1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395
|
Network Working Group M. Crawford
Request for Comments: 2464 Fermilab
Obsoletes: 1972 December 1998
Category: Standards Track
Transmission of IPv6 Packets over Ethernet Networks
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (1998). All Rights Reserved.
1. Introduction
This document specifies the frame format for transmission of IPv6
packets and the method of forming IPv6 link-local addresses and
statelessly autoconfigured addresses on Ethernet networks. It also
specifies the content of the Source/Target Link-layer Address option
used in Router Solicitation, Router Advertisement, Neighbor
Solicitation, Neighbor Advertisement and Redirect messages when those
messages are transmitted on an Ethernet.
This document replaces RFC 1972, "A Method for the Transmission of
IPv6 Packets over Ethernet Networks", which will become historic.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
2. Maximum Transmission Unit
The default MTU size for IPv6 [IPV6] packets on an Ethernet is 1500
octets. This size may be reduced by a Router Advertisement [DISC]
containing an MTU option which specifies a smaller MTU, or by manual
configuration of each node. If a Router Advertisement received on an
Ethernet interface has an MTU option specifying an MTU larger than
1500, or larger than a manually configured value, that MTU option may
be logged to system management but must be otherwise ignored.
Crawford Standards Track [Page 1]
RFC 2464 IPv6 Packets over Ethernet December 1998
For purposes of this document, information received from DHCP is
considered "manually configured" and the term Ethernet includes
CSMA/CD and full-duplex subnetworks based on ISO/IEC 8802-3, with
various data rates.
3. Frame Format
IPv6 packets are transmitted in standard Ethernet frames. The
Ethernet header contains the Destination and Source Ethernet
addresses and the Ethernet type code, which must contain the value
86DD hexadecimal. The data field contains the IPv6 header followed
immediately by the payload, and possibly padding octets to meet the
minimum frame size for the Ethernet link.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination |
+- -+
| Ethernet |
+- -+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source |
+- -+
| Ethernet |
+- -+
| Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 |
+- -+
| header |
+- -+
| and |
+- -+
/ payload ... /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
(Each tic mark represents one bit.)
Crawford Standards Track [Page 2]
RFC 2464 IPv6 Packets over Ethernet December 1998
4. Stateless Autoconfiguration
The Interface Identifier [AARCH] for an Ethernet interface is based
on the EUI-64 identifier [EUI64] derived from the interface's built-
in 48-bit IEEE 802 address. The EUI-64 is formed as follows.
(Canonical bit order is assumed throughout.)
The OUI of the Ethernet address (the first three octets) becomes the
company_id of the EUI-64 (the first three octets). The fourth and
fifth octets of the EUI are set to the fixed value FFFE hexadecimal.
The last three octets of the Ethernet address become the last three
octets of the EUI-64.
The Interface Identifier is then formed from the EUI-64 by
complementing the "Universal/Local" (U/L) bit, which is the next-to-
lowest order bit of the first octet of the EUI-64. Complementing
this bit will generally change a 0 value to a 1, since an interface's
built-in address is expected to be from a universally administered
address space and hence have a globally unique value. A universally
administered IEEE 802 address or an EUI-64 is signified by a 0 in the
U/L bit position, while a globally unique IPv6 Interface Identifier
is signified by a 1 in the corresponding position. For further
discussion on this point, see [AARCH].
For example, the Interface Identifier for an Ethernet interface whose
built-in address is, in hexadecimal,
34-56-78-9A-BC-DE
would be
36-56-78-FF-FE-9A-BC-DE.
A different MAC address set manually or by software should not be
used to derive the Interface Identifier. If such a MAC address must
be used, its global uniqueness property should be reflected in the
value of the U/L bit.
An IPv6 address prefix used for stateless autoconfiguration [ACONF]
of an Ethernet interface must have a length of 64 bits.
Crawford Standards Track [Page 3]
RFC 2464 IPv6 Packets over Ethernet December 1998
5. Link-Local Addresses
The IPv6 link-local address [AARCH] for an Ethernet interface is
formed by appending the Interface Identifier, as defined above, to
the prefix FE80::/64.
10 bits 54 bits 64 bits
+----------+-----------------------+----------------------------+
|1111111010| (zeros) | Interface Identifier |
+----------+-----------------------+----------------------------+
6. Address Mapping -- Unicast
The procedure for mapping IPv6 unicast addresses into Ethernet link-
layer addresses is described in [DISC]. The Source/Target Link-layer
Address option has the following form when the link layer is
Ethernet.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- Ethernet -+
| |
+- Address -+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Option fields:
Type 1 for Source Link-layer address.
2 for Target Link-layer address.
Length 1 (in units of 8 octets).
Ethernet Address
The 48 bit Ethernet IEEE 802 address, in canonical bit
order. This is the address the interface currently
responds to, and may be different from the built-in
address used to derive the Interface Identifier.
Crawford Standards Track [Page 4]
RFC 2464 IPv6 Packets over Ethernet December 1998
7. Address Mapping -- Multicast
An IPv6 packet with a multicast destination address DST, consisting
of the sixteen octets DST[1] through DST[16], is transmitted to the
Ethernet multicast address whose first two octets are the value 3333
hexadecimal and whose last four octets are the last four octets of
DST.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 1 1 0 0 1 1|0 0 1 1 0 0 1 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[13] | DST[14] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DST[15] | DST[16] |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8. Differences From RFC 1972
The following are the functional differences between this
specification and RFC 1972.
The Address Token, which was a node's 48-bit MAC address, is
replaced with the Interface Identifier, which is 64 bits in
length and based on the EUI-64 format [EUI64]. An IEEE-defined
mapping exists from 48-bit MAC addresses to EUI-64 form.
A prefix used for stateless autoconfiguration must now be 64 bits
long rather than 80. The link-local prefix is also shortened to
64 bits.
9. Security Considerations
The method of derivation of Interface Identifiers from MAC addresses
is intended to preserve global uniqueness when possible. However,
there is no protection from duplication through accident or forgery.
10. References
[AARCH] Hinden, R. and S. Deering "IP Version 6 Addressing
Architecture", RFC 2373, July 1998.
[ACONF] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
[DISC] Narten, T., Nordmark, E. and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998.
Crawford Standards Track [Page 5]
RFC 2464 IPv6 Packets over Ethernet December 1998
[EUI64] "Guidelines For 64-bit Global Identifier (EUI-64)",
http://standards.ieee.org/db/oui/tutorials/EUI64.html
[IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
11. Author's Address
Matt Crawford
Fermilab MS 368
PO Box 500
Batavia, IL 60510
USA
Phone: +1 630 840-3461
EMail: crawdad@fnal.gov
Crawford Standards Track [Page 6]
RFC 2464 IPv6 Packets over Ethernet December 1998
12. Full Copyright Statement
Copyright (C) The Internet Society (1998). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Crawford Standards Track [Page 7]
|