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Versions: 00 01

Network Working Group                                             D. Liu
Internet-Draft                                              China Mobile
Intended status: Standards Track                                R. Zhang
Expires: January 4, 2015                                   China Telecom
                                                                  L. Xue
                                                       J. Kaippallimalil
                                                                  Huawei
                                                           R. Pazhyannur
                                                           S. Gundavelli
                                                                   Cisco
                                                            July 3, 2014


   Specification Alternate Tunnel Information for Data Frames in WLAN
           draft-xue-opsawg-capwap-alt-tunnel-information-00

Abstract

   In IEEE 802.11 Wireless Local Area Network (WLAN) architecture, in
   order to meet the scalability requirement, customer data frames are
   desired to be distributed to an endpoint (e.g.  Access Router AR)
   different from the Access Controller (AC).  For tunneling the data
   frames, there are many known alternate tunnel technologies can be
   used, such as IP-GRE, IP-IP, CAPWAP, L2TP/L2TPv3 etc.  To assist a
   WTP to set up the alternate tunnels, this document extends the
   message elements to report WTP the specific alternate tunnel
   information.

Requirements Language

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

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."



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   This Internet-Draft will expire on January 4, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Data Frame Alternate Tunnel in WLAN . . . . . . . . . . . . .   3
     2.1.  CAPWAP  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  L2TP  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.3.  L2TPv3  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.4.  IP-GRE  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Alternate Tunnel Information TLV  . . . . . . . . . . . . . .   5
     3.1.  CAPWAP Information TLV  . . . . . . . . . . . . . . . . .   5
     3.2.  L2TP Information TLV  . . . . . . . . . . . . . . . . . .   8
     3.3.  L2TPv3 Information TLV  . . . . . . . . . . . . . . . . .   9
     3.4.  IP-GRE Tunnel Information TLV . . . . . . . . . . . . . .  10
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Control and Provisioning of Wireless Access Points (CAPWAP) (
   [RFC5415][RFC5416] )defines CAPWAP tunnel mode which can be used to
   encapsulate a station's data frames and control/management frames
   between the Wireless Transmission Point (WTP) and Access Controller
   (AC).  The customer data traffic on WTP can be either locally bridged
   or tunnelled to the AC.  Practically, some operators who have
   deployed large numbers of WTPs desire to distribute the data traffic
   to an different entity rather than AC for scalability reasons.  An




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   split architecture tunnelling data frames to ARs rather than ACs is
   defined in [I-D.ietf-opsawg-capwap-alt-tunnel], Figure 1.

             Tunnel to AR _________
            +-----+      (         )              +-----------------+
            | WTP |======+Internet +==============|Access Router(AR)|
            +-----+      (_________}              +-----------------+
                  \\      ________
                   \\    (        ) CAPWAP        +--------+
                      ++==Internet+===============|   AC   |
                     //  (        )               +--------+
                    //  ________
            +-----+//  (         )                +----------------+
            | WTP |====+Internet +================|  Access Router |
            +=====+    (_________}                +----------------+
             Tunnel to AR

       Figure 1: Figure 1: Centralized Control with Distributed Data

   A generic container for the extension message elements for this
   architecture have been already defined in
   [I-D.ietf-opsawg-capwap-alt-tunnel].  The IEEE 802.11 Alternate
   Tunnel Encapsulation message element Figure 2defined in
   [I-D.ietf-opsawg-capwap-alt-tunnel],allows the AC to select the
   alternate tunnel encapsulation and reports some tunnel specific
   information to WTP.  Indeed, there are many protocols may be used for
   this data frames alternate tunnel, such as IP-IP, IP-GRE, L2TP/
   L2TPv3, CAPWAP, etc.  The specific tunnel information for each of
   these potential tunnel protocols are defined in this document.

        0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
        |  Tunnel Type  | Tunnel Specific Information
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

         Figure 2: Figure 2: Alternate Tunnel Encapsulations Type

2.  Data Frame Alternate Tunnel in WLAN

2.1.  CAPWAP

   CAPWAP protocol ( [RFC5415][RFC5416]) may be used for data tunnel
   between WTP and AR asFigure 1.  According to CAPWAP with IEEE 802.11
   WLAN networks [RFC5416], WTP needs CAPWAP data tunnel information so
   as to distribute data frames to CAPWAP data tunnel to AR.  The
   following specific CAPWAP data tunnel information (not-exhaustive)
   should be configured on WTP,more details are described in
   Section 3.1.



