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Versions: 00 01 02 03 04 draft-ietf-trill-smart-endnodes

INTERNET-DRAFT                                             Radia Perlman
Intended Status: Proposed Standard                            Intel Labs
Expires: July 7, 2013                                          Fanwei Hu
                                                         ZTE Corporation
                                                         Donald Eastlake
                                                                  Huawei
                                                Kesava Vijaya Krupakaran
                                                                    Dell
                                                         January 3, 2013


                         TRILL Smart Endnodes
                 draft-perlman-trill-smart-endnodes-01


Abstract

   This draft addresses the problem of the size and freshness of the
   endnode learning table in access 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 to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

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

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

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

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





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Copyright and License Notice

   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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
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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.



Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Added information in TRILL-Hello . . . . . . . . . . . . . . .  4
   3.  Hello Exchange with RBridges . . . . . . . . . . . . . . . . .  5
   4.  Multi-homing . . . . . . . . . . . . . . . . . . . . . . . . .  5
   5.  Encapsulation and Decapsulation  . . . . . . . . . . . . . . .  6
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  8
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     8.1  Normative References  . . . . . . . . . . . . . . . . . . .  8
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  8





















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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]) ([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, looked
   up in a directory, 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 lost.

   For these reasons, it is desirable for an endnode E (whether it be
   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 has 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. 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 frames. Although E transmits
   TRILL-Hellos, E does not transmit or receive LSPs.




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   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, whether the tree selected is one of the ones
   that R has claimed it will choose).  When R receives (from the
   campus) a TRILL-encapsulated packet with R's nickname as egress, R
   checks whether the 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.

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].


2.  Added information in TRILL-Hello

   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 message to do this in is a TRILL-Hello.

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

   *  flag indicating willingness to have an attached smart endnode

   *  R's nickname (already included)

   *  trees that R can use when ingressing frames

   *  new TLV for smart endnode neighbor list

   *  set of { ({set of RBridge nicknames}, pseudonode nickname) pairs},
      which is a pseudonode nickname that can be used if the smart
      endnode is multihomed to all of the RBridge nicknames listed.

   E's TRILL-Hello must contain the following information:

   *  I don't want to form an RB-adjacency; merely to be a smart endnode

   *  For each VLAN
      (1) The set of MAC addresses I own
      (2) Whether I wish to receive ESADI for that VLAN

   Note that 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 (traditional 12 bit VLANs or 24-bit FGL Fine
      Grained Labels), 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([TRILL-ESADI])

      *  by querying a directory

      *  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
      specified.

   The attached RBridge R does the following:

   o  When receiving an encapsulated frame from a port with a smart
      endnode, with R's nickname as ingress, R forwards the packet to
      the specified egress nickname, as with any encapsulated packet.
      However, R MAY enforce that the inner source MAC and VLAN (or FGL)
      are as specified for the smart endnode, by dropping if the MAC (or
      VLAN/FGL) are not among the expected set from the smart endnode.

3.  Hello Exchange with RBridges

      The smart endnode E need 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 sees a 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.


4.  Multi-homing




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      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, this will cause distant RBridges (or smart endnodes)
       to keep changing their endnode table entry for D between (D, R1's
       nickname) and (D, R2's nickname). So it would be preferable for E
       to always encapsulate using the same nickname (R1 or R2) unless E
       detects a problem with connectivity using that nickname. And in
       this case, R1 and R2 need to be informed that the smart endnode
       might encapsulate with a different nickname, i.e., R1 might
       receive an encapsulated packet from smart endnode E using ingress
       nickname "R2".

   (2) R1 and R2 might indicate, in their Hello, another 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.  This does use a nickname, but hopefully
       would be shared by many end nodes multihomed to the same set of
       RBridges.


5.  Encapsulation and Decapsulation

       Consider a smart endnode E on a shared LAN wishing to communicate
       with D. First suppose D is not on the shared LAN. The draft
       already handles that case.

       Suppose D is on the same shared LAN as smart node E. If E does
       not know where D is, the packet needs to be flooded BOTH on the
       shared LAN as a native packet, and throughout the campus,
       encapsulated.

   (1) If E does not know where D is, then E sends two copies of the
       packet; one native, and one encapsulated.

   (2) If the Appointed Forwarder R receives a native packet on a port
       with smart endnode E, and the source MAC is one that E owns, then



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       R MUST discard the packet.

   (3) If R receives a native packet on a port with smart endnode E, and
       the destination MAC is one that E owns, then R MUST discard the
       packet.

   (4) The other non-AFs in the shared LAN behave as usual - they don't
       encapsulate native frames.


      This solution works regardless of whether D is a smart endnode or
      not. Smart endnode E will learn that D is on the shared link, and
      keep in its table (D, native on my link).  So in the future, E
      will send to D by transmitting natively. R MUST discard the packet
      because it notices the source MAC is owned by E. D will transmit
      to E natively, whether or not D is a smart endnode. R will also
      discard the packet in this case because the destination MAC is
      owned by E. So D and E will talk natively.

      If R receives a multicast from a remote RBridge, and the exit
      interface 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.



























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6.  Security Considerations

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

7.  IANA Considerations

      This document requires no IANA actions.


8.  References

8.1  Normative References

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

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

   [RFC6325] R. Perlman, D. Eastlake, et al, "RBridges: Base Protocol
              Specification", RFC 6325, July 2011.

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

   [RFC6326bis] D. Eastlake, A. Banerjee, et al, "Transparent
              Interconnection of Lots of Links (TRILL) Use of IS-IS",
              draft-eastlake-isis-rfc6326bis-09.txt, work in progress.

   [Directory] Linda, D., Eastlake, D., Perlman, R., and I. Gashinsky,
              "TRILL Edge Directory Assistance Framework", trill-
              directory-framework-01 (work in process).

   [TRILL-ESADI] Zhai, H., Hu, F., Perlman, R., and D. Eastlake,
              "TRILL(Transparent Interconnection of Lots of Links): The
              ESADI (End Station Address Distribution Information)
              Protocol", draft-ietf-trill-esadi-01(work in process).


Authors' Addresses


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

                 Phone: +1-408-765-8080



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                 Email: Radia@alum.mit.edu


                 Fangwei Hu
                 ZTE Corporation
                 No.889 Bibo Rd
                 Shanghai,   201203
                 China

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


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

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


                 Kesava Vijaya Krupakaran
                 Dell
                 Olympia Technology Park,
                 Guindy Chennai 600 032
                 India

                 Phone: +91 44 4220 8496
                 Email: Kesava_Vijaya_Krupak@Dell.com





















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