INTERNET-DRAFT                                           Donald Eastlake
Intended status: Proposed Standard                             Yizhou Li
                                                           Radia Perlman
Expires: April 19, 2014     October 20, 2013

                 TRILL: Interface Addresses APPsub-TLV

   This document specifies a TRILL (Transparent Interconnection of Lots
   of Links) IS-IS application sub-TLV that enables the reporting by a
   TRILL switch of sets of addresses such that all of the addresses in
   each set designate the same interface (port). For example, an EUI-48
   MAC (Extended Unique Identifier 48-bit, Media Access Control)
   address, IPv4 address, and IPv6 address can be reported as all
   corresponding to the same interface. Such information could be use in
   some cases to synthesize responses to or by-pass the need for the
   Address Resolution Protocol (ARP), the IPv6 Neighbor Discovery (ND)
   protocol, or the flooding of unknown MAC addresses.

Status of This Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Distribution of this document is unlimited. Comments should be sent
   to the TRILL working group mailing list.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at The list of Internet-Draft
   Shadow Directories can be accessed at

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Table of Contents

      1. Introduction............................................3
      1.1 Conventions Used in This Document......................3

      2. Format of the Interface Addresses APPsub-TLV............5

      3. IA APPsub-TLV sub-sub-TLVs.............................10
      3.1 AFN Size sub-sub-TLV..................................10
      3.2 Fixed Address sub-sub-TLV.............................11
      3.3 Data Label sub-sub-TLV................................11
      3.4 Topology sub-sub-TLV..................................12

      4. Security Considerations................................14

      5. IANA Considerations....................................15
      5.1 Additional AFN Number Allocation......................15
      5.2 IA APPsub-TLV Sub-Sub-TLVs SubRegistry................16


      Appendix A: Examples......................................18
      A.1 Simple Example........................................18
      A.2 Complex Example.......................................18

      Normative References......................................21
      Informational References..................................21
      Authors' Addresses........................................23

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1. Introduction

   This document specifies a TRILL (Transparent Interconnection of Lots
   of Links) [RFC6325] IS-IS application sub-TLV (APPsub-TLV [RFC6823])
   that enables the convenient representation of sets of addresses such
   that all of the addresses in each set designate the same interface
   (port). For example, an EUI-48 MAC (Extended Unique Identifier
   48-bit, Media Access Control [RFC5342bis]) address, IPv4 address, and
   IPv6 address can be reported as all three designating the same
   interface.  In addition, a Data Label (VLAN or Fine Grained Label
   (FGL [RFCfgl])) is specified for the interface along with the TRILL
   switch and, optional the TRILL switch port, from which the interface
   is reachable. Such information could be use in some cases to
   synthesize responses to or by-pass the need for the Address
   Resolution Protocol (ARP [RFC826]), the IPv6 Neighbor Discovery (ND
   [RFC4861]) protocol, or the flooding of unknown MAC addresses

   This APPsub-TLV appears inside the TRILL GENINFO TLV specified in
   [ESADI] but may also occur in other application contexts. Directory
   Assisted TRILL Edge services [DirectoryScheme] are expected to make
   use of this APPsub-TLV.

   Although, in some IETF protocols, address field types are represented
   by Ethertype [RFC5342bis] or Hardware Type [RFC5494], only Address
   Family Number (AFN) is used in this APPsub-TLV to represent address
   field type.

1.1 Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

   The terminology and acronyms of [RFC6325] are used herein along with
   the following additional acronyms and terms:

   AFN:   Address Family Number

   APPsub-TLV: Application sub-TLV [RFC6823].

   Data Label: VLAN or FGL.

   FGL:   Fine Grained Label [RFCfgl].

   IA:    Interface Addresses.

   RBridge: An alternative name for a TRILL switch.

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   TRILL switch: A device that implements the TRILL protocol.

