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TRILL (Transparent Interconnection of Lots of Links): ESADI (End Station Address Distribution Information) Protocol

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7357.
Authors Hongjun Zhai , fangwei hu , Radia Perlman , Donald E. Eastlake 3rd , Olen Stokes
Last updated 2013-11-25 (Latest revision 2013-07-15)
Replaces draft-hu-trill-rbridge-esadi
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
Stream WG state WG Consensus: Waiting for Write-Up
Document shepherd Erik Nordmark
Shepherd write-up Show Last changed 2013-11-15
IESG IESG state I-D Exists
Consensus boilerplate Unknown
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TRILL Working Group                                         Hongjun Zhai
INTERNET-DRAFT                                                Fangwei Hu
Intended status: Proposed Standard                                   ZTE
Updates: 6325                                              Radia Perlman
                                                              Intel Labs
                                                         Donald Eastlake
                                                             Olen Stokes
                                                        Extreme Networks
Expires: January 14, 2014                                  July 15, 2013

         TRILL (Transparent Interconnection of Lots of Links):
     ESADI (End Station Address Distribution Information) Protocol


   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 addresses and
   other information to TRILL switches participating in ESADI for the
   relevant Data Label.  This document updates RFC 6325, specifically
   the documentation of the ESADI protocol.

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: <>.

   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-

H. Zhai, et al                                                  [Page 1]
INTERNET-DRAFT                                              TRILL: ESADI

   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 The list of Internet-Draft
   Shadow Directories can be accessed at

H. Zhai, et al                                                  [Page 2]
INTERNET-DRAFT                                              TRILL: ESADI

Table of Contents

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

      2. ESADI Protocol Overview.................................6
      2.1 ESADI Virtual Link.....................................9
      2.2 ESADI Neighbor Determination..........................10
      2.3 ESADI Payloads........................................10

      3. ESADI DRB Determination................................12

      4. ESADI PDU processing...................................13
      4.1 Unicasting ESADI PDUs.................................13
      4.2 General Transmission of ESADI PDUs....................14
      4.3 General Receipt of ESADI PDUs.........................14
      4.4 Details of Receiving and Sending ESADI PDUs...........15
      4.4.1 ESADI-CSNP Receipt..................................15
      4.4.2 ESADI-PSNP Receipt..................................16
      4.4.3 ESADI-LSP Receipt...................................16
      4.4.4 Passage of Time.....................................16
      4.4.5 Neighbor Appearance.................................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..................................22
      6.3 Default Authentication................................23

      7. IANA Considerations....................................24
      7.1 ESADI Participation and Capability Flags..............24
      7.2 TRILL GENINFO TLV.....................................25

      8. Security Considerations................................27

      9. Acknowledgements.......................................27
      Normative references......................................28
      Informative References....................................29
      Appendix Z: Change History................................30
      Authors' Addresses........................................32

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]
   [rfc6326bis] 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, [RFCfgl]).  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].  The ESADI (End Station
   Address Distribution Information) protocol 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 additional types of

   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

   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, frames ingressed for
      that end station's MAC address 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 or more [RFC6325].

H. Zhai, et al                                                  [Page 4]
INTERNET-DRAFT                                              TRILL: ESADI

   MAC address reachability information, some ESADI parameters, and
   optionally 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 basic specification,
   essentially replacing the description of the ESADI protocol, and
   prevails over [RFC6325] where they conflict.

   Section 2 of this document is the ESADI protocol overview. Section 3
   specifies ESADI DRB determination.  Section 4 discusses the
   processing of ESADI PDUs. Section 5 discusses interaction with other
   modes of end station address learning. And Section 6 describes the
   ESADI-LSP contents.

1.2 Terminology

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

      Data Label - VLAN or FGL.

      FGL - Fine Grained Label [RFCfgl]

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

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

H. Zhai, et al                                                  [Page 5]
INTERNET-DRAFT                                              TRILL: ESADI

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). In essence, for each 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].) It is an
   implementation decision how independent the multiple ESADI instances
   at an RBridge are. 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 update process operates separately for each ESADI
   instance and independently from the TRILL IS-IS update process.

