draft-ietf-opsawg-capwap-alt-tunnel-01.txt   draft-ietf-opsawg-capwap-alt-tunnel-02.txt 
Network Working Group R. Zhang Network Working Group R. Zhang
Internet-Draft China Telecom Internet-Draft China Telecom
Intended status: Standards Track Z. Cao Intended status: Standards Track Z. Cao
Expires: January 26, 2015 H. Deng Expires: March 1, 2015 H. Deng
China Mobile China Mobile
R. Pazhyannur R. Pazhyannur
S. Gundavelli S. Gundavelli
Cisco Cisco
L. Xue L. Xue
Huawei Huawei
July 25, 2014 August 28, 2014
Alternate Tunnel Encapsulation for Data Frames in CAPWAP Alternate Tunnel Encapsulation for Data Frames in CAPWAP
draft-ietf-opsawg-capwap-alt-tunnel-01 draft-ietf-opsawg-capwap-alt-tunnel-02
Abstract Abstract
CAPWAP defines a specification to encapsulate a station's data frames CAPWAP defines a specification to encapsulate a station's data frames
between the Wireless Transmission Point (WTP) and Access Controller between the Wireless Transmission Point (WTP) and Access Controller
(AC) using CAPWAP. Specifically, the station's IEEE 802.11 data (AC) using CAPWAP. Specifically, the station's IEEE 802.11 data
frames can be either locally bridged or tunneled to the AC. When frames can be either locally bridged or tunneled to the AC. When
tunneled, a CAPWAP data channel is used for tunneling. In many tunneled, a CAPWAP data channel is used for tunneling. In many
deployments it is desirable to encapsulate date frames to an entity deployments it is desirable to encapsulate date frames to an entity
different from the AC for example to an Access Router (AR). Further, different from the AC for example to an Access Router (AR). Further,
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 26, 2015. This Internet-Draft will expire on March 1, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions used in this document . . . . . . . . . . . . 5 1.1. Conventions used in this document . . . . . . . . . . . . 5
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Alternate Tunnel Encapsulation . . . . . . . . . . . . . . . 6 2. Alternate Tunnel Encapsulation . . . . . . . . . . . . . . . 6
2.1. Description . . . . . . . . . . . . . . . . . . . . . . . 6 2.1. Description . . . . . . . . . . . . . . . . . . . . . . . 6
3. Protocol Considerations . . . . . . . . . . . . . . . . . . . 8 3. Protocol Considerations . . . . . . . . . . . . . . . . . . . 8
3.1. Supported Alternate Tunnel Encapsulations . . . . . . . . 8 3.1. Supported Alternate Tunnel Encapsulations . . . . . . . . 8
3.2. Alternate Tunnel Encapsulations Type . . . . . . . . . . 8 3.2. Alternate Tunnel Encapsulations Type . . . . . . . . . . 9
3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication . . 10 3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication . . 10
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 11 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . 11 7.1. Normative References . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
Service Providers are deploying very large Wi-Fi deployments (ranging Service Providers are deploying very large Wi-Fi deployments (ranging
from hundreds of thousands of APs (referred to as WTPs in CAPWAP from hundreds of thousands of APs (referred to as WTPs in CAPWAP
terminology) to millions of APs). These networks are designed to terminology) to millions of APs). These networks are designed to
carry traffic generated from mobile users. The volume in mobile user carry traffic generated from mobile users. The volume in mobile user
traffic is already very large (in the order of petabytes per day) and traffic is already very large (in the order of petabytes per day) and
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data frames are locally bridged, i.e., not carried over the CAPWAP data frames are locally bridged, i.e., not carried over the CAPWAP
data channel. The station's data frames are handled by the Access data channel. The station's data frames are handled by the Access
Router. However, in many deployments the operator managing the WTPs/ Router. However, in many deployments the operator managing the WTPs/
AC may be different from the operator providing the internet AC may be different from the operator providing the internet
connectivity to the WTPs. Further, the WTP operator may want (or be connectivity to the WTPs. Further, the WTP operator may want (or be
required by legal/regulatory requirements) to tunnel the traffic back required by legal/regulatory requirements) to tunnel the traffic back
to an Access Router in its network as shown in Figure 2. The to an Access Router in its network as shown in Figure 2. The
tunneling requirement may be driven by the need to apply policy at tunneling requirement may be driven by the need to apply policy at
the Access Router or a legal requirement to support lawful intercept the Access Router or a legal requirement to support lawful intercept
of user traffic. What this means is that local bridging does not of user traffic. What this means is that local bridging does not
meet their requirements. Their requriements are met either by having meet their requirements. Their requirements are met either by having
the WTP tunnel the station's traffic to the AC or the WTP support an the WTP tunnel the station's traffic to the AC or the WTP support an
alternate tunnel, i.e., a tunnel to an alternate entity different alternate tunnel, i.e., a tunnel to an alternate entity different
from the AC. This is the motivation for Alternate Tunnel from the AC. This is the motivation for Alternate Tunnel
encapsulation support where the data tunnels from the WTP are encapsulation support where the data tunnels from the WTP are
terminated at an AR (and more specifically at an end point different terminated at an AR (and more specifically at an end point different
from the AC). from the AC).