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2. Format of the Interface Addresses APPsub-TLV

   The Interface Addresses (IA) APPsub-TLV is used to advertise that a
   set of addresses indicate the same interface (port) within a Data
   Label (VLAN or FGL) and to associate that interface with the TRILL
   switch, and optionally the TRILL switch port, by which the interface
   is reachable.  These addresses can be in different address families.
   For example, it can be used to declare that a particular interface
   with specified IPv4, IPv6, and EUI-48 MAC addresses in some
   particular Data Label is reachable from a particular TRILL switch.

   The Template field in a particular Interface Addresses APPsub-TLV
   indicates the exact format of each Address Set it carries. Certain
   well-known sets of addresses are represented by special values. Other
   sets of addresses are specified by a list of AFNs. The Template
   format that uses a list of AFNs provides an explicit pattern for the
   type and order of addresses in each Address Set in an IA APPsub-TLV.

   A device or application making use of IA APPsub-TLV data is not
   required to make use of all IA data. For example, a device or
   application that was only interested in MAC and IPv6 addresses could
   ignore any IPv4 or other types of address information that was

      | Type = TBD    |                  (1 byte)
      | Length        |                  (1 byte)
      | Nickname                      |  (2 bytes)
      | Flags         |                  (1 byte)
      | Confidence    |                  (1 byte)
      | Addr Sets End |                  (1 byte)
      | Template ...                     (variable)
      | Address Set 1    (size determined by Template)     |
      | Address Set 2    (size determined by Template)     |
      |   ...
      | Address Set N    (size determined by Template)     |
      | optional sub-sub-TLVs ...

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                 Figure 1. The Interface Addresses APPsub-TLV

   o  Type: Interface Addresses TRILL APPsub-TLV type, set to TBD[#2
      suggested] (IA-SUBTLV).

   o  Length: Variable, minimum 6, maximum 250 when inside a TRILL
      GENINFO TLV [ESADI], maximum 255 in unconstrained contexts. If
      length is 5 or less or if the APPsub-TLV extends beyond an
      encompassing TRILL GENINFO TLV, the APPsub-TLV MUST be ignored.

   o  Nickname: The nickname of the TRILL switch by which the address
      sets are reachable. If zero, the address sets are reachable from
      the TRILL switch originating the message containing the APPsub-TLV
      (for example, an [ESADI] message).

   o  Flags: A byte of flags as follows:

          0 1 2 3 4 5 6 7
         |D|L|N|  RESV   |

         D: Directory flag: If D is one, the APPsub-TLV contains Push
            Directory information.

         L: Local flag: If L is one, the APPsub-TLV contains information
            learned locally by observing ingressed frames. (Both D and L
            can one in the same IA APPsub-TLV.)

         N: Notify flag: When a TRILL switch receives a new IA APPsub-
            TLV (one in a ESADI LSP fragment with a higher sequence
            number or a new message of some other type) and the N bit is
            one, the TRILL switch then checks the contens of the APPsub-
            TLV for IP address to MAC address mappings.  If an IPv4 to
            MAC address mapping is found, gratuitous ARPs [RFC826] are
            sent and if an IPv6 to MAC address mapping is found,
            spontaneous Neighbor Advertisements [RFC4861] are sent. In
            both cases, these are sent out all the ports of the TRILL
            switch that offer end station service and are in the VLAN or
            FGL of the APPsub-TLV information.

         RESV: Additional reserved flag bits that MUST be sent as zero
            and ignored on receipt.

   o  Confidence: This 8-bit unsigned quantity in the range 0 to 254
      indicates the confidence level in the addresses being transported
      [RFC6325]. A value of 255 is treated as if it was 254.

   o  Addr Sets End: The unsigned offset of the byte, within the IA
      APPsub-TLV value part, of the last byte of the last Address Set.

