Internet DRAFT - draft-xue-dhc-location-option

draft-xue-dhc-location-option






Network Working Group                                             L. Xue
Internet-Draft                                               B. Sarikaya
Intended status: Informational                                    Huawei
Expires: August 29, 2013                               February 25, 2013


                DHCP option for STA Location Information
                    draft-xue-dhc-location-option-01

Abstract

   This document introduces WTP information transported using DHCPv4/v6.
   In this procedure, DHCPv4/v6 snooping is deployed on the WTP node or
   AC node.  Then the WTP information can be inserted into the extension
   option of DHCPv4/v6 message.  GW obtain the WTP information of the
   subscriber through which the subscriber accesses network.

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 RFC 2119 [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
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   This Internet-Draft will expire on August 29, 2013.

Copyright 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



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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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.  Applicability  . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  DHCPv4/v6 Operation  . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  DHCPv4 Operation . . . . . . . . . . . . . . . . . . . . .  6
     3.2.  DHCPv6 Operation . . . . . . . . . . . . . . . . . . . . .  7
   4.  Location Information Option  . . . . . . . . . . . . . . . . .  8
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     7.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     7.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10




























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1.  Introduction

   WLAN (Wireless Local Area Network) features low cost and flexible,
   and even high speed wireless data access with open spectrum.  So it
   is becoming very popular these years.  Especially, it is a general
   case that currently WLAN is used to supplement cellular (2G/3G/LTE)
   network.  This provides a good chance for operators to offer
   broadband service with less CAPEX.

   Traditionally, WLAN consists of WTP and AC device as optional.  WTP
   is the physical or logical network entity that contains an RF antenna
   and wireless physical layer (PHY) to transmit and receive station
   traffic for wireless access networks, and then transmit the packet to
   the wireline network.  It works as media converter.  There are two
   kinds of WTP in exiting network, defined as standalone WTP and
   Controlled WTP.  The standalone WTP refers to the WTP in autonomous
   WLAN architecture.  Here standalone WTP response for all WLAN
   functionality, such as encryption/decryption, authentication, etc.
   Instead, controlled WTP refers to the WTP in centralized WLAN
   architecture.  In this case, WTP management and subscriber
   authentication are implemented on AC device.

   It is possible that AC isn't intelligent enough to aggregate all the
   WLAN critical functions in one, because the AC device is always
   enterprise device instead of carrier device.  It is costly in large-
   scale intelligent AC deployment, also it is challenge for operators.
   So it is a popular scenario to split the authentication function from
   AC to Gateway(GW), which is the existing authentication gateway for
   other service, such as PPP, etc.  This enables a better environment
   that diminishes the software and hardware upgrade for operators,
   shown in figure 1.

                                        +------+
                                        |      |
                                        |  AC  |
                                        |      |
                                        +--+---+
                                           |
                                           |
                                           |
     +------+     +------+              +--+---+     /-------\
     |      |     |      |              |      |    |         |
     | STA  | /-/ | WTP  +--------------+  GW  +----+ Service |
     |      |     |      |              |      |    |         |
     +------+     +------+              +------+     \-------/

                  Figure 1 Centralized WLAN Architecture




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   However, some issues arise meanwhile if the authentication moved out
   from the AC.  One of the issues is that Gateway can't obtain the WTP
   information(MAC address, etc) because the WTP management function is
   located in AC device.  The challenge is that WTP information for the
   subscriber is actually appreciated for operators.  For example,
   subscriber's location information (WTP information ) is required in
   the charging bill, in order to the collect statistical parameter or
   push advertisement to special WTP, or locate the fault exactly, etc.

   This document introduces WTP information transported using DHCPv4/v6.
   In this procedure, DHCPv4/v6 snooping is deployed on the WTP node or
   AC node.  The DHCPv4/v6 snooping node will recognize the DHCPv4/v6
   packets and insert the WTP information into the extension option of
   DHCPv4/v6 messages .  Then the subscriber's WTP information is
   transported.  GW obtains the WTP information through which the
   subscriber access network.  If the WTP information is MAC address,
   the subscriber location information will be obtained by GW.  Also GW
   can inform location information to AAA server, etc.  The operators
   can use this information to achieve some management, such as locating
   fault, push advertisement to special WTP, etc.

1.1.  Terminology

   This document uses the following terms.

   Wireless Termination Point (WTP)

   The physical or logical network entity that contains an RF antenna
   and wireless physical layer (PHY) to transmit and receive station
   traffic for wireless access networks.  This definition has the same
   meaning used in [RFC4118].  It also called AP.

