idnits 2.17.00 (12 Aug 2021) /tmp/idnits49149/draft-kawamura-ipv6-text-representation-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** The document seems to lack a License Notice according IETF Trust Provisions of 28 Dec 2009, Section 6.b.ii or Provisions of 12 Sep 2009 Section 6.b -- however, there's a paragraph with a matching beginning. Boilerplate error? (You're using the IETF Trust Provisions' Section 6.b License Notice from 12 Feb 2009 rather than one of the newer Notices. See https://trustee.ietf.org/license-info/.) Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([RFC4291]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document date (March 26, 2009) is 4803 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Unused Reference: 'RFC3493' is defined on line 465, but no explicit reference was found in the text Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force S. Kawamura 3 Internet-Draft NEC BIGLOBE, Ltd. 4 Intended status: Informational M. Kawashima 5 Expires: September 27, 2009 NEC AccessTechnica, Ltd. 6 March 26, 2009 8 A Recommendation for IPv6 Address Text Representation 9 draft-kawamura-ipv6-text-representation-00 11 Status of this Memo 13 This Internet-Draft is submitted to IETF in full conformance with the 14 provisions of BCP 78 and BCP 79. 16 Internet-Drafts are working documents of the Internet Engineering 17 Task Force (IETF), its areas, and its working groups. Note that 18 other groups may also distribute working documents as Internet- 19 Drafts. 21 Internet-Drafts are draft documents valid for a maximum of six months 22 and may be updated, replaced, or obsoleted by other documents at any 23 time. It is inappropriate to use Internet-Drafts as reference 24 material or to cite them other than as "work in progress." 26 The list of current Internet-Drafts can be accessed at 27 http://www.ietf.org/ietf/1id-abstracts.txt. 29 The list of Internet-Draft Shadow Directories can be accessed at 30 http://www.ietf.org/shadow.html. 32 This Internet-Draft will expire on September 27, 2009. 34 Copyright Notice 36 Copyright (c) 2009 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents in effect on the date of 41 publication of this document (http://trustee.ietf.org/license-info). 42 Please review these documents carefully, as they describe your rights 43 and restrictions with respect to this document. 45 Abstract 47 As IPv6 network grows, there will be more engineers and also non- 48 engineers who will have the need to use an IPv6 address in text. 50 While the IPv6 address architecture [RFC4291] section 2.2 depicts a 51 flexible model for text representation of an IPv6 address, this 52 flexibility has been causing problems for operators ,system 53 engineers, and customers. The following draft will describe the 54 problems that a flexible text representation has been causing. This 55 document also recommends a text representation method that best 56 avoids confusion. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 62 2. Text representation flexibility of RFC4291 . . . . . . . . . . 4 63 2.1. leading zeros . . . . . . . . . . . . . . . . . . . . . . 4 64 2.2. zero compression . . . . . . . . . . . . . . . . . . . . . 5 65 2.3. Uppercase or Lowercase . . . . . . . . . . . . . . . . . . 6 66 3. Problems Encountered with the Flexible Model . . . . . . . . . 6 67 3.1. Searching . . . . . . . . . . . . . . . . . . . . . . . . 6 68 3.1.1. General Summary . . . . . . . . . . . . . . . . . . . 6 69 3.1.2. Searching Spreadsheets and Text Files . . . . . . . . 6 70 3.1.3. Searching with Whois . . . . . . . . . . . . . . . . . 7 71 3.1.4. Searching for an Address in a Network Diagram . . . . 7 72 3.2. Parsing and Modifying . . . . . . . . . . . . . . . . . . 7 73 3.2.1. General Summary . . . . . . . . . . . . . . . . . . . 7 74 3.2.2. Logging . . . . . . . . . . . . . . . . . . . . . . . 7 75 3.2.3. Auditing. Case 1 . . . . . . . . . . . . . . . . . . . 8 76 3.2.4. Auditing. Case 2 . . . . . . . . . . . . . . . . . . . 8 77 3.2.5. Unexpected Modifying . . . . . . . . . . . . . . . . . 8 78 3.3. Operating . . . . . . . . . . . . . . . . . . . . . . . . 8 79 3.3.1. General Summary . . . . . . . . . . . . . . . . . . . 8 80 3.3.2. Customer Calls . . . . . . . . . . . . . . . . . . . . 9 81 3.3.3. Abuse . . . . . . . . . . . . . . . . . . . . . . . . 9 82 3.4. Other Minor Problems . . . . . . . . . . . . . . . . . . . 9 83 3.4.1. Changing Platforms . . . . . . . . . . . . . . . . . . 9 84 3.4.2. Preference in Documentation . . . . . . . . . . . . . 9 85 3.4.3. Legibility . . . . . . . . . . . . . . . . . . . . . . 9 86 4. A Recommendation for IPv6 Text Representation . . . . . . . . 10 87 4.1. Handling Leading Zeros . . . . . . . . . . . . . . . . . . 10 88 4.2. Lower Case . . . . . . . . . . . . . . . . . . . . . . . . 10 89 4.3. "::" usage . . . . . . . . . . . . . . . . . . . . . . . . 10 90 4.3.1. shorten as much as possible . . . . . . . . . . . . . 10 91 4.3.2. one 16bit 0 field . . . . . . . . . . . . . . . . . . 