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PROPOSED STANDARD
Updated by:8064
Network Working Group                                          A. ContaRequest for Comments: 2590                                       LucentCategory: Standards Track                                      A. Malis                                                                 Ascend                                                             M. Mueller                                                                 Lucent                                                               May 1999Transmission of IPv6 Packets over Frame Relay NetworksSpecificationStatus 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 (1999).  All Rights Reserved.Abstract   This memo describes mechanisms for the transmission of IPv6 packets   over Frame Relay networks.Table of Contents1. Introduction.................................................22. Maximum Transmission Unit....................................33. Frame Format.................................................44. Stateless Autoconfiguration..................................54.1 Generating the MID field.................................75. Link-Local Address...........................................96. Address Mapping -- Unicast, Multicast........................97. Sending Neighbor Discovery Messages.........................148. Receiving Neighbor Discovery Messages.......................159. Security Considerations.....................................1510. Acknowledgments............................................1611. References.................................................1612. Authors' Addresses.........................................1813. Full Copyright Statement...................................19Conta, et al.               Standards Track                     [Page 1]

RFC 2590             IPv6 over Frame Relay Networks             May 19991. Introduction   This document specifies the frame format for transmission of IPv6   packets over Frame Relay networks, the method of forming IPv6 link-   local addresses on Frame Relay links, and the mapping of the IPv6   addresses to Frame Relay addresses.  It also specifies the content of   the Source/Target link-layer address option used in Neighbor   Discovery [ND] and Inverse Neighbor Discovery [IND] messages when   those messages are transmitted over a Frame Relay link.  It is part   of a set of specifications that define such IPv6 mechanisms for Non   Broadcast Multi Access (NBMA) media [IPv6-NBMA], [IPv6-ATM], and a   larger set that defines such mechanisms for specific link layers   [IPv6-ETH], [IPv6-FDDI], [IPv6-PPP], [IPv6-ATM], etc...   The information in this document applies to Frame Relay devices which   serve as end stations (DTEs) on a public or private Frame Relay   network (for example, provided by a common carrier or PTT.) Frame   Relay end stations can be IPv6 hosts or routers. In this document   they are referred to as nodes.   In a Frame Relay network, a number of virtual circuits form the   connections between the attached stations (nodes). The resulting set   of interconnected devices forms a private Frame Relay group which may   be either fully interconnected with a complete "mesh" of virtual   circuits, or only partially interconnected.  In either case, each   virtual circuit is uniquely identified at each Frame Relay interface   (card) by a Data Link Connection Identifier (DLCI).  In most   circumstances, DLCIs have strictly local significance at each Frame   Relay interface.   A Frame Relay virtual circuit acts like a virtual-link (also referred   to as logical-link), with its own link parameters, distinct from the   parameters of other virtual circuits established on the same wire or   fiber. Such parameters are the input/output maximum frame size,   incoming/outgoing requested/agreed throughput, incoming/outgoing   acceptable throughput, incoming/outgoing burst size,   incoming/outgoing frame rate.   By default a DLCI is 10 bits in length. Frame Relay specifications   define also 16, 17, or 23 bit DLCIs. The former is not used, while   the latter two are suggested for use with SVCs.   Frame Relay virtual circuits can be created administratively as   Permanent Virtual Circuits -- PVCs -- or dynamically as Switched   Virtual Circuits -- SVCs.  The mechanisms defined in this document   are intended to apply to both permanent and switched Frame Relay   virtual circuits, whether they are point to point or point to multi-   point.Conta, et al.               Standards Track                     [Page 2]

