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Versions: (draft-perlman-trill-smart-endnodes) 00 01 02 03 04 05

TRILL WG                                                  Radia. Perlman
Internet-Draft                                           EMC Corporation
Intended status: Standards Track                             Fangwei. Hu
Expires: August 10, 2017                                 ZTE Corporation
                                                    Donald. Eastlake 3rd
                                                       Huawei technology
                                                      Kesava. Krupakaran
                                                                    Dell
                                                              Ting. Liao
                                                        February 6, 2017


                          TRILL Smart Endnodes
                 draft-ietf-trill-smart-endnodes-05.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 http://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 August 10, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://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.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Smart-Hello Mechanism between Smart Endnode and RBridge . . .   5
     4.1.  Smart-Hello Encapsulation . . . . . . . . . . . . . . . .   5
     4.2.  Edge RBridge's Smart-Hello  . . . . . . . . . . . . . . .   7
     4.3.  Smart Endnode's Smart-Hello . . . . . . . . . . . . . . .   7
   5.  Data Packet Processing  . . . . . . . . . . . . . . . . . . .   8
     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 . . . . . . . . . . . . . . . . . . . . .  12
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     10.1.  Informative References . . . . . . . . . . . . . . . . .  13
     10.2.  Normative References . . . . . . . . . . . . . . . . . .  13
   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 encapsulting to the incorrect egress RBridge, the
   traffic will get lost.

2.  Solution Overview

   The Smart Endnode solution proposed 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 the below figure as the example Smart Endnode scenario: RB1, RB2
   and RB3 are the RBridges in the TRILL domain, and smart SE1 and SE2
   are the smart ennodes which can encapsulate and decapsulate the TRILL
   packets.  RB1 is the edge RB and it is been attached by SE1 and SE2.
   RB1 assigns its nickname to 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 |-----+--| Endnode1 |
                 /  | +------+   +------+    +-----+     |  +----------+
  +----------+ /     \                                  /
  |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,
   and whether SE1 would like to receive ESADI packets.  The Smart-Hello
   is a light type of TRILL-hello formatted as a native RBridge Channel
   [RFC7178] message, which is used to announce the Smart Endnode
   capability and parameters (such as MAC address, VLAN ID etc.).  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.While 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.

3.  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.




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   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].

   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 named as transit RBridge.

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

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

4.  Smart-Hello Mechanism between Smart Endnode and RBridge

   The subsections below describe Smart-Hello messages.

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 end nodes it knows about on that link.

   The messages sent by Smart Endnodes and by edge RBridges that support
   Smart Endnodes are called "Smart-Hellos", and are carried through
   native RBridge Channel messages (see Section 4 of [RFC7178]).  They
   are structured as follows:







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            +----------+----------------+-------------+----------+
            | Ethernet | RBridge        | Smart-Hello | Ethernet |
            | Header   | Channel Header | Payload     | FCS      |
            +----------+----------------+-------------+----------+

                          Figure 2  Smart-Hello Structure

   In the Ethernet Header, the source MAC address is the address of the
   Smart Endnode or edge RBridge port on which the message is sent.  If
   the Smart-Hello is sent by a Smart Endnode and is multicast, the
   destination MAC address is All-Edge-RBridges.  If the Smart-Hello is
   unicast to an edge RBridge, the destination MAC address is the MAC
   address of the RBridge.  If the Smart-Hello is sent by an Edge
   RBridge and is multicast, the destination MAC address is TRILL-End-
   Stations, and if it is unicast to a Smart Endnode, the MAC address is
   the MAC address of the Smart Endnode.  The frame is sent in the
   Designated VLAN of the link so if a VLAN tag is present, it specifies
   that VLAN.  It is RECOMMENDED that Smart-Hellos be sent with priority
   7 to minimize the probability that they might be delayed or lost in
   any bridges that might be in the link.

   The RBridge Channel Header begins with the RBridge Channel Ethertype.
   In the RBridge Channel Header, the Channel Protocol number is as
   assigned by IANA (see Section 8) and in the flags field, the NA bit
   is one, the MH bit is zero and the setting of the SL bit is an
   implementation choice.

   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 3 Smart Parameters APPsub-TLV

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




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      Length: 4.

      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 Endndoes
      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.

