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Versions: (draft-hu-trill-rbridge-esadi) 00 01 02 03 04 05 06 07 08 09

TRILL Working Group                                         Hongjun Zhai
INTERNET-DRAFT                                                Fangwei Hu
Intended status: Proposed Standard                                   ZTE
Updates: 6325                                              Radia Perlman
                                                              Intel Labs
                                                         Donald Eastlake
                                                                  Huawei
                                                             Olen Stokes
                                                        Extreme Networks
Expires: Decemeber 6, 2014                                  June 7, 2014


                                 TRILL:
     ESADI (End Station Address Distribution Information) Protocol
                    <draft-ietf-trill-esadi-09.txt>



Abstract

   The IETF TRILL (Transparent Interconnection of Lots of Links)
   protocol provides least cost pair-wise data forwarding without
   configuration in multi-hop networks with arbitrary topologies and
   link technologies.  TRILL supports multi-pathing of both unicast and
   multicast traffic.  Devices that implement the TRILL protocol are
   called TRILL Switches or RBridges (Routing Bridges).

   ESADI (End Station Address Distribution Information) is an optional
   protocol by which a TRILL switch can communicate, in a Data Label
   (VLAN or Fine Grained Label) scoped way, end station address and
   reachability information to TRILL switches participating in ESADI for
   the relevant Data Label.  This document updates RFC 6325,
   specifically the documentation of the ESADI protocol, and is not
   backwards compatible.




Status of This Memo

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

   Distribution of this document is unlimited. Comments should be sent
   to the TRILL working group mailing list: <trill@ietf.org>.

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





H. Zhai, et al                                                  [Page 1]

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

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











































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Table of Contents

      1. Introduction............................................4
      1.1 Content and Precedence.................................5
      1.2 Terminology............................................5

      2. ESADI Protocol Overview.................................7
      2.1 ESADI Virtual Link....................................10
      2.2 ESADI Neighbor Determination..........................11
      2.3 ESADI Payloads........................................11

      3. ESADI DRB (Designated RBridge) Determination...........13

      4. ESADI PDU processing...................................14
      4.1 Unicasting ESADI PDUs.................................14
      4.2 General Transmission of ESADI PDUs....................15
      4.3 General Receipt of ESADI PDUs.........................16
      4.4 ESADI Reliable Flooding...............................16

      5. End Station Addresses..................................18
      5.1 Learning Confidence Level.............................18
      5.2 Forgetting End Station Addresses......................18
      5.3 Duplicate MAC Address.................................18

      6. ESADI-LSP Contents.....................................21
      6.1 ESADI Parameter Data..................................21
      6.2 MAC Reachability TLV..................................23
      6.3 Default Authentication................................23

      7. IANA Considerations....................................25
      7.1 ESADI Participation and Capability Flags..............25
      7.2 TRILL GENINFO TLV.....................................26

      8. Security Considerations................................28
      8.1 Privacy Considerations................................28

      9. Acknowledgements.......................................30

      Normative references......................................31
      Informative References....................................32

      Appendix A: Interoperability and Changes to [RFC6325].....34
      A.1 ESADI PDU Changes.....................................34
      A.2 Unicasting Changes....................................35
      A.3 Message Timing Changes and Suggestions................35
      A.4 Duplicate Address Reachability........................35

      Appendix Z: Change History................................36

      Authors' Addresses........................................40


H. Zhai, et al                                                  [Page 3]

INTERNET-DRAFT                                              TRILL: ESADI


1. Introduction

   The IETF TRILL (Transparent Interconnection of Lots of Links)
   protocol [RFC6325] provides least cost pair-wise data forwarding
   without configuration in multi-hop networks with arbitrary topologies
   and link technologies, safe forwarding even during periods of
   temporary loops, and support for multi-pathing of both unicast and
   multicast traffic.  TRILL accomplishes this with the IS-IS
   (Intermediate System to Intermediate System) [IS-IS] [RFC1195]
   [RFC7176] link-state routing protocol using a header with a hop
   count.  The design supports optimization of the distribution of
   multi-destination frames and two types of data labeling: VLANs
   (Virtual Local Area Networks [RFC6325]) and FGLs (Fine Grained
   Labels, [RFC7172]).  Devices that implement TRILL are called TRILL
   switches or RBridges (Routing Bridges).

   There are five ways a TRILL switch can learn end station addresses,
   as described in Section 4.8 of [RFC6325].  One of these is the ESADI
   (End Station Address Distribution Information) protocol, which is an
   optional Data Label scoped way TRILL switches can communicate, with
   each other, information such as end station addresses and their TRILL
   switch of attachment. A TRILL switch that is announcing interest in a
   Data Label MAY use the ESADI protocol to announce the end station
   address of some or all of its attached end stations in that Data
   Label to other TRILL switches that are running ESADI for that Data
   Label. (In the future, ESADI may also be used for other address and
   reachability information.)

   By default, TRILL switches with connected end stations learn
   addresses from the data plane when ingressing and egressing native
   frames although such learning can be disabled. The ESADI protocol's
   potential advantages over data plane learning include the following:

   1. Security advantages: (1a) The ESADI protocol can be used to
      announce end stations with an authenticated enrollment (for
      example enrollment authenticated by cryptographically based EAP
      (Extensible Authentication Protocol [RFC3748]) methods via
      [802.1X]). (1b) The ESADI protocol supports cryptographic
      authentication of its message payloads for more secure
      transmission.

   2. Fast update advantages: The ESADI protocol provides a fast update
      of end station MAC (Media Access Control) addresses and their
      TRILL switch of attachment.  If an end station is unplugged from
      one TRILL switch and plugged into another, ingressed frames with
      that end station's MAC address as their destination can be black
      holed. That is, they can be sent just to the older egress TRILL
      switch that the end station was connected to until cached address
      information at some remote ingress TRILL switch times out,
      possibly for tens of seconds [RFC6325].


H. Zhai, et al                                                  [Page 4]

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   MAC address reachability information, some ESADI parameters, and
   optional authentication information are carried in ESADI packets
   rather than in the TRILL IS-IS protocol.  As specified below, ESADI
   is, for each Data Label, a virtual logical topology overlay in the
   TRILL topology. An advantage of using ESADI over using TRILL IS-IS is
   that the end station attachment information is not flooded to all
   TRILL switches but only to TRILL switches advertising ESADI
   participation for the Data Label in which those end stations occur.




1.1 Content and Precedence

   This document updates [RFC6325], the TRILL base protocol
   specification, obsoleting and replacing the description of the TRILL
   ESADI protocol (Section 4.2.5 of [RFC6325] including all
   subsections), providing more detail on ESADI, updating other ESADI
   related sections of [RFC6325], and prevailing over [RFC6325] in any
   case where they conflict. For this reason, familiarity with [RFC6325]
   is particularly assumed.  These changes include a change to the
   format of ESADI-LSPs that is not backwards compatible; this change is
   justified by the substantially increased amount of information that
   can be carried and in light of the very limited, if any, deployment
   of RFC 6325 ESADI.  These changes are further discussed in Appendix
   A.

   Section 2 of this document is the ESADI protocol overview. Section 3
   specifies ESADI DRB (Designated RBridge) determination.  Section 4
   discusses the processing of ESADI PDUs (Protocol Data Units). Section
   5 discusses interaction with other modes of end station address
   learning. And Section 6 describes the ESADI-LSP (Link State PDU) and
   its contents.




1.2 Terminology

   This document uses the acronyms defined in [RFC6325] and the
   following:

      Data Label - VLAN or FGL.

      ESADI RBridge - An RBridge that is participating in ESADI for one
            or more Data Labels.

      FGL - Fine Grained Label [RFC7172].

      LSP - Link State PDU [IS-IS].


