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TRILL: Address Flush Message
draft-ietf-trill-address-flush-02

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8383.
Authors Hao Weiguo , Donald E. Eastlake 3rd , Yizhou Li , Mohammed Umair
Last updated 2017-03-08 (Latest revision 2017-01-26)
Replaces draft-hao-trill-address-flush
RFC stream Internet Engineering Task Force (IETF)
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Stream WG state WG Document
Document shepherd Susan Hares
IESG IESG state Became RFC 8383 (Proposed Standard)
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Send notices to "Susan Hares" <shares@ndzh.com>
draft-ietf-trill-address-flush-02
TRILL Working Group                                           Weiguo Hao
INTERNET-DRAFT                                           Donald Eastlake
Intended status: Proposed Standard                             Yizhou Li
                                                                  Huawei
                                                          Mohammed Umair
                                                              IPinfusion
Expires: July 26, 2017                                  January 26, 2017

                      TRILL: Address Flush Message
                <draft-ietf-trill-address-flush-02.txt>

Abstract

   The TRILL (TRansparent Interconnection of Lots of Links) protocol, by
   default, learns end station addresses from observing the data plane.
   In particular, it learns local MAC addresses and edge switch port of
   attachment from the receipt of local data frames and learns remote
   MAC addresses and edge switch of attachment from the decapsulation of
   remotely sourced TRILL Data packets.

   This document specifies a message by which an originating TRILL
   switch can explicitly request other TRILL switches to flush certain
   MAC reachability learned through the decapsulation of TRILL Data
   packets. This is a supplement to the TRILL automatic address
   forgetting and can assist in achieving more rapid convergence in case
   of topology or configuration change.

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: trill@ietf.org.

   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-
   Drafts.

   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."

W. Hao, et al                                                   [Page 1]
INTERNET-DRAFT                                     Address Flush Message

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
   Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

W. Hao, et al                                                   [Page 2]
INTERNET-DRAFT                                     Address Flush Message

Table of Contents

      1. Introduction............................................4
      1.1 Terminology and Acronyms...............................4

      2. Address Flush Message Details...........................6
      2.1 VLAN Block Only Case...................................7
      2.2 Extensible Case........................................8
      2.2.1 Blocks of VLANs.....................................11
      2.2.2 Bit Map of VLANs....................................11
      2.2.3 Blocks of FGLs......................................12
      2.2.4 list of FGLs........................................12
      2.2.5 Big Map of FGLs.....................................13
      2.2.6 All Data Labels.....................................13
      2.2.7 MAC Address List....................................14
      2.2.8 MAC Address Blocks..................................14

      3. IANA Considerations....................................16
      3.1 Address Flush RBridge Channel Protocol Number.........16
      3.2 TRILL Address Flush TLV Types.........................16

      4. Security Considerations................................17

      Normative References......................................18
      Informative References....................................18

      Acknowledgements..........................................18

      Authors' Addresses........................................19

W. Hao, et al                                                   [Page 3]
INTERNET-DRAFT                                     Address Flush Message

1. Introduction

   Edge TRILL (Transparent Interconnection of Lots of Links) switches
   [RFC6325] [RFC7780], also called edge RBridges, by default learn end
   station MAC address reachability from observing the data plane. On
   receipt of a native frame from an end station, they would learn the
   local MAC address attachment of the source end station. And on
   egressing (decapsulating) a remotely originated TRILL Data packet,
   they learn the remote MAC address and remote attachment TRILL switch.
   Such learning is all scoped by data label (VLAN or Fine Grained Label
   [RFC7172]).

   TRILL has mechanisms for timing out such learning and appropriately
   clearing it based on some network connectivity and configuration
   changes; however, there are circumstances under which it would be
   helpful for a TRILL switch to be able to explicitly flush (purge)
   certain learned end station reachability information in remote
   RBridges to achieve more rapid convergence. For example, in the case
   of topology change or reconfiguration in a bridged network attached
   to multiple edge RBridges. Section 6.2 of [RFC4762] is another
   example of use of such a mechanism.

   A TRILL switch R1 can easily flush any locally learned addresses it
   wants. This document specifies an RBridge Channel protocol [RFC7178]
   message to request flushing address information learned from
   decapsulating at remote RBridges.

1.1 Terminology and Acronyms

   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 [RFC2119].

   This document uses the terms and acronyms defined in [RFC6325] and
   [RFC7978] as well as the following:

      Data Label - VLAN or FGL.

