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Chokkanathapuram Sundaram 5 Expires: April 22, 2019 Cisco Systems, Inc. 6 October 19, 2018 8 PIM NULL Register packing 9 draft-ietf-pim-null-register-packing-00 11 Abstract 13 In PIM-SM networks PIM registers are sent from the first hop router 14 to the RP (Rendezvous Point) to signal the presence of Multicast 15 source in the network.There are periodic PIM Null registers sent from 16 first hop router to the RP to keep the state alive at the RP as long 17 as the source is active. The PIM null register packet carry 18 information about a single Multicast source and group. This document 19 defines a standard to send multiple Multicast source and group 20 information in a single pim null register packet and the 21 interoperability between the PIM routers which do not understand the 22 packet format with multiple Multicast source and group details. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at https://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on April 22, 2019. 41 Copyright Notice 43 Copyright (c) 2018 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (https://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 59 1.1. Conventions Used in This Document . . . . . . . . . . . . 2 60 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 61 2. PIM Register Stop format with capability option . . . . . . . 3 62 3. New PIM Null register format . . . . . . . . . . . . . . . . 4 63 4. New Packed PIM Register Stop format . . . . . . . . . . . . . 5 64 5. Protocol operation . . . . . . . . . . . . . . . . . . . . . 6 65 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 66 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 67 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 68 8.1. Normative References . . . . . . . . . . . . . . . . . . 7 69 8.2. Informative References . . . . . . . . . . . . . . . . . 8 70 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 72 1. Introduction 74 PIM Null registers are sent by First hop routers periodically for 75 Multicast streams to keep the states active on the RP as long as the 76 Multicast source is alive. As the number of multicast sources 77 increase, the number of PIM null register packets that are sent 78 increases at a given time. This results in more PIM packet 79 processing at RP and FHR. The control plane policing(COPP), monitors 80 the packets that gets processed by the control plane. Due to the 81 high rate at which NULL registers are received at the RP, this can 82 lead to COPP drops of Multicast PIM null register packets. This 83 draft proposes a method to efficiently pack multiple PIM null 84 registers and register stop into a single message as these packets 85 anyway don't contain data. The draft also proposes interoperability 86 with the routers that do not understand the new packet format. 88 1.1. Conventions Used in This Document 90 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 91 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 92 document are to be interpreted as described in RFC 2119 [RFC2119]. 94 1.2. Terminology 96 RP: Rendezvous Point 98 RPF: Reverse Path Forwarding 100 SPT: Shortest Path Tree 102 FHR: First Hop Router, directly connected to the source 104 LHR: Last Hop Router, directly connected to the receiver 106 2. PIM Register Stop format with capability option 108 A router (FHR) can decide to pack multiple NULL registers based on 109 the capability received from the RP as part of Register Stop. This 110 ensures compatibility with routers that don't support processing of 111 the new format. The capability information can be indicated by the 112 RP via the PIM register stop message sent to the FHR. Thus a FHR 113 will switch to the new format only when it learns RP is capable of 114 handling the packed null register messages. Conversely, a FHR that 115 doesn't support the new format can continue generating the PIM NULL 116 register the usual way since they don't check for the capability 117 information present in the Register stop message. To exchange the 118 capability information in the Register Stop message, the "reserved" 119 field can be used to indicate this capability in those register stop 120 messages. One bit of the reserved field is used to indicate the 121 "packing" capability (P bit). The rest of the bits in the "Reserved" 122 field will be retained for future use. 124 Figure 2: PIM Register Stop packet with capability option 126 0 1 2 3 127 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 1 128 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 |PIM Ver| Type |P| Reserved | Checksum | 130 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 | Group Address (Encoded-Group format) | 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Source Address (Encoded-Unicast format) | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 PIM Version, Reserved, Type, Checksum, Group Address, Source Address 137 Same as RFC 7761 (Section 4.9.4) 139 P Capability bit used to indicate support for Packed NULL Register 141 3. New PIM Null register format 143 PIM null-register packet format is enhanced to include the count of 144 the number of null-register records and pack multiple null-register 145 records in the same packet. Currently the data part in the NULL 146 register packet is a dummy