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PROPOSED STANDARD
Internet Engineering Task Force (IETF)                        R. PerlmanRequest for Comments: 8384                                      Dell EMCCategory: Standards Track                                          F. HuISSN: 2070-1721                                          ZTE Corporation                                                         D. Eastlake 3rd                                                                 T. Liao                                                     Huawei Technologies                                                               July 2018Transparent Interconnection of Lots of Links (TRILL) Smart EndnodesAbstract   This document addresses the problem of the size and freshness of the   endnode learning table in edge Routing Bridges (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 endnodes that are   Fine-Grained Label (FGL) aware.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available inSection 2 of RFC 7841.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttps://www.rfc-editor.org/info/rfc8384.Perlman, et al.              Standards Track                    [Page 1]

RFC 8384                  TRILL Smart Endnodes                 July 2018Copyright Notice   Copyright (c) 2018 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (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 Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .32.  Conventions Used in This Document . . . . . . . . . . . . . .32.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .32.2.  Requirements Language . . . . . . . . . . . . . . . . . .43.  Solution Overview . . . . . . . . . . . . . . . . . . . . . .44.  Smart-Hello Mechanism between Smart Endnode and RBridge . . .64.1.  Smart-Hello Encapsulation . . . . . . . . . . . . . . . .64.2.  Edge RBridge's Smart-Hello  . . . . . . . . . . . . . . .84.3.  Smart Endnode's Smart-Hello . . . . . . . . . . . . . . .85.  Processing Data Packets . . . . . . . . . . . . . . . . . . .105.1.  Data-Packet Processing for Smart Endnodes . . . . . . . .105.2.  Data-Packet Processing for Edge RBridge . . . . . . . . .116.  Multihoming Scenario  . . . . . . . . . . . . . . . . . . . .127.  Security Considerations . . . . . . . . . . . . . . . . . . .138.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .149.  References  . . . . . . . . . . . . . . . . . . . . . . . . .159.1.  Normative References  . . . . . . . . . . . . . . . . . .159.2.  Informative References  . . . . . . . . . . . . . . . . .16   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .16   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .17Perlman, et al.              Standards Track                    [Page 2]

RFC 8384                  TRILL Smart Endnodes                 July 20181.  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   encapsulate efficiently, the edge RBridge must keep an "endnode   table" consisting of (Media Access Control (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 End Station   Address Distribution Information (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 a MAC   address / Data Label pair in the table have 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 Document2.1.  Terminology   BUM: Broadcast, Unknown unicast, and Multicast.   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].Perlman, et al.              Standards Track                    [Page 3]

RFC 8384                  TRILL Smart Endnodes                 July 2018   FGL: Fine-Grained Label [RFC7172].   IS-IS: Intermediate System to Intermediate System [IS-IS].   LSP: Link State PDU.   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 that exclusively forwards encapsulated   frames.  It is also called a transit TRILL Switch.   TRILL: Transparent Interconnection of Lots of Links   [RFC6325][RFC7780].   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 inBCP 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.Perlman, et al.              Standards Track                    [Page 4]

RFC 8384                  TRILL Smart Endnodes                 July 2018   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 that can encapsulate and decapsulate the TRILL   packets.  RB1 is the edge RB to which SE1 and SE2 have attached.  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, Data 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, Data Label, TRILL   egress switch nickname) for endnodes corresponding with SE1 or SE2,   but RB1 does decapsulate and does learn (MAC, Data 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, Data 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 it can be   deleted, even if the entry has not timed out.   If SE1 wishes to correspond with destination MAC D, and no endnode   entry exists, SE1 will encapsulate the packet as an unknown   destination, or consult 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 ScenarioPerlman, et al.              Standards Track                    [Page 5]

RFC 8384                  TRILL Smart Endnodes                 July 2018   The mechanism in this document 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 inSection 5 of   [RFC8171].  The detailed content for a Smart Endnode's Smart-Hello is   defined inSection 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 Link State PDUs (LSPs) or   Extended Level 1 Flooding Scope (E-L1FS) FS LSPs [RFC7780].   Since a Smart Endnode can encapsulate TRILL Data packets, it can   cause the Inner.Label 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.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].Perlman, et al.              Standards Track                    [Page 6]

RFC 8384                  TRILL Smart Endnodes                 July 2018   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 subsections.  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 22.   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 are 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.   o  Flags: At this time, all of the Flags are reserved and MUST be      sent as zero and ignored on receipt.   o  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-TLVs appear in a Smart-Hello, that      Smart-Hello is ignored.Perlman, et al.              Standards Track                    [Page 7]

RFC 8384                  TRILL Smart Endnodes                 July 20184.2.  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 inSection 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 inSection 2.3.4 in      [RFC7176], is reused here.   o  Smart Endnode neighbor list.  The TRILL Neighbor TLV, specified insection 2.5 in [RFC7176], is reused for this purpose.   o  An Authentication TLV MAY also be included.4.3.  Smart Endnode's Smart-Hello   A new APPsub-TLV (Smart-MAC TLV) for use by Smart Endnodes is 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 the Smart   Endnode's Smart-Hello.  This APPsub-TLV appears inside a TRILL   GENINFO TLV.Perlman, et al.              Standards Track                    [Page 8]