10 92 4.3.3. when "::" can be used twice . . . . . . . . . . . . . 10 93 5. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 10 94 6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 95 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 96 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 97 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 98 9.1. Normative References . . . . . . . . . . . . . . . . . . . 11 99 9.2. Informative References . . . . . . . . . . . . . . . . . . 11 100 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 102 1. Introduction 104 A single IPv6 address can be text represented in many ways. Examples 105 are shown below. 107 2001:db8:0:0:1:0:0:1/128 109 2001:0db8:0:0:1:0:0:1/128 111 2001:db8::1:0:0:1/128 113 2001:db8::0:1:0:0:1/128 115 2001:0db8::1:0:0:1/128 117 2001:db8:0:0:1::1/128 119 2001:db8:0000:0:1::1/128 121 2001:DB8:0:0:1::1/128 123 All the above point to the same IPv6 address. This flexiblity has 124 caused many problems for operators, systems engineers, and customers. 125 The problems will be noted in section 3. 127 1.1. Requirements Language 129 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 130 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 131 document are to be interpreted as described in RFC 2119 [RFC2119]. 133 2. Text representation flexibility of RFC4291 135 Examples of flexibility in Section 2.2 of RFC4291 are described 136 below. 138 2.1. leading zeros 140 'It is not necessary to write the leading zeros in an individual 141 field.' 143 In other words, it is also not necessary to omit leading zeros. This 144 means that, it is possible to select such as the following example. 145 Last 16bit is different, but all these addresses are the same. 147 2001:db8:aaaa:bbbb:cccc:dddd:eeee:0001/128 149 2001:db8:aaaa:bbbb:cccc:dddd:eeee:001/128 151 2001:db8:aaaa:bbbb:cccc:dddd:eeee:01/128 153 2001:db8:aaaa:bbbb:cccc:dddd:eeee:1/128 155 2.2. zero compression 157 'A special syntax is available to compress the zeros. The use of 158 "::" indicates one or more groups of 16 bits of zeros.' 160 It is possible to select whether or not to omit just one 16bits of 161 zeros. 163 2001:db8:aaaa:bbbb:cccc:dddd::1/128 165 2001:db8:aaaa:bbbb:cccc:dddd:0:1/128 167 In case where there are more than one zero fields, there is a choice 168 of how much fields to shorten, such as described in the following 169 example. It is not necessary to omit the fields completely. 171 2001:db8:0:0:0::1/128 173 2001:db8:0:0::1/128 175 2001:db8:0::1/128 177 2001:db8::1/128 179 ... and more 181 In addition, RFC4291 in section 2.2 notes, 183 'The "::" can also be used to compress leading or trailing zeros 184 in an address.' 186 Therefore, it is possible to select such as the following example. 188 2001:db8::aaaa:0:0:1/128 190 2001:db8:0:0:aaaa::1/128 192 2.3. Uppercase or Lowercase 194 RFC4291 does not mention about Uppercase and Lowercase. Because it's 195 probably not special. However, it is possible to select such as the 196 following example. Last 16bit is different, but these are the same. 198 2001:db8:aaaa:bbbb:cccc:dddd:eeee:aaaa/128 200 2001:db8:aaaa:bbbb:cccc:dddd:eeee:AAAA/128 202 2001:db8:aaaa:bbbb:cccc:dddd:eeee:AaAa/128 204 ... more combinations 206 3. Problems Encountered with the Flexible Model 208 3.1. Searching 210 3.1.1. General Summary 212 A search of an IPv6 address if conducted through a UNIX system is 213 usually case sensitive and extended options to allow for regular 214 expression use will come in handy. However, there are many 215 applications in the internet today that do not provide this 216 capability. When searching for an IPv6 address in such systems, the 217 system engineer will have to try each and every possibility to search 218 for an address. This has critical impacts especially when trying to 219 deploy IPv6 over an enterprise network. 221 3.1.2. Searching Spreadsheets and Text Files 223 Spreadsheet applications and text editors on GUI systems, rarely have 224 the ability to search for a text using regular expression. Moreover, 225 there are many non-engineers (who are not aware of case sensitivity 226 and regular expression use) that use these application to manage IP 227 addresses. This has worked quite well with IPv4 since text 228 representation in IPv4 has very little flexibility. There is no 229 incentive to encourage these non-engineers to change their tool or 230 learn reagular expression when they decide to go dual-stack. If the 231 entry in the spreadsheet reads, 2001:db8::1:0:0:1, but the search was 232 conducted as 2001:db8:0:0:1::1, this will show a result of no match. 