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This must be updated to follow RFC 3978/3979, as updated by RFC 4748. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- ** The document seems to lack a 1id_guidelines paragraph about Internet-Drafts being working documents. ** The document seems to lack a 1id_guidelines paragraph about 6 months document validity. == There are 110 instances of lines with non-ascii characters in the document. == No 'Intended status' indicated for this document; assuming Proposed Standard Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The document seems to lack an IANA Considerations section. (See Section 2.2 of https://www.ietf.org/id-info/checklist for how to handle the case when there are no actions for IANA.) ** The document seems to lack separate sections for Informative/Normative References. All references will be assumed normative when checking for downward references. ** The document seems to lack a both a reference to RFC 2119 and the recommended RFC 2119 boilerplate, even if it appears to use RFC 2119 keywords. RFC 2119 keyword, line 61: '... it SHALL process the parts of the L...' RFC 2119 keyword, line 101: '... The code for this TLV SHALL be 250....' RFC 2119 keyword, line 103: '...r the code field MUST include a valid ...' RFC 2119 keyword, line 125: '...value field. The length field MUST be...' RFC 2119 keyword, line 130: '... an LSP a router MAY ignore TLVs of ty...' (9 more instances...) Miscellaneous warnings: ---------------------------------------------------------------------------- -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (February 2003) is 7741 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: '1' is mentioned on line 229, but not defined == Missing Reference: '3' is mentioned on line 237, but not defined -- Possible downref: Non-RFC (?) normative reference: ref. '4' == Outdated reference: A later version (-04) exists of draft-ietf-isis-hmac-03 ** Downref: Normative reference to an Informational draft: draft-ietf-isis-hmac (ref. '5') Summary: 8 errors (**), 0 flaws (~~), 5 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Internet Engineering Task Force��������������������������� P. Christian 2 INTERNET DRAFT���������������������������������������Christian Tena LTD 3 ������������������������������������������������������ ���February 2003 4 � 5 � 6 ������������������������ TLV for Experimental Use 7 ����������������� 8 � 9 Status of this Memo 11 This document is an Internet-Draft and is in full conformance with 12 all provisions of Section 10 of RFC 2026. 14 Internet Drafts are working documents of the Internet Engineering 15 Task Force (IETF), its Areas, and its Working Groups. Note that 16 other groups may also distribute working documents as Internet 17 Drafts. 19 Internet Drafts are draft documents valid for a maximum of six 20 months. Internet Drafts may be updated, replaced, or obsoleted by 21 other documents at any time. It is not appropriate to use Internet 22 Drafts as reference material or to cite them other than as a 23 "working draft" or "work in progress". 25 The list of current Internet-Drafts can be accessed at 26 http://www.ietf.org/ietf/1id-abstracts.txt 28 The list of Internet-Draft Shadow Directories can be accessed at 29 http://www.ietf.org/shadow.html. 31 This memo provides information for the Internet community. This memo 32 does not specify an Internet standard of any kind. 34 Distribution of this draft is unlimited. 35 ��� 36 ��� 37 1. Abstract 38 ��� 39 �� This document defines a TLV that may be used by any individual, 40 �� company or other organisation for experimental extensions to the 41 IS-IS routing protocol, and defines the format of the TLV. 42 ��� 43 ��� 44 2. Conventions used in this document 45 ��� 46 �� The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 47 �� "SHOULD", "SHOULD NOT", "RECOMMENDED",� "MAY", and "OPTIONAL" in 48 �� this document are to be interpreted as described in RFC 2119. 49 ��� 50 ��� 51 � 53 Christian Expires August 2003 1 54 ���������������������� TLV for Experimental Use 55 � 56 3. Introduction 57 ��� 58 �� IS-IS as defined in [1] has always been an extensible routing 59 �� protocol.� Extensions to IS-IS are encoded as a TLV.