RFC 8384                  TRILL Smart Endnodes                 July 2018    +-+-+-+-+-+-+-+-+    |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 23.   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 six 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 multihoming (seeSection 6).  If it is set to 0, it indicates that the Smart      Endnodes are not using multihoming.   o  RSV: 6 bits; reserved for the future use.   o  VLAN/FGL Data Label: 24 bits.  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 are the VLAN of all      subsequent MAC addresses in this APPsub-TLV, and the upper 12 bits      are 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.Perlman, et al.              Standards Track                    [Page 9]

RFC 8384                  TRILL Smart Endnodes                 July 20185.  Processing Data Packets   The subsections below specify the processing of Smart Endnode data   packets.  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 Endnodes   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 the (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 Broadcast, Unknown Unicast, and      Multicast (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 mentioningPerlman, et al.              Standards Track                   [Page 10]

RFC 8384                  TRILL Smart Endnodes                 July 2018   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.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) is      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., endnodes that are not 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.Perlman, et al.              Standards Track                   [Page 11]

RFC 8384                  TRILL Smart Endnodes                 July 2018   o  If RB1 receives a native multi-destination data frame, which is      sent by an endnode that is not a Smart Endnode, from a port,      including hybrid endnodes (Smart Endnodes and endnodes that are      not 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.   o  If RB1 receives a multi-destination TRILL Data packet from a      remote RBridge, and the exit port includes hybrid endnodes (Smart      Endnodes and endnodes that are not Smart Endnodes), it sends two      copies of multicast frames out the port, one as native and the      other as a TRILL-encapsulated frame.  When a Smart Endnode      receives a multi-destination TRILL Data packet, it learns the      remote (MAC address, Data Label, nickname) entry.  A Smart Endnode      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 endnodes that are Smart and non-Smart to different ports is      RECOMMENDED.6.  Multihoming Scenario   Multihoming is a common scenario for the Smart Endnode.  The Smart   Endnode is on a link attached to the TRILL domain in two places: edge   RBridges RB1 and RB2.  Take Figure 4 as an 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: Multihoming ScenarioPerlman, et al.              Standards Track                   [Page 12]

RFC 8384                  TRILL Smart Endnodes                 July 2018   Smart Endnode SE1 can choose either the nickname of RB1 or RB2 when   encapsulating and forwarding a TRILL Data packet.  If the active-   active load balance is considered for the multihoming scenario, the   Smart Endnode SE1 could use both the nickname of RB1 and RB2 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).   The solution for the MAC flip-flopping issue is to set a multihoming   bit in the RSV field of the TRILL Data packet.  When remote RBridge   RB3 or Smart Endnodes receive a data packet with the multihomed 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 multihoming group.  The ESADI is deployed among   the edge RBridges (seeSection 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 (seeSection 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.Perlman, et al.              Standards Track                   [Page 13]

RFC 8384                  TRILL Smart Endnodes                 July 2018   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].   For added security against the compromise of data due to its   misdelivery 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 has allocated APPsub-TLV type numbers for the Smart-MAC and   Smart-Parameters APPsub-TLVs.  The "TRILL APPsub-TLV Types under   IS-IS TLV 251 Application Identifier 1" registry has been updated as   follows.              +-----------+-------------------+------------+              |  Protocol |    Description    | Reference  |              +-----------+-------------------+------------+              |     22    |  Smart-Parameters |RFC 8384  |              |     23    |     Smart-MAC     |RFC 8384  |              +-----------+-------------------+------------+                                  Table 1Perlman, et al.              Standards Track                   [Page 14]

RFC 8384                  TRILL Smart Endnodes                 July 20189.  References9.1.  Normative References   [IS-IS]    International Organization for Standardization,              "Information technology -- Telecommunications and              information exchange between systems -- Intermediate              System to Intermediate System intra-domain routeing              information exchange protocol for use in conjunction with              the protocol for providing the connectionless-mode network              service (ISO 8473)", ISO/IEC 10589:2002, Second Edition,              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>.   [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>.Perlman, et al.              Standards Track                   [Page 15]

RFC 8384                  TRILL Smart Endnodes                 July 2018   [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 inRFC2119 Key Words",BCP 14,RFC 8174, DOI 10.17487/RFC8174,              May 2017, <https://www.rfc-editor.org/info/rfc8174>.9.2.  Informative References   [IEEE802.1AE]              IEEE, "IEEE Standard for Local and metropolitan area              networks -- Media Access Control (MAC) Security",              IEEE 802.1AE.   [IEEE802.1X]              IEEE, "IEEE Standard for Local and metropolitan area              networks -- Port-Based Network Access Control",              IEEE 802.1X.   [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>.Acknowledgements   The contributions of the following persons are gratefully   acknowledged: Mingui Zhang, Weiguo Hao, Linda Dunbar, Kesava Vijaya   Krupakaran, and Andrew Qu.Perlman, et al.              Standards Track                   [Page 16]

RFC 8384                  TRILL Smart Endnodes                 July 2018Authors' Addresses   Radia Perlman   Dell EMC   176 South Street   Hopkinton, MA  01748   United States of America   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   Huawei Technologies   1424 Pro Shop Court   Davenport, FL 33896   United States of America   Phone: +1-508-333-2270   Email: d3e3e3@gmail.com   Ting Liao   Huawei Technologies   Nanjing, Jiangsu  210012   China   Email: liaoting1@huawei.comPerlman, et al.              Standards Track                   [Page 17]

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