   Access Controller (AC)

   The network entity that provides WTP access to the network
   infrastructure in the data plane, control plane, management plane, or
   a combination therein, as defined in[RFC4118].

   Also the terms used in this document are accordant with the
   terminologies in [RFC2131].

   Gateway (GW)

   A device in operator access network, who can charge the subscriber
   authentication.  It maybe BRAS (Broadband Remote Access Server) or
   BNG (Broadband Network Gateway).





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2.  Applicability

   This specification applies when layer 2 network is deployed between
   WTP and GW or layer 2 network is deployed between WTP and AC.  In
   these cases, the procedure specified in this document should be used
   for WTP information transmission.  It occurs for two scenarios.

   o  AC is deployed as a standalone node, which is WTP management
      device and doesn't transport the traffic for the subscriber at
      all, shown in figure 2.

   o  AC is involved in the subscriber traffic transport, shown in
      figure 3.  The subscriber traffic can be transported via Layer 2
      network between WTP and AC.  Note:the layer 2 connection is
      assumed between AC and GW.

                                          +------+
                                          |      |
                                          |  AC  |
                                          |      |
                                          +--+---+
                                             |
                                             |
                                             |
     +------+     +------+ Traffic for STA+--+---+     /-------\
     |      |     |      +----------------+      |    |         |
     | STA  | /-/ | WTP  +----------------+  GW  +----+ Service |
     |      |     |      |   Layer 2      |      |    |         |
     +------+     +------+                +------+     \-------/


                        Figure 2 Traffic bypass AC

                           Traffic
    +------+     +------+  for STA  +------+   +------+   /-------\
    |      |     |      +-----------+      |   |      |  |         |
    | STA  | /-/ | WTP  +-----------+  AC  +---+  GW  +--+ Service |
    |      |     |      | Layer 2/  |      |   |      |  |         |
    +------+     +------+ CAPWAP TUN+------+   +------+   \-------/

                        Figure 3 Traffic through AC

   Moreover, this specification applies when DHCPv4/v6 snooping
   mentioned in [SAVI-DHCP] is deployed on WTP or AC node.  Any
   DHCPv4/v6 protocol agent and server that implements the mechanism
   described in this document assume that they follow the DHCPv4/v6
   general procedure [RFC2131].




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3.  DHCPv4/v6 Operation

   The DHCPv4/v6 procedure when DHCPv4/v6 snooping is deployed on WTP/AC
   node is described in this section.  Take the first scenario shown as
   follows for example.  The operation for the WTP information transport
   is shown in figure 4 via DHCPv4 and in figure 5 via DHCPv6

3.1.  DHCPv4 Operation

                                           +------+
                                           |      |
                                           |  AC  |
                                           |      |
                                           +--+---+
  +------+         +------+ Traffic for STA+--+---+             +------+
  |      |         |      +----------------+      |             |      |
  | STA  |    /-/  | WTP  +----------------+  GW  |             | AAA  |
  |      |         |      |   Layer 2      |      |             |      |
  +------+         +------+                +------+             +------+

     |                 |                      |                    |
     |             DHCP snooping              |                    |
     |                 |                      |                    |
     | DHCPv4 Discover |                      |                    |
     +---------------->|                      |                    |
     |             Insert WTP info            |                    |
     |            into DHCPv4 Message         |                    |
     |                 |                      |                    |
     |                DHCPv4 Discover(WTP MAC)|                    |
     |                 +--------------------->|                    |
     |        DHCPv4 offer                    |                    |
     |<----------------+----------------------+                    |
     | DHCPv4 Request  |                      |                    |
     +---------------->|                      |                    |
     |           Insert|WTP info              |                    |
     |          into DHCPv4 Message           |                    |
     |                 |                      |                    |
     |                DHCPv4 Request(WTP MAC) |                    |
     |                 +--------------------->|                    |
     |                 |                 GW obtain WTP info        |
     |        DHCPv4 ACK                 via DHCPv4 option         |
     |<----------------+----------------------+                    |
     |      Authentication Procedure          |                    |
     |<----------------+--------------------->|    WTP info        |
     |                 |                      |    via RADIUS      |
     |                 |                      +------------------->|
     |                 |                      |                    |




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                         Figure 4 DHCPv4 Operation

   1 DHCPv4 snooping is deployed on WTP node.  Then WTP node can capture
   the DHCPv4 message.

   2 STA initiates DHCPv4 procedure via DHCPv4 discovery message.

   3 WTP recognizes the DHCPv4 packets and inserts the WTP
   information,such as MAC address into the new DHCPv4 option of DHCPv4
   message, both DHCPv4 Discovery and DHCPv4 Request .

