TRILL WG                                                  Radia. Perlman
Internet-Draft                                                Intel Labs
Intended status: Standards Track                             Fangwei. Hu
Expires: April 20, 2015                                  ZTE Corporation
                                                    Donald. Eastlake 3rd
                                                       Huawei technology
                                                      Kesava. Krupakaran
                                                              Ting. Liao
                                                         ZTE Corporation
                                                        October 17, 2014

                          TRILL Smart Endnodes


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

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 20, 2015.

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Copyright Notice

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Smart-Hello Content . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Edge RBridge's Smart-Hello  . . . . . . . . . . . . . . .   4
     3.2.  Smart Endnode's Smart-Hello . . . . . . . . . . . . . . .   5
   4.  Frame Processing  . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Frame Processing for Smart Endnode  . . . . . . . . . . .   6
     4.2.  Frame Processing for Edge RBridge . . . . . . . . . . . .   6
   5.  Multi-homing  . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

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

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

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

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

   For these reasons, it is desirable for an endnode E (whether it is a
   server, hypervisor, or VM) to maintain the endnode table for remote
   endnodes that E is corresponding with.  This eliminates the need for
   the edge RBridge RBx, to which E is connected, to know about those
   nodes (unless some non-smart endnode attached to RBx is also
   corresponding with those nodes), Once D is unreachable for E, which
   could be determined through ICMP messages or other techniques, the
   smart endnode should delete the entry of (MAC, Data Label, nickname).
   If D moves to a new place, E should attempt to acquire a fresh entry
   for D by flooding to D, examining updates to the ESADI link state
   database,or consulting a directory.

   The mechanism in this draft is that E issue a Smart-Hello (even
   though E is just an endnode), indicating E's desire to act as a smart
   endnode, together with the set of MAC addresses and Data Labels that
   E owns, and whether E would like to receive ESADI packets.  E learns
   from RBx's Smart-Hello, whether RBx is capable of having a smart
   endnode neighbor, what RBx's nickname is, and which trees RBx can use
   when RBx ingresses multi-destination frames.  Although E transmits
   Smart-Hellos, E does not transmit or receive LSPs or E-L1FS FS-

   RBx will accept already-encapsulated TRILL Data packets from E
   (perhaps verifying that the source MAC and Data Label is indeed one
   of the ones that E owns, that the ingress RBridge field is RBx's, and
   if the packet is an encapsulated multi-destination frame, the tree
   selected is one of the ones that RBx has claimed it will choose).
   When RBx receives (from the campus) a TRILL Data packet with RBx's
   nickname as egress, RBx checks whether the destination MAC address
   and Data Label in the inner packet is one of the MAC addresses and
   Data Labels that E owns, and if so, RBx forwards the packet onto E's
   port, keeping it encapsulated.

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   Since a smart endnode can encapsulate TRILL Data frames, it can cause
   the Inner.Lable to be a Fine Grained Label [RFC7172], thus this
   method supports FGL aware endnodes.

2.  Terminology

   Edge RBridge: An RBridge providing endnode service on at least one of
   its ports.

   Data Label: VLAN or FGL.

   ESADI: End Station Address Distribution Information [RFC7357].

   FGL: Fine Grained Label [RFC7172].

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

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

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

   Transit RBridge: An RBridge exclusively forwards encapsulated frames.

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

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

3.  Smart-Hello Content

   Suppose endnode E is attached to RBridge RBx.  In order for E to act
   as a smart endnode, both E and RBx have to be signaled.  The logical
   choice of frame to do this is Smart-Hello.

3.1.  Edge RBridge's Smart-Hello

   For smart endnode operation, RBx's Smart-Hello must contain the
   following information:

   o  RBridge's nickname.  The nickname sub-TLV (Specified in section
      2.3.2 in [RFC7176])could be reused here, and TLV 242 (IS-IS router
      capability) should be updated to be carried in Smart-Hello frame.

   o  Tree that RBx can use when ingressing multi-destination frames.
      The Tree Identifiers Sub-TLV (Specified in section 2.3.4 in
      [RFC7176]) could be reused here.