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      This will be the byte just before the first sub-sub-TLV if any
      sub-sub-TLVs are present (see Section 3). If this is equal to
      Size, there are no sub-sub-TLVs. If this is greater than Size, the
      IA APPsub-TLV is corrupt and MUST be discarded.

   o  Template: The initial byte of this field is the unsigned integer
      K. If K has a value from 1 to 31, it indicates that this initial
      byte is followed by a list of K AFNs (Address Family Numbers) that
      specify the exact structure and order of each Address Set
      occurring later in the APPsub-TLV. K can be 1, which is the
      minimum valid value. If K is zero, the IA APPsub-TLV is ignored.
      If K is 32 to 254, the length of the Template field is one byte
      and its value is intended to correspond to a particular ordered
      set of AFNs some of which are specified below. If K is 255, the
      length of the Template filed is three bytes and the values of the
      second and third byte, considered as an unsigned integer in
      network byte order, are reserved to correspond to future specified
      ordered sets of AFNs.

      If the Template uses explicit AFNs, it looks like the following.

         |  K            |                  (1 byte)
         |  AFN 1                        |  (2 bytes)
         |  AFN 2                        |  (2 bytes)
         |   ...
         |  AFN K                        |  (2 bytes)

      For K in the 32 to 103 range, values indicate combinations of a
      specific number of MAC addresses, IPv4 addresses, IPv6 addresses,
      and TRILL switch port IDs in that order. The value of K is

         K = 32 + M + 3*v4 + 9*v6 + 36*P

      where M is 0, 1, or 2 (0 if no MAC address is present, 1 if a
      48-bit MAC is present, 2 if a MAC/24 (see Section 5.1) is
      present), v4 is the number of IPv4 addresses (limited to 0, 1, or
      2) and v6 is the number of IPv6 addresses (limited to 0 through 3
      inclusive), and P is the number of TRILL switch port IDs (limited
      to 0 or 1).  That equation specifies values of K from 32 through
      103. Values from 104 through 254 of the byte value are available
      for assignment by Expert Review (see Section 5). K = 255 indicates
      a three byte Template field as specified above. All values (0
      through 65,545) of this two byte value are available for
      assignment by Expert Review.

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      If an unknown Template K value in the range 104 to 254 is received
      or a K of 255 followed by an unknown two byte value, the IA
      APPsub-TLV MUST be ignored.

   o  AFN: A two-byte Address Family Number. The number of AFNs present
      is given by K. There are no AFNs if K is greater than 31. The AFN
      sequence specifies the structure of the Address Sets occurring
      later in the TLV. For example, if Template Size is 2 and the two
      AFNs present are the AFNs for EUI-48 and IPv4, in that order, then
      each Address set present will consist of a 6-byte MAC address
      followed by a 4-byte IPv4 address. If any AFNs are present that
      are unknown to the receiving IS and the length of the
      corresponding address is not provided by a sub-sub-TLV as
      specified below, the receiving IS will be unable to parse the
      Address Sets and MUST ignore the IA APPsub-TLV.

   o  Address Set: Each address set in the APPsub-TLV consists of
      exactly the same sequence of addresses of the types specified by
      the Template earlier in the APPsub-TLV. No alignment, other than
      to a byte boundary, is guaranteed. The addresses in each Address
      Set are contiguous with no unused bytes between them and the
      Address Sets are contiguous with no unused bytes between
      successive Address Sets. The Address Sets must fit within the TLV.
      If the product of the size of an Address Set and the number of
      Address Sets is so large that this is not true, the IA APPsub-TLV
      is ignored.

   o  sub-sub-TLVs: If the Address Sets indicated by Addr Sets End do
      not completely fill the Length of the APPsub-TLV, the remaining
      bytes are parsed as sub-sub-TLVs [RFC5305]. Any such sub-sub-TLVs
      that are not known to the receiving RBridge are ignored. Should
      this parsing not be possible, for example there is only one
      remaining byte or an apparent sub-sub-TLV extends beyond the end
      of the TLV, the containing IA APPsub-TLV is considered corrupt and
      is ignored. (Several sub-sub-TLV types are specified in Section