RFC 2590             IPv6 over Frame Relay Networks             May 1999   The keywords MUST, MUST NOT, MAY, OPTIONAL, REQUIRED, RECOMMENDED,   SHALL, SHALL NOT, SHOULD, SHOULD NOT are to be interpreted as defined   in [RFC 2119].2. Maximum Transmission Unit   The IPv6 minimum MTU is defined in [IPv6].   In general, Frame Relay devices are configured to have a maximum   frame size of at least 1600 octets. Therefore, the default IPv6 MTU   size for a Frame Relay interface is considered to be 1592.   A smaller than default frame size can be configured but of course not   smaller than the minimum IPv6 MTU.   An adequate larger than default IPv6 MTU and Frame Relay frame size   can be configured to avoid fragmentation. The maximum frame size is   controlled by the CRC generation mechanisms employed at the HDLC   level. CRC16 will protect frames up to 4096 bytes in length, which   reduces the effective maximum frame size to approximately 4088 bytes.   A larger desired frame size (such as that used by FDDI or Token   Ring), would require the CRC32 mechanism, which is not yet widely   used and is not mandatory for frame relay systems conforming to Frame   Relay Forum and ITU-T standards.   In general, if upper layers provide adequate error   protection/detection mechanisms, implementations may allow   configuring a Frame Relay link with a larger than 4080 octets frame   size but with a lesser error protection/detection mechanism at link   layer. However, because IPv6 relies on the upper and lower layer   error detection, configuring the IPv6 MTU to a value larger than 4080   is strongly discouraged.   Although a Frame Relay circuit allows the definition of distinct   maximum frame sizes for input and output, for simplification   purposes, this specification assumes symmetry, i.e. the same MTU for   both input and output.   Furthermore, implementations may limit the setting of the Frame Relay   maximum frame size to the interface (link, or card) level, which then   is enforced on all of the PVCs or SVCs on that interface (on that   link, or card). For an SVC, the maximum frame size parameter   negotiated during circuit setup will not exceed the configured   maximum frame size.Conta, et al.               Standards Track                     [Page 3]

RFC 2590             IPv6 over Frame Relay Networks             May 19993. IPv6 Frame Format   The IPv6 frame encapsulation for Frame Relay (for both PVCs and SVCs)   follows [ENCAPS], which allows a VC to carry IPv6 packets along with   other protocol packets. The NLPID frame format is used, in which the   IPv6 NLPID has a value of 0x8E:            0                       1                       (Octets)           +-----------------------+-----------------------+(Octets)0  |                                               |           /                 Q.922 Address                 /           /            (length 'n' equals 2 or 4)         /           |                                               |           +-----------------------+-----------------------+        n  | Control (UI)  0x03    |      NLPID  0x8E      |  NLPID           +-----------------------+-----------------------+  indicating      n+2  |                       .                       |  IPv6           /                       .                       /           /                  IPv6 packet                  /           |                       .                       |           +-----------------------+-----------------------+           |                                               |           +                      FCS                      +           |                                               |           +-----------------------+-----------------------+      "n" is the length of the Q.922 address which can be 2 or 4 octets.      The Q.922 representation of a DLCI (in canonical order - the first      bit is stored in the least significant, i.e., the right-most bit      of a byte in memory) [CANON] is the following:            7     6     5     4     3     2     1     0      (bit order)           +-----+-----+-----+-----+-----+-----+-----+-----+(octet) 0  |            DLCI(high order)       |  0  |  0  |           +-----+-----+-----+-----+-----+-----+-----+-----+        1  |  DLCI(low order)      |  0  |  0  |  0  |  1  |           +-----+-----+-----+-----+-----+-----+-----+-----+              10 bits DLCIConta, et al.               Standards Track                     [Page 4]