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   o  Access Router Information: IPv4 address, IPv6 address, Fully
      Qualified Domain Name (FQDN)

   o  Tunnel DTLS Policy

   o  IEEE 802.11 Tagging Mode Policy

2.2.  L2TP

   Layer Two Tunneling Protocol (L2TP) can pass PPP frames over an L2TP
   tunnel within a UDP datagram.  When AC selects the L2TP as the
   alternate tunnel encapsulation and reports the selection to WTP, WTP
   instates the L2TP data tunnel establishment with a specific AR.  This
   AR address should be configured to WTP during the calling request
   from hosts attaching to the WTP.  Additionally, there are some more
   tunnel information which need to configure according to [RFC2661],
   such as Maximum Transmission Unit (MTU) information and IPSec policy
   for L2TP.  The following specific tunnel information (not-exhaustive)
   are listed,more details are described in Section 3.2.

   o  Access Router Information: IPv4 address, IPv6 address, Fully
      Qualified Domain Name (FQDN)

   o  MTU

   o  IPSec Policy

2.3.  L2TPv3

   L2TPv3 borrows largely from L2TPv2.  L2TPv3 tunnel can be used over
   multiple Packet-Switched Network (PSN) such as IP, UDP, Frame Relay,
   ATM, MPLS, etc.  L2TPv3 tunnels the data packets may be utilized with
   or without the L2TP control channel, either via manual configuration
   or via other signaling methods to per-configure or distribute L2TP
   session information.  In this document, L2TPv3 control channel is
   assumed to establish, manage and tear down the L2TPv3 data tunnel.
   Similar tunnel information as L2TP(not-exhaustive) in Section 2.2
   should be configured on WTP,such as AR information, MTU, IPSec
   Policy.  More details are described in Section 3.3.

2.4.  IP-GRE

   In order to encapsulated data traffic using GRE ([RFC1701][RFC2784]
   ), WTP needs at least to obtain the destination node IP address of a
   GRE tunnel (e.g.,AR address) to encapsulate the GRE packets.
   Optionally, GRE Key Suboption ( [RFC2784] [RFC2890] ) is needed for
   WTP so as to configure the complementary tunnel information.  If WTP
   obtains the GRE Key suboption, the key MUST be inserted into the GRE



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   encapsulation header.  The Key is used for identifying extra context
   information about the received payload on AR.  The payload packets
   without the correspondent GRE Key or with an unmatched GRE Key will
   be silently dropped.

   The following specific GRE data tunnel information (not-exhaustive)
   should be configured on WTP, more details are described in
   Section 3.4.

   o  Access Router Information: IPv4 address, IPv6 address, Fully
      Qualified Domain Name (FQDN)

   o  GRE Key

3.  Alternate Tunnel Information TLV

3.1.  CAPWAP Information TLV

   New tunnel information TLVs are defined when CAPWAP alternate tunnel
   (Tunnel Type =0) is used :

   The AR IPv4 Address TLV: This TLV is used by AC to configure AR IPv4
   address to WTP.  WTP establishes CAPWAP data tunnel with the specific
   AR.  The format is shown as follows.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=1               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    .                     AR IPv4 Address                           .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 3: AR IPv4 Address TLV

   AR IPv4 Address: The AR IPv4 address serving WTP in the network.  Due
   to load-sharing and reliability requirement, there may be more than
   one AR IPv4 address provided.  The AR IPv4 address can be formatted
   via TLV for sub-TLVFigure 4:












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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type                 |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    | Prefer|              AR IPv4 Address                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       .
    +-+-+-+-+


                  Figure 4: Load-sharing AR IPv4 Sub-TLV

   Type: 1

   Prefer: The priority/cost of the following AR IPv4 address

   AR IPv4 Address: the IPv4 address of ARs which can serve the WTP in
   the network.