      Edge TRILL switch - A TRILL switch attached to one or more links
         that provide end station service.

      FGL - Fine Grained Label [RFC7172].

      Management VLAN - A VLAN in which all TRILL switches in a campus
         indicate interest so that multi-destination TRILL Data packets,
         including RBridge Channel messages [RFC7978], sent with that
         VLAN as the Inner.VLAN will be delivered to all TRILL switches
         in the campus. Usually no end station service is offered in the

W. Hao, et al                                                   [Page 4]
INTERNET-DRAFT                                     Address Flush Message

         Management VLAN.

      RBridge - An alternative name for a TRILL switch.

      TRILL switch - A device implementing the TRILL protocol.

W. Hao, et al                                                   [Page 5]
INTERNET-DRAFT                                     Address Flush Message

2. Address Flush Message Details

   The Address Flush message is an RBridge Channel protocol message
   [RFC7178].

   The general structure of an RBridge Channel packet on a link between
   TRILL switches is shown in Figure 1 below. The Protocol field in the
   RBridge Channel Header gives the type of RBridge Channel packet that
   indicates how to interpret the Channel Protocol Specific Payload
   [RFC7178].

                   +----------------------------------+
                   |           Link Header            |
                   +----------------------------------+
                   |           TRILL Header           |
                   +----------------------------------+
                   |     Inner Ethernet Addresses     |
                   +----------------------------------+
                   |     Data Label (VLAN or FGL)     |
                   +----------------------------------+
                   |      RBridge Channel Header      |
                   +----------------------------------+
                   | Channel Protocol Specific Payload|
                   +----------------------------------+
                   |    Link Trailer (FCS if Ethernet)|
                   +----------------------------------+

           Figure 1. RBridge Channel Protocol Message Structure

   An Address Flush RBridge Channel message by default applies to
   addresses within the Data Label that appears right after the Inner
   Ethernet Addresses.  Address Flush protocol messages are usually sent
   as multi-destination packets (TRILL Header M bit equal to one) so as
   to reach all TRILL switches offering end station service in the VLAN
   or FGL specified by that Data Label. Such messages SHOULD be sent at
   priority 6 since they are important control messages but lower
   priority than control messages that establish or maintain adjacency.

   Nevertheless:
   -  There are provisions for optionally indicating the Data Label(s)
      to be flushed for cases where the Address Flush message is sent
      over a Management VLAN or the like.
   -  An Address Flush message can be sent unicast, if it is desired to
      clear addresses at one TRILL switch only.

W. Hao, et al                                                   [Page 6]
INTERNET-DRAFT                                     Address Flush Message

2.1 VLAN Block Only Case

   Figure 2 below expands the RBridge Channel Header and Channel
   Protocol Specific Payload from Figure 1 for the case of the VLAN only
   based Address Flush message. This form of the Address Flush message
   is optimized for flushing MAC addressed based on nickname and blocks
   of VLANs.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   RBridge Channel Header:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    RBridge-Channel (0x8946)   |  0x0  | Channel Protocol = TBD |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Address Flush Protocol Specific:
      +-+-+-+-+-+-+-+-+
      | K-nicks       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Nickname 1                    | Nickname 2                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Nickname ...                  | Nickname K-nicks              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | K-VLBs        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | RESV  | Start.VLAN 1          | RESV  | End.VLAN 1            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | RESV  | Start.VLAN 2          | RESV  | End.VLAN 2            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | RESV  | Start.VLAN ...        | RESV  | End.VLAN ...          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | RESV  | Start.VLAN K-VLBs     | RESV  | End.VLAN K-VLBs       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 2. Address Flush Message - VLAN Case

   The fields in Figure 2 related to the Address Flush message are as
   follows:

      Channel Protocol:  The RBridge Channel Protocol value allocated
         for Address Flush (see Section 3).

      K-nicks: K-nicks is the number of nicknames listed as an unsigned
         integer. If this is zero, the ingress nickname in the TRILL
         Header [RFC6325] is considered to be the only nickname to which
         the message applies. If non-zero, it given the number of
         nicknames listed right after K-nicks to which the message
         applies and, in this non-zero case, the flush does not apply to
         the ingress nickname in the TRILL Header unless it is also

W. Hao, et al                                                   [Page 7]
INTERNET-DRAFT                                     Address Flush Message

         listed. The messages flushes address learning due to egressing
         TRILL Data packets that had an ingress nickname to which the
         message applies.