   ESADI does no routing so there is no reason for pseudo-nodes in ESADI
   and none are created. This allows re-purposing one byte of the LSP ID
   field to expand the number of possible fragments from 2**8 to 2**16.
   In [IS-IS], the "LSP ID" field is 8 bytes. (Actually it is the length
   of System ID plus 2, but we will assume a 6-byte System ID.)  The top
   6 bytes of the LSP ID are the router's System ID, the next byte is
   non-zero for pseudo-nodes, and the bottom byte is the fragment
   number. In ESADI-LSPs, there is just the System ID followed by two
   bytes of fragment number.  The same change is made to the LSP ID
   field of the Remaining Lifetime TLV which is used in EASDI-CSNP and
   ESADI-PSNP. The bottom byte of the ESADI CSNP/PSNP Header Source ID
   is always zero.

   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 6]
INTERNET-DRAFT                                              TRILL: ESADI

                    |          Link Header           |
                    |       TRILL Data Header        |
                    |   Inner Ethernet Addresses     |
                    |           Data Label           |
                    |         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 stripped by
   an Ethernet port out of which the packet was sent.

H. Zhai, et al                                                  [Page 7]
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) ...
      | 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 always 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 8]
INTERNET-DRAFT                                              TRILL: ESADI

   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

   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) ...
      | 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 transit 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 [ClearCorrect] and are running

H. Zhai, et al                                                  [Page 9]
INTERNET-DRAFT                                              TRILL: ESADI

   ESADI for that Data Label. No "routing" computation or routing
   decisions ever have 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 [RFCfgl]. 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

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 [ClearCorrect]) 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, and when RB2 is no longer announcing
   participation in Data Label X ESADI, it ceases to be a neighbor for
   the Data Label X ESADI instance. All these considerations being Data
   Label scoped. Because of these mechanisms, there are no "Hellos" sent
   in ESADI.

   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 [rfc6326bis]. (See Section 7.1)

2.3 ESADI Payloads

   TRILL ESADI packet payloads are structured like IS-IS Level 1 LSP,
   CSNP, and PSNP PDUs, 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 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

H. Zhai, et al                                                 [Page 10]
INTERNET-DRAFT                                              TRILL: ESADI

   parameters of the advertising RBridge (see Section 6.1) and possibly
   authentication information (see Section 6.3) are included. Future
   uses of ESADI may distribute other types of 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 is ignored.

H. Zhai, et al                                                 [Page 11]
INTERNET-DRAFT                                              TRILL: ESADI

3. ESADI DRB Determination

   Because ESADI does no adjacency announcement or routing, the ESADI-
   DRB never creates a pseudonode. But a DRB (Designated RBridge
   [RFC6327]) 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 a TRILL IS-IS broadcast link
   [RFC6327] 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 [ClearCorrect], 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 and there is no "Port ID".

H. Zhai, et al                                                 [Page 12]
INTERNET-DRAFT                                              TRILL: ESADI

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, and simply uses the campus Sz MTU.

4.1 Unicasting ESADI PDUs

   In 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-LSP and ESADI-PSNP
   PDUs MAY be TRILL unicast if it is confirmed that the destination
   RBridge supports receiving unicast ESADI PDUs (see Section 6.1).

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

   " TRILL ESADI Packets

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

      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 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."

H. Zhai, et al                                                 [Page 13]
INTERNET-DRAFT                                              TRILL: ESADI

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

4.2 General Transmission of ESADI PDUs

   An ESADI instance SHOULD NOT transmit any ESADI PDUs if it has no
   ESADI neighbors. They 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(Inner.VLAN/Inner.FGL) 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 ESDAI instance; however, if a
   larger payload is received, it is processed normally. (See [RFC6325]
   and [ClearCorrect] for discussions of Sz and MTU.)

   The format of a unicast ESADI packet is the format of 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.

   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.

4.3 General Receipt of ESADI PDUs

   Because ESADI neighbor adjacency is in terms of System ID, all PDU
   acceptance tests that in TRILL/IS-IS check that the PDU is from an
   adjacent router instead check that the System ID is that of an ESADI
   neighbor and do not check either the source Inner or Outer SNPA/MAC.

