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Versions: (draft-perlman-trill-smart-endnodes) 00 01 02 03 04 05 06 07 08 09 10 11 RFC 8384

TRILL WG                                                   Radia Perlman
Internet-Draft                                                  Dell EMC
Intended status: Standards Track                              Fangwei Hu
Expires: September 12, 2018                              ZTE Corporation
                                                         Donald Eastlake
                                                               Ting Liao
                                                     Huawei Technologies
                                                            Mar 11, 2018


                          TRILL Smart Endnodes
                 draft-ietf-trill-smart-endnodes-11.txt

Abstract

   This draft addresses the problem of the size and freshness of the
   endnode learning table in edge RBridges, by allowing endnodes to
   volunteer for endnode learning and encapsulation/decapsulation.  Such
   an endnode is known as a "Smart Endnode".  Only the attached edge
   RBridge can distinguish a "Smart Endnode" from a "normal endnode".
   The Smart Endnode uses the nickname of the attached edge RBridge, so
   this solution does not consume extra nicknames.  The solution also
   enables Fine Grained Label aware endnodes.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on September 12, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents



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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions used in this document . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   3.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Smart-Hello Mechanism between Smart Endnode and RBridge . . .   5
     4.1.  Smart-Hello Encapsulation . . . . . . . . . . . . . . . .   6
     4.2.  Edge RBridge's Smart-Hello  . . . . . . . . . . . . . . .   7
     4.3.  Smart Endnode's Smart-Hello . . . . . . . . . . . . . . .   7
   5.  Data Packet Processing  . . . . . . . . . . . . . . . . . . .   9
     5.1.  Data Packet Processing for Smart Endnode  . . . . . . . .   9
     5.2.  Data Packet Processing for Edge RBridge . . . . . . . . .  10
   6.  Multi-homing Scenario . . . . . . . . . . . . . . . . . . . .  11
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     10.1.  Informative References . . . . . . . . . . . . . . . . .  13
     10.2.  Normative References . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   The IETF TRILL (Transparent Interconnection of Lots of Links)
   protocol [RFC6325] [RFC7780] provides optimal pair-wise data frame
   forwarding without configuration, safe forwarding even during periods
   of temporary loops, and support for multipathing of both unicast and
   multicast traffic.  TRILL accomplishes this by using IS-IS [IS-IS]
   [RFC7176] link state routing and encapsulating traffic using a header
   that includes a hop count.  Devices that implement TRILL are called
   "RBridges" (Routing Bridges) or "TRILL Switches".

   An RBridge that attaches to endnodes is called an "edge RBridge" or
   "edge TRILL Switch", whereas one that exclusively forwards
   encapsulated frames is known as a "transit RBridge" or "transit TRILL
   Switch".  An edge RBridge traditionally is the one that encapsulates
   a native Ethernet frame with a TRILL header, or that receives a
   TRILL-encapsulated packet and decapsulates the TRILL header.  To



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   encapsulate efficiently, the edge RBridge must keep an "endnode
   table" consisting of (MAC, Data Label, TRILL egress switch nickname)
   sets, for those remote MAC addresses in Data Labels currently
   communicating with endnodes to which the edge RBridge is attached.

   These table entries might be configured, received from ESADI
   [RFC7357], looked up in a directory [RFC7067], or learned from
   decapsulating received traffic.  If the edge RBridge has attached
   endnodes communicating with many remote endnodes, this table could
   become very large.  Also, if one of the MAC addresses and Data Labels
   in the table has moved to a different remote TRILL switch, it might
   be difficult for the edge RBridge to notice this quickly, and because
   the edge RBridge is encapsulating to the incorrect egress RBridge,
   the traffic will get lost.

2.  Conventions used in this document

2.1.  Terminology

   Edge RBridge: An RBridge providing endnode service on at least one of
   its ports.  It is also called an edge TRILL Switch.

   Data Label: VLAN or FGL.

   DRB: Designated RBridge [RFC6325].

   ESADI: End Station Address Distribution Information [RFC7357].

   FGL: Fine Grained Label [RFC7172].

   IS-IS: Intermediate System to Intermediate System [IS-IS].

   PDU: Protocol Data Unit.

   RBridge: Routing Bridge, an alternative name for a TRILL switch.