   Different IA APPsub-TLVs within the same or different LSPs or other
   data structures may have different Templates. The same AFN may occur
   more than once in a Template and the same address may occur in
   different address sets. For example, an EUI-48 MAC address interface
   might have three different IPv6 addresses. This could be represented
   by an IA APPsub-TLV whose Template specifically provided for one
   EUI-48 address and three IPv6 addresses, which might be an efficient
   format if there were multiple interfaces with that pattern.
   Alternatively, a Template with one EUI-48 and one IPv6 address could
   be used in an IA APPsub-TLV with three address sets each having the
   same EUI-48 address but different IPv6 addresses, which might be the
   most efficient format if only one interface had multiple IPv6
   addresses and other interfaces had only one IPv6 address.

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   In order to be able to parse the Address Sets, a receiving RBridge
   must know at least the size of the address each AFN the Template
   specifies; however, the presence of the Addr Set End field means that
   the sub-sub-TLVs, if any, can always be located by a receiver.  An
   RBridge can be assumed to know the size of the AFNs mentioned in
   Section 5. Should an RBridge wish to include an AFN that some
   receiving RBridge in the campus may not know, it SHOULD include an
   AFN-Size sub-sub-TLV as described below. If an IA APPsub-TLV is
   received with one or more AFNs in its template for which the
   receiving RBridge does not know the length and for which an AFN-Size
   sub-sub-TLV is not present, that IA APPsub-TLV MUST be ignored.

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3. IA APPsub-TLV sub-sub-TLVs

   IA APPsub-TLVs can have trailing sub-sub-TLVs [RFC5305] as specified
   below.  These sub-sub-TLVs occur after the Address Sets and the
   amount of space available for sub-sub-TLVs is determined from the
   overall IA APPsub-TLV length and the value of the Addr Set End byte.

   There is no ordering restriction on sub-sub-TLVs. Unless otherwise
   specified each sub-sub-TLV type can occur zero, one, or many times in
   an IA APPsub-TLV.

3.1 AFN Size sub-sub-TLV

   Using this sub-TLV, the originating RBridge can specify the size of
   an address type. This is useful under two circumstances as follows:

   1. One or more AFNs that are unknown to the receiving RBridge appears
      in the template. If an AFN Size sub-sub-TLV is present for each
      such AFN, then at least the IA APPsub-TLV can be parsed and
      possibly other addresses in each address set can still be used.

   2. If an AFN occurs in the Template that represents a variable length
      address, this sub-sub-TLV gives its size for all occurrences in
      that IA APPsub-TLV. (It is believed that the addresses specified
      by all currently assigned AFNs are fixed length.)

      | Type = AFNsz  |                  (1 byte)
      | Length        |                  (1 byte)
      | AFN Size Record(s)                            |  (3 bytes)

   Where each AFN Size Record is structured as follows:

      |  AFN                          |  (2 bytes)
      |  AdrSize      |                  (1 byte)

   o  Type: AFN-Size sub-sub-TLV type, set to 1 (AFNsz).

   o  Length: 3*n where n is the number of AFN Size Records present. If
      Length is not a multiple of 3, the sub-sub-TLV MUST be ignored.

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   o  AFN Size Record(s): Zero or more 3-byte records, each giving the
      size of an address type identified by an AFN,

   o  AFN: The AFN whose length is being specified by the AFN Size

   o  AdrSize: The length in bytes of addresses specified by the AFN
      field as an unsigned integer.

   An AFN Size sub-sub-TLV for any AFN known to the receiving RBridge is
   compared with the size known to the RBridge. If they differ the IA
   APPsub-TLV is assumed to be corrupt and MUST be ignored.