H. Zhai, et al                                                  [Page 5]

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      LSP number zero - A Link State PDU with fragment number equal to
            zero.

      PDU - Protocol Data Unit.

      TRILL switch - an alternative name for an RBridge.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   Capitalized IANA Considerations terms such as "IETF Review" as to be
   interpreted as described in [RFC5226].







































H. Zhai, et al                                                  [Page 6]

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2. ESADI Protocol Overview

   ESADI is a Data Label scoped way for TRILL switches (also known as
   RBridges) to announce and learn end station addresses rapidly and
   securely.  An RBridge that is announcing participation in ESADI for
   one or more Data Labels is called an ESADI RBridge.

   ESADI is a separate optional protocol from the mandatory TRILL IS-IS
   implemented by all RBridges in a campus.  There is a separate ESADI
   instance for each Data Label (VLAN or FGL) if ESADI is being used for
   that Data Label. In essence, for each such Data Label, there is a
   modified instance of the IS-IS reliable flooding mechanism in which
   ESADI RBridges may choose to participate. (These are not the
   instances specified in [RFC6822].) Multiple ESADI instances may share
   implementation components within an RBridge as long as that sharing
   preserves the independent operation of each instance of the ESADI
   protocol. For example, the ESADI link state database could be in a
   single database with a field in each record indicating the Data Label
   to which it applies or could be a separate database per Data Label.
   But the ESADI update process operates separately for each ESADI
   instance and independently from the TRILL IS-IS update process.

   ESADI does no routing calculations so there is no reason for pseudo-
   nodes in ESADI and none are created (Pseudo-nodes [IS-IS] are a
   construct for optimizing routing calculations.) Furthermore, there
   may be a requirement for a relatively large amount of data to be
   distributed through ESADI which might take a large number of ESADI-
   LSP fragments. ESADI-LSP, ESADI-CSNP, and ESADI-PSNP (ESADI Link
   State PDU, Complete Sequence Number PDU, and Partial Sequence Number
   PDU) payloads are therefore formatted as Extended Level 1 Circuit
   Scope (E-L1CS) PDUs [FS-LSP] (see also Section 6). This allows up to
   2**16 fragments but does not support link state data associated with
   pseudo-nodes.

   After the TRILL header, ESADI packets have an inner Ethernet header
   with the Inner.MacDA of "All-Egress-RBridges" (formerly called "All-
   ESADI-RBridges"), an inner Data Label specifying the VLAN or FGL of
   interest, and the "L2-IS-IS" Ethertype followed by the ESADI payload
   as shown in Figure 1.













H. Zhai, et al                                                  [Page 7]

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                    +--------------------------------+
                    |          Link Header           |
                    +--------------------------------+
                    |       TRILL Data Header        |
                    +--------------------------------+
                    |   Inner Ethernet Addresses     |
                    +--------------------------------+
                    |           Data Label           |
                    +--------------------------------+
                    |       L2-IS-IS Ethertype       |
                    +--------------------------------+
                    |         ESADI Payload          |
                    +--------------------------------+
                    |          Link Trailer          |
                    +--------------------------------+

                   Figure 1. TRILL ESADI Packet Overview

   TRILL ESADI packets sent on an Ethernet link are structured as shown
   below.  The outer VLAN tag will not be present if it was not included
   by the Ethernet port that sent the packet.































H. Zhai, et al                                                  [Page 8]

INTERNET-DRAFT                                              TRILL: ESADI


   Outer Ethernet Header:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Next Hop Destination Address                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Next Hop Destination Addr.    | Sending RBridge Port MAC Addr.|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Sending RBridge Port MAC Address              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ...Ethernet frame tagging including optional Outer.VLAN tag...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Ethertype = TRILL      0x22F3 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   TRILL Header:                      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                      | V | R |M|Op-Length| Hop Count |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Egress Nickname               | Ingress (Origin) Nickname     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Inner Ethernet Header:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      All-Egress-RBridges                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | All-Egress-RBridges cont.     | Origin RBridge MAC Address    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                Origin RBridge MAC Address continued           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  VLAN or FGL Data Label (4 or 8 bytes) [RFC7172] ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Ethertype = L2-IS-IS   0x22F4 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ESADI Payload (formatted as IS-IS):
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | IS-IS Common Header, IS-IS PDU Specific Fields, IS-IS TLVs    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Frame Check Sequence:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  FCS (Frame Check Sequence)                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 2: ESADI Ethernet Link Packet Format

   The Next Hop Destination Address or Outer.MacDA is the All-RBridges
   multicast address if the ESADI PDU is being multicast. If it is being
   unicast, the Next Hop Destination Address is the unicast address of
   the next hop RBridge.  The VLAN for the Outer.VLAN information, if
   present, will be the Designated VLAN for the link on which the packet
   is sent. The V and R fields will be zero while the M field will be
   one unless the ESADI PDU was unicast, in which case the M field will
   be zero. The Data Label specified will be the VLAN or FGL to which
   the ESADI packet applies. The Origin RBridge MAC Address or
   Inner.MacSA MUST be a MAC address unique across the campus owned by


H. Zhai, et al                                                  [Page 9]

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   the RBridge originating the ESADI packet, for example, any of its
   port MAC addresses if it has any Ethernet ports, and each RBridge
   MUST use the same Inner.MacSA for all of the ESADI packets that
   RBridge originates.

   TRILL ESADI packets sent on a PPP link are structured as shown below
   [RFC6361].

   PPP Header:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | PPP = TNP (TRILL data) 0x005D |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   TRILL Header:                      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                      | V | R |M|Op-Length| Hop Count |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Egress Nickname               | Ingress (Origin) Nickname     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   Inner Ethernet Header:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      All-Egress-RBridges                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | All-Egress-RBridges cont.     | Origin RBridge MAC Address    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                Origin RBridge MAC Address continued           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  VLAN or FGL Data Label (4 or 8 bytes) [RFC7172] ...
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Ethertype = L2-IS-IS   0x22F4 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ESADI Payload (formatted as IS-IS):
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | IS-IS Common Header, IS-IS PDU Specific Fields, IS-IS TLVs    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   PPP Check Sequence:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       PPP Check Sequence                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                  Figure 3: ESADI PPP Link Packet Format




2.1 ESADI Virtual Link

   All RBridges forward ESADI packets as if they were ordinary TRILL
   Data packets.  Because of this forwarding, it appears to an instance
   of the ESADI protocol at an RBridge that it is directly connected by
   a multi-access virtual link to all RBridges in the campus that are
   data reachable from it (see Section 2 of [RFC7180]) and are running


H. Zhai, et al                                                 [Page 10]

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   ESADI for that Data Label. No "routing" calculation (least cost path
   or distribution tree construction) ever has to be performed by ESADI.
   An ESADI RBridge merely transmits the ESADI packets it originates on
   this virtual link as described for TRILL Data packets in [RFC6325]
   and [RFC7172]. For multicast ESADI packets it may use any
   distribution tree that it might use for an ordinary multi-destination
   TRILL Data packet. RBridges that do not implement the ESADI protocol,
   do not have it enabled, or are not participating for the Data Label
   of an ESADI packet do not decapsulate or locally process the TRILL
   ESADI packet.  Thus, ESADI packets are transparently tunneled through
   transit RBridges.




2.2 ESADI Neighbor Determination

   The ESADI instance for Data Label X at an RBridge RB1 determines who
   its adjacent ESADI neighbors are by examining the TRILL IS-IS link
   state database for RBridges that are data reachable from RB1 (see
   Section 2 of [RFC7180]) and are announcing their participation in
   Data Label X ESADI. When an RBridge RB2 becomes data unreachable from
   RB1 or the relevant entries for RB2 are purged from the core IS-IS
   link state database, it is lost as a neighbor and also dropped from
   any ESADI instances from the point of view of RB1, and when RB2 is no
   longer announcing participation in Data Label X ESADI, it ceases to
   be a neighbor for any Data Label X ESADI instance. All these
   considerations are Data Label scoped. Because of these mechanisms
   whereby an ESADI instance at an ESADI RBridge can determine its ESADI
   adjacencies by examining the TRILL IS-IS link state database, there
   are no "Hellos" sent in ESADI and no adjacency information is carried
   in ESADI-LSPs.