   Smart Endnode: An endnode that has the capability specified in this
   document including learning and maintaining (MAC, Data Label,
   Nickname) entries and encapsulating/decapsulating TRILL frame.

   Transit RBridge: An RBridge exclusively forwards encapsulated frames.
   It is also called a transit TRILL Switch.

   TRILL: Transparent Interconnection of Lots of Links
   [RFC6325][RFC7780].






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   TRILL ES-IS: TRILL End System to Intermediate System, is a variation
   of TRILL IS-IS designed to operate on a TRILL link among and between
   one or more TRILL switches and end stations on that link[RFC8171].

   TRILL Switch: a device that implements the TRILL protocol; an
   alternative term for an RBridge.

2.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  Solution Overview

   The Smart Endnode solution defined in this document addresses the
   problem of the size and freshness of the endnode learning table in
   edge RBridges.  An endnode E, attached to an edge RBridge R, tells R
   that E would like to be a "Smart Endnode", which means that E will
   encapsulate and decapsulate the TRILL frame, using R's nickname.
   Because E uses R's nickname, this solution does not consume extra
   nicknames.

   Take Figure 1 as the example Smart Endnode scenario: RB1, RB2 and RB3
   are the RBridges in the TRILL domain, and SE1 and SE2 are the Smart
   Endnodes which can encapsulate and decapsulate the TRILL packets.
   RB1 is the edge RB that SE1 and SE2 have attached to.  RB1 assigns
   one of its nicknames to be used by SE1 and SE2.

   Each Smart Endnode, SE1 and SE2, uses RB1's nickname when
   encapsulating, and maintains an endnode table of (MAC, label, TRILL
   egress switch nickname) for remote endnodes that it (SE1 or SE2) is
   corresponding with.  RB1 does not decapsulate packets destined for
   SE1 or SE2, and does not learn (MAC, label, TRILL egress switch
   nickname) for endnodes corresponding with SE1 or SE2, but RB1 does
   decapsulate, and does learn (MAC, label, TRILL egress switch
   nickname) for any endnodes attached to RB1 that have not declared
   themselves to be Smart Endnodes.

   Just as an RBridge learns and times out (MAC, label, TRILL egress
   switch nickname), Smart Endnodes SE1 and SE2 also learn and time out
   endnode entries.  However, SE1 and SE2 might also determine, through
   ICMP messages or other techniques that an endnode entry is not
   successfully reaching the destination endnode, and can be deleted,
   even if the entry has not timed out.




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   If SE1 wishes to correspond with destination MAC D, and no endnode
   entry exists, SE1 will encapsulate the packet as an unknown
   destination, or consulting a directory [RFC7067] (just as an RBridge
   would do if there was no endnode entry).

+----------+
|SE1(Smart |
|Endnode1) |  \      +------------------------------+
+----------+   \    /                                \
                \  /+------+   +------+    +-----+    \   +-----------+
                /-+-| RB 1 |---|  RB2 |----| RB3 |-----+--|Endnode3   |
               /  | +------+   +------+    +-----+     |  |MAC=D      |
+----------+ /     \                                  /   +-----------+
|SE2(Smart |        \                                /
| Endnode2)|         +------------------------------+
+----------+
                   Figure 1 Smart Endnode Scenario

   The mechanism in this draft is that the Smart Endnode SE1 issues a
   Smart-Hello, indicating SE1's desire to act as a Smart Endnode,
   together with the set of MAC addresses and Data Labels that SE1 owns.
   The Smart-Hello is used to announce the Smart Endnode capability and
   parameters (such as MAC address, Data Label etc.).  The Smart-Hello
   is a type of TRILL ES-IS PDU, which is specified in section 5 of
   [RFC8171].  The detailed content for a Smart Endnode's Smart-Hello is
   defined in section 4.

   If RB1 supports having a Smart Endnode neighbor it also sends Smart-
   Hellos.  The Smart Endnode learns from RB1's Smart-Hellos what RB1's
   nickname is and which trees RB1 can use when RB1 ingresses multi-
   destination frames.  Although Smart Endnode SE1 transmits Smart-
   Hellos, it does not transmit or receive LSPs or E-L1FS FS-LSPs
   [RFC7780].