   AR IPv6 Address TLV: This TLV is used by AC to configure AR IPv6
   address to WTP.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=2               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    .                     AR IPv6 Address                           .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 5: AR IPv6 Address TLV

   AR IPv6 Address: The AR IPv6 prefix serving WTP in the network.Due to
   load-sharing and reliability requirement, there may be more than one
   AR IPv6 address provided.  The AR IPv6 address can be formatted via
   TLV for sub-TLVFigure 6:














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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type                 |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    | Prefer|              AR IPv6 Address                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       .
    +-+-+-+-+

                  Figure 6: Load-sharing AR IPv6 sub-TLV

   Type: 1

   Prefer: The priority/cost of the following AR IPv6 address

   AR FQDN TLV: This TLV is used by AC to configure FQDN to WTP.  Based
   on the FQDN, WTP can acquire AR IP address via DNS.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=3               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    .                     AR FQDN                                   .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                           Figure 7: AR FQDN TLV

   AR FQDN: The AR FQDN serving WTP in the network.Due to reliability
   reasons, more than one AR FQDN can be provided via sub-TLV:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type                 |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    | Prefer|              FQDN                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       .
    +-+-+-+-+

                       Load-sharing AR FQDN sub-TLV

   Type: 1

   Prefer: The priority/cost of the following AR FQDN.




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   Tunnel DTLS Policy TLV: This TLV reports WTP the tunnel Datagram
   Transport Layer Security (DTLS) policy of CAPWAP data tunnel with AR.
   If the policy value is set to 1, WTP establishes a secure DTLS
   session with the selected AR.  Otherwise, the CAPWAP data frames are
   not secured using DTLS.  Especially, if there are multiple ARs used
   due to load balance or reliability reasons, the tunnel DTLS policy
   TLV Figure 8must be carried together with each of the AR sub-TLV.
   WTP must clear the tunnel DTLS policy for each tunnel to a AR.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=4               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                    Tunnel DTLS Policy                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 8: Tunnel DTLS Policy TLV

   Tunnel DTLS Policy: If value is 1, the CAPWAP date frames to AR will
   be secured using DTLS.  Otherwise, DTLS is not used.

   IEEE 802.11 Tagging Mode Policy TLV: This TLVFigure 9 reports WTP the
   way to tag IEEE 802.11 packet.  CAPWAP ([RFC5415][RFC5416]) defines a
   tunnel mode that specifies the frame tunneling type to be used for
   802.11 data frames from stations.  The WTP may tunnel client data
   frames to the AR, using 802.3 frame tunnel mode or 802.11 frame
   tunnel mode.  If value is 1, the WTP will use 802.3 frame tunnel
   mode, if value is 0, the WTP will forward 802.11 frame directly to
   the AR.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=4               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                    Tunnel DTLS Policy                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 9: IEEE 802.11 Tagging Mode Policy TLV

3.2.  L2TP Information TLV

   The following new TLVs are needed when the alternate tunnel is L2TP
   (Tunnel Type =1) :






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   The TLVs mentioned Figure 3Figure 5Figure 7should be used for WTP to
   identify ARs.  WTP initiates L2TP tunnel establishment procedure with
   the specific ARs.

   MTU TLVFigure 10: L2TP protocol makes no special efforts to optimize
   packet fragmentation.  AC reports the MTU which can be provided on
   WTP.  Generally, the MTU on WTP should be no more than the MTU on the
   path minus the encapsulation headers, such as IP header, L2TP header,
   PPP header, etc.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=4               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                        MTU TLV                                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                            Figure 10: MTU TLV

   IPSec Policy TLV: IPSec may be used for end to end L2TP security.  If
   the value is set to 1, the L2TP packet encryption is provided by
   IPsec mode.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=5               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                       IPSec Policy                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 11: IPSec Policy TLV

3.3.  L2TPv3 Information TLV

   The following new TLVs are used when the alternate tunnel is L2TPv3
   (Tunnel Type =2) :

   The TLVs mentioned Figure 3Figure 5Figure 7should be used for WTP to
   identify ARs.  WTP initiates L2TPv3 tunnel establishment procedure
   with the specific ARs.

   MTU TLVFigure 10: AC reports the MTU can be provided on WTP.
   Generally, the MTU on WTP should be no more than the MTU on the path
   minus the encapsulation headers, such as IP header, L2TP header etc.