      Nickname: A listed nickname to which it is intended that the
         Address Flush message apply.  If an unknown or reserved
         nickname occurs in the list, it is ignored but the address
         flush operation is still executed with the other nicknames. If
         an incorrect nickname occurs in the list, so some address
         learning is flushed that should not have been flush, the
         network will still operate correctly but will be less efficient
         as the incorrectly flushed learning is re-learned.

      K-VLBs: K-VLBs is the number of VLAN blocks present as an unsigned
         integer. If this byte is zero, the message is the more general
         format specified in Section 2.2. If it is non-zero, it gives
         the number of blocks of VLANs present.

      RESV: 4 reserved bits. MUST be sent as zero and ignored on
         receipt.

      Start.VLAN, End.VLAN: These 12-bit fields give the beginning and
         ending VLAN IDs of a block of VLANs. The block includes both
         the starting and ending values so a block of size one is
         indicated by setting End.VLAN equal to Start.VLAN. If
         Start.VLAN is 0x000, it is treated as if it was 0x001. If
         End.VLAN is 0xFFF, it is treated as if it was 0xFFE. If
         End.VLAN is smaller than Start.VLAN, considering both as
         unsigned integers, that VLAN block is ignored but the address
         flush operation is still executed with other VLAN blocks in the
         message.

   This message flushes all addresses in an applicable VLAN learned from
   egressing TRILL Data packets with an applicable nickname as ingress.
   To flush addresses for all VLANs, it is easy to specify a block
   covering all valid VLAN IDs, this is, from 0x001 to 0xFFE.

2.2 Extensible Case

   A more general form of the Address Flush message is provided to
   support flushing by FGL and more efficient encodings of VLANs and
   FGLs where using a set of contiguous blocks if cumbersome. It also
   supports optionally specifying the MAC addresses to clear. This form
   is extensible.

   It is indicated by a zero in the byte shown in Figure 2 as "K-VLBs"
   followed by other information encoded as TLVs.

W. Hao, et al                                                   [Page 8]
INTERNET-DRAFT                                     Address Flush Message

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   RBridge Channel Header:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    RBridge-Channel (0x8946)   |  0x0  | Channel Protocol = TBD |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Flags        |  ERR  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Address Flush Protocol Specific:
      +-+-+-+-+-+-+-+-+
      | K-nicks       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Nickname 1                    | Nickname 2                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Nickname ...                  | Nickname K-nicks              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | 0             |  TLVs ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...

             Figure 3. Address Flush Message - Extensible Case

      Channel Protocol, K-nicks, Nickname: These fields are as specified
         in Section 2.1.

      TLVs: If the byte immediately before the TLVs field, which is the
         byte labeled "K-VLBs" in Figure 2, is zero, as shown in Figure
         3, the remainder of the message consists of TLVs encoded as
         shown in Figure 4.

             0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
            | Type          | Length        | Value
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

                           Figure 4. Type, Length, Value

            Type: The 8 bit TLV type as shown in the table below. See
         subsections of this Section 2.2 for details on each type
         assigned below. If the type is reserved or not known by a
         receiving RBridge, that receiving RBridge ignores the value and
         can easily skip to the next TLV by use of the Length byte.
         There is no provision for a list of VLAN IDs TLV as there are
         few enough of them that an arbitrary subset of VLAN IDs can be
         represented as a bit map.

W. Hao, et al                                                   [Page 9]
INTERNET-DRAFT                                     Address Flush Message

                Type       Description       Reference
               ------   ------------------  -----------------
                   0     Reserved            [this document]
                   1     Blocks of VLANs     [this document]
                   2     Bit Map of VLANs    [this document]
                   3     Blocks of FGLs      [this document]
                   4     List of FGLs        [this document]
                   5     Bit Map of FGLs     [this document]
                   6     All Data Labels     [this document]
                   7     MAC Address List    [this document]
                   8     MAC Address Blocks  [this document]
               9-254     Unassigned
                 255     Reserved            [this document]

         RBridges that implement the Address Flush message

      Length: The 8-bit unsigned integer length of the remaining
         information in the TLV after the length byte. The length MUST
         NOT imply that the value extends beyond the end of RBridge
         Channel Protocol Specific Payload area. If it does, the Address
         Flush message is corrupt and MUST be ignored.

      Value: Depends on the TLV type.

   The TLVs in an extensible Address Flush message are parsed with types
   unknown by the receiving RBridge ignored.
   