   Since a Smart Endnode can encapsulate TRILL Data packets, it can
   cause the Inner.Lable to be a Fine Grained Label [RFC7172], thus this
   method supports FGL aware endnodes.  When and how a Smart Endnode
   decides to use the FGL instead of VLANs to encapsulate the TRILL Data
   packet is out of scope in this document.

4.  Smart-Hello Mechanism between Smart Endnode and RBridge

   The subsections below describe Smart-Hello messages.








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4.1.  Smart-Hello Encapsulation

   Although a Smart Endnode is not an RBridge, does not send LSPs or
   maintain a copy of the link state database, and does not perform
   routing calculations, it is required to have a "Hello" mechanism (1)
   to announce to edge RBridges that it is a Smart Endnode and (2) to
   tell them what MAC addresses it is handling in what Data Labels.
   Similarly, an edge RBridge that supports Smart Endnodes needs a
   message (1) to announce that support, (2) to inform Smart Endnodes
   what nickname to use for ingress and what nickname(s) can be used as
   egress nickname in a multi-destination TRILL Data packet, and (3) the
   list of Smart Endnodes it knows about on that link.

   The messages sent by Smart Endnodes and by edge RBridges that support
   Smart Endnodes are called "Smart-Hellos".  The Smart-Hello is a type
   of TRILL ES-IS PDU, which is specified in [RFC8171].

   The Smart-Hello Payload, both for Smart-Hellos sent by Smart Endnodes
   and for Smart-Hellos sent by Edge RBridges, consists of TRILL IS-IS
   TLVs as described in the following two sub-sections.  The non-
   extended format is used so TLVs, sub-TLVs, and APPsub-TLVs have an
   8-bit size and type field.  Both types of Smart-Hellos MUST include a
   Smart-Parameters APPsub-TLV as follows inside a TRILL GENINFO TLV:

                 +-+-+-+-+-+-+-+-+-
                 |Smart-Parameters|                 (1 byte)
                 +-+-+-+-+-+-+-+-+-
                 |    Length      |                 (1 byte)
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |        Holding Time           |  (2 bytes)
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 |             Flags             |  (2 bytes)
                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 2 Smart Parameters APPsub-TLV


   o Type: APPsub-TLV type Smart-Parameters, value is TBD1.

   o Length: 4.

   o Holding Time: A time in seconds as an unsigned integer.  It has the
   same meaning as the Holding Time field in IS-IS Hellos [IS-IS].  A
   Smart Endnode and an Edge RBridge supporting Smart Endnodes MUST send
   a Smart-Hello at least three times during their Holding Time.  If no
   Smart-Hellos is received from a Smart Endnode or Edge RBridge within
   the most recent Holding Time it sent, it is assumed that it is no
   longer available.



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   o Flags: At this time all of the Flags are reserved and MUST be send
   as zero and ignored on receipt.

   If more than one Smart Parameters APPsub-TLV appears in a Smart-
   Hello, the first one is used and any following ones are ignored.  If
   no Smart Parameters APPsub-TLV appears in a Smart-Hello, that Smart-
   Hello is ignored.

4.2.  Edge RBridge's Smart-Hello

   The edge RBridge's Smart-Hello contains the following information in
   addition to the Smart-Parameters APPsub-TLV:

   o RBridge's nickname.  The nickname sub-TLV, specified in section
   2.3.2 in [RFC7176], is reused here carried inside a TLV 242 (IS-IS
   router capability) in a Smart-Hello frame.  If more than one nickname
   appears in the Smart-Hello, the first one is used and the following
   ones are ignored.

   o Trees that RB1 can use when ingressing multi-destination frames.
   The Tree Identifiers Sub-TLV, specified in section 2.3.4 in
   [RFC7176], is reused here.

   o Smart Endnode neighbor list.  The TRILL Neighbor TLV, specified in
   section 2.5 in [RFC7176], is reused for this purpose.

   An Authentication TLV MAY also be included.

4.3.  Smart Endnode's Smart-Hello

   A new APPsub-TLV (Smart-MAC TLV) is defined for use by Smart Endnodes
   as defined below.  In addition, there will be a Smart-Parameters
   APPsub-TLV and there MAY be an Authentication TLV in a Smart Endnode
   Smart-Hello.