� Critically [1] 60 �� has always defined that when an IS-IS router receives an LSP, that 61 it SHALL process the parts of the LSP that it understands, and SHALL 62 flood the entire LSP, including all TLVs whether they are understood 63 or not, on to other routers in the network. 64 ��� 65 �� Thus information that is encoded into a TLV and placed in an LSP by 66 �� a router will be propagated to every other router in an IS-IS level- 67 �� 1 area or level-2 subdomain, even by implementations that were never 68 designed with that particular TLV in mind. 69 ��� 70 �� The basic function of an IS-IS TLV is identified by the first byte 71 �� of the TLV (the code).� Thus there are only 256 possible TLV codes.� 72 �� Certain TLVs have been defined to include sub-TLVs so that a single 73 �� TLV code can be used for multiple functions. 74 ��� 75 �� No single authority assigns TLV codes, [3] lists most known TLV 76 �� codes at this time.� Also no TLV code was ever defined for 77 experimental use. 78 ��� 79 �� The extensible nature of IS-IS has made the use of TLVs in LSPs for 80 �� non-standard purposes so useful that in the absence of a central 81 �� authority for assigning TLV type numbers vendors have occasionally 82 �� simply chosen a number and hoped for the best.� The risk is that 83 �� such a TLV code may then be chosen by another organization at a 84 �� later time for a different function, thus creating an 85 �� interoperability problem. Also this accelerates the depletion of the 86 �� 256 possible TLV codes. 87 ��� 88 �� This document specifies a TLV that may be used for experimental 89 purposes, and a mechanism that insures that different 90 implementations using this TLV can exist in the same network without 91 creating interoperability problems. 92 ��� 93 �� By using this new TLV, companies, individuals or institutions may 94 �� use extensions to IS-IS without fear of interoperability problems 95 �� with other organizations in the future, and the available pool of 96 �� TLV codes will no longer be diminished by experimental use. 97 ��� 98 � 99 4. TLV code for experimental use 100 ��� 101 �� The code for this TLV SHALL be 250. 102 ��� 103 �� TLVs that use 250 for the code field MUST include a valid IEEE 104 �� assigned OUI as the first three bytes of the value of the TLV. 106 The structure of the TLV is shown in the diagram below. 108 Christian Expires August 2003 2 109 ���������������������� TLV for Experimental Use 111 No. of Octets 112 +---------------------------+ 113 | CODE =250 | 1 114 +---------------------------+ 115 | LENGTH =n+3 | 1 116 +---------------------------+ 117 | OUI | 3 118 +---------------------------+ 119 | DATA | n 120 +---------------------------+ 122 Structure of the Experiemental TLV 124 The three octet OUI plus the data octets together constitute a 125 normal IS-IS variable length value field. The length field MUST be 126 set to the number of octets of data plus three. 128 For more information about OUIs refer to [4]. 130 �� On receipt of an LSP a router MAY ignore TLVs of type 250 that 131 �� include an OUI from a different organization, but MUST flood the LSP 132 �� onwards as per [1]. 133 ��� �� 134 �� After the first three bytes of the value field of the TLV subsequent 135 �� bytes may be used freely for any purpose (within the limitations set 136 out in this document) provided that the resultant TLV is conformant 137 with [1]. 138 ��� 139 �� Many organizations will have access to only one or a few OUIs.� 140 �� Implementers are free to format the value field after their OUI into 141 �� sub-TLVs so that the TLV may be used for multiple purposes, and would 142 be well advised to do so. 144 5. Using experimental information to modify SPF 146 All routers in an IS-IS routed network need to calculate routes 147 such that they all arrive at the same shortest path for a given 148 destination. 150 If this does not happen then routing loops and blackholes are likely 151 to occur. 153 Therefore a router MUST NOT calculate a route differently due to 154 information that it receives in an experimental TLV. Shortest paths 155 MUST continue to be calculated as per [1] and [2]. 