   Participation announcement in a VLAN scoped ESADI instance is through
   setting a flag bit in the Interested VLANs sub-TLV and announcement
   for an FGL scoped ESADI instance is through setting a flag bit in the
   Interested Labels sub-TLV [RFC7176]. (See Section 7.1)




2.3 ESADI Payloads

   TRILL ESADI packet payloads are structured like IS-IS Extended Level
   1 Circuit Scoped (E-L1CS) LSP, CSNP, and PSNP PDUs [FS-LSP], except
   as indicated below, but are always TRILL encapsulated on the wire as
   if they were TRILL Data packets.  The information distributed by the
   ESADI protocol includes a list of local end station MAC addresses
   connected to the originating RBridge and, for each such address, a
   one octet unsigned "confidence" rating in the range 0-254 (see


H. Zhai, et al                                                 [Page 11]

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   Section 6.2). It is entirely up to the originating RBridge which
   locally connected MAC addresses it wishes to advertise via ESADI and
   with what confidence. It MAY advertise all, some, or none of such
   addresses. In addition, some ESADI parameters of the advertising
   RBridge (see Section 6.1) and optionally authentication information
   (see Section 6.3) are included. Future uses of ESADI may distribute
   other similar address and reachability information.

   TRILL ESADI-LSPs MUST NOT contain a Data Label ID in their payload.
   The Data Label to which the ESADI data applies is the Data Label of
   the TRILL Data packet enclosing the ESADI payload. If a Data Label ID
   could occur within the payload, it might conflict with that TRILL
   Data packet Data Label and could conflict with any future Data Label
   mapping scheme that may be adopted [VLANmapping]. If a VLAN or FGL ID
   field within an ESADI-LSP PDU does include a value, that field's
   contents MUST be ignored.




































H. Zhai, et al                                                 [Page 12]

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3. ESADI DRB (Designated RBridge) Determination

   Because ESADI does no adjacency announcement or routing, the ESADI-
   DRB never creates a pseudonode. But a DRB (Designated RBridge
   [RFC7177]) is still needed for ESADI-LSP synchronization by issuing
   ESADI-CSNP PDUs and responding to ESADI-PSNP PDUs.

   Generally speaking, the DRB election on the ESADI virtual link (see
   Section 2.1) operates similarly to the DRB election on a TRILL IS-IS
   broadcast link, as described in Section 4.2.1 ("DRB Election
   Details") of [RFC7177], with the following exceptions: In the Data
   Label X ESADI-DRB election at RB1 on an ESADI virtual link, the
   candidates are the local ESADI instance for Data Label X and all
   remote ESADI instances at RBridges that (1) are data reachable from
   RB1 [RFC7180], and (2) are announcing in their TRILL IS-IS LSP that
   they are participating in ESADI for Data Label X. The winner is the
   instance with the highest ESADI Parameter 7-bit priority field with
   ties broken by System ID, comparing fields as unsigned integers with
   the larger magnitude considered higher priority. "SNPA/MAC address"
   is not considered in this tie breaking and there is no "Port ID".
































H. Zhai, et al                                                 [Page 13]

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4. ESADI PDU processing

   Data Label X ESADI neighbors are usually not connected directly by a
   physical link, but are always logically connected by a virtual link
   (see Section 2.1). There could be hundreds or thousands of ESADI
   RBridges (TRILL switches) on the virtual link.  There are only ESADI-
   LSP, ESADI-CSNP and ESADI-PSNP PDUs used in ESADI. In particular,
   there are no Hello or MTU PDUs because ESADI does not build a
   topology, does not do any routing calculations, and does not
   determine MTU, using the campus Sz. (Sz is the TRILL campus wide
   minimum link MTU (see [RFC6325] and [RFC7180]).)




4.1 Unicasting ESADI PDUs

   For [IS-IS], PDU multicasting is normal on a local link and no effort
   is made to optimize to unicast because on the typical physical link
   for which IS-IS was designed (commonly a piece of multi-access
   Ethernet cable) any frame made the link busy for that frame time. But
   to ESADI instances, what appears to be a simple multi-access link is
   generally a set of multi-hop distribution trees that may or may not
   be pruned.  Thus, transmitting a multicast frame on such a tree can
   impose a substantially greater load than transmitting a unicast
   frame. This load may be justified if there are likely to be multiple
   listeners but may not be justified if there is only one recipient of
   interest.  For this reason, under some circumstances, ESADI PDUs MAY
   be TRILL unicast if it is confirmed that the destination RBridge
   supports receiving unicast ESADI PDUs (see Section 6.1).

   The format of a unicast ESADI packet is the format of a multicast
   TRILL ESADI packet, in Section 2 above, except as follows:

   o  On an Ethernet link, in the Outer Ethernet Header the Outer.MacDA
      is the unicast address of the next hop RBridge.

   o  In the TRILL header, the M bit is set to zero and the Egress
      Nickname is the nickname of the destination RBridge.

   To support unicasting of ESADI PDUs, Section 4.6.2.2 of [RFC6325] is
   replaced with the following:

   "4.6.2.2. TRILL ESADI Packets

      If M=1, the egress nickname designates the distribution tree.  The
      packet is forwarded as described in Section 4.6.2.5.  In addition,
      if the forwarding RBridge is (1) interested in the specified VLAN
      or Fine Grained Label [RFC7172], (2) implements the TRILL ESADI
      protocol, and (3) ESADI is enabled for that VLAN or Fine Grained


H. Zhai, et al                                                 [Page 14]

INTERNET-DRAFT                                              TRILL: ESADI


      Label, the inner frame is decapsulated and provided to that local
      ESADI protocol.

      If M=0 and the egress nickname is not that of the receiving
      RBridge, the packet is forwarded as for known unicast TRILL Data
      in Section 4.6.2.4. If M=0 and the egress nickname is that of the
      receiving RBridge and the receiving RBridge supports unicast ESADI
      PDUs, then the ESADI packet is decapsulated and processed if it
      meets the three numbered conditions in the paragraph above,
      otherwise it is discarded."

   The references to "4.6.2.2", "4.6.2.4", and "4.6.2.5" above refer to
   those sections in [RFC6325].




4.2 General Transmission of ESADI PDUs

   Following the usual [IS-IS] rules, an ESADI instance does not
   transmit any ESADI PDUs if it has no ESADI adjacencies. Such
   transmission would just be a waste of bandwidth.

   The MTU available to ESADI payloads is at least 24 bytes less than
   that available to TRILL IS-IS because of the additional fields
   required ( 2(TRILL Ethertype) + 6(TRILL Header) + 6(Inner.MacDA) +
   6(Inner.MacSA) + 4/8(Data Label) bytes). Thus the inner ESADI
   payload, starting with the Intradomain Routeing Protocol
   Discriminator byte, MUST NOT exceed Sz minus 24 for a VLAN ESADI
   instance or Sz minus 28 for an FGL ESADI instance; however, if a
   larger payload is received, it is processed normally. (See [RFC6325]
   and [RFC7180] for discussions of Sz and MTU.)

   In all cases where this document says that an ESADI PDU is multicast,
   if the transmitting RBridge has only one neighbor and that neighbor
   advertises support for unicast, the PDU MAY be unicast (see Section
   4.1).