   If there are several VLANs/FGL Data Labels for that Smart Endnode,
   the Smart-MAC APPsub-TLV is included several times in Smart Endnode's
   Smart-Hello.  This APPsub-TLV appears inside a TRILL GENINFO TLV.













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    +-+-+-+-+-+-+-+-+
    |Type=Smart-MAC |                          (1 byte)
    +-+-+-+-+-+-+-+-+
    |   Length      |                          (1 byte)
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |F|M|   RSV     |  VLAN/FGL Data Label  |  (4 bytes)
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          MAC (1)       (6 bytes)                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      .................                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          MAC (N)       (6 bytes)                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 3 Smart-MAC APPsub-TLV


   o Type: TRILL APPsub-TLV Type Smart-MAC, value is TBD2.

   o Length: Total number of bytes contained in the value field of the
   TLV, that is, the sum of the length of the F/M/RSV/FGL Data Label
   fields and 6 times the number of MAC addresses present.  So, if there
   are n MAC addresses, this is 4+6*n.

   o F: 1 bit.  If it is set to 1, it indicates that the endnode
   supports FGL data labels [RFC7172], and that this Smart-MAC APPsub-
   TLV has an FGL in the following VLAN/FGL field.  Otherwise, the VLAN/
   FGL Data Label field is a VLAN ID.(See below for the format of the
   VLAN/FGL Data Label field).

   o M: 1 bit.  If it is set to 1, it indicates multi-homing(See
   Section 6).  If it is set to 0, it indicates that the Smart Endnodes
   are not using multi-homing.

   o RSV: 6 bits, is reserved for the future use.

   o VLAN/FGL Data Label: 24bits.  If F is 1, this field is a 24-bit FGL
   Data Label for all subsequent MAC addresses in this APPsub-TLV.
   Otherwise, if F is 0, the lower 12 bits is the VLAN of all subsequent
   MAC addresses in this APPsub-TLV, and the upper 12 bits is not
   used(sent as zero and ignored on receipt).  If there is no VLAN/FGL
   data label specified, the VLAN/FGL Data Label is zero.

   o MAC(i): This is a 48-bit MAC address reachable in the Data Label
   sent by the Smart Endnode that is announcing this APPsub-TLV.






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5.  Data Packet Processing

   The subsections below specify Smart Endnode data packet processing.
   All TRILL Data packets sent to or from Smart Endnodes are sent in the
   Designated VLAN [RFC6325] of the local link but do not necessarily
   have to be VLAN tagged.

5.1.  Data Packet Processing for Smart Endnode

   A Smart Endnode does not issue or receive LSPs or E-L1FS FS-LSPs or
   calculate topology.  It does the following:

   o  A Smart Endnode maintains an endnode table of (the MAC address of
      remote endnode, Data Label, the nickname of the edge RBridge's
      attached) entries of end nodes with which the Smart Endnode is
      communicating.  Entries in this table are populated the same way
      that an edge RBridge populates the entries in its table:

      *  learning from (source MAC address ingress nickname) on packets
         it decapsulates.

      *  by querying a directory [RFC7067].

      *  by having some entries configured.

   o  When Smart Endnode SE1 wishes to send unicast frame to remote node
      D, if (MAC address of remote endnode D, Data Label, nickname)
      entry is in SE1's endnode table, SE1 encapsulates the ingress
      nickname as the nickname of the RBridge(RB1), egress nickname as
      indicated in D's table entry.  If D is unknown, SE1 either queries
      a directory or encapsulates the packet as a multi-destination
      frame, using one of the trees that RB1 has specified in RB1's
      Smart-Hello.  The mechanism for querying a directory is given in
      [RFC8171].

   o  When SE1 wishes to send a BUM packet to the TRILL campus, SE1
      encapsulates the packet using one of the trees that RB1 has
      specified.

   If the Smart Endnode SE1 sends a multi-destination TRILL Data packet,
   the destination MAC of the outer Ethernet is the All-RBridges
   multicast address.