233 One example where this will cause problem is, when the search is 234 being conducted to assign a new address from a pool, and a check was 235 being done to see if it was not in use. This may cause problems to 236 the end-hosts or end-users. This type of address management is very 237 often seen in enterprise networks and also in ISPs. 239 3.1.3. Searching with Whois 241 The whois utility is used by a wide range of people today. When a 242 record is set to the whois database, one will likely check the output 243 to see if the entry is correct. If a entity was recorded as 2001: 244 db8::/48, but the whois ouput showed 2001:0db8:0000::/48, most non- 245 engineers would think that their input was wrong, and will likely 246 retry several times or make a frustrated call to the database 247 hostmaster. If there was a need to register the same address on 248 different systems, and each system showed a different text 249 representation, this would confuse people even more. 251 3.1.4. Searching for an Address in a Network Diagram 253 Network diagrams and blue-prints contain IP addresses of systems. In 254 times of trouble shooting, there may be a need to search through a 255 diagram to find the point of failure (for example, if a traceroute 256 stopped at 2001:db8::1, one would search the diagram for that 257 address). This is a technique quite often in use in enterprise 258 networks and managed services. Again, the different flavors of text 259 representation will result in a time-consuming search, leading to 260 longer MTTR in times of trouble. 262 3.2. Parsing and Modifying 264 3.2.1. General Summary 266 With all the possible text representation ways, each application must 267 include a module, object, link, etc. to a function that will parse 268 IPv6 addresses in a manner that no matter how it is represented, they 269 will mean the same address. This is not too much a problem if the 270 output is to be just 'read' or 'managed' by a network engineer. 271 However, many system engineers who integrate complex computer systems 272 to corporate customers will have difficulties finding that their 273 favorite tool will not have this function, or will encounter 274 difficulties such as having to rewrite their macro's or scripts for 275 their customers. It must be noted that each additional line of a 276 program will result in increased development fees that will be 277 charged to the customers. 279 3.2.2. Logging 281 If an application were to ouput a log summary that represented the 282 address in full (such as 2001:0db8:0000:0000:1111:2222:3333:4444), 283 the output would be highly unreadable compared to the IPv4 output. 284 The address would have to be parsed and reformed to make it useful 285 for human reading. This will result in additional code on the 286 applications which will result in extra fees charged to the 287 customers. Sometimes, logging for critical systems is done by 288 mirroring the same traffic to two different systems. Care must be 289 taken that no matter what the log output is, the logs should be 290 parsed so they will mean the same. 292 3.2.3. Auditing. Case 1 294 When a router or any other network appliance machine configuration is 295 audited, there are many methods to compare the configuration 296 information of a node. Sometimes, auditing will be done by just 297 comparing the changes made each day. In this case, if configuration 298 was done such that 2001:db8::1 was changed to 2001:0db8:0000:0000: 299 0000:0000:0000:0001 just because the new engineer on the block felt 300 it was better, a simple diff will tell you that a different address 301 was configured. If this was done on a wide scale network, people 302 will be focusing on 'why the extra zeros were put in' instead of 303 doing any real auditing. Lots of tools are just plain diffs that do 304 not take into account address representation rules. 306 3.2.4. Auditing. Case 2 308 Node configurations will be matched against a information system that 309 manages IP addresses. If output notation is different, there will 310 need to be a script that is implemented to cover for this. An SNMP 311 GET of an interface address and text representation in a humanly 312 written text file is highly unlikely to match on first try. 314 3.2.5. Unexpected Modifying 316 Sometimes, a system will take an address and modify it as a 317 convenience. For example, a router may take an input of 318 2001:0db8:0::1 and make the ouput 2001:db8::1 (which is seen in som 319 RIR databases). If the zeros were inputed for a reason, the outcome 320 may be somewhat unexpected. 322 3.3. Operating 324 3.3.1. General Summary 326 When an operator sets an IPv6 address of a system as 2001:db8:0:0:1: 327 0:0:1/128, the system may take the address and show the configuration 328 result as 2001:DB8::1:0:0:1/128. A distinguished engineer will know 329 that the right address is set, but an operator, or a customer that is 330 communicating with the operator to solve a problem, is usually not as 331 distinguished as we would like. Again, the extra load in checking 332 that the IP address is the same as was intended, will result in fees 333 that will be charged to the customers. 335 3.3.2. Customer Calls 337 When a customer calls to inquire about a suspected outage, IPv6 338 address representation should be handled with care. Not all 339 customers are engineers nor have the same skill in IPv6 technology. 