   A priority bit to indicate that an LSP fragment should be flooded
   with high priority is provided by [FS-LSP]. This bit SHOULD be set on
   ESADI-LSP fragment zero because it is important that the ESADI
   Parameters APPsub-TLV get through promptly.  This bit SHOULD NOT be
   set on other ESADI-LSP fragments to avoid giving undue priority to
   less urgent PDUs.








H. Zhai, et al                                                 [Page 15]

INTERNET-DRAFT                                              TRILL: ESADI


4.3 General Receipt of ESADI PDUs

   In contrast with layer 3 IS-IS PDU acceptance tests, which check the
   source inner and outer SNPA/MAC in order to verify that a PDU is from
   an adjacent TRILL switch, in TRILL ESADI, adjacency is based on
   system ID, so the system ID inside the PDU is all that is tested for.

   If an ESADI instance believes that it has no ESADI neighbors, it
   ignores any ESADI PDUs it receives.




4.4 ESADI Reliable Flooding

   The IS-IS reliable flooding mechanism (the Update Process) is
   modified for ESADI in the ways listed below. Except as otherwise
   stated, the ESADI update process works as described in [IS-IS],
   [RFC1195], and [FS-LSP].

   When an ESADI instance sees that it has a new ESADI neighbor, its
   self-originated ESADI-LSP fragments are scheduled to be sent and MAY
   be unicast to that neighbor if the neighbor is announcing in its LSP
   that it supports unicast ESADI (see Section 6.1). If all the other
   ESADI instances for the same Data Label send their self-originated
   ESADI-LSPs immediately, there may be a surge of traffic to that new
   neighbor. So the ESADI instances SHOULD wait an interval of time
   before sending their ESADI-LSP(s) to a new neighbor.  The interval
   time value is up to the device implementation. One suggestion is that
   the interval time can be assigned a random value with a range based
   on the RBridge's nickname (or any one of its nicknames if it holds
   more than one) such as ( 2000 * nickname / 2**16 ) milliseconds
   assuming "nickname" to be an unsigned quantity.

   All the TRILL switches participating in an ESADI instance for some
   Data Label appear to ESADI to be adjacent. Thus the originator of any
   active ESADI-LSP fragment always appears to be on link and, to spread
   the burden of such response, could be the RBridge to respond to any
   ESADI-CSNP or PSNP request for that fragment. However, under very
   rare circumstances, it could be that some version of the LSP fragment
   with a higher sequence number is actually held by another ESADI
   RBridge on the link, so non-originators need to be able to respond
   eventually.  Thus, when the receipt of a CSNP or PSNP causes the
   SRMflag (Send Routing Message flag [IS-IS]) to be set for an LSP
   fragment, action is as specified in [IS-IS] for the originating ESADI
   RBridge of the fragment; however, at a non-originating ESADI RBridge,
   when changing the SRMflag from 0 to 1, the lastSent timestamp [IS-IS]
   is also set to the current time minus

              minimumLSPTimeInterval * Random (Jitter) / 100


H. Zhai, et al                                                 [Page 16]

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   (where minimumLSPTimeInterval, Random, and Jitter are as in [IS-IS]).
   This will delay and jitter the transmission of the LSP fragment by
   non-originators. This gives the originator more time to send the
   fragment and provides more time for such an originator transmitted
   copy to traverse the likely multi-hop path to non-originators and
   clear the SRMflag for the fragment at non-originators.

   The multi-hop distribution tree method with Reverse Path Forwarding
   Check used for multicast distribution by TRILL will typically be less
   reliable than transmission over a single local broadcast link hop.
   For LSP synchronization robustness, in addition to sending ESADI-
   CSNPs as usual when it is DRB, an ESADI RBridge SHOULD also transmit
   an ESADI-CSNP for an ESADI instance if all of the following
   conditions are met:

   o  it sees one or more ESADI neighbors for that instance, and
   o  it does not believe it is DRB for the ESADI instance, and
   o  it has not received or sent an ESADI-CSNP PDU for the instance for
      the average of the CSNP Time (see Section 6.1) of the DRB and its
      CSNP Time.
































H. Zhai, et al                                                 [Page 17]

INTERNET-DRAFT                                              TRILL: ESADI


5. End Station Addresses

   The subsections below discuss end station address considerations in
   the context of ESADI.




5.1 Learning Confidence Level

   The confidence level mechanism [RFC6325] allows an RBridge campus
   manager to cause certain address learning sources to prevail over
   others. MAC address information learned through a registration
   protocol, such as [802.1X] with a cryptographically based EAP
   [RFC3748] method, might be considered more reliable than information
   learned through the mere observation of data traffic.  When such
   authenticated learned address information is transmitted via the
   ESADI protocol, the use of authentication in the TRILL ESADI-LSP
   packets could make tampering with it in transit very difficult.  As a
   result, it might be reasonable to announce such authenticated
   information via the ESADI protocol with a high confidence, so it
   would be used in preference to any alternative learning from data
   observation.




5.2 Forgetting End Station Addresses

   The end station addresses learned through the TRILL ESADI protocol
   should be forgotten through changes in ESADI-LSPs. The time out of
   the learned end station address is up to the originating RBridge that
   decides when to remove such information from its ESADI-LSPs (or up to
   ESADI protocol timeouts if the originating RBridge becomes
   unreachable).

   If RBridge RBn participating in the TRILL ESADI protocol for Data
   Label X no longer wishes to participate in ESADI, it ceases to
   participate by (1) clearing the ESADI participation bit in the
   appropriate Interested VLANs or Interested Labels sub-TLV and (2)
   sending a final ESADI-LSP nulling out its ESADI-LSP information.




5.3 Duplicate MAC Address

   With ESADI, it is possible to persistently see occurrences of the
   same MAC address in the same Data Label being advertised as reachable
   by two or more RBridges. The specification of how to handle this


H. Zhai, et al                                                 [Page 18]

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   situation in [RFC6325] is updated by replacing the last sentence of
   the last paragraph of Section 4.2.6 of [RFC6325] as shown below to
   provide better traffic spreading while avoiding possible address
   flip-flopping.

   As background, assume some end station or set of end stations ESn
   have two or more ports with the same MAC address in the same Data
   Label with the ports connected to different RBridges (RB1, RB2, ...)
   by separate links.  With ESADI, some other RBridge, RB0, can
   persistently see that MAC address in that Data Label connected to
   multiple RBridges. When RB0 ingresses a frame, say from ES0, destined
   for that MAC and label, the current [RFC6325] text permits a wide
   range of behavior.  In particular, [RFC6325] would permit RB0 to use
   some rule such as always encapsulate to the egress with the lowest
   System ID, which would put all of this traffic through only one of
   the egress RBridges and one of the end station ports.  With that
   behavior, there would be no load spreading, even if there were
   multiple different ingress RBridges and/or different MAC addresses
   with the same reachability. [RFC6325] also would also permit RB0 to
   send different traffic to different egresses by doing ECMP at a flow
   level, which would likely result in return traffic for RB0 to egress
   to ES0 from various of RB1, RB2, ... for the same MAC and label. The
   resulting address reachability flip-flopping perceived at RB0 could
   cause problems.

   This update to [RFC6325] avoids these potential difficulties by
   requiring RB0 to use one of the following two policies: (1) only
   encapsulate to one egress RBridge for any particular MAC and label
   but to select that egress pseudo-randomly based on the topology
   including MAC reachability or (2) if it will not be disturbed by the
   returning TRILL Data packets showing the same MAC and label flip-
   flopping between different ingresses, it may use ECMP.  Assuming
   multiple ingress RBridges and/or multiple MAC and label addresses,
   strategy 1 should result in load spreading without address flip-
   flopping while strategy 2 will produce better load spreading than
   strategy 1 but with address flip-flopping from the point of view of
   RB0.