IPv4 header which carries the source and 147 group information and the other fields are unused. To indicate that 148 the null register is in a new format the "Type" field in the PIM 149 register packet format is used. To indicate the number of null 150 register records a new field "record count" is introduced which can 151 hold 8 bit value (max 255 records can be packed) which can be based 152 on MTU. Even though null registers are supposed to be sent exactly 153 every 60s, its fine to send a null register earlier, so as to merge 154 the registers. When one register is sent, multiple registers can be 155 packed together which are close enough in time. 157 Figure 1: New PIM NULL Register packet format 158 0 1 2 3 159 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 1 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 |PIM Ver| Type | Reserved | Checksum | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | Record count | Reserved2 | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 | Group Address[1] (Encoded-Group format) | 166 | Source Address[1] (Encoded-Unicast format) | 167 . . 168 . . 169 . . 170 . . 171 . Group Address[N] . 172 | Source Address[N] | 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 PIM Version, Reserved, Checksum 176 Same as RFC 7761 (Section 4.9.3) 178 Type 179 The new packed NULL Register type value TBD 181 Record count 182 The count of the number of packed NULL register records. 183 A record consists of Group and Source Address 185 Group Address 186 IP address of the Multicast Group 188 Source Address 189 IP Address of the Multicast Source 191 4. New Packed PIM Register Stop format 193 The PIM register stop can be optimized to include multiple multicast 194 group and source information. The Record count can indicate the 195 number of S,G records that are packed and the Type value is used to 196 indicate the new format. 198 Figure 3: New PIM Packed Register Stop packet formats 199 0 1 2 3 200 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 1 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 |PIM Ver| Type | Reserved | Checksum | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | Record count | Reserved2 | 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | Group Address[1] (Encoded-Group format) | 207 | Source Address[1] (Encoded-Unicast format) | 208 . . 209 . . 210 . . 211 . . 212 . Group Address[N] . 213 | Source Address[N] | 214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 216 PIM Version, Reserved, Checksum 217 Same as RFC 7761 (Section 4.9.3) 219 Type 220 The new packed Register Stop type value TBD 222 Record count 223 The count of the number of packed register stop records. 224 A record consists of Group and Source Address 226 Group Address 227 IP address of the Multicast Group 229 Source Address 230 IP Address of the Multicast Source 232 5. Protocol operation 233 The following combinations exist - 234 FHR and RP both support the new PIM Register formats - 235 a. FHR sends the PIM register towards the RP when a new source is detected 236 b. RP sends a modified register stop towards the FHR that includes capability 237 information by setting the P bit (Figure 2) 238 c. Based on the receipt of the modified Register Stop, FHR will start packing 239 of NULL registers using the new packed register format (Figure 1) 240 d. RP processes the NULL registers and can generate Register Stop messages by 241 packing multiple S,Gs towards the same FHR (Figure 3) 243 FHR supports but RP doesn't support new PIM Register formats- 244 a. FHR sends the PIM register towards the RP 245 b. RP sends a normal register stop without any capability information 246 c. FHR then sends NULL registers in the old format 248 RP supports but FHR doesn't support the new PIM Register formats- 249 a. FHR sends the PIM register towards the RP 250 b. RP sends a modified register stop towards the FHR that includes 251 capability information 252 c. Since FHR doesn't support the new format, it sends NULL registers 253 in the old format 255 6. IANA Considerations 257 This document requires the assignment of 2 new PIM message types for 258 the packed pim register and pim register stop. 260 7. Acknowledgments 262 The authors would like to thank Stig Venaas and Umesh Dudani for 263 contributing to the original idea and also their very helpful 264 comments on the draft. 266 8. References 268 8.1. Normative References 270 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 271 Requirement Levels", BCP 14, RFC 2119, 272 DOI 10.17487/RFC2119, March 1997, 273 . 275 [RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I., 276 Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent 277 Multicast - Sparse Mode (PIM-SM): Protocol Specification 278 (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March 279 2016, . 281 8.2. Informative References 283 [RFC3973] Adams, A., Nicholas, J., and W. Siadak, "Protocol 284 Independent Multicast - Dense Mode (PIM-DM): Protocol 285 Specification (Revised)", RFC 3973, DOI 10.17487/RFC3973, 286 January 2005, . 288 Authors' Addresses 290 Vikas Ramesh Kamath 291 VMware 292 3401 Hillview Ave 293 Palo Alto CA 94304 294 USA 296 Email: vkamath@vmware.com 298 Ramakrishnan Chokkanathapuram Sundaram 299 Cisco Systems, Inc. 300 Tasman Drive 301 San Jose CA 95134 302 USA 304 Email: ramaksun@cisco.com