RFC 2590             IPv6 over Frame Relay Networks             May 1999            7     6     5     4     3     2     1     0      (bit order)           +-----+-----+-----+-----+-----+-----+-----+-----+(octet) 0  |            DLCI(high order)       |  0  |  0  |           +-----+-----+-----+-----+-----+-----+-----+-----+        1  |  DLCI                 |  0  |  0  |  0  |  0  |           +-----+-----+-----+-----+-----+-----+-----+-----+        2  |             DLCI(low order)             |  0  |           +-----+-----+-----+-----+-----+-----+-----+-----+        3  |       unused (set to 0)           |  1  |  1  |           +-----+-----+-----+-----+-----+-----+-----+-----+              17 bits DLCI            7     6     5     4     3     2     1     0      (bit order)           +-----+-----+-----+-----+-----+-----+-----+-----+(octet) 0  |            DLCI(high order)       |  0  |  0  |           +-----+-----+-----+-----+-----+-----+-----+-----        1  |  DLCI                 |  0  |  0  |  0  |  0  |           +-----+-----+-----+-----+-----+-----+-----+-----+        2  |             DLCI                        |  0  |           +-----+-----+-----+-----+-----+-----+-----+-----+        3  |       DLCI (low order)            |  0  |  1  |           +-----+-----+-----+-----+-----+-----+-----+-----+              23 bits DLCI   The encapsulation of data or control messages exchanged by various   protocols that use SNAP encapsulation (with their own PIDs) is not   affected. The encoding of the IPv6 protocol identifier in such   messages MUST be done according to the specifications of those   protocols, and [ASSNUM].4. Stateless Autoconfiguration   An interface identifier [AARCH] for an IPv6 Frame Relay interface   must be unique on a Frame Relay link [AARCH], and must be unique on   each of the virtual links represented by the VCs terminated on the   interface.   The interface identifier for the Frame Relay interface is locally   generated by the IPv6 module.   Each virtual circuit in a Frame Relay network is uniquely identified   on a Frame Relay interface by a DLCI. Furthermore, a DLCI can be seen   as an identification of the end point of a virtual circuit on a Frame   Relay interface. Since each Frame Relay VC is configured or   established separately, and acts like an independent virtual-link   from other VCs in the network, or on the interface, link, wire orConta, et al.               Standards Track                     [Page 5]

RFC 2590             IPv6 over Frame Relay Networks             May 1999   fiber, it seems beneficial to view each VC's termination point on the   Frame Relay interface as a "pseudo-interface" or "logical-interface"   overlaid on the Frame Relay interface. Furthermore, it seems   beneficial to be able to generate and associate an IPv6   autoconfigured address (including an IPv6 link local address) to each   "pseudo-interface", i.e. end-point of a VC, i.e. to each DLCI on a   Frame Relay interface.   In order to achieve the benefits described above, the mechanisms   specified in this document suggest constructing the Frame Relay   interface identifier from 3 distinct fields (Fig.1):   (a)  The "EUI bits" field. Bits 6 and 7 of the first octet,        representing the EUI-64 "universal/local" and respectively        "individual/group" bits converted to IPv6 use. The former is set        to zero to reflect that the 64 bit interface identifier value        has local significance [AARCH]. The latter is set to 0 to        reflect the unicast address [AARCH].   (b)  The "Mid" field. A 38 bit field which is generated with the        purpose of adding uniqueness to the interface identifier.   (c)  The "DLCI" field. A 24 bit field that MAY hold a 10, 17, or 23        bit DLCI value which MUST be extended with 0's to 24 bits. A        DLCI based interface identifier -- which contains a valid DLCI        -- SHOULD be generated as a result of successfully establishing        a VC -- PVC or SVC.        If a DLCI is not known, the field MUST be set to the        "unspecified DLCI" value which consists of setting each of the        24 bits to 1.   Since DLCIs are local to a Frame Relay node, it is possible to have   Frame Relay distinct virtual circuits within a Frame Relay network   identified with the same DLCI values.Conta, et al.               Standards Track                     [Page 6]