   OLD [RFC6325] Section 4.2.6 text:
      "... If confidences are also tied between the duplicates, for
      consistency it is suggested that RB2 direct all such frames (or
      all such frames in the same ECMP flow) toward the same egress
      RBridge; however, the use of other policies will not cause a
      network problem since transit RBridges do not examine the
      Inner.MacDA for known unicast frames."

   NEW [RFC6325] Section 4.2.6 text:
      "...

      If confidences are also tied between the duplicates then RB2 MUST


H. Zhai, et al                                                 [Page 19]

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      adopt one of the following two strategies:

      1. In a pseudo-random way [RFC4086], select one of the egress
         RBridges that is least cost from RB2 and to which the
         destination MAC appears to be attached and send all traffic for
         the destination MAC and VLAN (or FGL [RFC7172]) to that egress.
         This pseudo-random choice need only be changed when there is a
         change in campus topology or MAC attachment information. Such
         pseudo-random selection will, over a population of ingress
         RBridges, probabilistically spread traffic over the possible
         egress RBridges. Reasonable inputs to the pseudo-random
         selection are the ingress RBridge System ID and/or nickname,
         the VLAN or FGL, the destination MAC address, and a vector of
         the RBridges with connectivity to that MAC and VLAN or FGL.
         There is no need for different RBridges to use the same pseudo-
         random function.

         As an example of such a pseudo-random function, if there are k
         egress RBridges (RB0, RB1, ..., RB(k-1)) all reporting
         attachment to address MACx in Data Label DLy, then an ingress
         RBridge RBin could select the one to which it will send all
         unicast TRILL Data packets addressed to MACx in DLy based on
         the following:

            FNV-32(RBin | MACx | DLy | RB0 | RB1 | ... | RB(k-1)) mod k

            where FNV is specified in [FNV], RBx means the nickname for
            RBridge RBx, "|" means concatenation, MACx is the
            destination MAC address, DLy is the Data Label, and "mod k"
            means the integer division remainder of the output of the
            FNV-32 function considered as a positive integer divided by
            k.

      2. If RB2 supports ECMP and will not be disturbed by return
         traffic from the same MAC and VLAN (or FGL [RFC7172]) coming
         from a variety of different RBridges, then it MAY send traffic
         using ECMP at the flow level to the egress RBridges that are
         least cost from RB2 and to which the destination MAC appears to
         be attached."













H. Zhai, et al                                                 [Page 20]

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6. ESADI-LSP Contents

   The only PDUs used in ESADI are the ESADI-LSP, ESADI-CSNP, and ESADI-
   PSNP PDUs. Currently, the contents of an ESADI-LSP consists of zero
   or more MAC Reachability TLVs, optionally an Authentication TLV, and
   exactly one ESADI parameter APPsub-TLV. Other similar data may be
   included in the future and, as in [IS-IS], an ESADI instance ignores
   any TLVs or sub-TLVs it does not understand. Because these PDUs are
   formatted as Extended Level 1 Circuit Scope (E-L1CS) PDUs [FS-LSP],
   the Type and Length fields in the TLVs are 16-bit.

   This section specifies the format for the ESADI parameter data
   APPsub-TLV, gives the reference for the ESADI MAC Reachability TLV,
   and discusses default authentication configuration.

   For robustness, the payload for an ESADI-LSP number zero and any
   ESADI-CSNP or ESADI-PSNP covering fragment zero MUST NOT exceed 1470
   minus 24 bytes in length (1446 bytes) if it has an Inner.VLAN or 1470
   minus 28 bytes (1442 bytes) if it has an Inner.FGL.  But if an ESADI-
   LSP number zero or such an ESADI-CSNP or ESADI-PSNP is received that
   is longer, it is still processed normally. (As stated in Section
   4.3.1 of [RFC6325], 1470 bytes was chosen to make it extremely
   unlikely that a TRILL control packet, even with reasonable additional
   headers, tags, and/or encapsulation, would encounter MTU problems on
   an inter-RBridge link.)




6.1 ESADI Parameter Data

   The figure below presents the format of the ESADI parameter data.
   This APPsub-TLV MUST be included in a TRILL GENINFO TLV in ESADI-LSP
   number zero. If it is missing from ESADI-LSP number zero or if ESADI-
   LSP number zero is not known, priority for the sending RBridge
   defaults to 0x40 and CSNP Time defaults to 30. If there is more than
   one occurrence in ESADI-LSP number zero, the first occurrence will be
   used. Occurrences of the ESADI parameter data APPsub-TLV in non-zero
   ESADI-LSP fragments are ignored.













H. Zhai, et al                                                 [Page 21]

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            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            | Type                          |   (2 bytes)
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            | Length                        |   (2 bytes)
            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            |R| Priority    |                   (1 byte)
            +-+-+-+-+-+-+-+-+
            | CSNP Time     |                   (1 byte)
            +-+-+-+-+-+-+-+-+
            | Flags         |                   (1 byte)
            +---------------+
            | Reserved for expansion            (variable)
            +-+-+-+-...

                   Figure 4. ESADI Parameter APPsub-TLV

   Type: set to ESADI-PARAM subTLV (TRILL APPsub-TLV type 0x0001). Two
      bytes because this APPsub-TLV appears in an Extended TLV [FS-LSP].

   Length: Variable with a minimum of 3 but must fit within the ESADI
      packet. This field is encoded as an unsigned integer in network
      byte order [FS-LSP].

   R: A reserved bit that MUST be sent as zero and ignored on receipt.

   Priority: The Priority field gives the originating RBridge's priority
      for being DRB on the ESADI instance virtual link (see Section 3)
      for the Data Label in which the PDU containing the parameter data
      was sent. It is an unsigned seven-bit integer with larger
      magnitude indication higher priority.  It defaults to 0x40 for an
      RBridge participating in ESADI for which it has not been
      configured.

   CSNP Time: An unsigned byte that gives the amount of time in seconds
      during which the originating RBridge, if it is DRB on the ESADI
      virtual link, will send at least three EASDI-CSNP PDUs. It
      defaults to 30 seconds for an RBridge participating in ESADI for
      which it has not been configured.

   Flags: A byte of flags associated with the originating ESADI instance
      as follows:

                  0   1   2   3   4   5   6   7
               +---+---+---+---+---+---+---+---+
               | UN|           RESV            |
               +---+---+---+---+---+---+---+---+

         The UN flag indicates that the RBridge originating the ESADI-
         LSP, including this ESADI Parameter Data, will accept and
         properly process ESADI PDUs sent by TRILL unicast (see Section


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INTERNET-DRAFT                                              TRILL: ESADI


         4.1). The remaining RESV bits are reserved for future use and
         MUST be sent as zero and ignored on receipt.

   Reserved for future expansion: Future versions of the ESADI
      Parameters APPsub-TLV may have additional information. A receiving
      ESADI RBridge ignores any additional data here unless it
      implements such future expansion(s).




6.2 MAC Reachability TLV

   The primary information in TRILL ESADI-LSP PDUs consists of MAC
   Reachability (MAC-RI) TLVs specified in [RFC6165].  These TLVs
   contain one or more unicast MAC addresses of end stations that are
   both on a port and in a VLAN for which the originating RBridge is
   appointed forwarder, along with the one octet unsigned Confidence in
   this information with a value in the range 0-254. If such a TLV is
   received containing a confidence of 255, it is treated as if the
   confidence was 254. (This is to assure that any received address
   information can be overridden by local address information statically
   configured with a Confidence of 255.)

   The TLVs in TRILL ESADI PDUs, including the MAC-RI TLV, MUST NOT
   contain the Data Label ID. If a Data Label ID is present in the MAC-
   RI TLV, it is ignored. In the ESADI PDU, only the Inner.VLAN or
   Inner.FGL tag indicates the Data Label to which the ESADI-LSP
   applies.