Tunnel to AR _________ Tunnel to AR _________
+-----+ ( ) +-----------------+ +-----+ ( ) +-----------------+
| WTP |======+Internet +==============|Access Router(AR)| | WTP |======+Internet +==============|Access Router(AR)|
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like the IP address of the tunnel termination point.) The WTP sets like the IP address of the tunnel termination point.) The WTP sets
up the alternate tunnel using the alternate tunnel encapsulation up the alternate tunnel using the alternate tunnel encapsulation
message element. message element.
When the WTP detects an alternate tunnel failure, the WTP informs the When the WTP detects an alternate tunnel failure, the WTP informs the
AC using a message element (defined in this specification), WTP AC using a message element (defined in this specification), WTP
Alternate Tunnel Fail Indication. The message element has a status Alternate Tunnel Fail Indication. The message element has a status
field that indicates whether the message denotes reporting a failure field that indicates whether the message denotes reporting a failure
or the clearing of the previously reported failure. or the clearing of the previously reported failure.
For the case where AC is unreachable but the tunnel end point is
still reachable, the WTP behavior is up to the implementation. For
example, the WTP could either choose to tear down the tunnel or let
the existing user's traffic continue to be tunneled.
3. Protocol Considerations 3. Protocol Considerations
3.1. Supported Alternate Tunnel Encapsulations 3.1. Supported Alternate Tunnel Encapsulations
This message element is sent by a WTP to communicate its capability This message element is sent by a WTP to communicate its capability
to support alternate tunnel encapsulations. The message element to support alternate tunnel encapsulations. The message element
contains the following fields: contains the following fields:
0 1 2 3 0 1 2 3
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 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
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Figure 5: Alternate Tunnel Encapsulations Type Figure 5: Alternate Tunnel Encapsulations Type
o Type: <IANA-2> for Alternate Tunnel Encapsulation Type o Type: <IANA-2> for Alternate Tunnel Encapsulation Type
o Length: > 4 o Length: > 4
o Tunnel-Type: The tunnel type is specified by a 2 byte value. This o Tunnel-Type: The tunnel type is specified by a 2 byte value. This
specification defines the values from zero (0) to five (5) as specification defines the values from zero (0) to five (5) as
given below. The remaining values are reserved for future use. given below. The remaining values are reserved for future use.
* 0: CAPWAP. This refers to a CAPWAP data channel described in * 0: CAPWAP. This refers to a CAPWAP data channel described in
[RFC5415][RFC5416]. Additional decscription in [RFC5415][RFC5416]. Additional description in
[I-D.xue-opsawg-capwap-alt-tunnel-information]. [I-D.xue-opsawg-capwap-alt-tunnel-information].
* 1: L2TP. This refers to tunnel encapsulation described in * 1: L2TP. This refers to tunnel encapsulation described in
[RFC2661]. [RFC2661].
* 2: L2TPv3. This refers to tunnel encapsulation described in * 2: L2TPv3. This refers to tunnel encapsulation described in
[RFC3931]. [RFC3931].
* 3: IP-in-IP. This refers to tunnel encapsulation described in * 3: IP-in-IP. This refers to tunnel encapsulation described in
[RFC2003]. [RFC2003].
