resilient MPLS Rings and Multicast 9 draft-ietf-mpls-rmr-multicast-00 11 Abstract 13 With Resilient MPLS Rings (RMR), although all existing multicast 14 procedures and solutions can work as is, there are optimizations that 15 could be done for RSVP-TE P2MP tunnel signaling and Fast-ReRouting 16 for both mLDP and RSVP-TE P2MP tunnels. This document describes RMR 17 multicast on a high level, with detailed protocol procedure for RSVP- 18 TE P2MP optimizations specified in a separate document. This 19 document also discusses end to end multicast when there are RMRs. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at https://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on January 30, 2020. 38 Copyright Notice 40 Copyright (c) 2019 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (https://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. P2MP/MP2MP Tunnels on a Ring . . . . . . . . . . . . . . . . 3 57 2.1. Tunnel Protection and FRR . . . . . . . . . . . . . . . . 3 58 3. End to End Tunnels with Rings . . . . . . . . . . . . . . . . 4 59 4. End to End Native Multicast with Rings . . . . . . . . . . . 4 60 4.1. Native Multicast in the Global Routing Table . . . . . . 4 61 4.2. mLDP Inband Signaling . . . . . . . . . . . . . . . . . . 4 62 4.3. Overlay Multicast Services . . . . . . . . . . . . . . . 4 63 4.3.1. Tunnel Segmentation . . . . . . . . . . . . . . . . . 5 64 5. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 65 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 66 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 67 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 68 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 69 9.1. Normative References . . . . . . . . . . . . . . . . . . 6 70 9.2. Informative References . . . . . . . . . . . . . . . . . 6 71 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 73 1. Introduction 75 This document discusses how multicast works with Resilient MPLS Rings 76 [I-D.ietf-mpls-rmr]. It is expected that readers are familiar with 77 the concept and terms in [I-D.ietf-mpls-rmr]. 79 All existing multicast procedures and solutions can work as is. This 80 include both mpls multicast tunnels and end-to-end multicast that 81 makes use of multicast tunnels. Ring topology is just a special case 82 of general topologies so all existing RSVP-TE P2MP [RFC4875] and mLDP 83 [RFC6388] tunnels can be set up using existing protocols and 84 procedures. An Ingress Replication (IR) tunnel [RFC7988] consists a 85 bunch of P2P LSPs, and it does not matter whether a component LSP is 86 a plain old LSP or a Ring LSP. 88 On the other hand, there are optimizations that could be done for 89 RSVP-TE P2MP tunnel signaling and Fast-ReRouting (FRR) for both mLDP 90 and RSVP-TE P2MP tunnels. This document describes that on a high 91 level, and discusses end to end multicast when there are RMRs even 92 though RMR could be transparent to multicast. 94 2. P2MP/MP2MP Tunnels on a Ring 96 Because mLDP label mapping messages are merged as they propagate from 97 the leaves towards the root, ring topology does not lead to any 98 further optimization in tunnel signaling. 100 However RSVP-TE P2MP tunnel signaling and procedures can be greatly 101 optimized, as specified in [I-D.zzhang-teas-rmr-rsvp-p2mp]. 103 2.1. Tunnel Protection and FRR 105 Each node on a ring signals two counter-rotating MP2P Ring LSPs to 106 itself. As these LSPs are self-signaled after the discovery of the 107 ring, they can be used to protect P2MP LSPs on ring. So neither mLDP 108 nor RSVP-TE has to setup a separate P2P bypass LSPs for link and node 109 protection. For instance, consider a ring with 8 nodes: 111 Root 112 R0 . . . R1 113 . . 115 R7 R2 Leaf 116 | . . | 117 Anti- | . RingID=17 . | 118 Clockwise v . . v Clockwise 119 Leaf R6 R3 120 . . 121 R5 . . . R4 Leaf 123 Figure 1: Ring with 8 nodes 125 Further, suppose a P2MP LSP is signaled with R0 as a root and R2, R4 126 and R6 as leafs. The P2MP LSP is formed as follows: 128 R0 129 . . 130 . . 131 . . 132 R6 R2 133 . 134 . 135 R4 137 Figure 2: P2MP LSP 139 In the event of a link failure between R2 and R3, R2 the Point of 140 Local Repair (PLR) tunnels P2MP LSP traffic on a anti-clockwise ring 141 LSP to R3 the Merge Point (MP). Once the traffic is out of the ring 142 LSP on R3, it uses the regular P2MP LSP to reach R4. Similarly in 143 the event of a node failure R3, R2 the PLR tunnels P2MP LSP traffic 144 to R4 (the MP), which is also the leaf. Thus, the P2MP LSP uses the 145 existing RSVP-TE ring LSPs for link and node protection. 147 3. End to End Tunnels with Rings 149 Consider a provider network that consists of one or more rings, 150 optionally with a general topology connecting the rings. Multicast 151 VPN [RFC6514], Ethernet VPN [RFC7432], VPLS [RFC4761] [RFC4762], or 152 Global Table Multicast (GTM) via MVPN [RFC7716] overlay services are 153 provided where end-to-end multipoint tunnels are needed across the 154 entire network. 156 If the end to end tunnels are established by RSVP-TE P2MP, there is 157 not much optimization that can be done for RMR, unless overlay- 158 assisted tunnel segmentation is used. That is described in 159 Section 4.3.1. 161 If the end to end tunnels are established by mLDP and RSVP-TE 162 signaling is desired on part of the network, mLDP Over Targeted 163 Sessions [RFC7060] can be used (without the help from the overlay 164 service) to stack part of an mLDP tunnel over a RSVP-TE P2MP tunnel. 