6.3 Default Authentication

   The Authentication TLV may be included in ESADI PDUs [RFC5310] [IS-
   IS]. The default for ESADI PDU Authentication is based on the state
   of TRILL IS-IS shared secret authentication for TRILL IS-IS LSP PDUs.
   If TRILL IS-IS authentication and ESADI are implemented at a TRILL
   switch, then ESADI MUST be able to use the authentication algorithms
   implemented for TRILL IS-IS and implement the keying material
   derivation function given below.  If ESADI authentication has been
   manually configured, that configuration is not restricted by the
   configuration of TRILL IS-IS security.

   If TRILL IS-IS authentication is not in effect for LSP PDUs
   originated by a TRILL switch then, by default, ESADI PDUs originated
   by that TRILL switch are also unsecured.

   If such IS-IS LSP PDU authentication is in effect at a TRILL switch


H. Zhai, et al                                                 [Page 23]

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   then, unless configured otherwise, ESADI PDUs sent by that switch
   MUST use the same algorithm in their Authentication TLVs.  The ESADI
   authentication keying material used is derived from the IS-IS LSP
   shared secret keying material as detailed below. However, such
   authentication MAY be configured to use some other keying material.

        HMAC-SHA256 ( "TRILL ESADI", IS-IS-LSP-shared-key )

   In the above HMAC-SHA256 is as described in [FIPS180] [RFC6234] and
   "TRILL ESADI" is the eleven byte US ASCII [ASCII] string indicated.
   IS-IS-LSP-shared-key is secret keying material being used by the
   originating TRILL switch for IS-IS LSP authentication.








































H. Zhai, et al                                                 [Page 24]

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7. IANA Considerations

   IANA allocation and registry considerations are given below. Three
   new sub-registries are created in the TRILL Parameters registry
   located at http://www.iana.org/assignments/trill-parameters, two in
   Section 7.1 and one in Section 7.2, and various code points assigned.




7.1 ESADI Participation and Capability Flags

   IANA Action 1:

   IANA is requested to create the following new sub-registry called
   "Interested VLANs Flag Bits" in the TRILL Parameters registry.

      Sub-Registry: Interested VLANs Flag Bits

      Registration Procedures: IETF Review

      Note: These bits appear in the Interested VLANs record within the
      Interested VLANs and Spanning Tree Roots Sub-TLV (INT-VLAN)
      specified in [RFC7176].

      References: [RFC7176], [This document]

         Bit  Mnemonic  Description                      Reference
         ---  --------  -----------                      ---------
           0     M4     IPv4 Multicast Router Attached   [RFC7176]
           1     M6     IPv6 Multicast Router Attached   [RFC7176]
           2      -     Unassigned
           3     ES     ESADI Participation              This document
          4-15    -     (used for a VLAN ID)             [RFC7176]
         16-19    -     Unassigned
         20-31    -     (used for a VLAN ID)             [RFC7176]

   The creation of this sub-registry as immediately above assigns bit 3
   as the ESADI Participation bit in the Interested VLANs and Spanning
   Tree Roots Sub-TLV. If The ESADI Participation bit is a one, it
   indicates that the originating RBridge is participating in ESADI for
   the indicated Data Label(s).

   IANA Action 2:

   IANA is requested to create the following new sub-registry called
   "Interested Labels Flag Bits" in the TRILL Parameters registry.





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      Sub-Registry: Interested Labels Flag Bits

      Registration Procedures: IETF Review

      Note: These bits appear in the Interested Labels record within the
      Interested Labels and Spanning Tree Roots Sub-TLV (INT-LABEL)
      specified in [RFC7176].

      References: [RFC7176], [this document]

         Bit  Mnemonic  Description                      Reference
         ---  --------  -----------                      ---------
           0     M4     IPv4 Multicast Router Attached   [RFC7176]
           1     M6     IPv6 Multicast Router Attached   [RFC7176]
           2     BM     Bit Map                          [RFC7176]
           3     ES     ESADI Participation              This document
          4-7     -     Unassigned

   The creation of this sub-registry as immediately above assigns bit 3
   as the ESADI Participation bit in the Interested Labels and Spanning
   Tree Roots Sub-TLV. If The ESADI Participation bit is a one, it
   indicates that the originating RBridge is participating in ESADI for
   the indicated Data Label(s).




7.2 TRILL GENINFO TLV

   IANA Action 3:

      IANA is requested to allocate the IS-IS Application Identifier TBD
      [1 suggested] under the Generic Information TLV (#251) [RFC6823]
      for TRILL.

   IANA Action 4:

   IANA is requested to create a subregistry in the TRILL Parameters
   Registry as follows:













H. Zhai, et al                                                 [Page 26]

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      Sub-Registry:  TRILL APPsub-TLV Types under IS-IS TLV #251
                     Application Identifier #TBD

      Registration Procedures: IETF Review with additional
            requirements on the documentation of the use being
            registered as specified in Section 7.2 of <this
            document>.

      Note: Types greater than 255 are only usable in contexts
            permitting a type larger than one byte, such as Extended
            TLVs [FS-LSP].

      Reference: <this RFC>

               Type      Name              Reference
            ----------  --------          -----------
                    0   Reserved          <this RFC>
                    1   ESADI-PARAM       <this RFC>
                2-254   Unassigned        <this RFC>
                  255   Reserved          <this RFC>
            256-65534   Unassigned        <this RFC>
                65535   Reserved          <this RFC>

   TRILL APPsub-TLV Types 2 through 254 and 256 through 65534 are
   available for assignment by IETF Review. The RFC causing such an
   assignment will also include a discussion of security issues and of
   the rate of change of the information being advertised.  TRILL
   APPsub-TLVs MUST NOT alter basic IS-IS protocol operation including
   the establishment of adjacencies, the update process, and the
   decision process for TRILL IS-IS [IS-IS], [RFC1195], [RFC7177]. The
   TRILL Generic Information TLV MUST NOT be used in an IS-IS instance
   zero [RFC6822] LSP but may be used in FS-LSPs [FS-LSP].

   The V, I, D, and S flags in the initial flags byte of a TRILL Generic
   Information TLV have the meanings specified in [RFC6823] but are not
   currently used as TRILL operates as a Level 1 IS-IS area and no
   semantics are hereby assigned to the inclusion of an IPv4 and/or IPv6
   address via the I and V flags. Thus these I and V flags MUST be zero;
   however, if either or both is one, the space that should be taken by
   and IPv4 and/or IPv6 address respectively is skipped over and
   ignored.  Furthermore, use of multi-level IS-IS is an obvious
   extension for TRILL [MultiLevel] and future IETF Standards Actions
   may update or obsolete this specification to provide for the use of
   any or all of these flags in the TRILL GENINFO TLV.

   The ESADI Parameters information, for which TRILL APPsub-TLV 1 is
   hereby assigned, is compact and slow changing (see Section 6.1).

   For Security Considerations related to ESADI and the ESADI parameters
   APPsub-TLV, see Section 8.


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8. Security Considerations

   ESADI PDUs can be authenticated through the inclusion of the
   Authentication TLV [RFC5310]. Defaults for such authentication are
   described in Section 6.3.

   The ESADI-LSP data primarily announces MAC address reachability
   within a Data Label. Such reachability can, in some cases, be an
   authenticated registration (for example, a layer 2 authenticated
   registration using cryptographically based EAP (Extensible
   Authentication Protocol [RFC3748]) methods via [802.1X]). The
   combination of these techniques can cause EASDI MAC reachability
   information to be substantially more trustworthy than MAC
   reachability learned from observation of the data plane.
   Nevertheless, ESADI still involves trusting all other RBridges in the
   TRILL campus, at least those that have the keying material necessary
   to construct a valid Authentication TLV.