   The processing requirements based on support for Address Flush
   Channel message plus the additional types:  
 
   Basic RBridges functionality:  All RBridges supporting the Address
   Flush Channel message MUST implement type 1 (Blocks of VLANs),
   type 2 (Bit map of VLANs), and type 6 (All Data labels).  Type 6
   indicates that all addresses are to be flushed for all data labels.
  
   Optional RBridges functionality:  RBridges SHOULD implement types 7
   and type 8 so that specific MAC addresses can be can be flushed.  
   If a set of RBridges does not implement types 7 and 8, the flush
   will be inefficient as those not intent to be flashed will have to
   be relearned. 
 
   FGL functionality : All RBridges implementing the FGL ingress/egress
   support and the Address Flush Channel message MUST implement
   type 3 (Blocks of FGLs), type 4 (Lists of FGLs),
   and type 5 (Bit Map of FGL).  An RBridge that is merely FGL 
   safe [RFC7172], but cannot egress TRILL data packets, SHOULD ignore
   the FGL types with the Address Flush Channel message as it will not
   learn any MAC addresses with FGL scope from the MAC data plane. 

   The parsing of the TLVs in an Rbridge Channel Message in the Address
   Flush Protocol Specific TLVS by a receiving bridge results in three
   items: 
    
W. Hao, et al                                                  [Page 10]
INTERNET-DRAFT                                     Address Flush Message

   1)   A flag indicating whether one or more types
        6 TLVs (All Data Labels) were encountered.
   2)   A set of Data labels and blocks of data labels compiled from
        VLAN TLVs (types 1 and 2), and/or FGL TLVs (types 3, 4, and 5).    
   3)   If a MAC TLVs types (type 6 and 7)  are implemented, a set of 
        MAC addresses and Blocks of MAC addresses from the MAC TLVs. 
        
   For the following flag settings, the processing is as follows: 
   a)   If the set of MAC addresses and Block of MAC address is null
        (item 3 above) then Address Flush applies to all messages. 
   b)   If the  All-Data-label-found flag (item 1 above) is true, 
        then the address flush message applies to all data labels.
        The set of Data label and block of data labels (item 2 above)
        does not have any effect. 
   c)   If the All-Data-label-found flag (item 1 above) is false, then
        the Address Flush message applies to the set of 
        Data labels (see item 2 above) found in VLAn 
        TLVs (types 1 and 2), and/or FGLs TLVS (types 3, 4, and 5).
        If the set of Data Labels (see item 2 above) is null, the 
        Address Flush message does nothing. 

2.2.1 Blocks of VLANs

   If the TLV Type is 1, the value is a list of blocks of VLANs as
   follows:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 1      | Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | RESV  | Start.VLAN 1          | RESV  | End.VLAN 1            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | RESV  | Start.VLAN 2          | RESV  | End.VLAN 2            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | RESV  | Start.VLAN ...        | RESV  | End.VLAN ...          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The meaning of Start.VLAN and End.VLAN is as specified in Section
   2.1. Length MUST be a multiple of 4. If Length is not a multiple of
   4, the TLV is corrupt and the Address Flush message MUST be ignored.

2.2.2 Bit Map of VLANs

   If the TLV Type is 2, the value is a bit map of VLANs as follows:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 2      | Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
      | RESV  | Start.VLAN            | Bits...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

   The value portion of the TLV begins with two bytes having the 12-bit

   
W. Hao, et al                                                  [Page 11]
INTERNET-DRAFT                                     Address Flush Message
   
   starting VLAN ID right justified (the top 4 bits are as specified in
   Section 2.1 RESV). This is followed by bytes with one bit per VLAN
   ID. The high order bit of the first byte is for VLAN N, the next to
   the highest order bit is for VLAN N+1, the low order bit of the first
   byte is for VLAN N+7, the high order bit of the second byte, if there
   is a second byte, is for VLAN N+8, and so on. If that bit is a one,
   the Address Flush message applies to that VLAN. If that bit is a
   zero, then addresses that have been learned in that VLAN are not
   flushed.  Note that Length MUST be at least 2. If Length is 0 or 1
   the TLV is corrupt and the Address Flush message MUST be ignored.
   
   VLAN IDs do not wrap around. If there are enough bytes so that some
   bits correspond to VLAN ID 0xFFF or higher, those bits are ignored
   but the message is still processed for bits corresponding to valid
   VLAN IDs.