3.2 Fixed Address sub-sub-TLV

   There may be cases where, in an Interface Addresses APP-subTLV, the
   same address would appear in every address set across the APP-subTLV.
   To avoid wasted space, this sub-sub-TLV can be used to indicate such
   a fixed address. The address or addresses incorporated into the sets
   by this sub-sub-TLV are NOT mentioned in the IA APPsub-TLV Template.

      | Type=FIXEDADR |                 (1 byte)
      | Length        |                 (1 byte)
      | AFN           |                 (2 bytes)
      | Fixed Address                   (variable)

   o  Type: Data Label sub-sub-TLV type, set to 2 (FIXEDADR).

   o  Length: variable, minimum 3. If Length is 2 or less, the sub-sub-
      TLV MUST be ignored.

   o  AFN: Address Family Number of the Fixed Address.

   o  Fixed Address: The address of the type indicated by the preceding
      AFN field that is considered to be part of every Address Set in
      the IA APPsub-TLV.

3.3 Data Label sub-sub-TLV

   This sub-sub-TLV indicates the Data Label within which the interfaces
   listed in the IA APPsub-TLV are reachable. It is useful if the IA

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   APPsub-TLV occurs outside of the context of an [ESADI] or other type
   of message specifying the Data Label or if it is desired and
   permitted to override that specification.  Multiple occurrences of
   this sub-sub-TLV indicate that the interface is reachable in all of
   the Data Labels given.

      |Type=DATALEN   |                 (1 byte)
      | Length        |                 (1 byte)
      | Data Label                      (variable)

      o  Type: Data Label sub-TLV type, set to 3 (LABEL).

      o  Length: 2 or 3. If Length is some other value, the sub-sub-TLV
         is ignored.

      o  Data Label: If length is 2, the bottom 12 bits of the Data
         Label are a VLAN ID and the top 4 bits are reserved (MUST be
         sent as zero and ignored on receipt). If the length is 3, the
         three Data Label bytes contain an FGL [RFCfgl].

3.4 Topology sub-sub-TLV

   The presence of this sub-sub-TLV indicates that the interfaces given
   in the IA APPsub-TLV are reachable in the topology give. It is useful
   if the IA APPsub-TLV occurs outside of the context of an [ESADI] or
   other type of message indicating the topology or if it is desired and
   permitted to override that specification. If it occurs multiple
   times, then the Address Sets are in all of the topologies given.

      |Type=DATALEN   |                  (1 byte)
      | Length        |                  (1 byte)
      | RESV  |        Topology       |  (2 bytes)

      o  Type: Topology sub-TLV type, set to 4 (TOPOLOGY).

      o  Length: 2. If Length is some other values, the sub-sub-TLV is

      RESV: Four reserved bits. MUST be sent as zero and ignored on

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      o  Topology: The 12-bit topology number [RFC5120].

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4. Security Considerations

   The integrity of address mapping and reachability information and the
   correctness of Data Labels (VLANs or FLGs [RFCfgl]) are very
   important.  Forged, altered, or incorrect address mapping or Data
   Labeling can lead to delivery of packets to the incorrect party,
   violating security policy. However, this document merely describes a
   data format and does not provide any explicit mechanisms for securing
   that information, other than a few trivial consistency checks that
   might detect some corrupted data. Security on the wire, or in
   storage, for this data is to be providing by the transport or storage
   used. For example, when transported with [ESADI], [ESADI] security
   mechanisms can be used.

   The address mapping and reachability information, if known to be
   complete and correct, can be used to detect some cases of forged
   packet source addresses [DirectoryFramework]. In particular, if
   native traffic is received by a TRILL switch that would otherwise
   accept it but authoritative data indicates the source address should
   not be reachable from the receiving TRILL switch, that traffic should
   be discarded. The data format specified in this document may
   optionally include RBridge Port ID number so that this forged address
   filtering can be optionally applied with port granularity.

   See [RFC6325] for general TRILL Security Considerations.

