draft-ietf-opsawg-capwap-alt-tunnel-10.txt   draft-ietf-opsawg-capwap-alt-tunnel-11.txt 
Opsawg Working Group R. Zhang Opsawg Working Group R. Zhang
Internet-Draft China Telecom Internet-Draft China Telecom
Intended status: Experimental R. Pazhyannur Intended status: Experimental R. Pazhyannur
Expires: March 9, 2018 S. Gundavelli Expires: June 21, 2018 S. Gundavelli
Cisco Cisco
Z. Cao Z. Cao
H. Deng H. Deng
Z. Du Z. Du
Huawei Huawei
September 5, 2017 December 18, 2017
Alternate Tunnel Encapsulation for Data Frames in CAPWAP Alternate Tunnel Encapsulation for Data Frames in CAPWAP
draft-ietf-opsawg-capwap-alt-tunnel-10 draft-ietf-opsawg-capwap-alt-tunnel-11
Abstract Abstract
Control and Provisioning of Wireless Access Points (CAPWAP) defines a Control and Provisioning of Wireless Access Points (CAPWAP) defines a
specification to encapsulate a station's data frames between the specification to encapsulate a station's data frames between the
Wireless Transmission Point (WTP) and Access Controller (AC). Wireless Transmission Point (WTP) and Access Controller (AC).
Specifically, the station's IEEE 802.11 data frames can be either Specifically, the station's IEEE 802.11 data frames can be either
locally bridged or tunneled to the AC. When tunneled, a CAPWAP data locally bridged or tunneled to the AC. When tunneled, a CAPWAP data
channel is used for tunneling. In many deployments encapsulating channel is used for tunneling. In many deployments encapsulating
data frames to an entity other than the AC (for example to an Access data frames to an entity other than the AC (for example to an Access
skipping to change at page 2, line 7 skipping to change at page 2, line 7
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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 March 9, 2018. This Internet-Draft will expire on June 21, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://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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3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication . . . 12 3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication . . . 12
4. Alternate Tunnel Types . . . . . . . . . . . . . . . . . . . 13 4. Alternate Tunnel Types . . . . . . . . . . . . . . . . . . . 13
4.1. CAPWAP based Alternate Tunnel . . . . . . . . . . . . . . 13 4.1. CAPWAP based Alternate Tunnel . . . . . . . . . . . . . . 13
4.2. PMIPv6 based Alternate Tunnel . . . . . . . . . . . . . . 14 4.2. PMIPv6 based Alternate Tunnel . . . . . . . . . . . . . . 14
4.3. GRE based Alternate Tunnel . . . . . . . . . . . . . . . 15 4.3. GRE based Alternate Tunnel . . . . . . . . . . . . . . . 15
5. Alternate Tunnel Information Elements . . . . . . . . . . . . 15 5. Alternate Tunnel Information Elements . . . . . . . . . . . . 15
5.1. Access Router Information Elements . . . . . . . . . . . 15 5.1. Access Router Information Elements . . . . . . . . . . . 15
5.1.1. AR IPv4 List Element . . . . . . . . . . . . . . . . 16 5.1.1. AR IPv4 List Element . . . . . . . . . . . . . . . . 16
5.1.2. AR IPv6 List Element . . . . . . . . . . . . . . . . 16 5.1.2. AR IPv6 List Element . . . . . . . . . . . . . . . . 16
5.2. Tunnel DTLS Policy Element . . . . . . . . . . . . . . . 17 5.2. Tunnel DTLS Policy Element . . . . . . . . . . . . . . . 17
5.3. IEEE 802.11 Tagging Mode Policy Element . . . . . . . . . 18 5.3. IEEE 802.11 Tagging Mode Policy Element . . . . . . . . . 19
5.4. CAPWAP Transport Protocol Element . . . . . . . . . . . . 20 5.4. CAPWAP Transport Protocol Element . . . . . . . . . . . . 20
5.5. GRE Key Element . . . . . . . . . . . . . . . . . . . . . 20 5.5. GRE Key Element . . . . . . . . . . . . . . . . . . . . . 22
5.6. IPv6 MTU Element . . . . . . . . . . . . . . . . . . . . 21 5.6. IPv6 MTU Element . . . . . . . . . . . . . . . . . . . . 23
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
7. Security Considerations . . . . . . . . . . . . . . . . . . . 23 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 23 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 25
