TRILL WG                                                   Radia Perlman
Internet-Draft                                                Intel Labs
Intended status: Standards Track                              Fangwei Hu
Expires: April 4, 2014                                   ZTE Corporation
                                                     Donald Eastlake 3rd
                                                       Huawei technology
                                                Kesava Vijaya Krupakaran
                                                               Ting Liao
                                                         ZTE Corporation
                                                                Oct 2013

                          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.

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
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   This Internet-Draft will expire on April 4, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
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   ( in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

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

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1.  Introduction

   The IETF TRILL (Transparent Interconnection of Lots of Links)
   protocol implemented by devices called RBridges (Routing Bridges,
   [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([RFC1195])
   ([RFC6165]) ([I-D.ietf-isis-rfc6326bis])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 removes the TRILL header.
   To encapsulate, the edge RBridge must keep an "endnode table"
   consisting of (MAC, TRILL egress switch nickname) pairs, for those
   MAC addresses currently communicating with endnodes to which the edge
   RBridge is attached.

   These table entries might be configured, received from ESADI
   ([I-D.ietf-trill-esadi]), looked up in a
   directory([I-D.ietf-trill-directory-framework]), or learned from
   received traffic.  If the edge RBridge has many attached endnodes,
   this table could become large.  Also, if one of the MAC addresses in
   the table has moved to a different switch, it might be difficult for
   the edge RBridge to notice this quickly, and because the edge RBridge
   is tunneling to the incorrect egress RBridge, the traffic will get

   For these reasons, it is desirable for an endnode E (whether it is a
   server, hypervisor, or VM) to maintain the endnode table for nodes
   that E is corresponding with.  This eliminates the need for the
   attached RBridge R to know about those nodes (unless some non-smart
   endnode attached to R is also corresponding with those nodes), and it
   enables E to immediately discard an entry of (D, egress nickname), if
   E cannot talk to D. Then E can attempt to acquire a fresh entry for D
   by flooding to D, listening for ESADI,or consulting a directory.

   The mechanism in this draft is that E issue a TRILL-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 that E owns, and
   whether E would like to receive ESADI frame.  E learns from R's
   Hello, whether R is capable of having a smart endnode neighbor, what
   R's nickname is, and which trees R can use when R ingresses

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   multidestination frames.  Although E transmits TRILL-Hellos, E does
   not transmit or receive LSPs.

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

2.  TRILL-Hello Content

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

2.1.  Edge RBridge's TRILL-Hello

   For smart endnode operation, R's TRILL-Hello must contain the
   following information:

   o  RBridge's nickname.  The nickname sub-TLV (Specified in section
      2.3.2 in [I-D.ietf-isis-rfc6326bis])could be reused here, and TLV
      242 (ISIS router capability) should be updated to be carried in
      TRILL-Hello frame.

   o  Tree roots that R can use when ingressing multidestination frames.
      The Tree Identifiers Sub-TLV(Specified in section 2.3.4 in
      [I-D.ietf-isis-rfc6326bis]) could be reused here.

   o  Smart endnode neighbor list.  The TRILL Neighbor TLV(Specified in
      section 2.5 in [I-D.ietf-isis-rfc6326bis]) could be reused.

2.2.  Smart Endnode's TRILL-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 TRILL-Hello.

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    | 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
      could receive ESADI frame.

   o  F: one bit.  If it sets to 1, which indicats that the endnode
      supports FGL data label, otherwise, the VLAN/FGL Data Label
      (([I-D.ietf-trill-fine-labeling])) 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

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

3.  Frame Processing

3.1.  Frame Processing for Smart Endnode

   Smart endnode E does not issue LSPs, nor does it receive LSPs or
   calculate topology.  E does the following:

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   o  E maintains an endnode table of (MAC, nickname) of end nodes with
      which the smart endnode is communicating.  If E is attached to
      multiple VLANs (or FGL), there would be a separate (MAC, nickname)
      table for each VLAN/FGL that E is attached to.  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([I-D.ietf-trill-esadi]).

      *  by querying a directory([I-D.ietf-trill-directory-framework]).

      *  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=R, egress nickname as indicated in D's table entry.  If D
      is unknown, D either queries a directory or encapsulates the
      packet as a multidestination frame, using one of the trees that R
      has specified in R's TRILL-Hello.

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

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

3.2.  Frame Processing for Edge RBridge

   The attached RBridge R does the following:

   o  If receiving an encapsulated unicast data frame from a port with a
      smart endnode, with R's nickname as ingress, R forwards the frame
      to the specified egress nickname, as with any encapsulated frame.
      However, R MAY filter the encapsulation frame based on the inner
      source MAC and VLAN (or FGL) as specified for the smart endnode.
      If the MAC (or VLAN/FGL) are not among the expected set of the
      smart endnode, the frame would be dropped by the edge RBridge.

   o  If receiving an mulitdestination data TRILL frame from a port with
      smart endnode, RBridge R forwards the TRILL encapsulation to the
      TRILL campus based on the distribution tree.  If there are some

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      normal endnodes(i.e, non-smart endnode) attached to RBridge R, R
      should decapsulates the frame and sends the native frame to these

   o  When R receives a mulicast 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 address.

4.  Multi-homing

   Now suppose E is attached to the TRILL campus in two places: to
   RBridges R1 and R2.  There are two ways for this to work:

   (1)  E can choose either R1 or R2's nickname, when encapsulating a
        frame, whether the encapsulated frame is sent via R1 or R2.  If
        E wants to do active-active load splitting, and uses R1's
        nickname when forwarding through R1, and R2's nickname when
        forwarding through R2, which will cause the flip-floping of the
        endnode table entry in the remote RBridges(or smart endnodes).
        This issues could be solved by setting 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, R1's nickname) and (E, R2's nickname) will be
        coexist as two entries for that MAC address.

   (2)  R1 and R2 might indicate, in their Hello, a virtual nickname
        that attached end nodes may use if they are multihomed to R1 and
        R2, separate from R1 and R2's nicknames (which they would also
        list in their 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
        R1 or R2.  If E loses connectivity to R2, then E would revert to
        using R1'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.

5.  Security Considerations

   For general TRILL Security Considerations, see([RFC6325]).

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6.  Acknowledgements

7.  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 TRILL-
   Hello frame.

8.  Normative References

              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-01
              (work in progress), April 2013.

              Senevirathne, T., Pathangi, J., and J. Hudson,
              "Coordinated Multicast Trees (CMT) for TRILL",
              draft-ietf-trill-cmt-02 (work in progress), October 2013.

              Dunbar, L., Eastlake, D., Perlman, R., and I. Gashinsky,
              "TRILL (Transparent Interconnection of Lots of Links):
              Edge Directory Assistance Framework",
              draft-ietf-trill-directory-framework-07 (work in
              progress), August 2013.

              Zhai, H., Hu, F., Perlman, R., Eastlake, D., and O.
              Stokes, "TRILL (Transparent Interconnection of Lots of
              Links): ESADI (End Station Address Distribution
              Information) Protocol", draft-ietf-trill-esadi-03 (work in
              progress), July 2013.

              Eastlake, D., Zhang, M., Agarwal, P., Perlman, R., and D.
              Dutt, "TRILL (Transparent Interconnection of Lots of
              Links): Fine-Grained Labeling",
              draft-ietf-trill-fine-labeling-07 (work in progress),
              May 2013.

   [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

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              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.

Authors' Addresses

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

   Phone: +1-408-765-8080

   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

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   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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