   However, there may be cases where it is not necessary to authenticate
   ESADI PDUs despite using authenticated registration for end stations
   because of a significant threat of forged packets on end station
   links when that threat is not present for inter-RBridge trunks.  For
   example a TRILL campus with secure RBridges and inter-RBridge links
   configured as trunks but some end stations connected via IEEE 802.11
   wireless access links might use 802.11 authentication for the
   connection of such end stations but not necessarily authenticate
   ESADI PDUs. Note that if the IS-IS LSPs in a TRILL campus are
   authenticated, perhaps due to a concern about forged packets, the
   ESADI PDUs will be authenticated by default as provided in Section
   6.3.

   MAC reachability learned from the data plane (the TRILL default) is
   overwritten by any future learning of the same type. ESADI
   advertisements are represented in Data Label scoped link state
   database. Thus ESADI makes visible any multiple attachments of the
   same MAC address within a Data Label to different RBridges (see
   Section 5.3). This may or may not be an error or misconfiguration but
   ESADI at least makes it explicitly and persistently visible, which
   would not be the case with data plane learning.

   For general TRILL Security Considerations, see [RFC6325].




8.1 Privacy Considerations

   The address reachability information distributed by ESADI has
   substantial privacy considerations under many, but not all,
   circumstances.


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   For example, if ESADI were used in a TRILL campus with independent
   user end stations at the edge, the MAC addresses of such end stations
   could uniquely identify the users of those end stations.  Their
   reachability would be sensitive information and, particularly if
   logged, be revealing of their users.  On the other hand, if TRILL is
   being used to implement an Internet Exchange Point (IXP) to connect
   Internet Service Providers (ISPs), the MAC addresses being advertised
   in ESADI would typically be those of the ISP's directly connected IP
   router ports, since Layer 3 routers bound the TRILL campus, for which
   there would be few privacy concerns.

   However, records of MAC attachment, including a modest amount of
   history, perhaps a few days worth, can be useful in managing a
   network and troubleshooting network problems. It might, in some
   cases, also be legally required or required for billing purposes or
   the like.

   Network operators should seek a reasonable balance between these
   competing considerations for the circumstances of their particular
   networks where ESADI is in use. They should not maintain logs of MAC
   reachability information for any longer than is clearly required.































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9. Acknowledgements

   The authors thank the following, listed in alphabetic order, for
   their suggestions and contributions:

      David Black, Somnath Chatterjee, Adrian Farrel, Stephen Farrell,
      Sujay Gupta, Russ Housley, Pearl Liang, Kathleen Moriarty, Thomas
      Narten, Erik Nordmark, and Mingui Zhang.

   This document was produced with raw nroff. All macros used were
   defined in the source file.









































H. Zhai, et al                                                 [Page 30]

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Normative references

   [ASCII] - American National Standards Institute (formerly United
         States of America Standards Institute), "USA Code for
         Information Interchange", ANSI X3.4-1968, 1968.  ANSI X3.4-1968
         has been replaced by newer versions with slight modifications,
         but the 1968 version remains definitive for the Internet.

   [FIPS180] - "Secure Hash Standard (SHS)", United States of American,
         National Institute of Science and Technology, Federal
         Information Processing Standard (FIPS) 180-4, March 2012,
         http://csrc.nist.gov/publications/fips/fips180-4/fips-180-4.pdf

   [FS-LSP] - Ginsberg, L., S. Previdi, Y. Yang, "IS-IS Flooding Scope
         LSPs", draft-ietf-isis-fs-lsp, in RFC Editor's queue.

   [IS-IS] - International Organization for Standardization,
         "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, Nov
         2002.

   [RFC1195] - Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
         dual environments", RFC 1195, December 1990.

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

   [RFC4086] - Eastlake 3rd, D., Schiller, J., and S. Crocker,
         "Randomness Requirements for Security", BCP 106, RFC 4086, June
         2005.

   [RFC5226] - Narten, T. and H. Alvestrand, "Guidelines for Writing an
         IANA Considerations Section in RFCs", BCP 26, RFC 5226, May
         2008.

   [RFC5310] - Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
         and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC
         5310, February 2009.

   [RFC6165] - Banerjee, A. and D. Ward, "Extensions to IS-IS for
         Layer-2 Systems", RFC 6165, April 2011.

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

   [RFC6361] - Carlson, J. and D. Eastlake 3rd, "PPP Transparent
         Interconnection of Lots of Links (TRILL) Protocol Control


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         Protocol", RFC 6361, August 2011.

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

   [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, May 2014.

   [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, May 2014.

   [RFC7177] - Eastlake 3rd, D., Perlman, R., Ghanwani, A., Yang, H.,
         and V. Manral, "Transparent Interconnection of Lots of Links
         (TRILL): Adjacency", RFC 7177, May 2014.

   [RFC7180] - Eastlake 3rd, D., Zhang, M., Ghanwani, A., Manral, V.,
         and A. Banerjee, "Transparent Interconnection of Lots of Links
         (TRILL): Clarifications, Corrections, and Updates", RFC 7180,
         May 2014.




Informative References

   [802.1X] - IEEE 802.1, "IEEE Standard for Local and metropolitan area
         networks / Port-Based Network Access Control", IEEE Std
         802.1X-2010, 5 February 2010.

   [FNV] - G. Fowler, L. Noll, K. Vo & D. Eastlake, "The FNV Non-
         Cryptographic Hash Algorithm", draft-eastlake-fnv, Work in
         progress.

   [RFC3748] - Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
         Levkowetz, Ed., "Extensible Authentication Protocol (EAP)", RFC
         3748, June 2004.

   [RFC6234] - Eastlake 3rd, D. and T. Hansen, "US Secure Hash
         Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, May
         2011.

   [RFC6822] - Previdi, S., Ed., Ginsberg, L., Shand, M., Roy, A., and
         D. Ward, "IS-IS Multi-Instance", RFC 6822, December 2012.

   [MultiLevel] - Perlman, R., D. Eastlake, A. Ghanwani, H. Zhai,
         "Multilevel TRILL (Transparent Interconnection of Lots of
         Links)", draft-perlman-trill-rbridge-multilevel, work in
         progress.


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   [VLANmapping] - Perlman, R., D. Dutt, A. Banerjee, A. Rijhsinghani,
         and D. Eastlake, "RBridges: Campus VLAN and Priority Regions",
         draft-ietf-trill-rbridge-vlan-mapping, work in progress.

















































H. Zhai, et al                                                 [Page 33]

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Appendix A: Interoperability and Changes to [RFC6325]

   This appendix summarizes the significant changes this document makes
   to the TRILL base protocol specification [RFC6325].  Although
   simultaneous use of [RFC6325] ESADI and ESADI as specified in this
   document in a TRILL campus is very unlikely due to non-deployment of
   [RFC6325] ESADI, this Appendix also discusses, for each change, the
   interoperability considerations should such simultaneous use occur.




A.1 ESADI PDU Changes

   The format of ESADI-LSP, ESADI-CSNP, and ESADI-PSNP PDU payloads is
   changed from the IS-IS Level 1 format [IS-IS] to the Extended Level 1
   Circuit Scoped format (E-L1CS) specified in [FS-LSP]. This change is
   not backwards compatible with [RFC6325]. It is made in light of the
   256 times greater information carrying capacity of the E- L1CS format
   compared with the base IS-IS format. It is anticipated that this
   greater carrying capacity will be needed, under some circumstances,
   to carry end station addressing information or other similar address
   and reachability information that is added to ESADI in the future.

   The PDU numbers used for the ESADI LSP, CSNP, and PSNP PDUs in
   [RFC6325] are 18, 24, and 26 [IS-IS]. With this document, the format
   changes and the PDU numbers change to 10, 11, and 12 [FS-LSP].  The
   use of different PDU numbers assures that a PDU will not be mis-
   parsed.  Because of this, implementations of this document and
   implementations of [RFC6325] ESADI will discard each other's PDUs.
   Thus address reachability or other information distributed through
   either type of ESADI implementation will only be communicated to
   other implementations of the same type and the two communities will
   not communicate any information with each other.

