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Banthia 6 Cisco Systems, Inc. 7 November 2, 2019 9 PIM Null register packing 10 draft-ietf-pim-null-register-packing-04 12 Abstract 14 In PIM-SM networks PIM registers are sent from the first hop router 15 to the RP (Rendezvous Point) to signal the presence of Multicast 16 source in the network. There are periodic PIM Null registers sent 17 from first hop router to the RP to keep the state alive at the RP as 18 long as the source is active. The PIM Null register packet carries 19 information about a single Multicast source and group. This document 20 defines a standard to send multiple Multicast source and group 21 information in a single pim Null register packet and the 22 interoperability between the PIM routers which do not understand the 23 packet format with multiple Multicast source and group details. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on May 5, 2020. 42 Copyright Notice 44 Copyright (c) 2019 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 1.1. Conventions Used in This Document . . . . . . . . . . . . 2 61 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 62 2. PIM Register Stop format with capability option . . . . . . . 3 63 3. New PIM Null register message . . . . . . . . . . . . . . . . 4 64 4. New PIM Register Stop message format . . . . . . . . . . . . 4 65 5. Protocol operation . . . . . . . . . . . . . . . . . . . . . 5 66 6. PIM Anycast RP considerations . . . . . . . . . . . . . . . . 6 67 7. PIM RP router version downgrade . . . . . . . . . . . . . . . 6 68 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 69 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 70 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 71 10.1. Normative References . . . . . . . . . . . . . . . . . . 7 72 10.2. Informative References . . . . . . . . . . . . . . . . . 7 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 75 1. Introduction 77 PIM Null registers are sent by First hop routers periodically for 78 Multicast streams to keep the states active on the RP as long as the 79 Multicast source is alive. As the number of multicast sources 80 increases, the number of PIM Null register packets that are sent 81 increases at a given time. This results in more PIM packet 82 processing at RP and FHR. The control plane policing (COPP), 83 monitors the packets that gets processed by the control plane. Due 84 to the high rate at which Null registers are received at the RP, this 85 can lead to COPP drops of Multicast PIM Null register packets. This 86 draft proposes a method to efficiently pack multiple PIM Null 87 registers and register stop into a single message as these packets 88 anyway don't contain data. The draft also proposes interoperability 89 with the routers that do not understand the new packet format. 91 1.1. Conventions Used in This Document 93 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 94 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 95 document are to be interpreted as described in RFC 2119 [RFC2119]. 97 1.2. Terminology 99 RP: Rendezvous Point 101 RPF: Reverse Path Forwarding 103 SPT: Shortest Path Tree 105 FHR: First Hop Router, directly connected to the source 107 LHR: Last Hop Router, directly connected to the receiver 109 2. PIM Register Stop format with capability option 111 A router (FHR) can decide to pack multiple Null registers based on 112 the capability received from the RP as part of Register Stop. This 113 ensures compatibility with routers that don't support processing of 114 the new format. The capability information can be indicated by the 115 RP via the PIM register stop message sent to the FHR. Thus a FHR 116 will switch to the new format only when it learns RP is capable of 117 handling the packed Null register messages. Conversely, a FHR that 118 doesn't support the new format can continue generating the PIM Null 119 register the current way. To exchange the capability information in 120 the Register Stop message, the "reserved" field can be used to 121 indicate this capability in those register stop messages. One bit of 122 the reserved field is used to indicate the "packing" capability (P 123 bit). The rest of the bits in the "Reserved" field will be retained 124 for future use. 126 Figure 1: PIM Register Stop message with capability option 128 0 1 2 3 129 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 1 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 |PIM Ver| Type |P| Reserved | Checksum | 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Group Address (Encoded-Group format) | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 | Source Address (Encoded-Unicast format) | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 PIM Version, Reserved, Type, Checksum, Group Address, Source Address 139 Same as RFC 7761 (Section 4.9.4) 141 P Capability bit used to indicate support for Packed Null Register 143 3. New PIM Null register message 145 New PIM Null register message format includes a count to indicate the 146 number of Null register records in the message. 