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   o  Smart endnode neighbor list.  The TRILL Neighbor TLV (Specified in
      section 2.5 in [RFC7176]) could be reused.

3.2.  Smart Endnode's Smart-Hello

   A new TLV (S-MAC TLV)is defined for smart endnode.  If there are
   several VLANs for that smart endnode, the TLV could be filled several
   times in smart endnode's Smart-Hello.

    | Type= S-MAC   |                  (1 byte)
    |   Length      |                  (1 byte)
    |E|F|RESV| VLAN/FGL Data Label  |  (2 bytes or 4 bytes)
    |                          MAC (1)       (6 bytes)                 |
    |                      .................                           |
    |                          MAC (N)       (6 bytes)                 |

                      Figure 1 S-MAC TLV

   o  Type: S-MAC, the value is TBD.

   o  Length: Total number of bytes contained in the value field.

   o  E: one bit.  If it sets to 1, which indicates that the endnode
      should receive ESADI frames.

   o  F: one bit.  If it sets to 1, which indicates that the endnode
      supports FGL data label, otherwise, the VLAN/FGL Data Label
      [RFC7172] field is the VLAN ID.

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

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

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

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4.  Frame Processing

4.1.  Frame Processing for Smart Endnode

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

   o  E maintains an endnode table of (MAC, Data Label, nickname)
      entries of end nodes with which the smart endnode is
      communicating.  Entries in this table are populated the same way
      that an edge RBridge populates the entries in its table:

      *  learning from (source, ingress) on packets it decapsulates.

      *  from ESADI[RFC7357].

      *  by querying a directory [RFC7067].

      *  by having some entries configured.

   o  When E wishes to transmit to unicast destination D, if (D,
      nickname) is in E's endnode table, E encapsulates with ingress
      nickname=RBx, egress nickname as indicated in D's table entry.  If
      D is unknown, D either queries a directory or encapsulates the
      packet as a multi-destination frame, using one of the trees that
      RBx has specified in RBx's Smart-Hello.

   o  When E wishes to transmit to a multicast or broadcast destination,
      E encapsulates the packet using one of the trees that RBx has

   The smart endnode E need not send Smart-Hellos as frequently as
   normal RBridges.  These Smart-Hellos could be periodically unicast to
   the Appointed Forwarder RBx.  In case RBx crashes and restarts, or
   the DRB changes, and E receives the Smart-Hello without mentioning E,
   then E SHOULD send a Smart-Hello immediately.  If RBx is AF for any
   of the VLANs that E claims, RBx MUST list E in its Smart-Hellos as a
   smart endnode neighbor.

4.2.  Frame Processing for Edge RBridge

   The attached RBridge RBx does the following:

   o  If receiving an encapsulated unicast data frame from a port with a
      smart endnode, with RBx's nickname as ingress, RBx forwards the
      frame to the specified egress nickname, as with any encapsulated
      frame.  However, RBx MAY filter the encapsulation frame based on
      the inner source MAC and Data Label as specified for the smart

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      endnode.  If the MAC (or Data Label) are not among the expected
      set of the smart endnode, the frame would be dropped by the edge

   o  If receiving an mulit-destination TRILL Data packet from a port
      with smart endnode, RBridge RBx forwards the TRILL encapsulation
      to the TRILL campus based on the distribution tree.  If there are
      some normal endnodes (i.e, non-smart endnode) attached to RBridge
      RBx, RBx should decapsulates the frame and sends the native frame
      to these ports.

   o  When RBx receives a multicast frame from a remote RBridge, and the
      exit ports includes hybrid endnodes, it should send two copies of
      mulicast frames, one as native and the other as TRILL encapsulated
      frame.  When smart endnode receives the encapsulated frame, it
      learns the remote (MAC, Data Label, Nickname) set, A smart
      endnodes ignores any native data frames.  The normal endnode
      receives the native frame and learns the remote MAC address and
      ignore the native frame.  This transit solution may bring some
      complex for the edge RBridge and waste network bandwidth, so it is
      recommended to avoid the hybrid endnodes scenario by attaching the
      smart endnodes and non-smart endnodes to different ports when
      deployed.  Another solution is that if there are one or more
      endnodes on a link, the non-smart endnodes are ignored on a link;
      but we can configure a port to support mixed links.  The RBx only
      sends TRILL encapsulated frame to the link in this situation.