   4 The WTP information for the subscriber can be obtained by GW via
   DHCPv4 option.  GW treats this information as subscriber profile.

   5 After IP address assignment, the authentication procedure is
   initiated.  During the authentication procedure, WTP info can be
   transported to AAA service via RADIUS message.  The operators can use
   this information to achieve some management, such as locating fault,
   push advertisement to special WTP, etc.  This step is out the scope
   of this specification.

   As the other scenario shown in figure 3, AC is responsible to
   transport subscriber traffic from AP to GW.  Because AC manages and
   configures WTP, it is assumed that AC has record the WTP MAC address.
   So here, the DHCPv4 snooping function is deployed on AC node, and the
   procedure is same as shown in figure 6.

3.2.  DHCPv6 Operation























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                                           +------+
                                           |      |
                                           |  AC  |
                                           |      |
                                           +--+---+
  +------+         +------+ Traffic for STA+--+---+             +------+
  |      |         |      +----------------+      |             |      |
  | STA  |    /-/  | WTP  +----------------+  GW  |             | AAA  |
  |      |         |      |   Layer 2      |      |             |      |
  +------+         +------+                +------+             +------+

     |                 |                      |                    |
     |             DHCP snooping              |                    |
     |                 |                      |                    |
     | DHCPv6 Solicit  |                      |                    |
     +---------------->|                      |                    |
     |             Insert WTP info            |                    |
     |            into DHCPv6 Message         |                    |
     |                 |                      |                    |
     |                DHCPv6 Solicit (WTP MAC)|                    |
     |                 +--------------------->|                    |
     |        DHCPv6  Advertise               |                    |
     |<----------------+----------------------+                    |
     | DHCPv6 Request  |                      |                    |
     +---------------->|                      |                    |
     |           Insert|WTP info              |                    |
     |          into DHCPv6 Message           |                    |
     |                 |                      |                    |
     |                DHCPv6 Request(WTP MAC) |                    |
     |                 +--------------------->|                    |
     |                 |                 GW obtain WTP info        |
     |        DHCPv6 Reply               via DHCPv6 option         |
     |<----------------+----------------------+                    |
     |      Authentication Procedure          |                    |
     |<----------------+--------------------->|    WTP info        |
     |                 |                      |    via RADIUS      |
     |                 |                      +------------------->|
     |                 |                      |                    |

                         Figure 5 DHCPv6 Operation

   The procedure of DHCPv6 is similar as DHCPv4.  The detailed
   description is ignored.


4.  Location Information Option

   This documents defines a new option called Location Information



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   Option.  It is an optional option for the specific subscriber's WTP
   information transport.  The format of the DHCPv4 Location Information
   Option is:

    0               1               2                 3             4
     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |     code      |    Length     |      WTP information          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |     WTP information (cont)    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


              Figure 6 Location Information Option for DHCPv4

   The code is recommended to the value still unassigned.  In this
   document, value 140 is suggested.

   The length is 6, while the WTP information field is just filled with
   WTP MAC address.

   The format of the DHCPv6 location information option for DHCPv6 is
   shown as follows.  The location information option follows the common
   base format defined in [RFC3315].
    0               1               2                 3             4
     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |       option-code             |      option-len               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                WTP information                                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 7 Locaiton information Option for DHCPv6

   The option-code is recommended an unsigned integer to identify
   location information option for DHCPv6.  Value 35 is suggested.

   The length is 6, while the WTP information field is just filled with
   WTP MAC address.

   However, the WTP information will be extended in next version if more
   requirement can be clarified.


5.  IANA Considerations

   TBD




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6.  Security Considerations

   TBD


7.  References

7.1.  Normative References

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

   [RFC2131]  Droms, R., "Dynamic Host Configuration Protocol",
              RFC 2131, March 1997.

   [RFC2132]  Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
              Extensions", RFC 2132, March 1997.

   [RFC3315]  Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
              and M. Carney, "Dynamic Host Configuration Protocol for
              IPv6 (DHCPv6)", RFC 3315, July 2003.

   [RFC3369]  Housley, R., "Cryptographic Message Syntax (CMS)",
              RFC 3369, August 2002.

   [RFC4118]  Yang, L., Zerfos, P., and E. Sadot, "Architecture Taxonomy
              for Control and Provisioning of Wireless Access Points
              (CAPWAP)", RFC 4118, June 2005.

7.2.  Informative References

   [SAVI-DHCP]
              "draft-ietf-savi-dhcp", June 2012.


Authors' Addresses

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

   Email: xueli@huawei.com







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   Behcet Sarikaya
   Huawei
   5340 Legacy Dr.
   Plano, TX  75024

   Email: sarikaya@ieee.org













































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