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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=4               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                        MTU TLV                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                            Figure 12: MTU TLV

   IPSec Policy TLV: IPSec may be used for end to end L2TPv3 security
   issue.  If the value is set to 1, the L2TPv3 packet encryption is
   provided by IPsec mode.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=5               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                       IPSec Policy                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 13: IPSec Policy TLV

   L2TPv3 Encapsulation TLV: L2TPv3 can be used over IP or UDP as
   defined in [RFC3931].  While L2TPv3 over IP is not as NAT-friendly as
   L2TP over UDP, so AC need to configure the proper L2TPv3
   encapsulation to WTP in NAT scenario.  If the value is 1, L2TPv3 will
   be send over IP, otherwise, L2TPv3 over UDP will be applied.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=5               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                       L2TPv3 Encapsulation                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Figure 14: L2TPv3 Encapsulation TLV

3.4.  IP-GRE Tunnel Information TLV

   The following new IP-GRE tunnel information TLVs are used, when
   tunnel is IP-GRE (Tunnel Type =4) :

   The TLVs mentioned Figure 3Figure 5Figure 7should be used for WTP to
   identify ARs.  WTP encapsulates the customer upstream packet via AR
   address as destination address in GRE header.



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   GRE Key TLV: If WTP receives the GRE Key TLV, WTP must insert the GRE
   Key to the encapsulation packet.  And AR as decapsulating tunnel
   endpoint identifies packets belonging to a traffic flow based on the
   Key value.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type=4               |          Length               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-------------------------------+
    |                     GRE Key                                   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         IP-GRE Tunnel GRE Key TLV

4.  IANA Considerations

   To be specified in later versions.

5.  Security Considerations

   To be specified in later versions.

6.  References

6.1.  Normative References

   [RFC1701]  Hanks, S., Li, T., Farinacci, D., and P. Traina, "Generic
              Routing Encapsulation (GRE)", RFC 1701, October 1994.

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

   [RFC2401]  Kent, S. and R. Atkinson, "Security Architecture for the
              Internet Protocol", RFC 2401, November 1998.

   [RFC2661]  Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
              G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"",
              RFC 2661, August 1999.

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
              March 2000.

   [RFC2890]  Dommety, G., "Key and Sequence Number Extensions to GRE",
              RFC 2890, September 2000.





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   [RFC3931]  Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
              Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.

   [RFC4347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security", RFC 4347, April 2006.

   [RFC5415]  Calhoun, P., Montemurro, M., and D. Stanley, "Control And
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Specification", RFC 5415, March 2009.

   [RFC5416]  Calhoun, P., Montemurro, M., and D. Stanley, "Control and
              Provisioning of Wireless Access Points (CAPWAP) Protocol
              Binding for IEEE 802.11", RFC 5416, March 2009.

6.2.  Informative References

   [I-D.ietf-opsawg-capwap-alt-tunnel]
              Zhang, R., Cao, Z., Deng, H., Pazhyannur, R., Gundavelli,
              S., and L. Xue, "Alternate Tunnel Encapsulation for Data
              Frames in CAPWAP", draft-ietf-opsawg-capwap-alt-tunnel-00
              (work in progress), May 2014.

Authors' Addresses

   Dapeng Liu
   China Mobile
   Unit 2, 28 Xuanwumenxi Ave, Xuanwu District
   Beijing  100053
   China

   Email: liudapeng@chinamobile.com


   Rong Zhang
   China Telecom
   No. 109 Zhongshandadao avenue
   Guangzhou  510630
   China

   Email: zhangr@gsta.com











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Li Xue
Huawei
No.156 Beiqing Rd. Z-park, Shi-Chuang-Ke-Ji-Shi-Fan-Yuan, HaiDian District
Beijing  100095
China

Email: xueli@huawei.com


   John Kaippallimalil
   Huawei
   5430 Legacy Drive, Suite 175
   Plano, TX  75024

   Email: john.kaippallimalil@huawei.com


   Rajesh S. Pazhyannur
   Cisco
   170 West Tasman Drive
   San Jose,  CA 95134
   USA

   Email: rpazhyan@cisco.com


   Sri Gundavelli
   Cisco
   170 West Tasman Drive
   San Jose,  CA 95134
   USA

   Email: sgundave@cisco.com


















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