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5. IANA Considerations

   As specified below, IANA has allocated new AFN numbers and IANA is
   requested create the TRILL IS-APPsub-TLV sub-sub-TLV subregistry.

5.1 Additional AFN Number Allocation

   IANA has alocated AFN numbers as follows:

        Number   Description      References
        ------   -----------      ----------

        16391    OUI              This document.
        16392    MAC/24           This document.
        16393    MAC/40           This document.
        16394    IPv6/64          This document.
        16395    RBridge Port ID  This document.

   The OUI AFN is provided so that MAC addresses can be abbreviated if
   they have the same upper 24 bits. In particular, if there is an OUI
   provided as a Fixed Address sub-sub-TLV (see Section 5.2.2) then,
   whenever a MAC/24 or MAC/40 address appears within an Address Set (as
   indicated by the Template), the OUI is used as the first 24 bits of
   the actual MAC address for the Address Set. An OUI provided by a
   Fixed Address sub-sub-TLV is ignored if the IA APPsub-TLV has no
   MAC/24 or MAC/40 in its template.

   MAC/24 is a 24-bit suffix intended to be pre-fixed by an OUI as in
   the previous paragraph. In the absence of an OUI specified as a Fixed
   Address in the same APPsub-TLV, an Address Set MAC/24 address entry
   cannot be used.

   MAC/40 is a suffix as specified above except that it is 40-bit so the
   result of combining it with an OUI is a 64-bit MAC address.

   IPv6/64 is an 8-byte quantity that is the first 64 bits of an IPv6
   address. If present, there will normally be an EUI-48 or EUI-64
   address in the address set to provide the lower 64 bits of the IPv6
   address. For this purpose, an EUI-48 is expanded to 64 bits as
   described in [RFC5342bis].

   Other AFNs can be found at

   The following already allocated AFN values may be particularly useful
   for IA APPsub-TLVs:

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       Hex    Decimal   Description   References
      -----   -------   -----------   ----------
       0001         1    IPv4
       0002         2    IPv6
       4005    16,389    48-bit MAC    [RFC5342bis]
       4006    16,390    64-bit MAC    [RFC5342bis]

5.2 IA APPsub-TLV Sub-Sub-TLVs SubRegistry

   IANA is requested to establish a new subregistry of the TRILL
   Parameter Registry for sub-sub-TLVs of the Interface Addresses
   APPsub-TLV with initial contents as shown below.

      Name:       Interface Addresses APPsub-TLV Sub-Sub-TLVs

      Procedure:  Expert Review

      Reference:  This document

         Type   Description       Reference
         ----   -----------       ---------
           0    Reserved
           1    AFN Size          This document
           2    Fixed Address     This document
           3    Data Label        This document
           4    Topology          This document
         5-254  Available
          255   Reserved

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   The authors gratefully acknowledge the contributions and review by
   the following:

         Linda Dunbar

   The document was prepared in raw nroff. All macros used were defined
   within the source file.

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Appendix A: Examples

   Below are example IA APPsub-TLVs.

A.1 Simple Example

   Below is an annotated IA APPsub-TLV carrying two simple pairs of
   EUI-48 MAC addresses and IPv4 addresses from a Push Directory
   [DirectoryFramework]. No sub-sub-TLVs are included.

      0x02(TBD)     Type: Interface Addresses
      26            Size: 26 (=0x1A)
      0x1234        RBridge Nickname from which reachable
      0b10000000    Flags: Push Directory data
      0xE3          Confidence
      26            Address Sets End: 26 (=0x1A)
      35            Template: 35 (0x23) = 32 + 1(MAC48) + 3*1(IPv4)

            Address Set One
      0x00005E0053A9   48-bitMAC address    IPv4 address

            Address Set Two
      0x00005E00536B   48-bit MAC address    IPv4 address

   Size includes 6 for the fixed fields though and including the one
   byte template, plus 2 times the Address Set size. Each Address Set is
   10 bytes, 6 for the 48-bit MAC address plus 4 for the IPv4 address.
   So total size is 6 + 2*10 = 26.