RFC 2590             IPv6 over Frame Relay Networks             May 1999             7     6     5     4     3     2     1     0   (bit order)            +-----+-----+-----+-----+-----+-----+-----+-----+(Octets) 0  |                                   |"EUI bits" |            +                                   +-----+-----+         1  |                                               |            +                                               +         2  |                   "Mid"                       |            +                                               +         3  |                                               |            +                                               +         4  |                                               |            +-----+-----+-----+-----+-----+-----+-----+-----+         5  |                                               |            +                                               +         6  |                   "DLCI"                      |            +                                               +         7  |                                               |            +-----+-----+-----+-----+-----+-----+-----+-----+            Fig.1 Frame Relay Pseudo-Interface Identifier   The Duplicate Address Detection specified in [AUTOCONF] is used   repeatedly during the interface identifier and local-link address   generation process, until the generated identifier and consequently   the link-local address on the link -- VC -- are unique.4.1  Generating the "Mid" field.   The "Mid" can be generated in multiple ways. This specification   suggests two mechanisms: (b.1)  "Use of Local Administrative Numbers"        The "Mid" is filled with the result of merging:   (b.1.1)  A random number of 6 bits in length (Fig.2).   (b.1.2)  The Frame Relay Node Identifier -- 16 bits -- is a user            administered value used to locally identify a Frame Relay            node (Fig.2).   (b.1.3)  The Frame Relay Link Identifier -- 16 bits -- is a numerical            representation of the Frame Relay interface or link (Fig.2).Conta, et al.               Standards Track                     [Page 7]

RFC 2590             IPv6 over Frame Relay Networks             May 1999             7     6     5     4     3     2     1     0  (bit order)            +-----+-----+-----+-----+-----+-----+-----+-----+(Octets) 0  |          Random Number            |    MBZ    |            +-----------------------------------+-----+-----+         1  |                                               |            +          Frame Relay Node Identifier          +         2  |                                               |            +-----+-----+-----+-----+-----+-----+-----+-----+         3  |                                               |            +          Frame Relay Link Identifier          +         4  |                                               |            +-----+-----+-----+-----+-----+-----+-----+-----+         5  |                                               |            +                                               +         6  |                    "DLCI"                     |            +                                               +         7  |                                               |            +-----+-----+-----+-----+-----+-----+-----+-----+            Fig.2  Frame Relay Pseudo-Interface Identifier   or, (b.2)  "Use of The Frame Relay address - E.164 [E164], X.121       [X25] numbers, or NSAP [NSAP] address"       If a Frame Relay interface has an E.164 or a X.121 number, or an       NSAP address, the "Mid" field MUST be filled in with a number       resulted from it as follows:  the number represented by the BCD       encoding of the E.164 or X.121 number, or the binary encoding of       the NSAP address is truncated to 38 bits (Fig.3). Since the Frame       Relay interface identifier has a "local" significance, the use of       such a value has no real practical purposes other than adding to       the uniqueness of the interface identifier on the link. Therefore       the truncation can be performed on the high order or low order       bits. If the high order bits truncation does not provide       uniqueness on the link -- perhaps the DLCI value is not unique --       this most likely means that the VC spans more for instance than a       national and/or international destination area for an E.164       number, and therefore the truncation of the low order bits should       be performed next, which most likely will provide the desired       uniqueness.Conta, et al.               Standards Track                     [Page 8]

RFC 2590             IPv6 over Frame Relay Networks             May 1999             7     6     5     4     3     2     1     0     (bit order)            +-----+-----+-----+-----+-----+-----+-----+-----+(Octets) 0  |                                   |    MBZ    |            +                                   +-----+-----+         1  |                                               |            +          E.164, X.121 (BCD encoding)          +         2  |               or NSAP Address                 |            +                                               +         3  |            (truncated to 38 bits)             |            +                                               +         4  |                                               |            +-----+-----+-----+-----+-----+-----+-----+-----+         5  |                                               |            +                                               +         6  |                    "DLCI"                     |            +                                               +         7  |                                               |            +-----+-----+-----+-----+-----+-----+-----+-----+            Fig.3   Frame Relay (Pseudo) Interface Identifier5. Link-Local Addresses   The IPv6 link-local address [AARCH] for an IPv6 Frame Relay interface   is formed by appending the interface identifier, formed as defined   above, to the prefix FE80::/64 [AARCH].       10 bits            54 bits                  64 bits     +----------+-----------------------+----------------------------+     |1111111010|         (zeros)       |Frame Relay Interface Ident.|     +----------+-----------------------+----------------------------+6. Address Mapping -- Unicast, Multicast   The procedure for mapping IPv6 addresses to link-layer addresses is   described in [IPv6-ND]. Additionally, extensions to Neighbor   Discovery (ND) that allow the mapping of link-layer addresses to IPv6   addresses are defined as Inverse Neighbor Discovery (IND) in [IND].   This document defines the formats of the link-layer address fields   used by ND and IND. This specification does not define an algorithmic   mapping of IPv6 multicast addresses to Frame Relay link-layer   addresses.   The Source/Target Link-layer Address option used in Neighbor   Discovery and Inverse Neighbor Discovery messages for a Frame Relay   link follows the general rules defined by [IPv6-ND]. IPv6 addresses   can map two type of identifiers equivalent to link-layer addresses:Conta, et al.               Standards Track                     [Page 9]

