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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PIM WG A. Boers 3 Internet-Draft IJ. Wijnands 4 Intended status: Informational E. Rosen 5 Expires: April 26, 2007 Cisco Systems, Inc. 6 October 23, 2006 8 Format for using TLVs in PIM messages 9 draft-ietf-pim-join-attributes-02 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt. 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 This Internet-Draft will expire on April 26, 2007. 36 Copyright Notice 38 Copyright (C) The Internet Society (2006). 40 Abstract 42 This document describes a generic TLV attribute encoding format to be 43 added to PIM join messages. 45 Table of Contents 47 1. Conventions used in this document . . . . . . . . . . . . . . . 3 48 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 49 3. Use of the Attribute Field in Join Messages . . . . . . . . . . 3 50 3.1. Attribute join . . . . . . . . . . . . . . . . . . . . . . 3 51 3.2. Transitive attributes . . . . . . . . . . . . . . . . . . . 3 52 3.3. Attribute Hello Option . . . . . . . . . . . . . . . . . . 3 53 3.4. Conflicting attributes . . . . . . . . . . . . . . . . . . 4 54 3.5. Attribute Convergence . . . . . . . . . . . . . . . . . . . 5 55 3.6. Multiple attributes . . . . . . . . . . . . . . . . . . . . 5 56 3.7. Applicability of the attributes . . . . . . . . . . . . . . 5 57 3.8. PIM attribute packet format . . . . . . . . . . . . . . . . 5 58 3.8.1. PIM Join packet format . . . . . . . . . . . . . . . . 5 59 3.8.2. PIM Attribute Hello option . . . . . . . . . . . . . . 6 60 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 61 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 62 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7 63 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 64 7.1. Normative References . . . . . . . . . . . . . . . . . . . 7 65 7.2. Informative References . . . . . . . . . . . . . . . . . . 7 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 67 Intellectual Property and Copyright Statements . . . . . . . . . . 9 69 1. Conventions used in this document 71 In this document, the key words "MUST", "MUST NOT", "REQUIRED", 72 "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", 73 and "OPTIONAL" are to be interpreted as described in RFC 2119 and 74 indicate requirement levels for compliant PIM-SM implementations. 76 2. Introduction 78 It is sometimes convenient to add additional information to PIM join 79 messages. The generic PIM encoding format is not always optimal to 80 do this. This document defines a new field in the PIM Join message 81 that allows it to use TLVs, hereby called the attribute field. The 82 content and purpose of this attribute field is outside the scope of 83 this document, only the generic encoding format is described here. 85 3. Use of the Attribute Field in Join Messages 87 3.1. Attribute join 89 Attribute fields are defined similar to the PIM source encoding type 90 as defined in [RFC4601]. A source address without any additional 91 TLV's should be processed identically to a source address in the 92 default source encoding. 94 Multiple TLV's from the same or different type are permitted in a 95 single source address in any order. 97 3.2. Transitive attributes 99 It may be desired to have routers that understand the generic 100 attribute format, forward the attributes regardless of whether they 101 understand the TLV's encoded in the attribute not. For this the 102 first bit in the Type field is reserved. If this bit is set then the 103 router MUST forward the TLV upstream in case the router does not 104 understand that type. If this bit is not set the router MUST NOT 105 forward the TLV upstream in the case the router does not understand 106 that type. 108 3.3. Attribute Hello Option 110 A new PIM source type has been defined to include the Attribute 111 field. This source type is included in a normal PIM Join. Each 112 router on a connected network needs to be able to understand and 113 parse the Join message. Therefore we include a new PIM hello option 114 to advertise our capability to parse and process the new source type. 116 We can only send a PIM Join which includes an attribute if ALL 117 routers on the network support the new option. (Even a router which 118 is not the upstream neighbor must be able parse to the packet in 119 order to do Join suppression or overriding.) Option value TBD. 121 Having the attribute hello option does not guarantee that all 122 neighbors understand all possible individual attributes. As there's 123 no immediate way to act on a neighbor's incapability to process 124 certain attribute types, it is not desired to have a hello option for 125 each possible attribute type. 127 3.4. Conflicting attributes 129 It's possible that a router receives conflicting attribute 130 information from different downstream routers. Conflicts only occur 131 with attributes of the same type. If two different attributes of two 132 different types are received they should both be processed and 133 forwarded. 135 ( Edge A1 ) ( Edge B1 )---- [R1] 136 / \ / 137 / \ / 138 [S] ( Core ) 139 \ / \ 140 \ / \ 141 ( Edge A2 ) ( Edge B2 )---- [R2] 143 Figure 2 145 An example join attribute in this case is an exit router. There are 146 2 receivers for the same group connected to Edge B1 and B2. Suppose 147 that edge router B1 prefers A1 as the exit point and B2 prefers A2 as 148 exit point to reach the source S. If both Edge B1 and B2 send a Join 149 including an attribute to prefer their exit router in the network and 150 they cross the same core router, the core router will get conflicting 151 attribute information for the source. If this happens we use the 152 Attribute from the PIM adjacency with the numerically smallest IP 153 address. In the case of IPv6, the link local address will be used. 154 When two neighbors have the same IP address, either for IPv4 or IPv6, 155 the interface index must be used as a tie breaker. The attributes 156 from other sending routers may be kept around in case the best 157 attribute gets pruned or expires, we are able to immediately use the 158 second best attribute and converge quickly without waiting for the 159 next periodic update. If a TLV has its own definition for conflict 160 resolution it is preferred over the conflict resolution above. 