2.2.3 Blocks of FGLs

   If the TLV Type is 3, the value is a list of blocks of FGLs as
   follows:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 3      | Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Start.FGL 1                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | End.FGL 1                                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Start.FGL 2                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | End.FGL 2                                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Start.FGL ...                                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | End.FGL ...                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The TLV value consists of sets of Start.FGL and End.FGL numbers. The
   Address Flush information applies to the FGLs in that range,
   inclusive. A single FGL is indicated by setting both Start.FGL and
   End.FGL to the same value. If End.FGL is less than Start.FGL,
   considering them as unsigned integers, that block is ignored but the
   Address Flush message is still processed for any other blocks
   present. For this Type, Length MUST be a multiple of 6; if it is not,
   the TLV is corrupt and the Address Flush message MUST be discarded if
   the receiving RBridge implements Type 3.

2.2.4 list of FGLs

   If the TLV Type is 4, the value is a list of FGLs as follows:

W. Hao, et al                                                  [Page 12]
INTERNET-DRAFT                                     Address Flush Message

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 4      | Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | FGL 1                                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | FGL 2                                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | FGL ...                                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The TLV value consists of FGL numbers each in 3 bytes. The Address
   Flush message applies to those FGLs. For this Type, Length MUST be a
   multiple of 3; if it is not, the TLV is corrupt and the address flush
   Message MUST be discarded if the receiving RBridge implements Type 4.

2.2.5 Big Map of FGLs

   If the TLV Type is 5, the value is a bit map of FGLs as follows:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 5      | Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Start.FGL                                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Bits...
      +-+-+-+-+-+-+-+-

   The TLV value consists of three bytes with the 24-bit starting FGL
   value N. This is followed by bytes with one bit per FGL. The high
   order bit of the first byte is for FGL N, the next to the highest
   order bit is for FGL N+1, the low order bit of the first byte is for
   FGL N+7, the high order bit of the second byte, if there is a second
   byte, is for FGL N+8, and so on. If that bit is a one, the Address
   Flush message applies to that FGL. If that bit is a zero, then
   addresses that have been learned in that FGL are not flushed. Note
   that Length MUST be at least 3. If Length is 0, 1, or 2 for a Type 5
   TLV, the TLV is corrupt and the Address Flush message MUST be
   discarded.  FGLs do not wrap around. If there are enough bytes so
   that some bits correspond to an FGL higher than 0xFFFFFF, those bits
   are ignored but the message is still processed for bits corresponding
   to valid FGLs.

2.2.6 All Data Labels

   If the TLV Type is 6, the value is null as follows:

W. Hao, et al                                                  [Page 13]
INTERNET-DRAFT                                     Address Flush Message

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 6      | Length = 0    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   This type is used when a RBridge want to withdraw all Address for all
   the Data Labels (all VLANs and FGLs), Length MUST be zero. If Length
   is any other value, the TLV is corrupt and the Address Flush message
   MUST be ignored.

2.2.7 MAC Address List

   If the TLV Type is 7, the value is a list of MAC addresses as
   follows:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 7      | Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC 1 upper half                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC 1 lower half                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC 2 upper half                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC 2 lower half                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC ... upper half                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC ... lower half                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The TLV value consists of a list of 48-bit MAC addresses. Length MUST
   be a multiple of 6. If it is not, the TLV is corrupt and the Address
   Flush message MUST be ignored if the receiving RBridge implements
   Type 7.

2.2.8 MAC Address Blocks

   If the TLV Type is 8, the value is a list of blocks of MAC addresses
   as follows:

W. Hao, et al                                                  [Page 14]
INTERNET-DRAFT                                     Address Flush Message

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type = 7      | Length        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.start 1 upper half                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.start 1 lower half                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.end 1 upper half                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.end 1 lower half                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.start 2 upper half                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.start 2 lower half                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.end 2 upper half                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.end 2 lower half                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.start ... upper half                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.start ... lower half                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.end ... upper half                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | MAC.end ... lower half                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The TLV value consists of sets of Start.MAC and End.MAC numbers. The
   Address Flush information applies to the 48-bit MAC Addresses in that
   range, inclusive. A single MAC Address is indicated by setting both
   Start.MAC and End.MAC to the same value. If End.MAC is less than
   Start.MAC, considering them as unsigned integers, that block is
   ignored but the Address Flush message is still processed for any
   other blocks present. For this Type, Length MUST be a multiple of 12;
   if it is not, the TLV is corrupt and the Address Flush message MUST
   be discarded if the receiving RBridge implements Type 7.