RFC 2590             IPv6 over Frame Relay Networks             May 1999   DLCIs, and Frame Relay Addresses.  Therefore, for Frame Relay, this   document defines two distinct formats for the ND and IND messages   Link-Layer Address field:   (a)  DLCI Format -- used in ND and/or IND messages on VCs that were        established prior to the ND or IND message exchange --  mostly        PVCs. The use on SVCs makes sense with Inverse Neighbor        Discovery [IND] messages if IND is employed after the successful        establishing of an SVC to gather information about other IPv6        addresses assigned to the remote node and that SVC.   (b)  Frame Relay Address Format -- used mostly prior to establishing        a new SVC, to get the  Frame Relay remote node identifier        (link-layer address) mapping to a certain IPv6 address.        Note: An implementation may hold both types of link layer        identifiers in the Neighbor Discovery cache. Additionally, in        case of multiple VCs between two nodes, one node's Neighbor        Discovery cache may hold a mapping of one of the remote node's        IPv6 addresses to each and every DLCI identifying the VCs.        The mechanisms which in such an implementation would make the        distinction between the Neighbor Discovery Cache mapping of an        IPv6 address to a "Frame Relay Address Format" and a "DLCI        Format" link-layer address, or among several mappings to a "DLCI        Format" addresses are beyond the scope of this specification.        The use of the override "O" bit in the advertisement messages        that contain the above Link-Layer Address formats SHOULD be        consistent with the [ND] specifications. Additionally, there        should be consistency related to the type of Link-Layer Address        format: an implementation should override one address format in        its Neighbor Discovery cache with the same type of address        format.   The "DLCI Format" is defined as follows:              7     6     5     4     3     2     1     0    (bit order)             +-----+-----+-----+-----+-----+-----+-----+-----+          0  |                      Type                     |             +-----+-----+-----+-----+-----+-----+-----+-----+          1  |                     Length                    |             +-----+-----+-----+-----+-----+-----+-----+-----+Conta, et al.               Standards Track                    [Page 10]

RFC 2590             IPv6 over Frame Relay Networks             May 1999   with a DLCI (Q.922 address) encoded as option value:              7     6     5     4     3     2     1     0    (bit order)             +-----+-----+-----+-----+-----+-----+-----+-----+          2  |                                   |  1  |  1  |             +              unused               +-----+-----+          3  |                                               |             +-----+-----+-----+-----+-----+-----+-----+-----+          4  |            DLCI(high order)       |  0  |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----+          5  |  DLCI(low order)      |  0  |  0  |  0  |  1  |             +-----+-----+-----+-----+-----+-----+-----+-----+          6  |                                               |             +                   Padding                     +          7  |                   (zeros)                     |             +-----+-----+-----+-----+-----+-----+-----+-----+                 10 bits DLCI              7     6     5     4     3     2     1     0    (bit order)             +-----+-----+-----+-----+-----+-----+-----+-----+          2  |                                   |  1  |  1  |             +              unused               +-----+-----+          3  |                                               |             +-----+-----+-----+-----+-----+-----+-----+-----+          4  |            DLCI(high order)       |  0  |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----+          5  |  DLCI                 |  0  |  0  |  0  |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----+          6  |             DLCI(low order)             |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----+          7  |       unused (set to 0)           |  1  |  1  |             +-----+-----+-----+-----+-----+-----+-----+-----+                 17 bits DLCIConta, et al.               Standards Track                    [Page 11]

