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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PIM Z. Zhang 3 Internet-Draft Juniper Networks 4 Intended status: Informational K. Patel 5 Expires: April 21, 2016 Cisco Systems 6 October 19, 2015 8 Protocol Dependent Multicast Signaling 9 draft-zzhang-pim-pds-00 11 Abstract 13 This document describes a general idea of multicast signaling based 14 on extensions to unicast protocols. 16 Requirements Language 18 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 19 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 20 document are to be interpreted as described in RFC2119. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on April 21, 2016. 39 Copyright Notice 41 Copyright (c) 2015 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. BGP Based PIM-PDS . . . . . . . . . . . . . . . . . . . . . . 3 58 3. IGP Based PIM-PDS . . . . . . . . . . . . . . . . . . . . . . 3 59 4. Security Considerations . . . . . . . . . . . . . . . . . . . 4 60 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 61 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 62 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 63 6.2. Informative References . . . . . . . . . . . . . . . . . 4 64 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 66 1. Motivation 68 Protocol Independent Multicast (PIM) has been the prevailing 69 multicast protocol for many years. Despite its success, it has two 70 drawbacks: 72 o Complexity originated from RPT/SPT switchover and data driven 73 nature for PIM-ASM. 75 o Periodical protocol state refreshes due to the soft state nature. 77 While PIM-SSM removes the complexity of PIM-ASM, there have not been 78 a good way of discovering sources, limiting its deployment. PIM-Port 79 (PIM over Reliable Transport) solves the soft state issue, though its 80 deployment has also been limited. 82 Partly because of the complexity concern, some Data Center operators 83 have been avoiding deploying multicast in their networks. 85 Data Center operators are also inclined to reduce the number of 86 routing protocols as much as possible, to reduce operational 87 complexity and expenses. For example, with [draft-ietf-rtgwg-bgp- 88 routing-large-dc], BGP is used as the only routing protocol, w/o any 89 IGPs. Some other data centers may still choose to run traditional 90 IGPs, but in either case, it may be desired to not run another 91 protocol for multicast purposes. 93 PIM builds multicast distribution trees from the receiver ends 94 towards the sources or Rendezvous Points. Traffic flows from the 95 sources/RPs towards receivers in the reverse direction of unicast 96 traffic from receivers towards the sources/RPs, hence the term 97 Reverse Path Forwarding. With PIM, the term "protocol indpendent" 98 comes from the fact that, the routes used for RPF purpose can be 99 learned from any protocol, unlike in DVMRP case where the RPF routes 100 are distributed via DVMRP itself, or in MOSPF case where OSPF routes 101 are used to build the trees. 103 Without changing the principle of multicast tree building based on 104 the reverse path routes learned from any protocol, the tree building 105 and maintenance do not have to rely on PIM protocol messages. 106 Rather, it could be done by extensions to whatever unicast protocols 107 used, so that only one protocol needs to be operated in a network. 108 For that, we introduce a new flavor of PIM - Protocol Dependent 109 Signaling (PIM-PDS). 111 The following sections discussed two options at very high level. 112 Detailed specifications are out scope of this introductory document. 114 2. BGP Based PIM-PDS 116 BGP-MVPN [RFC 6514] uses BGP to signal VPN customer multicast state 117 over provider networks. It removes the above mentioned problems, and 118 the deployment experiences have been encouraging. [draft-ietf-bess- 119 mvpn-pe-ce] adapts the concept of BGP-MVPN to PE-CE links, and 120 [draft-zzhang-bess-bgp-multicast] extends it further to general 121 topologies, so that it can deployed in any network where BGP is 122 running, or can be run, throughout or on most routers. 124 In a nut shell, [draft-zzhang-bess-bgp-multicast] is PIM with BGP 125 based join/prune signaling, and BGP based source discovery in case of 126 ASM. The same RPF procedures as in PIM are used for each router to 127 determine the RPF neighbor for a particular source or RPA (in case of 128 Bidirectional Tree). Except in the Bidirectional Tree case, no (*,G) 129 join is used - LHR routers discover the sources for ASM and then 130 joins towards the sources directly. 132 3. IGP Based PIM-PDS 134 Both MOSPF [RFC 1584] and recent IGP Mutlicast Architecture [draft- 135 yong-rtgwg-igp-multicast-arch] are based on flooding multicast 136 membership information everywhere, even though the information is 137 only needed on the relevant multicast distribution trees. As a 138 result, the scaling is severely limited. With PIM-PDS, IGP link- 139 scoped flooding can be used tree construction and maintenance - the 140 receiver interest is only signaled towards the sources/RPs, and 141 merging/aggregation will happen along the way. 143 4. Security Considerations 145 This document only describes high level concepts and does not attempt 146 to address possible security issues. Separate documents, if written, 147 would address those. 149 5. Acknowledgements 151 6. References 153 6.1. Normative References 155 [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, 156 "Protocol Independent Multicast - Sparse Mode (PIM-SM): 157 Protocol Specification (Revised)", RFC 4601, 158 DOI 10.17487/RFC4601, August 2006, 159 . 161 6.2. Informative References 163 [I-D.ietf-bess-mvpn-pe-ce] 164 Patel, K., Rosen, E., and Y. Rekhter, "BGP as an MVPN PE- 165 CE Protocol", draft-ietf-bess-mvpn-pe-ce-00 (work in 166 progress), April 2015. 168 [I-D.ietf-rtgwg-bgp-routing-large-dc] 169 Lapukhov, P., Premji, A., and J. Mitchell, "Use of BGP for 170 routing in large-scale data centers", draft-ietf-rtgwg- 171 bgp-routing-large-dc-02 (work in progress), April 2015. 173 [I-D.yong-rtgwg-igp-multicast-arch] 174 Yong, L., Weiguo, H., Eastlake, D., Qu, A., Hudson, J., 175 and U. Chunduri, "IGP Multicast Architecture", draft-yong- 176 rtgwg-igp-multicast-arch-01 (work in progress), November 177 2014. 179 [I-D.zzhang-bess-bgp-multicast] 180 Zhang, J. and K. Patel, "BGP Based Multicast", draft- 181 zzhang-bess-bgp-multicast-00 (work in progress), October 182 2015. 184 [RFC1075] Waitzman, D., Partridge, C., and S. Deering, "Distance 185 Vector Multicast Routing Protocol", RFC 1075, 186 DOI 10.17487/RFC1075, November 1988, 187 . 189 [RFC1584] Moy, J., "Multicast Extensions to OSPF", RFC 1584, 190 DOI 10.17487/RFC1584, March 1994, 191 . 193 [RFC6514] Aggarwal, R., Rosen, E., Morin, T., and Y. Rekhter, "BGP 194 Encodings and Procedures for Multicast in MPLS/BGP IP 195 VPNs", RFC 6514, DOI 10.17487/RFC6514, February 2012, 196 . 198 Authors' Addresses 200 Zhaohui Zhang 201 Juniper Networks 203 EMail: zzhang@juniper.net 205 Keyur Patel 206 Cisco Systems 208 EMail: keyupate@cisco.com