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

H. Zhai, et al                                                 [Page 14]
INTERNET-DRAFT                                              TRILL: ESADI

4.4 Details of Receiving and Sending ESADI PDUs

             Event     |     Section
            Receive    |   See
           ESADI-CSNP  |   Section 4.4.1
            Receive    |   See
           ESADI-PSNP  |   Section 4.4.2
            Receive    |   See
           ESADI-LSP   |   Section 4.4.3
            Passage    |   See
            of Time    |   Section 4.4.4
            Neighbor   |   See
           Appearance  |   Section 4.4.5

4.4.1 ESADI-CSNP Receipt

   If an ESADI RBridge RB1 believes it is DRB on a virtual link for Data
   Label X, it ignores an ESADI-CSNP it receives.

   If RB1 believes it is not DRB:

      When RB1 receives an ESADI-CSNP from RB2 and detects that it has
      ESADI-LSPs that RB2 is missing, it sets the transmission flag only
      for its own ESADI-LSPs that RB2 is missing. Missing ESADI-LSPs
      originated by other ESADI RBridges will be detected by those other
      ESADI RBridges because all data reachable ESADI RBridges
      participating for Data Label X are adjacent.

      When RB1 receives an ESADI-CSNP from RB2 and detects that it is
      missing ESADI-LSPs originated by RBridges reachable from RB1 that
      RB2 has, it generates one or more ESADI-PSNP PDUs. Generally,
      ESADI-PSNPs are multicast and may be fragmented as with IS-IS
      PSNPs; however, if RB1 is missing ESADI-LSPs from RBx and RBx is
      advertising unicast ESADI PDU support, RB1 MAY construct one or
      more EASDI-PSNP fragments listing only RBx ESADP-LSPs and unicast
      those ESADI-PSNPs to RBx.

H. Zhai, et al                                                 [Page 15]
INTERNET-DRAFT                                              TRILL: ESADI

4.4.2 ESADI-PSNP Receipt

   When RBx receives an ESADI-PSNP PDU, if RBx is the originator of any
   ESADI-LSPs requested by the ESADI-PSNP those ESADI-LSPs will be
   multicast on the virtual link.

4.4.3 ESADI-LSP Receipt

   Processing of a received ESADI-LSP is as in IS-IS.

   In the case of receiving an ESADI-LSP with a smaller sequence number
   than the copy stored in the local EASDI Link State Database the local
   ESADI instance will also schedule multicasting its stored copy.

4.4.4 Passage of Time

   If an ESADI instance believes it is DRB, it multicasts an ESADI-CSNP
   periodically (thrice per CSNP Time, see Section 6.1) to keep the link
   state database synchronized among its neighbors on the virtual link.

   The multi-hop TRILL multi-destination packet distribution with
   Reverse Path Forwarding Check will typically be less reliable than
   the single hop link-local LSP synchronization of TRILL IS-IS.
   Therefore, for LSP synchronization robustness, in addition to sending
   ESADI-CSNPs 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 CSNP Time (see Section 6.1) of the DRB.

4.4.5 Neighbor Appearance

   When an ESADI instance sees that it has a new neighbor, its self-
   originated EASDI-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

H. Zhai, et al                                                 [Page 16]
INTERNET-DRAFT                                              TRILL: ESADI

   neighbor. So the ESADI instances SHOULD wait an interval of time
   before sending their ESADI-LSP to a new neighbor.  The interval time
   value is up to the device implementation and is subject to the usual
   IS-IS timing jitter. 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 ( 2 *
   nickname / 0xFFC0 ) seconds.

H. Zhai, et al                                                 [Page 17]
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5. End Station Addresses

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

5.1 Learning Confidence Level

   The confidence level mechanism 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

   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 with the same Data Label being advertised as
   reachable by two or more RBridges. The specification of how to handle
   this situation in [RFC6325] is updated by replacing the last sentence

H. Zhai, et al                                                 [Page 18]
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   of the last paragraph of Section 4.2 of [RFC6325] as shown below to
   provide better traffic spreading while avoiding possible address