162 3.5. Attribute Convergence 164 An attribute is included in a PIM Join message together with the 165 source information. If the attribute for this source is changed, we 166 trigger a new PIM Join message to the upstream router. This causes 167 the new attribute to be propagated. This new attribute implicitly 168 removes the old attribute upstream. If processing the new attribute 169 results in a change in the distribution tree, a PIM Prune message may 170 be sent. This PIM Prune does not need to carry any attribute, the 171 sender of the prune and the source and group information is enough to 172 identify the entry. The attribute information is removed immediately 173 and possibly a new attribute is chosen from the database if 174 available. 176 3.6. Multiple attributes 178 A PIM Join can contain multiple attributes. The attributes are 179 encoded as TLVs associated with a new PIM source type in the PIM 180 message. When a PIM Join with multiple attributes is received, each 181 type is processed separately. For each type, the first attribute of 182 that type is processed, and the action taken depends upon the type. 183 This may or may not result in the processing of the next attribute. 184 Attributes that the router understands but are not processed MUST be 185 passed upstream unchanged. 187 3.7. Applicability of the attributes 189 PIM Joins with attributes can be applied to both shared-trees rooted 190 at a Rendezvous Point (RP) and shortest-path trees as described in 191 [RFC4601]. 193 3.8. PIM attribute packet format 195 3.8.1. PIM Join packet format 197 There is no space in the default PIM source encoding to include a 198 attribute field. Therefore we introduce a new source encoding type. 199 The attributes are formatted as TLV's. The new Encoded source 200 address looks like this: 202 0 1 2 3 203 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 1 204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 205 | Addr Family | Encoding Type | Rsrvd |S|W|R| Mask Len | 206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 207 | Source Address (Encoded-Source format) | 208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 209 |F|S| Type | Length | Value 210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..... 211 |F|S| Type | Length | Value 212 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..... 213 . . . 214 . . . 216 F bit, Forward Unknown TLV. If this bit is set the TLV is forwarded 217 regardless if the router understands the Type. 219 S bit, Bottom of Stack. If this bit is set then this is the last TLV 220 in the stack. 222 Type field of the TLV is 6 bits. 224 Length field of the TLV is 1 byte. 226 The other fields are the same as described in the RFC 4601. 227 [RFC4601]. 229 The source TLV encoding type: TBD. 231 3.8.2. PIM Attribute Hello option 233 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 1 234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 235 | OptionType = TBD | OptionLength = 0 | 236 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 238 Option type: TBD. 240 4. IANA Considerations 242 This document requires a new PIM Hello Option value and a new PIM 243 Join Encoding type. 245 5. Security Considerations 247 Security of the join attribute is only guaranteed by the security of 248 the PIM packet, so the security considerations for PIM join packets 249 as described in PIM-SM [RFC4601] apply here. 251 6. Acknowledgments 253 The authors would like to thank Stig Venaas, James Lingard, Bharat 254 Joshi, Marshall Eubanks, Pekka Savola and Tom Pusateri for their 255 input. 257 7. References 259 7.1. Normative References 261 [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, 262 "Protocol Independent Multicast - Sparse Mode (PIM-SM): 263 Protocol Specification (Revised)", RFC 4601, August 2006. 265 7.2. Informative References 267 Authors' Addresses 269 Arjen Boers 270 Cisco Systems, Inc. 271 Avda. Diagonal, 682 272 Barcelona 08034 273 Spain 275 Email: aboers@cisco.com 277 IJsbrand Wijnands 278 Cisco Systems, Inc. 279 De kleetlaan 6a 280 Diegem 1831 281 Belgium 283 Email: ice@cisco.com 284 Eric Rosen 285 Cisco Systems, Inc. 286 1414 Massachusetts Avenue 287 Boxborough, Ma 01719 289 Email: erosen@cisco.com 291 Full Copyright Statement 293 Copyright (C) The Internet Society (2006). 295 This document is subject to the rights, licenses and restrictions 296 contained in BCP 78, and except as set forth therein, the authors 297 retain all their rights. 299 This document and the information contained herein are provided on an 300 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 301 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET 302 ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, 303 INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE 304 INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 305 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 307 Intellectual Property 309 The IETF takes no position regarding the validity or scope of any 310 Intellectual Property Rights or other rights that might be claimed to 311 pertain to the implementation or use of the technology described in 312 this document or the extent to which any license under such rights 313 might or might not be available; nor does it represent that it has 314 made any independent effort to identify any such rights. 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