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
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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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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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