   See Section 2 for more information on Template.

A.2 Complex Example

   Below is an annotated IA APPsub-TLV carrying three sets of addresses,
   each consisting of an EUI-48 MAC address, an IPv4 addresses, an IPv6
   address, and an RBridge Port ID, all from a Push Directory
   [DirectoryFramework]. The IPv6 address for each address set is
   synthesized from the MAC address given in that set and the IPv6/64
   64-bit prefix provided through a Fixed Address sub-sub-TLV. In
   addition, a sub-sub-TLV is included that provides an FGL which
   overrides whatever Data Label may be provided by the envelope (for
   example [ESADI]) within which this IA APPsub-TLV occurs.

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      0x02(TBD)     Type: Interface Addresses
      59            Size: 59 (=0x3B)
      0x4321        RBridge Nickname from which reachable
      0b10000000    Flags: Push Directory data
      0xD3          Confidence
      42            Address Sets End: 42 (=0x2A)
      72            Template: 72(0x48)=32+1(MAC48)+3*1(IPv4)+36*1(P)

            Address Set One
      0x00005E0053DE   48-bitMAC address   IPv4 address
      0x1DE3           RBridge Port ID

            Address Set Two
      0x00005E0053E3   48-bit MAC address     IPv4 address
      0x1DEE           RBridge Port ID

            Address Set Three
      0x00005E0053D3   48-bit MAC address      IPv4 address
      0x01DE           RBridge Port ID

            sub-sub-TLV One
      0x03             Type: Data Label
      0x03             Length: implies FGL
      0xD3E3E3         Fine Grained Label

            sub-sub-TLV Two
      0x02             Type: Fixed Address
      0x0A             Size: 0x0A = 10
      0x400A           AFN: IPv6/64
      0x0x20010DB800000000   IPv6 Prefix: 2001:DB8::

   See Section 2 for more information on Template.

   The Fixed Address sub-sub-TLV causes the IPv6/64 value give to be
   treated as if it occurred as a 4th entry inside each of the three
   Address Sets. When there is an IPv6/64 entry and a 48-bit MAC entry,
   the MAC value is expanded by inserting 0xFFFE immediately after the
   OUI and the resulting 64-bit value is used as the lower 64 bits of
   the resulting IPv6 address [RFC5342bis]. As a result, a receiving
   TRILL switch would treat the three Address Sets shown as if they had
   an IPv6 address in them as follows:

D. Eastlake, et al                                             [Page 19]

INTERNET-DRAFT                                      TRILL: IA APPsub-TLV

            Address Set One
      0x20010DB80000000000005EFFFE0053DE  IPv6 Address

            Address Set Two
      0x20010DB80000000000005EFFFE0053E3  IPv6 Address

            Address Set Three
      0x20010DB80000000000005EFFFE0053D3  IPv6 Address

   As an alternative to the compact "well know value" Template encoding
   used in this example above, the less compact explicit AFN encoding
   could have been used. In that case, the IA APPsub-TLV would have
   started as follows:

      0x02(TBD)     Type: Interface Addresses
      65            Size: 65 (=0x41)
      0x4321        RBridge Nickname from which reachable
      0b10000000    Flags: Push Directory data
      0xD3          Confidence
      48            Address Sets End: 48 (=0x30)
      0x3           Template: 3 AFNs
      0x4005        AFN: 48-bit MAC
      0x0001        AFN: IPv4
      0x400B        AFN: RBridge Port ID

   As a final point, since the 48-bit MAC addresses in these three
   Address Sets all have the same OUI (the IANA OUI [RFC5342bis]), it
   would have been possible to just have a MAC/24 value giving the lower
   24 bits of the MAC in each Address Set. The OUI would them be
   supplied by a second Fixed Address sub-sub-TLV proving the OUI. With
   N Address Sets, this would have saved 3*N or 9 bytes in this case at
   the cost of 7 bytes (1 each for the type and length of the sub-sub-
   TLV, 2 for the OUI AFN number, and 3 for the OUI). So, even with just
   three Address Sets, there would be a small net saving of 2 bytes. The
   savings would grow with a larger number of Address Sets.