   As background, assume some end station or set of end stations have
   two or more ports with the same MAC&label with each port connected to
   different RBridges (RB1, RB2, ...) by separate links. (Label is a
   VLAN or FGL.) With ESADI, some other RBridge, RB0, can persistently
   see that MAC&label connected to multiple RBridges. When RB0 ingresses
   a frame destined for that MAC&label, the current [RFC6325] text
   permits a wide range of behavior.  In particular, it would permit RB0
   to use some rule such as always send to the egress with the lowest
   System ID, which would put all of this traffic through one of the
   egress RBridges and one of the end station ports.  There would be no
   load spreading even if there were multiple different ingress RBridges
   and/or different MAC addresses. It 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 to RB0 from RB1,
   RB2, ... for the same MAC&label. The resulting address flip-flopping
   could cause problems.  This update to [RFC6325] avoids these
   potential difficulties by requiring RB0 to either (1) use only one
   egress for a particular MAC&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&label flip-flopping between different ingresses, it may
   use ECMP.  Assuming multiple ingress RBridges and/or multiple MAC
   addresses, strategy 1 should result in load spreading without address
   flip-flopping while strategy 2 will produce more uniform load
   spreading with address flip-flopping from the point of view of RB0.

   OLD [RFC6325] 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] text:

      If confidences are also tied between the duplicates then RB2 MUST
      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) to that egress. This
         pseudo-random choice need only be changed when there is a
         change in campus topology or MAC attachment information. Such

H. Zhai, et al                                                 [Page 19]
INTERNET-DRAFT                                              TRILL: ESADI

         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. There is
         no need for different RBridges to use the same pseudo-random

      2. If RB2 supports ECMP and will not be disturbed by return
         traffic from the same MAC and VLAN (or FGL) coming from
         different ingress 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

H. Zhai, et al                                                 [Page 20]
INTERNET-DRAFT                                              TRILL: ESADI

6. ESADI-LSP Contents

   The only PDUs used in ESADI are the Level 1 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 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.

   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 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 is received that is
   longer, it is still processed normally.

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.

                | Type          |           (1 byte)
                | Length        |           (1 byte)
                |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 1).

H. Zhai, et al                                                 [Page 21]
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   Length: Set to 2 to 255.

   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

   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|         Reserved          |

         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. The
         remaining 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 as 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 with a confidence of 255, it is treated as if the confidence
   was 254. (This is to assure that any received address information can

H. Zhai, et al                                                 [Page 22]
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   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

6.3 Default Authentication

   The Authentication TLV may be included in ESADI PDUs. The default for
   ESADI PDU Authentication is based on the state of TRILL IS-IS shared
   secret authentication for 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
   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 23]
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7. IANA Considerations

   IANA allocation and registry considerations are given below.

7.1 ESADI Participation and Capability Flags

   IANA is requested to allocate bit TBD [3 recommended] as the "ESADI
   Participation" bit in the Interested VLANs sub-TLV and the Interested
   Labels sub-TLVs [rfc6326bis]. If The ESADI Participation bit is a
   one, it indicates that the originating RBridge is participating in
   ESADI for the indicated VLAN(s) or FGL(s). In addition, IANA is
   requested to create two sub-registries in the TRILL Parameters
   Registry for such bits as follows:

      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).

      References: [rfc6326bis], [This document]

         Bit  Mnemonic  Description                      Reference
         ---  --------  -----------                      ---------
           0     M4     IPv4 Multicast Router Attached   [rfc6326bis]
           1     M6     IPv6 Multicast Router Attached   [rfc6326bis]
           2      -     available for allocation
           3     ES     ESADI Participation              This document
          4-15    -     (used for a VLAN ID)             [rfc6326bis]
         16-19    -     available for allocation
         20-31    -     (used for a VLAN ID)             [rfc6326bis]

H. Zhai, et al                                                 [Page 24]
INTERNET-DRAFT                                              TRILL: ESADI

      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).