   The Smart Endnode SE1 need not send Smart-Hellos as frequently as
   normal RBridges.  These Smart-Hellos could be periodically unicast to
   the Appointed Forwarder RB1.  In case RB1 crashes and restarts, or
   the DRB changes and SE1 receives the Smart-Hello without mentioning
   SE1, SE1 SHOULD send a Smart-Hello immediately.  If RB1 is Appointed



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   Forwarder for any of the VLANs that SE1 claims, RB1 MUST list SE1 in
   its Smart-Hellos as a Smart Endnode neighbor.

5.2.  Data Packet Processing for Edge RBridge

   The attached edge RBridge processes and forwards TRILL Data packets
   based on the endnode property rather than for encapsulation and
   forwarding the native frames the same way as the traditional
   RBridges.  There are several situations for the edge RBridges as
   follows:

   o If receiving an encapsulated unicast TRILL Data packet from a port
   with a Smart Endnode, with RB1's nickname as ingress, the edge
   RBridge RB1 forwards the frame to the specified egress nickname, as
   with any encapsulated frame.  However, RB1 SHOULD filter the
   encapsulation frame based on the inner source MAC and Data Label as
   specified for the Smart Endnode.  If the MAC (or Data Label) are not
   among the expected entries of the Smart Endnode, the frame would be
   dropped by the edge RBridge.  If the edge RBridge does not perform
   this check, it makes it easier for a rogue end station to inject
   bogus TRILL Data packets into the TRILL campus.

   o If receiving a unicast TRILL Data packet with RB1's nickname as
   egress from the TRILL campus, and the destination MAC address in the
   enclosed packet is a MAC address that has been listed by a "Smart
   Endnode", RB1 leaves the packet encapsulated to that Smart Endnode.
   The outer Ethernet destination MAC is the destination Smart Endnode's
   MAC address, the inner destination MAC address is either the Smart
   Endnode's MAC address or some other MAC address that the Smart
   Endnode advertised in its Smart Hello, and the outer Ethernet source
   MAC address is the RB1's port MAC address.  The edge RBridge still
   decreases the Hop count value by 1, for there is one hop between the
   RB1 and Smart Endnode.

   o If receiving a multi-destination TRILL Data packet from a port with
   a Smart Endnode, RBridge RB1 forwards the TRILL encapsulation to the
   TRILL campus based on the distribution tree indicated by the egress
   nickname.  If the egress nickname does not correspond to a
   distribution tree, the packet is discarded.  If there are any normal
   endnodes (i.e, non-Smart Endnodes) attached to the edge RBridge RB1,
   RB1 decapsulates the frame and sends the native frame to these ports
   possibly pruned based on multicast listeners, in addition to
   forwarding the multi-destination TRILL frame to the rest of the
   campus.

   o If RB1 receives a native multi-destination data frame, which is
   sent by a non-Smart Endnode, from a port, including hybrid endnodes
   (Smart Endnodes and non-Smart Endnodes), RB1 will encapsulate it as



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   multi-destination TRILL Data packet , and send the encapsulated
   multi-destination TRILL Data Packet out that same port to the Smart
   Endnodes attached to the port, and also send the encapsulated multi-
   destination TRILL Data Packet to the TRILL campus through other
   ports.

   o If RB1 receives a multi-destination TRILL Data packet from a remote
   RBridge, and the exit port includes hybrid endnodes(Smart Endnodes
   and non-Smart Endnodes), it sends two copies of multicast frames out
   the port, one as native and the other as TRILL encapsulated frame.
   When Smart Endnode receives multi-destination TRILL Data packet, it
   learns the remote (MAC address, Data Label, Nickname) entry.  A Smart
   Endnodes ignores native data frames.  A normal (non-Smart) Endnode
   receives the native frame and learns the remote MAC address and
   ignores the TRILL data packet.  This transit solution may bring some
   complexity for the edge RBridge and waste network bandwidth resource,
   so avoiding the hybrid endnodes scenario by attaching the Smart
   Endnodes and non-Smart Endnodes to different ports is RECOMMENDED.

6.  Multi-homing Scenario

   Multi-homing is a common scenario for the Smart Endnode.  The Smart
   Endnode is on a link attached to the TRILL domain in two places: to
   edge RBridge RB1 and RB2.  Take the figure below as example.  The
   Smart Endnode SE1 is attached to the TRILL domain by RB1 and RB2
   separately.  Both RB1 and RB2 could announce their nicknames to SE1.