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INTERNET-DRAFT                                      TRILL: IA APPsub-TLV

Normative References

   [RFC826] Plummer, D., "An Ethernet Address Resolution Protocol", RFC
         826, November 1982.

   [RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
         Requirement Levels", BCP 14, RFC 2119, March 1997

   [RFC4861] - Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
         "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
         September 2007.

   [RFC5120] - Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
         Topology (MT) Routing in Intermediate System to Intermediate
         Systems (IS-ISs)", RFC 5120, February 2008.

   [RFC5305] - Li, T. and H. Smit, "IS-IS Extensions for Traffic
         Engineering", RFC 5305, October 2008.

   [RFC5342bis] - Eastlake 3rd, D., "IANA Considerations and IETF
         Protocol Usage for IEEE 802 Parameters", BCP 141, RFC 5342,
         September 2008.

   [RFC6325] - Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
         Ghanwani, "Routing Bridges (RBridges): Base Protocol
         Specification", RFC 6325, July 2011.

   [RFC6823] - Ginsberg, L., Previdi, S., and M. Shand, "Advertising
         Generic Information in IS-IS", RFC 6823, December 2012.

   [RFCfgl] - D. Eastlake, M. Zhang, P. Agarwal, R. Perlman, D. Dutt,
         "TRILL: Fine-Grained Labeling", draft-ietf-trill-fine-
         labeling-07.txt, in RFC Editor's queue.

Informational References

   [ARP reduction] - Shah, et. al., "ARP Broadcast Reduction for Large
         Data Centers", Oct 2010.

   [DirectoryFramework] - Dunbar, L., D. Eastlake, R. Perlman, I.
         Gashinsky, "TRILL Edge Directory Assistance Framework", draft-
         ietf-trill-directory-framework-07.txt, in RFC Editor's queue.

   [DirectoryScheme] - Dunbar, L., D. Eastlake, R. Perlman, I.
         Gashinsky, Y. Li, "TRILL": Directory Assistance Mechanisms",
         draft-dunbar-trill-scheme-for-directory-assist, work in

D. Eastlake, et al                                             [Page 21]

INTERNET-DRAFT                                      TRILL: IA APPsub-TLV

   [ESADI] - Zhai, H., F. Hu, R. Perlman, D. Eastlake, O. Stokes, "TRILL
         (Transparent Interconnection of Lots of Links): The ESADI (End
         Station Address Distribution Information) Protocol", draft-
         ietf-trill-esadi-03.txt, work in progress.

   [RFC5494] - Arkko, J. and C. Pignataro, "IANA Allocation Guidelines
         for the Address Resolution Protocol (ARP)", RFC 5494, April

D. Eastlake, et al                                             [Page 22]

INTERNET-DRAFT                                      TRILL: IA APPsub-TLV

Authors' Addresses

   Donald Eastlake
   Huawei Technologies
   155 Beaver Street
   Milford, MA 01757 USA

   Phone: +1-508-333-2270

   Yizhou Li
   Huawei Technologies
   101 Software Avenue,
   Nanjing 210012 China

   Phone: +86-25-56622310

   Radia Perlman
   Intel Labs
   2200 Mission College Blvd.
   Santa Clara, CA 95054-1549 USA

   Phone: +1-408-765-8080

D. Eastlake, et al                                             [Page 23]

INTERNET-DRAFT                                      TRILL: IA APPsub-TLV

Copyright, Disclaimer, and Additional IPR Provisions

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D. Eastlake, et al                                             [Page 24]