RFC 2590             IPv6 over Frame Relay Networks             May 1999              7     6     5     4     3     2     1     0    (bit order)             +-----+-----+-----+-----+-----+-----+-----+-----+          2  |                                   |  1  |  1  |             +              unused               +-----+-----+          3  |                                               |             +-----+-----+-----+-----+-----+-----+-----+-----+          4  |            DLCI(high order)       |  0  |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----          5  |  DLCI                 |  0  |  0  |  0  |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----+          6  |             DLCI                        |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----+          7  |       DLCI (low order)            |  0  |  1  |             +-----+-----+-----+-----+-----+-----+-----+-----+                 23 bits DLCI     Option fields:        Type        1 for Source Link-layer address.                    2 for Target Link-layer address.        Length      The Length of the Option (including the Type                    and Length fields) in units of 8 octets.                    It has the value 1.        Link-Layer Address        The DLCI encoded as a Q.922 address.      Description        The "DLCI Format" option value field has two components:        (a)  Address Type -- encoded in the first two bits of the first             two octets. Both bits are set to 1 to indicate the DLCI             format. The rest of the bits in the two first octets are             not used -- they MUST be set to zero on transmit and MUST             be ignored by the receiver.        (b)  DLCI -- encoded as a Q.922 address padded with zeros to the             last octet of the 6 octets available for the entire Link-             Layer Address field of this format.Conta, et al.               Standards Track                    [Page 12]

RFC 2590             IPv6 over Frame Relay Networks             May 1999   The "Frame Relay Address Format" is defined as follows:              7     6     5     4     3     2     1     0    (bit order)             +-----+-----+-----+-----+-----+-----+-----+-----+          0  |                      Type                     |             +-----+-----+-----+-----+-----+-----+-----+-----+          1  |                     Length                    |             +-----+-----+-----+-----+-----+-----+-----+-----+   with an E.164, X.121, number or NSAP  address encoded as option   value:              7     6     5     4     3     2     1     0    (bit order)             +-----+-----+-----+-----+-----+-----+-----+-----+          2  |             size                  |  1  |  0  |             +-----+-----+-----+-----+-----+-----+-----+-----+          3  |            E.164 or X.121, or NSAP            |             +---          Address Family Number          ---+          4  |               (Assigned Number)               |             +-----+-----+-----+-----+-----+-----+-----+-----+          5  |                                               |             /       E.164, or X.121 number (BCD encoded)    /             /               or  NSAP address                /      4+size |                                               |             +-----+-----+-----+-----+-----+-----+-----+-----+      5+size |                                               |             /                    Padding                    /             /                    (zeros)                    /   8*Length-1|                                               |             +-----+-----+-----+-----+-----+-----+-----+-----+      Option fields:        Type        1 for Source Link-layer address.                    2 for Target Link-layer address.        Length      The length of the Option (including the                    Type and Length fields) in units of 8 octet.                    It may have the value:                     2 -- for E.164, or X.121 numbers or NSAP                          addresses not longer than 11 octets                          [E164], [X25], [NSAP].                     3 -- for NSAP addresses longer than 11 but                          not longer than 19 octets.Conta, et al.               Standards Track                    [Page 13]