5.  Multi-homing

   Now suppose E is attached to the TRILL campus in two places: to
   RBridges RB1 and RB2.  There are two ways for this to work:

   (1)  E can choose either RB1 or RB2's nickname, when encapsulating a
        frame, whether the encapsulated frame is sent via RB1 or RB2.
        If E wants to do active-active load splitting, and uses RB1's
        nickname when forwarding through RB1, and RB2's nickname when
        forwarding through RB2, which will cause the flip-floping of the
        endnode table entry in the remote RBridges (or smart endnodes).
        One solution is to set a multi-homing bit in the RESV field of
        the TRILL data Frame.  When remote RBs or smart endnodes receive
        the data frame with the multi-homed bit set, the MAC entry (E,
        RB1's nickname) and (E, RB2's nickname) will be coexist as two
        entries for that MAC address.  Another solution is to extend the
        ESADI protocol to distribute multiple attachments of a MAC
        address of a multi-homing group.(Please refer to the option C in
        section 4 of [I-D.ietf-trill-aa-multi-attach] for details).

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   (2)  RB1 and RB2 might indicate, in their Smart-Hello, a virtual
        nickname that attached end nodes may use if they are multihomed
        to RB1 and RB2, separate from RB1 and RB2's nicknames (which
        they would also list in their Smart-Hello).  This would be
        useful if there were many end nodes multihomed to the same set
        of RBridges.  This would be analogous to a pseudonode nickname;
        return traffic would go via the shortest path from the source to
        the endnode, whether it is RB1 or RB2.  If E loses connectivity
        to RB2, then E would revert to using RB1's nickname.  In order
        to avoid RPF check issue for multi-destination frame, the
        affinity TLV [I-D.ietf-trill-cmt] is recommended to be used in
        this solution.

6.  Security Considerations

   For general TRILL Security Considerations, see [RFC6325].

7.  Acknowledgements

8.  IANA Considerations

   IANA is requested to allocate a S-MAC TLV identifier.  TLV 242(ISIS
   router capability) is required to updated to be carried by Smart-
   Hello frame.

9.  Normative References

              Eastlake, D., Zhang, M., Perlman, R., Banerjee, A.,
              Ghanwani, A., and S. Gupta, "TRILL: Clarifications,
              Corrections, and Updates", draft-eastlake-trill-
              rfc7180bis-00 (work in progress), October 2014.

              Zhang, M., Perlman, R., Corporation, Z., Durrani, D.,
              Shaikh, M., and S. Gupta, "TRILL Active-Active Edge Using
              Multiple MAC Attachments", draft-ietf-trill-aa-multi-
              attach-01 (work in progress), August 2014.

              Senevirathne, T., Pathangi, J., and J. Hudson,
              "Coordinated Multicast Trees (CMT) for TRILL", draft-ietf-
              trill-cmt-04 (work in progress), October 2014.

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

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

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

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

   [RFC7067]  Dunbar, L., Eastlake, D., Perlman, R., and I. Gashinsky,
              "Directory Assistance Problem and High-Level Design
              Proposal", RFC 7067, November 2013.

   [RFC7172]  Eastlake, 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, 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.

   [RFC7357]  Zhai, H., Hu, F., Perlman, R., Eastlake, D., and O.
              Stokes, "Transparent Interconnection of Lots of Links
              (TRILL): End Station Address Distribution Information
              (ESADI) Protocol", RFC 7357, September 2014.

Authors' Addresses

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

   Phone: +1-408-765-8080

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   Fangwei Hu
   ZTE Corporation
   No.889 Bibo Rd
   Shanghai  201203

   Phone: +86 21 68896273

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

   Phone: +1-508-634-2066

   Kesava Vijaya Krupakaran
   Olympia Technology Park
   Guindy Chennai   600 032

   Phone: +91 44 4220 8496

   Ting Liao
   ZTE Corporation
   No.50 Ruanjian Ave.
   Nanjing, Jiangsu  210012

   Phone: +86 25 88014227

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