Internet DRAFT - draft-xue-dhcp-location-option
draft-xue-dhcp-location-option
Network Working Group L. Xue
Internet-Draft Huawei
Intended status: Informational B. Sarikaya
Expires: August 22, 2013 Huawei USA
February 18, 2013
DHCPv4 and DHCPv6 options for Access Point Location Information
draft-xue-dhcp-location-option-00
Abstract
This document introduces Control and Provisioning of Wireless Access
Points Wireless Termination Point information transported using DHCP.
In this procedure, DHCP snooping is deployed on the Wireless
Termination Point node or Access Controller node. Then the Wireless
Termination Point information can be inserted into the DHCP message
in extension option. Because the DHCP messages is send out from the
subscriber, so binding between Wireless Termination Point information
and subscriber is set up after this procedure. Then Gateway obtains
the Wireless Termination Point information through the subscriber
access 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.
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This Internet-Draft will expire on August 22, 2013.
Copyright Notice
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Copyright (c) 2013 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Applicability . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. DHCP Operation . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Location Information Option . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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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 WLAN is used to supplement cellular (2G/3G/LTE) network.
It provides a good chance for operators to provide broadband service
with less CAPEX.
Traditionally, the 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 in this
point. There are two types to WTP in exiting network, defined as
standalone WTP and controlled WTP. The standalone WTP refers to the
WTP in autonomous WLAN architecture. WTP is responsible for all WLAN
functionality, such as encryption/decryption, authentication, etc.
Instead, controlled WTP refers to the WTP in centralized WLAN
architecture. In that case, WTP management and subscriber
authentication is implemented on AC device.
It is possible that AC in the existing network 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 deployment the software and hardware
upgrade risks for carriers. So it is a popular scenario to split the
authentication function from AC to Service Gateway, 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, if the authentication moved out from the AC, some issues
arise meanwhile. One of the issues is that Service 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 appreciated for operators in
the charge bill, in order to the collect statistical parameter and
push advertisement to special WTP, or locate the fault locating
exactly, etc.
This document introduces WTP information transported using DHCP. In
this procedure, DHCP snooping is deployed on the WTP node or AC node.
Then the WTP information can be inserted into the DHCP message in
extension option. Because the DHCP messages is send out from the
subscriber, so binding between WTP information and subscriber is set
up after this procedure. Then GW obtain the WTP information through
which the subscriber access network.
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].
2. Applicability
This specification applies when layer 2 network is deployed between
WTP and GW, where DHCP relay function isn't deployed on the access
device. In these cases, the procedure specified here should be used
for WTP information transmission. This can occur for two scenarios.
First, the AC is deployed as a standalone node, which doesn't
transport the traffic for the subscriber at all, shown in figure 2.
Other, the AC deployed on the path between WTP and GW, is involved in
the subscriber traffic transport, shown in figure 3. In the second
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case, the layer 2 connection is assumed between AC and GW as noted.
+------+
| |
| 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, the specification applies when DHCP snooping mentioned in
[I-D.ietf-savi-dhcp] must be deployed on WTP or AC node. Any DHCP
protocol agent and server that implements the mechanisms described in
this document can assume that they follow the DHCP general procedure
must follow [RFC2131].
3. DHCP Operation
The DHCP procedure when DHCP snooping is deployed on WTP/AC node is
described in this section. Take the scenario as subscriber traffic
bypass AC (figure 3) for example. The operation for the WTP
information transport is shown in figure 4.
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+------+
| |
| AC |
| |
+--+---+
+------+ +------+ Traffic for STA+--+---+ +------+
| | | +----------------+ | | |
| STA | /-/ | WTP +----------------+ GW | | AAA |
| | | | Layer 2 | | | |
+------+ +------+ +------+ +------+
| | | |
| 1 DHCP snooping | |
| | | |
| 2 DHCP Discover | | |
+---------------->| | |
| 3a Insert WTP info | |
| into DHCP message | |
| | | |
| |DHCP Discover(WTP MAC)| |
| +--------------------->| |
| DHCP offer | |
|<----------------+----------------------+ |
| DHCP Request | | |
+---------------->| | |
| 3b Insert|WTP info | |
| into DHCP message | |
| | | |
| |DHCP Request(WTP MAC) | |
| +--------------------->| |
| | 4 GW obtain WTP info |
| DHCP ACK via DHCP option |
|<----------------+----------------------+ |
| Authentication Procedure | |
|<----------------+--------------------->| 5 WTP info |
| | | via RADIUS |
| | +------------------->|
| | | |
Figure 4 DHCP Operation
1 DHCP snooping is deployed on WTP node. Then WTP node can capture
the DHCP message.
2 STA initiates DHCP procedure via DHCP discovery message.
3 WTP can insert the WTP information,such as MAC address into the new
DHCP option of DHCP message, both DHCP Discovery and DHCP Request .
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4 The WTP information for the subscriber can be obtained by GW via
DHCP option. The 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. Then the subscriber
bill can be created contain the access WTP information. This step is
out the scope of this specification.
As the other scenario shown in figure 3, the AC is deployed on the
path between WTP and GW. Additionally, AC is responsible to
transport subscriber traffic from AP to GW. In this case, AC manages
and configures WTP. We assume AC has record the WTP MAC address. So
here, the DHCP snooping function is deployed on AC node in this
scenario. However, the procedure is same as shown in figure 4.
4. Location Information Option
This documents defines a new option called Location Information
Option. It is an optional option for the specific subscriber's WTP
information transport. The format of the Location Information Option
is:
code length WTP information field
+-------+-------+-----------------------------------------------+
| | | |
| | | |
| | | |
+-------+-------+-----------------------------------------------+
8 16 n
Figure 5 Location Information Option
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 in
WTP MAC address.
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.
[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
[I-D.ietf-savi-dhcp]
Bi, J., Wu, J., Yao, G., and F. Baker, "SAVI Solution for
DHCP", draft-ietf-savi-dhcp-15 (work in progress),
September 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 USA
5340 Legacy Dr.
Plano, TX 75024
Email: sarikaya@ieee.org
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