                        . .....................
                        .  +------+           .
                        .  | RB1  |           .
                        . /+------+           .
           +----------+ ./            +-----+ .    +----------+
           |SE1(Smart |/.             | RB3 |......| Smart    |
           | Endnode1)| .\            +-----+ .    | Endnode2 |
           +----------+ . \                   .    +----------+
                        .  +-----+            .
                        .  | RB2 |   TRILL    .
                        .  +-----+   Domain   .
                        .......................

                          Figure 4 Multi-homing Scenario


   Smart Endnode SE1 can choose either RB1 or RB2's nickname, when
   encapsulating and forwarding a TRILL data packet.  If the active-
   active load balance is considered for the multi-homing scenario, the
   Smart Endnode SE1 could use both RB1 and RB2's nickname to
   encapsulate and forward TRILL Data packet.  SE1 uses RB1's nickname



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   when forwarding through RB1, and RB2's nickname when forwarding
   through RB2.  This will cause MAC flip-flopping(see [RFC7379]) of the
   endnode table entry in the remote RBridges (or Smart Endnodes).  The
   solution for the MAC flip-flopping issue is to set a multi- homing
   bit in the RSV field of the TRILL data packet.  When remote RBridge
   RB3 or Smart Endnodes receives a data packet with the multi-homed bit
   set, the endnode entries (SE1's MAC address, label, RB1's nickname)
   and (SE1's MAC address, label, RB2's nickname) will coexist as
   endnode entries in the remote RBridge.  (An alternative solution
   would be to use the ESADI protocol to distribute multiple attachments
   of a MAC address of a multi-homing group, The ESADI is deployed among
   the edge RBridges (See section 5.3 of [RFC7357])).

7.  Security Considerations

   Smart-Hellos can be secured by using Authentication TLVs based on
   [RFC5310].  If they are not secured, then it is easier for a rogue
   end station that does not posses the required keying material to be
   falsely recognized as a valid Smart Endnode.

   For general TRILL Security Considerations, see [RFC6325].  As stated
   there, since end stations are connected to edge RBridge ports by
   Ethernet, those ports MAY require end stations to authenticate
   themselves using [IEEE802.1X] and authenticate and encrypt traffic
   to/from the RBridge port with [IEEE802.1AE].

   If they misbehave, Smart Endnodes can forge arbitrary ingress and
   egress nicknames in the TRILL Headers of the TRILL Data packets they
   construct.  Decapsulating at egress RBridges or remote Smart Endnodes
   that believe such a forged ingress nickname would send future traffic
   destined for the inner source MAC address of the TRILL Data frame to
   the wrong edge RBridge if data plane learning is in use.  Because of
   this, an RBridge port should not be configured to support Smart
   Endnodes unless the end stations on that link are trusted or can be
   adequately authenticated.

   As with any end station, Smart Endnodes can forge the outer MAC
   addresses of packets they send (See Section 6 of [RFC6325].)  Because
   they encapsulate TRILL Data packets, they can also forge inner MAC
   addresses.  The encapsulation performed by Smart Endnodes also means
   they can send data in any Data Label which means they must be trusted
   in order to enforce a security policy based on Data Labels.

   The TRILL-Hello is a type of TRILL ES-IS, and is defined in
   [RFC8171].  Receiving and processing TRILL-Hello for RBridges and
   Smart Endnodes would not bring more security and vulnerability issues
   than the TRILL ES-IS security defined in [RFC8171].




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   For added security against the compromise of data due to its mis-
   delivery for any reason, including the above, end-to-end encryption
   and authentication should be considered; that is, encryption and
   authentication from source end station to destination end station.

   The mechanism described in this document requires Smart Endnodes to
   be aware of the MAC address(es) of the TRILL edge RBridge(s) to which
   they are attached and the egress RBridge nickname from which the
   destination of the packets is reachable.  With that information,
   Smart Endnodes can learn a substantial amount about the topology of
   the TRILL domain.  Therefore, there could be a potential security
   risk when the Smart Endnodes are not trusted or are compromised.

8.  IANA Considerations

   IANA is requested to allocate APPsub-TLV type numbers for the Smart-
   MAC and Smart-Parameters APPsub-TLVs from the range below 256 and
   update the "TRILL APPsub-TLV Types under IS-IS TLV 251 Application
   Identifier 1" registry as follows.