      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.

   o  An Autentication 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 |RSV | VLAN/FGL Data Label  |  (2 bytes or 4 bytes)
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          MAC (1)       (6 bytes)                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      .................                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          MAC (N)       (6 bytes)                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 4 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.

   o  F: one bit.  If it sets to 1, which indicates that the endnode
      supports FGL data label, otherwise, the VLAN/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.

   o  RSV: 2 bits or 6 bits, is reserved for the future use.  If VLAN/
      FGL Data Label indicates the VLAN ID(F flag sets to 0), the RESV
      field is 2 bits long.  Otherwise it is 6 bits.

   o  VLAN/FGL Data Label: This carries a 12-bits VLAN identifier or
      24-bits FGL Data Label that is valid for all subsequent MAC
      addresses in this APPsub-TLV, or the value zero if no VLAN/FGL
      data label is specified.

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

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.







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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  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 with ingress
      nickname=the nicknamae 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 out of
      scope for this document.

   o  When SE1 wishes to send a a multi-destination (multicast, unknown
      unicast, or broadcast) 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 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 through native RBridge Channel messages.
   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 Forwarder for any of the VLANs that
   SE1 claims, RB1 MUST list SE1 in its Smart-Hellos as a Smart Endnode
   neighbor.







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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 MAY 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.

   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 listed as "smart endnode", RB1 leaves the
      packet encapsulated when forwarding to the smart endnode, and both
      the outer and inner Ethernet destination MAC is the destination
      smart endnod's MAC address, 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 an 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 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 .





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   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.  Another solution is
      that if there are one or more endnodes on a link, the non-Smart
      Endnodes are ignored on a link; but we can configure a port to
      support mixed links.  If RB1 is configured that the link is "Smart
      Endnode only", then it will only send and receive TRILL-
      encapsulated frames on that link.  If it is configured to "non-
      smart-endnodes only" on a port, it will only send and receive
      native frames from that port.

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 5 Multi-homing Scenario


   There are two candiated solutions for the mulit-homing scenario:





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   (1)  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 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).  One 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.  Another solution is 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]).

   (2)  Smart Endnode uses a virtual nickname when encapsulating and
        forwarding TRILL Data Packet.  The virtual nickname is carried
        in the RB1 and RB2's Smart-Hello, which is separate from RB1 and
        RB2's nicknames(The RB1 and RB's nicknames are also listed in
        their Smart-Hello).  In order to avoid RPF check issue for
        multi-destination frame, the affinity TLV[RFC7783] is used in
        this solution.  While how to deploy the affinity TLV in the
        multi-homing scenario is out of scope in this document.

7.  Security Considerations

   Smart-Hellos can be secured by using Authentication TLVs based on
   [RFC5310].

   For general TRILL Security Considerations, see [RFC6325].

   For native RBridge channel Security Considerations, see [RFC7178].

8.  IANA Considerations

   IANA is requested to allocate an RBridge Channel Protocol number
   (0x005 suggested) to indicate a Smart-Hello frame and update the
   "RBridge Channel Protocols" registry as follows.









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             +-------------+--------------+------------------+
             |   Protocol  | Description  |    Reference     |
             +-------------+--------------+------------------+
             |  TBD[0x005] | Smart-Hello  | [this document]  |
             +-------------+--------------+------------------+

                                  Table 1

   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-Hello  | [this document]  |
              |    TBD2   |  Smart-MAC   | [this document]  |
              +-----------+--------------+------------------+

                                  Table 2

9.  Acknowledgements

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

10.  References

10.1.  Informative References

   [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, <http://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, <http://www.rfc-editor.org/info/rfc7379>.

10.2.  Normative References

   [IS-IS]    ISO/IEC 10589:2002, Second Edition,, "opendaylight", 2002.






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   [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, <http://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,
              <http://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,
              <http://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,
              <http://www.rfc-editor.org/info/rfc7176>.

   [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>.

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

   [RFC7783]  Senevirathne, T., Pathangi, J., and J. Hudson,
              "Coordinated Multicast Trees (CMT) for Transparent
              Interconnection of Lots of Links (TRILL)", RFC 7783,
              DOI 10.17487/RFC7783, February 2016,
              <http://www.rfc-editor.org/info/rfc7783>.






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Authors' Addresses

   Radia Perlman
   EMC Corporation
   2010 156th Ave NE, suite #200
   Bellevue, WA  98007
   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


   Donald Eastlake,3rd
   Huawei technology
   155 Beaver Street
   Milford, MA 01757
   USA

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


   Kesava Vijaya Krupakaran
   Dell
   Olympia Technology Park
   Guindy Chennai   600 032
   India

   Phone: +91 44 4220 8496
   Email: Kesava_Vijaya_Krupak@Dell.com


   Ting Liao
   Nanjing, Jiangsu  210012
   China

   Email: liaoting82@163.com




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