340 The NOC will have to take extra steps to humanly parse the address to 341 avoid having to explain to the customers that 2001:db8:0:1::1 is the 342 same as 2001:db8::1:0:0:0:1. This is one thing that will never 343 happen in IPv4 because IPv4 address cannot be abbreviated. 345 3.3.3. Abuse 347 Network abuse is reported along with the abusing IP address. This 348 'reporting' could take any shape or form of the flexible model. A 349 team that handles network abuse must be able to tell the difference 350 between a 2001:db8::1:0:1 and 2001:db8:1::0:1. Mistakes in the 351 placement of the "::" will result in a critical situation. A system 352 that handles these incidents should be able to handle any type of 353 input and parse it in a correct manner. Also, incidents are reported 354 over the phone. It is unnecessary to report if the letter is an 355 uppercase or lowercase. However, when a letter is spelled uppercase, 356 people tend to clarify that it is uppercase, which is unnecessary 357 information. 359 3.4. Other Minor Problems 361 3.4.1. Changing Platforms 363 When an engineer decides to change the platform of a running service, 364 the same code may not work as expected due to the difference in IPv6 365 address text representation. Usually, a change in a platform (e.g. 366 Unix to Windows, Cisco to Juniper) will result in a major change of 367 code, but flexibility in address representation will increase the 368 work load which will again, result in fees that will be charged to 369 the customers, and also longer down time of systems. 371 3.4.2. Preference in Documentation 373 A document that is edited by more than one author, may become harder 374 to read. 376 3.4.3. Legibility 378 Capital case D and 0 can be quite often misread. 380 4. A Recommendation for IPv6 Text Representation 382 4.1. Handling Leading Zeros 384 Leading zeros should be chopped for human legibility and easier 385 searching. Also, a single 16 bit 0000 field should be represented as 386 just 0. Place holder zeros are often cause of mis-reading. 388 4.2. Lower Case 390 Recent implementations tend to represent IPv6 address as lower case. 391 It is better to use lower case to avoid problems such as described in 392 section 3.3.3 and 3.4.3. 394 4.3. "::" usage 396 4.3.1. shorten as much as possible 398 The use of "::" should be used to its maximum capability (i.e. 2001: 399 db8::0:1/128 is not very clean). 401 4.3.2. one 16bit 0 field 403 "::" should not be used to shorten just one 16bit 0 field for it 404 would tend to mislead that there are more than one 16 bit field that 405 is shortened. 407 4.3.3. when "::" can be used twice 409 When cases where it is possible to use "::" in two or more different 410 sections of an address, implementation to shorten the side with more 411 16bit 0 fields are more common (i.e. latter is shortened in 2001:0:0: 412 1:0:0:0:1/128). When the length of 16bit 0 fields are equal (i.e. 413 2001:db8:0:0:1:0:0:1/128), the former is usually shortened. One idea 414 to avoid any confusion, is for the operator to not use 16bit field 0 415 in the first 64 bits. By nature IPv6 addresses are usually assigned 416 or allocated to end-users as longer than 32 bits (typicaly 48bit or 417 longer). 419 5. Conclusion 421 For developers, it is recommended that they use inet_ntop() or 422 WSAAddressToString(). These have a consistent rule with this draft. 423 If you have difficulties using these functions, it is desirable to 424 adapt the recommended rule. For all those who have the need of text 425 representing an IPv6 address, the following is a summary of the 426 recommended rules. 428 (1) omit leading zeros 430 (2) use lower case 432 (3) "::" used to their maximum extent whenever possible 434 (4) "::" used where shortens address the most 436 (5) "::" used in the former part in case of a tie breaker 438 (6) do not shorten one 16bit 0 field 440 6. Security Considerations 442 None. 444 7. IANA Considerations 446 None. 448 8. Acknowledgements 450 The authors would like to thank Jan Zorz, Randy Bush, Yuichi Minami, 451 Toshimitsu Matsuura for their generous and helpful comments. 453 9. References 455 9.1. Normative References 457 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 458 Architecture", RFC 4291, February 2006. 460 9.2. Informative References 462 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 463 Requirement Levels", BCP 14, RFC 2119, March 1997. 465 [RFC3493] Gilligan, R., Thomson, S., Bound, J., McCann, J., and W. 466 Stevens, "Basic Socket Interface Extensions for IPv6", 467 RFC 3493, February 2003. 469 Authors' Addresses 471 Seiichi Kawamura 472 NEC BIGLOBE, Ltd. 473 14-22, Shibaura 4-chome 474 Minatoku, Tokyo 108-8558 475 JAPAN 477 Phone: +81 3 3798 6085 478 Email: kawamucho@mesh.ad.jp 480 Masanobu Kawashima 481 NEC AccessTechnica, Ltd. 482 800, Shimomata 483 Kakegawa-shi, Shizuoka 436-8501 484 JAPAN 486 Phone: +81 537 23 9655 487 Email: kawashimam@necat.nec.co.jp