148 Figure 2: New PIM Null Register message format 149 0 1 2 3 150 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 1 151 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 |PIM Ver| Type |SubType| Rsvd | Checksum | 153 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 | count | Reserved2 | 155 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 | Group Address[1] (Encoded-Group format) | 157 | Source Address[1] (Encoded-Unicast format) | 158 . . 159 . . 160 . . 161 . . 162 . Group Address[N] . 163 | Source Address[N] | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 PIM Version, Reserved, Checksum 167 Same as RFC 7761 (Section 4.9.3) 169 Type, SubType 170 The new packed Null Register Type and SubType values TBD 172 count 173 The count of the number of packed Null register records. 174 A record consists of Group and Source Address 176 Group Address 177 IP address of the Multicast Group 179 Source Address 180 IP Address of the Multicast Source 182 4. New PIM Register Stop message format 184 The new PIM register stop is message includes a count to indicate the 185 number of records that are present in the message. 187 Figure 3: New PIM Register Stop message format 188 0 1 2 3 189 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 1 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 |PIM Ver| Type |SubType| Rsvd | Checksum | 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 | count | Reserved2 | 194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 | Group Address[1] (Encoded-Group format) | 196 | Source Address[1] (Encoded-Unicast format) | 197 . . 198 . . 199 . . 200 . . 201 . Group Address[N] . 202 | Source Address[N] | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 205 PIM Version, Reserved, Checksum 206 Same as RFC 7761 (Section 4.9.3) 208 Type 209 The new Register Stop Type and SubType values TBD 211 Record count 212 The count of the number of packed register stop records. 213 A record consists of Group and Source Address 215 Group Address 216 IP address of the Multicast Group 218 Source Address 219 IP Address of the Multicast Source 221 5. Protocol operation 222 The following combinations exist - 223 FHR and RP both support the new PIM Register formats - 224 a. FHR sends the PIM register towards the RP when a new source is 225 detected 226 b. RP sends a modified register stop towards the FHR that includes 227 capability 228 information by setting the P bit (Figure 2) 229 c. Based on the receipt of new Register Stop, FHR will 230 start packing of Null registers using the new packed register 231 format (Figure 1) 232 d. RP processes the new Null register message and can generate new 233 register Stop messages by packing multiple S,Gs towards the same 234 FHR (Figure 3) 236 FHR supports but RP doesn't support new PIM Register formats- 237 a. FHR sends the PIM register towards the RP 238 b. RP sends a normal register stop without any capability 239 information 240 c. FHR then sends Null registers in the old format 242 RP supports but FHR doesn't support the new PIM Register formats- 243 a. FHR sends the PIM register towards the RP 244 b. RP sends a modified register stop towards the FHR that includes 245 capability information 246 c. Since FHR doesn't support the new format, it sends Null 247 registers in the old format 249 6. PIM Anycast RP considerations 251 The new PIM register format should be enabled only if its supported 252 by all PIM anycast RP members in the RP set for the RP address. 254 7. PIM RP router version downgrade 256 Consider a PIM RP router that downgrades to a software version which 257 does not support the PIM register packing and was previously 258 supporting the PIM register packing. The FHR that sends the packed 259 PIM register message will not get a PIM register stop message back. 260 In such scenarios the FHR can send an unpacked PIM register and check 261 the PIM register stop to see if the capability option for packed 262 register is set or not. If its not set then the FHR will continue 263 sending unpacked PIM register messages. 265 8. IANA Considerations 267 This document requires the assignment of 2 new PIM message types for 268 the packed pim register and pim register stop. 270 9. Acknowledgments 272 The authors would like to thank Stig Venaas, Anish Peter and Umesh 273 Dudani for their helpful comments on the draft. 275 10. References 277 10.1. Normative References 279 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 280 Requirement Levels", BCP 14, RFC 2119, 281 DOI 10.17487/RFC2119, March 1997, 282 . 284 [RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I., 285 Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent 286 Multicast - Sparse Mode (PIM-SM): Protocol Specification 287 (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March 288 2016, . 290 10.2. Informative References 292 [RFC3973] Adams, A., Nicholas, J., and W. Siadak, "Protocol 293 Independent Multicast - Dense Mode (PIM-DM): Protocol 294 Specification (Revised)", RFC 3973, DOI 10.17487/RFC3973, 295 January 2005, . 297 Authors' Addresses 299 Vikas Ramesh Kamath 300 VMware 301 3401 Hillview Ave 302 Palo Alto CA 94304 303 USA 305 Email: vkamath@vmware.com 307 Ramakrishnan Chokkanathapuram Sundaram 308 Cisco Systems, Inc. 309 Tasman Drive 310 San Jose CA 95134 311 USA 313 Email: ramaksun@cisco.com 314 Raunak Banthia 315 Cisco Systems, Inc. 316 Tasman Drive 317 San Jose CA 95134 318 USA 320 Email: rbanthia@cisco.com