      References: [rfc6326bis], [this document]

         Bit  Mnemonic  Description                      Reference
         ---  --------  -----------                      ---------
           0     M4     IPv4 Multicast Router Attached   [rfc6326bis]
           1     M6     IPv6 Multicast Router Attached   [rfc6326bis]
           2     BM     Bit Map                          [rfc6326bis]
           3     ES     ESADI Participation              This document
          4-7     -     available for allocation


   IANA is requested to allocate an IS-IS Application Identifier under
   the Generic Information TLV (#251) [RFC6823] for TRILL and to create
   a subregistry in the TRILL Parameters Registry for "TRILL APPsub-TLVs
   under IS-IS TLV #251 Application Identifier #TBD".  The initial
   contents of this subregistry are as follows:

             Type   Name                Reference
            ------ --------            -----------
                0  Reserved            <this RFC>
                1  ESADI-PARAM         <this RFC>
            2-254  Available           <this RFC>
              255  Reserved            <this RFC>

   TRILL APPsub-TLV Types 2 through 254 are available for allocation by
   IETF Review. The RFC causing such an allocation 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 TRILL IS-IS
   adjacencies, the IS-IS update process, and the decision process for
   TRILL IS-IS [IS-IS] [RFC1195] [RFC6327]. The TRILL Generic
   Information TLV MUST NOT be used in an IS-IS instance zero [RFC6822].

   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 flags MUST be zero;
   however, use of multi-level IS-IS is an obvious extension for TRILL

H. Zhai, et al                                                 [Page 25]
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   [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.

H. Zhai, et al                                                 [Page 26]
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8. Security Considerations

   ESADI PDUs can be authenticated through the inclusion of the
   Authentication TLV as described in Section 6.3. The ESADI LSP data
   primarily announces MAC&label reachability. 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.

   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&label to different RBridges. 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

   For general TRILL Security Considerations, see [RFC6325].

9. Acknowledgements

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

      Somnath Chatterjee and Thomas Narten

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

H. Zhai, et al                                                 [Page 27]
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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,

   [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

   [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

   [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.

   [RFC6327] - Eastlake 3rd, D., Perlman, R., Ghanwani, A., Dutt, D.,
         and V. Manral, "Routing Bridges (RBridges): Adjacency", RFC
         6327, July 2011.

   [RFC6361] - Carlson, J. and D. Eastlake 3rd, "PPP Transparent
         Interconnection of Lots of Links (TRILL) Protocol Control
         Protocol", RFC 6361, August 2011.

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

   [ClearCorrect] - Eastlake, D., Zhang, M., Ghanwani, A., Manral, V.,
         A. Benerjee, "TRILL: Clarifications, Corrections, and Updates",

H. Zhai, et al                                                 [Page 28]
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         draft-ietf-trill-clear-correct, in RFC Editor's queue.

   [rfc6326bis] - Eastlake, D., Senevirathne, T., Ghanwani, A., Dutt,
         D., and A. Banerjee, "Transparent Interconnection of Lots of
         Links (TRILL) Use of IS-IS", draft-ietf-isis-rfc6326bis, work
         in progress.

   [RFCfgl] - Eastlake, D., M. Zhang, P. Agarwal, R. Perlman, D. Dutt,
         "TRILL (Transparent Interconnection of Lots of Links): Fine-
         Grained Labeling", draft-ietf-trill-fine-labeling, work in

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.

   [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

   [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

   [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 29]
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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 of [RFC6325].

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

   6. Additional minor changes.

H. Zhai, et al                                                 [Page 30]
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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

   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.

H. Zhai, et al                                                 [Page 31]
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Authors' Addresses

   Hongjun Zhai
   ZTE Corporation
   68 Zijinghua Road
   Nanjing 200012 China

   Phone: +86-25-52877345

   Fangwei Hu
   ZTE Corporation
   889 Bibo Road
   Shanghai 201203 China

   Phone: +86-21-68896273

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

   Phone: +1-408-765-8080

   Donald Eastlake
   Huawei R&D USA
   155 Beaver Street
   Milford, MA 01757 USA

   Phone: +1-508-333-2270

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


H. Zhai, et al                                                 [Page 32]
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Copyright and IPR Provisions

   Copyright (c) 2013 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
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   publication of this document. Please review these documents
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   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.  The definitive version of
   an IETF Document is that published by, or under the auspices of, the
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   language to the contrary, or terms, conditions or rights that differ
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   published or posted by such Contributor, or included with or in such

H. Zhai, et al                                                 [Page 33]