165 If the RSVP-TE P2MP tunnel is over a ring, then the optimization 166 described earlier can be used. 168 4. End to End Native Multicast with Rings 170 Consider a network that consists of some rings. In this network, 171 end-to-end native multicast can take various forms described below. 173 4.1. Native Multicast in the Global Routing Table 175 This is typically signaled by PIM [RFC7761] end to end. This works 176 for any topology and RMR does not make any difference. 178 4.2. mLDP Inband Signaling 180 This is specified in [RFC6826] [RFC7246] [RFC7438]. When part of a 181 native (s,g) or (*,g) multicast tree needs to go over an mLDP domain, 182 an mLDP tunnel is created for each multicast tree for the domain. 183 RMR does not make any differences here. 185 4.3. Overlay Multicast Services 187 Overlay multicast services provided by MVPN/GTM/EVPN/VPLS use overlay 188 multicast signaling to signal customer multicast state and tunnel 189 binding. PE-PE multipoint underlay tunnels are used to distribute 190 multicast packets among PEs. Any kind of tunnel can be used, whether 191 the provider network has rings or not, with or without the RMR 192 related optimizations (Section 3). 194 4.3.1. Tunnel Segmentation 196 The MVPN/GTM/EVPN/VPLS PEs could span across ASes or areas. When the 197 PE-PE multipoint tunnels cannot be signaled across AS/area 198 boundaries, segmentation procedures can be used, as specified in 199 [RFC6514, RFC7024] and [I-D.ietf-bess-evpn-bum-procedure-updates]. 200 With the base MVPN/GTM/EVPN/VPLS procedures, PEs advertise I/S-PMSI 201 A-D routes to signal traffic to tunnel binding, and the routes carry 202 type and identification of multi-point tunnels used to carry 203 corresponding traffic. With segmentation, the ASBRs/ABRs become 204 segmentation points and they change the tunnel type/identification 205 when they re-advertise the routes to the next AS/area. With this, 206 each AS/area has its own tunnel of different type/identification, 207 stitched together by the ASBRs/ABRs. 209 With segmentation, different RMRs could have their own tunnels, and 210 RSVP-TE P2MP optimizations for RMRs could be applied. Notice that 211 this is different from Section 3 in that overlay signaling is 212 involved. 214 5. Summary 216 As described above, multicast in the presence of RMRs can work as is. 217 RSVP-TE P2MP tunnel signaling can be optimized (to be specified 218 separately). Tunnel protection/FRR can also be optimized for mLDP/ 219 RSVP-TE P2MP tunnels. 221 6. Security Considerations 223 This is an informational document that describes how existing 224 multicast protocols can be used with RMR, as well as possible RMR 225 specific enhancements that will be specified separately. There are 226 no security concerns to be discussed here, as they are already 227 discussed in existing protocols or will be discussed in the 228 specification for the enhancements. 230 7. IANA Considerations 232 This document does not request any allocations from IANA. The RFC 233 Editor is requested to remove this section before publication. 235 8. Acknowledgements 237 The authors sincerely thank Loa Andersson for his careful review, 238 comments and suggestions. 240 9. References 242 9.1. Normative References 244 [I-D.ietf-mpls-rmr] 245 Kompella, K. and L. Contreras, "Resilient MPLS Rings", 246 draft-ietf-mpls-rmr-11 (work in progress), June 2019. 248 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 249 Requirement Levels", BCP 14, RFC 2119, 250 DOI 10.17487/RFC2119, March 1997, 251 . 253 9.2. Informative References 255 [I-D.zzhang-teas-rmr-rsvp-p2mp] 256 Zhang, Z., Deshmukh, A., and R. Singh, "RSVP-TE P2MP 257 Tunnels on RMR", draft-zzhang-teas-rmr-rsvp-p2mp-02 (work 258 in progress), January 2019. 260 [RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private 261 LAN Service (VPLS) Using BGP for Auto-Discovery and 262 Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007, 263 . 265 [RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private 266 LAN Service (VPLS) Using Label Distribution Protocol (LDP) 267 Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007, 268 . 270 [RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. 271 Yasukawa, Ed., "Extensions to Resource Reservation 272 Protocol - Traffic Engineering (RSVP-TE) for Point-to- 273 Multipoint TE Label Switched Paths (LSPs)", RFC 4875, 274 DOI 10.17487/RFC4875, May 2007, 275 . 277 [RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B. 278 Thomas, "Label Distribution Protocol Extensions for Point- 279 to-Multipoint and Multipoint-to-Multipoint Label Switched 280 Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011, 281 . 283 [RFC7060] Napierala, M., Rosen, E., and IJ. Wijnands, "Using LDP 284 Multipoint Extensions on Targeted LDP Sessions", RFC 7060, 285 DOI 10.17487/RFC7060, November 2013, 286 . 288 [RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I., 289 Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent 290 Multicast - Sparse Mode (PIM-SM): Protocol Specification 291 (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March 292 2016, . 294 [RFC7988] Rosen, E., Ed., Subramanian, K., and Z. Zhang, "Ingress 295 Replication Tunnels in Multicast VPN", RFC 7988, 296 DOI 10.17487/RFC7988, October 2016, 297 . 299 Authors' Addresses 301 Zhaohui Zhang 302 Juniper Networks 304 EMail: zzhang@juniper.net 306 Santosh Esale 307 Juniper Networks, Inc. 309 EMail: sesale@juniper.net