* 4: PMIPv6. This refers to the tunneling encapsulation * 4: PMIPv6. This refers to the tunneling encapsulation
described in [RFC5213] described in [RFC5213]
* 5: GRE-IPv4. This refers to GRE encapsulation with IPv4 as the
delivery protocol as described in [RFC2784]
* 6: GRE-IPv6. This refers to GRE encapsulation with IPv6 as the
delivery protocol as described in [RFC2784]
o Info Element: This field contains tunnel specific configuration o Info Element: This field contains tunnel specific configuration
parameters to enable the WTP to setup the alternate tunnel. For parameters to enable the WTP to setup the alternate tunnel. For
example if the tunnel type is CAPWAP then this field may contain example if the tunnel type is CAPWAP then this field may contain
the following (non-exhaustive) list of parameters the following (non-exhaustive) list of parameters
* Access Router IPv4 address * Access Router IPv4 address
* Access Router IPv6 address * Access Router IPv6 address
* Tunnel DTLS Policy * Tunnel DTLS Policy
* IEEE 802.11 Tagging Policy * IEEE 802.11 Tagging Policy
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needs to be between 1 and 1023. needs to be between 1 and 1023.
o <IANA-3>. This specification defines the IEEE 802.11 WTP o <IANA-3>. This specification defines the IEEE 802.11 WTP
Alternate Tunnel Failure Indication message element in Alternate Tunnel Failure Indication message element in
Section 3.3. This element needs to be registered in the existing Section 3.3. This element needs to be registered in the existing
CAPWAP Message Element Type registry, defined in [RFC5415]. The CAPWAP Message Element Type registry, defined in [RFC5415]. The
Type value for this element needs to be between 1024 and 2047. Type value for this element needs to be between 1024 and 2047.
o Tunnel-Type: This specification defines the Alternate Tunnel o Tunnel-Type: This specification defines the Alternate Tunnel
Encapsulations Type message element. This element contains a Encapsulations Type message element. This element contains a
field Tunnel-Type. The namespace for the field is 16 bits field Tunnel-Type. The namespace for the field is 16 bits
(0-65535)). This specification defines values, zero (0) through (0-65535)). This specification defines values, zero (0) through
five (5) and can be found in Section 3.2. The remaining values six (6) and can be found in Section 3.2. The remaining values
(6-65535) are controlled and maintained by IANA and require an (6-65535) are controlled and maintained by IANA and require an
Expert Review. IANA needs to create a Tunnel-Type registry whose Expert Review. IANA needs to create a Tunnel-Type registry whose
format is given below. format is given below.
Tunnel-Type Type Value Reference Tunnel-Type Type Value Reference
CAPWAP 0 CAPWAP 0
L2TP 1 L2TP 1
L2TPv3 2 L2TPv3 2
IP-IP 3 IP-IP 3
PMIPv6 4 PMIPv6 4
GRE-IPv4 5
GRE-IPv6 6
5. Security Considerations 5. Security Considerations
This document introduces three new CAPWAP WTPssage elements. These This document introduces three new CAPWAP WTP message elements.
elements are transported within CAPWAP Control messages as the These elements are transported within CAPWAP Control messages as the
existing message elements. Therefore, this document does not existing message elements. Therefore, this document does not
introduce any new security risks compared to [RFC5415] and [RFC5416]. introduce any new security risks compared to [RFC5415] and [RFC5416].
The security considerations described in [RFC5415] and [RFC5416] The security considerations described in [RFC5415] and [RFC5416]
apply here as well. apply here as well.
6. Contributors 6. Contributors
This document stems from the joint work of Hong Liu, Yifan Chen, This document stems from the joint work of Hong Liu, Yifan Chen,
Chunju Shao from China Mobile Research. Chunju Shao from China Mobile Research.
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7.1. Normative References 7.1. Normative References
[RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003, [RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003,
October 1996. October 1996.
[RFC2661] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn, [RFC2661] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"", G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"",
RFC 2661, August 1999. RFC 2661, August 1999.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
March 2000.
[RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling [RFC3931] Lau, J., Townsley, M., and I. Goyret, "Layer Two Tunneling
Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005. Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5415] Calhoun, P., Montemurro, M., and D. Stanley, "Control And [RFC5415] Calhoun, P., Montemurro, M., and D. Stanley, "Control And
Provisioning of Wireless Access Points (CAPWAP) Protocol Provisioning of Wireless Access Points (CAPWAP) Protocol
Specification", RFC 5415, March 2009. Specification", RFC 5415, March 2009.
 End of changes. 14 change blocks. 
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