RFC 2590             IPv6 over Frame Relay Networks             May 1999                     4 -- for NSAP addresses longer than 19 octets                          (not longer than the maximum NSAP address                          length) [NSAP].        Link-Layer Address       The E.164, X.121, number encoded in                                 Binary Coded Decimal (BCD), or the NSAP                                 address.   Description     The "Frame Relay Address" option value has three components:     (a)  Address Type -- encoded in the first two bits of the first          octet.  The first bit is set to 0, the second bit is set to 1.     (b)  Size -- encoded in the last (high order) 6 bits of the first          octet. The maximum value of the field is the maximum size of          the E.164, X.121, or NSAP addresses.     (c)  Address Family Number -- the number assigned for the E.164,          X.121, or NSAP address family [ASSNUM].     (d)  E.164, X.121, number -- encoded in BCD (two digits per octet).          If the E.164, or X.121 has an even number of digits the          encoding will fill all encoding octets -- half the number of          digits. If the E.164, or X.121 number has an odd number of          digits, the lowest order digit fills only half of an octet --          it is placed in the first 4 bits of the last octet of the          E.164, or X.121 BCD encoding. The rest of the field up to the          last octet of the 11 octets available is padded with zeros.          NSAP address -- the NSAP address. It is padded with zeros if          the NSAP address does not fit in a number of octets that makes          the length of the option an even number of 8 octets.7. Sending Neighbor Discovery Messages   Frame Relay networks do not provide link-layer native multicasting   mechanisms. For the correct functioning of the Neighbor Discovery   mechanisms, link-layer multicasting must be emulated.   To emulate multicasting for Neighbor Discovery (ND) the node MUST   send frames carrying ND multicast packets to all VCs on a Frame Relay   interface. This applies to ND messages addressed to both all-node and   solicited-node multicast addresses. This method works well with PVCs.   A mesh of PVCs MAY be configured and dedicated to multicast traffic   only.  An alternative to a mesh of PVCs is a set of point-to-   multipoint PVCs.Conta, et al.               Standards Track                    [Page 14]

RFC 2590             IPv6 over Frame Relay Networks             May 19998. Receiving Neighbor Discovery Messages   If a Neighbor Discovery Solicitation message received by a node   contains the Source  link-layer  address option with a DLCI, the   message MUST undergo Frame Relay specific preprocessing required for   the correct interpretation of the field during the ND protocol engine   processing. This processing is done before the Neighbor Discovery   message is processed by the Neighbor Discovery (ND) protocol engine.   The motivation for this processing is the local significance of the   DLCI fields in the Neighbor Discovery message: the DLCI significance   at the sender node is different than the DLCI significance at the   receiver node. In other words, the DLCI that identifies the Frame   Relay virtual circuit at the sender may be different than the DLCI   that identifies the virtual circuit at the receiver node.   Furthermore, the sender node may not be aware of the DLCI value at   the receiver. Therefore, the Frame Relay specific preprocessing   consists in modifying the Neighbor Discovery Solicitation message   received, by storing into the Source link-layer address option the   DLCI value of the virtual circuit on which the frame was received, as   known to the receiver node. The DLCI value being stored must be   encoded in the appropriate format (see previous sections). The   passing of the DLCI value from the Frame Relay module to the Neighbor   Discovery preprocessing module is an implementation choice.9. Security Considerations   The mechanisms defined in this document for generating an IPv6 Frame   Relay interface identifier are intended to provide uniqueness at link   level -- virtual circuit.  The protection against duplication is   achieved by way of IPv6 Stateless Autoconfiguration Duplicate Address   Detection mechanisms. Security protection against forgery or accident   at the level of the mechanisms described here is provided by the IPv6   security mechanisms [IPSEC], [IPSEC-Auth], [IPSEC-ESP] applied to   Neighbor Discovery [IPv6-ND] or Inverse Neighbor Discovery [IND]   messages.   To avoid an IPsec Authentication verification failure, the Frame   Relay specific preprocessing of a Neighbor Discovery Solicitation   message that contains a DLCI format Source link-layer address option,   MUST be done by the receiver node after it completed IP Security   processing.Conta, et al.               Standards Track                    [Page 15]