           +-----------+-------------------+------------------+
           |  Protocol |    Description    |    Reference     |
           +-----------+-------------------+------------------+
           |    TBD1   |  Smart-Parameters | [this document]  |
           |    TBD2   |     Smart-MAC     | [this document]  |
           +-----------+-------------------+------------------+

                                  Table 1

9.  Acknowledgements

   The contributions of the following persons are gratefully
   acknowledged: Mingui Zhang, Weiguo Hao, Linda Dunbar, Kesava Vijaya
   Krupakaran and Andrew Qu.

10.  References

10.1.  Informative References

   [IEEE802.1AE]
              "IEEE Standard for Local and metropolitan area networks--
              Media Access Control (MAC) Security.", 2006.

   [IEEE802.1X]
              "IEEE Standard for Local and metropolitan area networks--
              Port-Based Network Access Control", 2010.





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   [RFC7067]  Dunbar, L., Eastlake 3rd, D., Perlman, R., and I.
              Gashinsky, "Directory Assistance Problem and High-Level
              Design Proposal", RFC 7067, DOI 10.17487/RFC7067, November
              2013, <https://www.rfc-editor.org/info/rfc7067>.

   [RFC7379]  Li, Y., Hao, W., Perlman, R., Hudson, J., and H. Zhai,
              "Problem Statement and Goals for Active-Active Connection
              at the Transparent Interconnection of Lots of Links
              (TRILL) Edge", RFC 7379, DOI 10.17487/RFC7379, October
              2014, <https://www.rfc-editor.org/info/rfc7379>.

10.2.  Normative References

   [IS-IS]    ISO/IEC 10589:2002, Second Edition,, "Intermediate System
              to Intermediate System Intra-Domain Routing Exchange
              Protocol for use in Conjunction with the Protocol for
              Providing the Connectionless-mode Network Service (ISO
              8473)", 2002.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5310]  Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
              and M. Fanto, "IS-IS Generic Cryptographic
              Authentication", RFC 5310, DOI 10.17487/RFC5310, February
              2009, <https://www.rfc-editor.org/info/rfc5310>.

   [RFC6325]  Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
              Ghanwani, "Routing Bridges (RBridges): Base Protocol
              Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
              <https://www.rfc-editor.org/info/rfc6325>.

   [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,
              <https://www.rfc-editor.org/info/rfc7172>.

   [RFC7176]  Eastlake 3rd, D., Senevirathne, T., Ghanwani, A., Dutt,
              D., and A. Banerjee, "Transparent Interconnection of Lots
              of Links (TRILL) Use of IS-IS", RFC 7176,
              DOI 10.17487/RFC7176, May 2014,
              <https://www.rfc-editor.org/info/rfc7176>.






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   [RFC7357]  Zhai, H., Hu, F., Perlman, R., Eastlake 3rd, D., and O.
              Stokes, "Transparent Interconnection of Lots of Links
              (TRILL): End Station Address Distribution Information
              (ESADI) Protocol", RFC 7357, DOI 10.17487/RFC7357,
              September 2014, <https://www.rfc-editor.org/info/rfc7357>.

   [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,
              <https://www.rfc-editor.org/info/rfc7780>.

   [RFC8171]  Eastlake 3rd, D., Dunbar, L., Perlman, R., and Y. Li,
              "Transparent Interconnection of Lots of Links (TRILL):
              Edge Directory Assistance Mechanisms", RFC 8171,
              DOI 10.17487/RFC8171, June 2017,
              <https://www.rfc-editor.org/info/rfc8171>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Authors' Addresses

   Radia Perlman
   Dell EMC
   176 South Street
   Hopkinton, MA  01748
   USA

   Phone: +1-206-291-367
   Email: radiaperlman@gmail.com


   Fangwei Hu
   ZTE Corporation
   No.889 Bibo Rd
   Shanghai  201203
   China

   Phone: +86 21 68896273
   Email: hu.fangwei@zte.com.cn









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

   Phone: +1-508-634-2066
   Email: d3e3e3@gmail.com


   Ting Liao
   Huawei Technologies
   Nanjing, Jiangsu  210012
   China

   Email: liaoting1@huawei.com



































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