157 Christian Expires August 2003 3 158 ���������������������� TLV for Experimental Use 160 6. Correct use of Experimental TLV in LSPs 162 Some implementations recalculate SPF each time that they receive a 163 new LSP. In the least case an implementation needs to decide 164 whether a new LSP is significant or not. If one router constantly 165 transmits LSPs into the network then others may not perform well. 167 Additionally LSPs are flooded to every router in a level-1 area or 168 level-2 subdomain, and are therefore not a particularly efficient 169 way of carrying a piece of information simply from router A to 170 router B. 172 Consequently the experimental TLV SHOULD NOT be used within LSPs as 173 any kind of general transport mechanism, and the experimental TLV 174 SHOULD NOT cause frequent transmission of LSPs into the network. 176 In general it would be preferable to transmit information in an 177 experimental TLV at such time as an LSP would be normally be 178 transmitted anyway, if this is possible. 180 These particular restrictions do not apply to use of the 181 experimental TLV in Hello and Sequence Number packets. 183 7. Authentication of PDUs 185 If HMAC authentication of IS-IS PDUs that contain an experimental 186 TLV is used then the experimental TLV MUST be included in the HMAC 187 calculation. 189 ��� 190 8. Documenting an Experimental TLV 192 Without an understanding of what an experimental TLV has been used 193 for an operator is not able to make an informed decision as to 194 whether or not to deploy it in their network. 196 Implementors SHOULD document the use of an Experimental TLV in an 197 experimental status RFC. Experimental RFCs MAY be submitted 198 directly to the RFC editor and do not necessarily need to discussed 199 by the workgroup. Details may be found in section 4.2.3 of RFC 200 2026 [6]. 202 If such documentation is not available then an operator SHOULD 203 consider the interoperability and security of an implementation 204 to be unknown. 206 Christian Expires August 2003 4 207 ���������������������� TLV for Experimental Use 209 9. Security Considerations 211 �� The contents of IS-IS PDUs are not protected by encryption, 212 �� so the contents of TLVs in LSPs are visible throughout the 213 �� routing area or domain, while the contents of Hello Packets, 214 �� CSNPs, and PSNPs are visible to observers on the link they 215 �� are sent to.� The addition of MD5 authentication, as described 216 �� in [5] can increase the integrity of TLVs, while encryption could 217 increase their confidentiality.� 219 �� The general extensibility of the TLV mechanism has always allowed 220 �� the addition of new information, and the possibility of conflicting 221 �� interpretations of such information by different implementations.� 222 �� This proposal does not introduce a new quality of information; it 223 �� simply allows an increase in the quantity of such additions.� As 224 �� such, it represents no new security issues for IS-IS. 226 �� 227 10. References 228 ��� 229 �� [1] ISO, "Intermediate system to Intermediate system routeing 230 �� information exchange protocol for use in conjunction with the 231 �� Protocol for providing the Connectionless-mode Network Service 232 (ISO 8473)", ISO/IEC 10589:1992. 234 [2] RFC 1195, Use of OSI IS-IS for Routing in TCP/IP and Dual 235 Environments, R Callon, December 1990 236 ��� 237 �� [3] RFC 3359, Reserved TLV Codepoints in ISIS 238 Tony Przygienda, August 2002 240 [4] IEEE OUI and Company_id Assignments 241 http://standards.ieee.org/regauth/oui/index.shtml 243 [5] draft-ietf-isis-hmac-03.txt, IS-IS Cryptographic Authentication 244 Tony Li, RJ Atkinson, July 2001 246 [6] RFC 2026, The Internet Standards Process -- Revision 3 247 Scott O. Bradner, October 1996 249 11. Acknowledgments 250 ��� 251 �� The author takes no credit for this work as the concept was 252 �� discussed in the IS-IS Working Group before the author even became 253 �� an active participant.� Suggestions for acknowledgement gladly 254 �� received. 256 Christian Expires August 2003 5 257 ���������������������� TLV for Experimental Use 259 12. Author's Addresses 260 ��� 261 �� Philip Christian 262 �� Christian Tena LTD 263 �� Hatfield Heath 264 �� Essex, CM22 7AH UK 265 ��� 266 �� Email: philip.christian@christiantena.co.uk 268 Christian Expires August 2003 6