RFC 2590             IPv6 over Frame Relay Networks             May 199910. Acknowledgments   Thanks to D. Harrington, and M. Merhar for reviewing  this document   and providing useful suggestions. Also thanks to G. Armitage for his   reviewing and suggestions. Many thanks also to Thomas Narten for   suggestions on improving the document.11. References   [AARCH]      Hinden, R. and S. Deering, "IPv6 Addressing                Architecture",RFC 2373, July 1998.   [ASSNUM]     Reynolds, J. and J. Postel, "Assigned Numbers", STD 2,RFC 1700, October 1994.  See also:http://www.iana.org/numbers.html   [AUTOCONF]   Thomson, S. and T. Narten, "IPv6 Stateless                Autoconfiguration",RFC 2462, December 1998.   [CANON]      Narten, T. and C. Burton, "A Caution on the Canonical                Ordering of Link-Layer Addresses",RFC 2469, December                1998.   [ENCAPS]     Brown, C. and A. Malis, "Multiprotocol Interconnect over                Frame Relay", STD 55,RFC 2427, November 1998.   [IND]        Conta, A., "Extensions to IPv6 Neighbor Discovery for                Inverse Discovery", Work in Progress, December 1998.   [IPv6]       Deering, S. and R. Hinden, "Internet Protocol Version 6                Specification",RFC 2460, December 1998.   [IPv6-ATM]   Armitage, G., Schulter, P. and M. Jork, "IPv6 over ATM                Networks",RFC 2492, January 1999.   [IPv6-ETH]   Crawford, M., "Transmission of IPv6 packets over                Ethernet Networks",RFC 2464, December 1998.   [IPv6-FDDI]  Crawford, M., "Transmission of IPv6 packets over FDDI                Networks",RFC 2467, December 1998.   [IPv6-NBMA]  Armitage, G., Schulter, P., Jork, M. and G. Harter,                "IPv6 over Non-Broadcast Multiple Access (NBMA)                networks",RFC 2491, January 1999.   [IPv6-ND]    Narten, T., Nordmark, E. and W. Simpson, "Neighbor                Discovery for IP Version 6 (IPv6)",RFC 2461, December                1998.Conta, et al.               Standards Track                    [Page 16]

RFC 2590             IPv6 over Frame Relay Networks             May 1999   [IPv6-PPP]   Haskin, D. and E. Allen, "IP Version 6 over PPP",RFC2472, December 1998.   [IPv6-TR]    Narten, T.,  Crawford, M. and M. Thomas, "Transmission                of IPv6 packets over Token Ring Networks",RFC 2470,                December 1998.   [IPSEC]      Atkinson, R. and S. Kent, "Security Architecture for the                Internet Protocol",RFC 2401, November 1998.   [IPSEC-Auth] Atkinson, R. and S. Kent, "IP Authentication Header",RFC 2402, December 1998.   [IPSEC-ESP]  Atkinson, R. and S. Kent, "IP Encapsulating Security                Protocol (ESP)",RFC 2406, November 1998.   [RFC2119]    Bradner, S., "Key words for use in RFCs to indicate                Requirement Levels",BCP 14,RFC 2119, March 1997.   [E164]       International Telecommunication Union - "Telephone                Network and ISDN Operation, Numbering, Routing, amd                Mobile Service", ITU-T Recommendation E.164, 1991.   [NSAP]       ISO/IEC, "Information Processing Systems -- Data                Communications -- Network Service Definition Addendum 2:                Network Layer Addressing". International Standard                8348/Addendum 2, ISO/IEC JTC 1, Switzerland 1988.   [X25]        "Information Technology -- Data Communications -- X.25                Packet Layer Protocol for Data Terminal Equipment",                International Standard 8208, March 1988.Conta, et al.               Standards Track                    [Page 17]

RFC 2590             IPv6 over Frame Relay Networks             May 199912. Authors' Addresses   Alex Conta   Lucent Technologies Inc.   300 Baker Ave, Suite 100   Concord, MA 01742   Phone: +1-978-287-2842   EMail: aconta@lucent.com   Andrew Malis   Ascend Communications   1 Robbins Rd   Westford, MA 01886   Phone: +1-978-952-7414   EMail: malis@ascend.com   Martin Mueller   Lucent Technologies Inc.   300 Baker Ave, Suite 100   Concord, MA 01742   PHone: +1-978-287-2833   EMail:  memueller@lucent.comConta, et al.               Standards Track                    [Page 18]

RFC 2590             IPv6 over Frame Relay Networks             May 199913.  Full Copyright Statement   Copyright (C) The Internet Society (1999).  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.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Conta, et al.               Standards Track                    [Page 19]

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