   Note that RBridges can use the TRILL mandatory-to-implement, enabled-
   by-default data plane address learning in addition to ESADI. (Section
   5 of this document and the material it references explain how to
   handle conflicts between different sources of address reachability
   information.) Simply leaving data plane address learning enabled
   would enable smooth incremental migration from [RFC6325] EASDI to the
   ESADI specification in this document, should that be necessary. The
   data plane address learning would fill in any gaps due to non-
   communication between the two types of ESADI implementation although
   without the speed or security advantages of ESADI.







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A.2 Unicasting Changes

   Unicasting of ESADI PDUs is optionally supported including replacing
   Section 4.6.2.2 of [RFC6325] with the new text given in Section 4.1
   of this document. This unicast support is backwards compatible
   because it is only used when the recipient RBridge signals its
   support.




A.3 Message Timing Changes and Suggestions

   The following timing relevant ESADI message changes and suggestions
   are included in this document:

   1. Provide for staggered delay for non-originators of ESADI-LSP
      fragments in response to requests for such fragments by CSNP and
      PSNP messages.

   2. Suggest staggered timing of unicast ESADI-LSPs when a new ESADI
      RBridge appears on the EASDI virtual link.

   These relate only to the timing of messages for congestion
   minimization.  Should a message be lost, due to congestion or
   otherwise, it will be later retransmitted as a normal part of the
   robust flooding mechanism used by ESADI.




A.4 Duplicate Address Reachability

   The handling of persistent reachability of the same MAC within the
   same Data Label from two or more RBridges is substantially modified
   including the explicit replacement of some text in Section 4.2.6 of
   [RFC6325] (see Section 5.3 of this document). There is no problem
   with a mixture of ESADI implementations in a TRILL campus, some
   conforming to [RFC6325] and some conforming with this document, for
   handling this condition. The more implementations conform to the
   improved behavior specified in this document for this condition, the
   better the traffic spreading will be and the less likely address
   flip-flopping problems are.









H. Zhai, et al                                                 [Page 35]

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Appendix Z: Change History

   RFC Editor: Please delete this section before publication.




Z.1 From -00 to -01

   1. Add Section 6.3 "Default Authentication".

   2. Add "Acknowledgements" Section.

   3. Change requirement from "MAY" to "SHOULD" for an ESADI RBridge
      that is not DRB to send an ESADI-CSNP if it does not receive an
      ESADI-CSNP in long enough.

   4. Default CSNP Time was listed as 30 in one place and 40 in another.
      Change to uniformly specify 30.

   5. Update references to RFC 6326 to reference the 6326bis draft.

   6. Relax allocation criteria for TRILL APPsub-TLV type code points
      from Standard Action to IETF Review.

   7. Numerous Editorial changes.




Z.2 From -01 to -02

   1. Extend to cover FGL and well as VLAN and introduce the term "Data
      Label" to cover both.

   2. Expand number of LSP fragments to 2**16.

   3. Simplify neighbor detection to no longer require possession of
      ESADI-LSP zero.

   4. Add update to last sentence of Section 4.2.6 of [RFC6325].

   5. Update references for publication of RFCs 6822 and 6823.

   6. Additional minor changes.







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Z.3 From -02 to -03

   1. Replace instances of "IS-IS and data unreachable" with just "data
      unreachable" as data unreachability implies IS-IS unreachability
      [RFC7180].

   2. With ESADI, there is just one virtual link on which all
      participating TRILL switches are adjacent. Thus, all of the useful
      ESADI-LSPs in an ESADI link state database are originated by a
      station on this virtual link. To avoid overworking the ESADI DRB
      on the link, ESADI-LSPs sent by a reachable TRILL switch in
      response to an ESADI-PSNP should be sent by the TRILL switch
      originating those EASDI-LSPs.

   3. Re-organize material on sending and receiving ESADI PDUs into more
      smaller subsections that cover all the different circumstances.

   4. Substantially expand Security Considerations section.

   5. Numerous editorial changes.




Z.4 From -03 to -04

   1. Change to using Extended Level 1 Circuit Scope [FS-LSP] for EASDI-
      LSP, ESADI-CSNP, and ESADI-PSNP PDUs.

   2. Update references to RFC 6327 to the rfc6327bis draft.

   3. Sort Informational References RFCs in numeric order.

   4. Add Appendix A: summary of changes to [RFC6325].

   5. Minor editing changes.




Z.5 From -04 to -05

   1. Expand Appendix A to be more complete and precise.

   2. Add L2-IS-IS Ethertype to Figure 1 so figure and text match.

   3. For clarification, add an example pseudo-random function to the
      new text in Section 5.3.

   4. Eliminate possible unicasting of PSNPs.


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   5. Provide for staggered delay for non-originators of ESADI-LSP
      fragments in response to requests for such fragments by CSNP and
      PSNP messages.

   6. In Section 7.2, cover inclusion in FS-LSPs as permitted by [FS-
      LSP].

   7. Some editing changes including expanding "MAC&label".




Z.6 From -05 to -06

   1. In Section 4.3: "a an adjacent" -> "an adjacent".

   2. In Section 4.4: "( 100 - Random (Jitter) )" -> Random(Jitter)".

   3. Add one Acknowledgement.




Z.7 From -06 to -07

   Update based on GENART and IANA reviews:

    1. Update and extend the first paragraph of Section 1.1 and items 2
       and 3 in Appendix A with particular attention to how this
       document updates RFC 6325 and backwards compatibility.

    2. Minor edits to the first part of Section 2 to clarify "pseudo-
       nodes" and the use of common components inside an RBridge
       implementation of the independent ESADI instances.

    3. Add references to [RFC7172] inside Figures 2 and 3.

    4. Section 2.1, minor edits for clarity.

    5. Section 2.2, "is ignored" -> "MUST be ignored".

    6. Section 3, minor edit to clarify DRB election references.

    7. Explain source of "1470 bytes" in Section 6.

    8. Add new second paragraph to Section 8 to clarify cases where you
       might want authenticated end-station registration but would not
       need ESADI-PDU authentication.

    9. Substantial editorial changes to the IANA Considerations (Section


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       7), based on IANA review, to clarify the requested IANA actions.

   10. Update Acknowledgements.

   11. Other minor editorial changes.




Z.8 From -07 to -08

   Update primarily based on IESG review

   1. Re-write of Appendix A to add substantial interoperability
      considerations material.

   2. Addition of Privacy Considerations subsection to Security
      Considerations.

   3. Addition of references to [RFC5310] in connection with
      authentication of ESADI PDUs.

   4. Update draft references due to RFC publications and add some
      Acknowledgements.

   5. Minor editorial changes.




Z.9 From -08 to -09

   1. Fix a few typos.

   2. Clarify encoding of Length field in Section 6.1.

   3. Clarify some wording in Section 1, list item 2.















H. Zhai, et al                                                 [Page 39]

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Authors' Addresses

   Hongjun Zhai
   ZTE Corporation
   68 Zijinghua Road
   Nanjing 200012 China

   Phone: +86-25-52877345
   Email: zhai.hongjun@zte.com.cn


   Fangwei Hu
   ZTE Corporation
   889 Bibo Road
   Shanghai 201203 China

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


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

   Phone: +1-408-765-8080
   Email: Radia@alum.mit.edu


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

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


   Olen Stokes
   Extreme Networks
   Pamlico Building One, Suite 100
   3306 East NC Hwy 54
   RTP, NC 27709 USA

   Email: ostokes@extremenetworks.com







H. Zhai, et al                                                 [Page 40]

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Copyright and IPR Provisions

   Copyright (c) 2014 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
   (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.






































H. Zhai, et al                                                 [Page 41]


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