W. Hao, et al                                                  [Page 15]
INTERNET-DRAFT                                     Address Flush Message

3. IANA Considerations

   Two IANA actions are requested as follows:

3.1 Address Flush RBridge Channel Protocol Number

   IANA is requested to assign TBD as the Address Flush RBridge Channel
   Protocol number from the range of RBridge Channel protocols allocated
   by Standards Action [RFC7178].

   The added RBridge Channel protocols registry entry on the TRILL
   Parameters web page is as follows:

         Protocol  Description       Reference
         --------  --------------    ------------------
            TBD    Address Flush     [this document]

3.2 TRILL Address Flush TLV Types

   IANA is requested to create a TRILL Address Flush TLV Types registry
   on the TRILL Parameters web page indented right after the RBridge
   Channel Protocols registry. Registry headers are as below. The
   initial entries are as in the table in Section 2.2 above.

      Registry:  TRILL Address Flush TLV Types
      Registration Procedures: IETF Review
      Reference:  [this document]

W. Hao, et al                                                  [Page 16]
INTERNET-DRAFT                                     Address Flush Message

4. Security Considerations

   The Address Flush RBridge Channel Protocol provides no security
   assurances or features. However, the Address Flush protocol messages
   can be secured by use of the RBridge Channel Header Extension
   [RFC7978].

   See [RFC7178] for general RBridge Channel Security Considerations.

   See [RFC6325] for general TRILL Security Considerations.

W. Hao, et al                                                  [Page 17]
INTERNET-DRAFT                                     Address Flush Message

Normative References

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

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

   [RFC7172] - Eastlake 3rd, D., Zhang, M., Agarwal, P., Perlman, R.,
         and D. Dutt, "Transparent Interconnection of Lots of Links
         (TRILL): Fine-Grained Labeling", RFC 7172, DOI
         10.17487/RFC7172, May 2014, <http://www.rfc-
         editor.org/info/rfc7172>.

   [RFC7178] - Eastlake 3rd, D., Manral, V., Li, Y., Aldrin, S., and D.
         Ward, "Transparent Interconnection of Lots of Links (TRILL):
         RBridge Channel Support", RFC 7178, DOI 10.17487/RFC7178, May
         2014, <http://www.rfc-editor.org/info/rfc7178>.

   [RFC7780] - Eastlake 3rd, D., Zhang, M., Perlman, R., Banerjee, A.,
         Ghanwani, A., and S. Gupta, "Transparent Interconnection of
         Lots of Links (TRILL): Clarifications, Corrections, and
         Updates", RFC 7780, DOI 10.17487/RFC7780, February 2016,
         <http://www.rfc-editor.org/info/rfc7780>.

   [RFC7978] - Eastlake 3rd, D., Umair, M., and Y. Li, "Transparent
         Interconnection of Lots of Links (TRILL): RBridge Channel
         Header Extension", RFC 7978, DOI 10.17487/RFC7978, September
         2016, <http://www.rfc-editor.org/info/rfc7978>.

Informative References

   [RFC4762] - Lasserre, M., Ed., and V. Kompella, Ed., "Virtual Private
         LAN Service (VPLS) Using Label Distribution Protocol (LDP)
         Signaling", RFC 4762, January 2007.

Acknowledgements

   The following are thanked for their contributions:

      Henning Rogge

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

W. Hao, et al                                                  [Page 18]
INTERNET-DRAFT                                     Address Flush Message

Authors' Addresses

      Weiguo Hao
      Huawei Technologies
      101 Software Avenue,
      Nanjing 210012, China

      Phone: +86-25-56623144
      Email: haoweiguo@huawei.com

      Donald E. Eastlake, 3rd
      Huawei Technologies
      155 Beaver Street
      Milford, MA 01757 USA

      Phone: +1-508-333-2270
      EMail: d3e3e3@gmail.com

      Yizhou Li
      Huawei Technologies
      101 Software Avenue,
      Nanjing 210012
      China

      Phone: +86-25-56624629
      Email: liyizhou@huawei.com

      Mohammed Umair
      IPinfusion
      RMZ Centennial Mahadevapura Post
      Bangalore, 560048 India

      Email: mohammed.umair2@gmail.com

W. Hao, et al                                                  [Page 19]
INTERNET-DRAFT                                     Address Flush Message

Copyright, Disclaimer, and Additional IPR Provisions

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   document authors. All rights reserved.

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W. Hao, et al                                                  [Page 20]