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.1. Normative References . . . . . . . . . . . . . . . . . . 23 9.1. Normative References . . . . . . . . . . . . . . . . . . 25
9.2. Informative References . . . . . . . . . . . . . . . . . 24 9.2. Informative References . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27
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 Access Points, APs (referred to as WTPs from hundreds of thousands of Access Points, APs (referred to as WTPs
in CAPWAP terminology) to millions of APs. These networks are in CAPWAP terminology) to millions of APs. These networks are
designed to carry traffic generated from mobile users. The volume in designed to carry traffic generated from mobile users. The volume in
mobile user traffic is already very large and expected to continue mobile user traffic is already very large and expected to continue
growing rapidly. As a result, operators are looking for scalable growing rapidly. As a result, operators are looking for scalable
solutions that can meet the increasing demand. The scalability solutions that can meet the increasing demand. The scalability
skipping to change at page 5, line 23 skipping to change at page 5, line 23
// Data Frames +----------+ // Data Frames +----------+
// //
+-----+ +-----+
| WTP | | WTP |
+-----+ +-----+
Figure 2: Centralized Control and Centralized Data Figure 2: Centralized Control and Centralized Data
The key difference with the locally bridged system is that the data The key difference with the locally bridged system is that the data
frames are tunneled to the AC instead of being locally bridged. frames are tunneled to the AC instead of being locally bridged.
There are two shortcomings with system in Figure 2. 1) They do not There are two shortcomings with the system in Figure 2. 1) They do
allow the WTP to tunnel data frames to an endpoint different from the not allow the WTP to tunnel data frames to an endpoint different from
AC and 2) They do not allow the WTP to tunnel data frames using any the AC and 2) They do not allow the WTP to tunnel data frames using
encapsulation other than CAPWAP (as specified in Section 4.4.2 of any encapsulation other than CAPWAP (as specified in Section 4.4.2 of
[RFC5415]). [RFC5415]).
Figure 3 shows a system where the WTP tunnels data frames to an Figure 3 shows a system where the WTP tunnels data frames to an
alternate entity different from the AC. The WTP also uses an alternate entity different from the AC. The WTP also uses an
alternate tunnel encapsulation such as such as L2TP, L2TPv3, IP-in- alternate tunnel encapsulation such as L2TP, L2TPv3, IP-in-IP, IP/
IP, IP/GRE, etc. This enables 1) independent scaling of data plane GRE, etc. This enables 1) independent scaling of data plane and 2)
and 2) leveraging of commonly used tunnel encapsulations such as leveraging of commonly used tunnel encapsulations such as L2TP, GRE,
L2TP, GRE, etc. etc.
Alternate Tunnel to AR (L2TPv3, IP-IP, CAPWAP, etc.) Alternate Tunnel to AR (L2TPv3, IP-IP, CAPWAP, etc.)
_________ _________
+-----+ ( ) +-----------------+ +-----+ ( ) +-----------------+
| WTP |======+Internet +==============|Access Router(AR)| | WTP |======+Internet +==============|Access Router(AR)|
+-----+ (_________) +-----------------+ +-----+ (_________) +-----------------+
\\ ________ CAPWAP Control \\ ________ CAPWAP Control
\\ ( ) Channel +--------+ \\ ( ) Channel +--------+
++=+Internet+========================| AC | ++=+Internet+========================| AC |
// (________)CAPWAP Data Channel: +--------+ // (________)CAPWAP Data Channel: +--------+
// IEEE 802.11 Mgmt traffic // IEEE 802.11 Mgmt traffic
// _________ // _________
+-----+ ( ) +----------------+ +-----+ ( ) +----------------+
| WTP |====+Internet +================| Access Router | | WTP |====+Internet +================| Access Router |
+-----+ (_________) +----------------+ +-----+ (_________) +----------------+
Alternate Tunnel to AR (L2TPv3, IP-IP, CAPWAP, etc.) Alternate Tunnel to AR (L2TPv3, IP-in-IP, CAPWAP, etc.)
Figure 3: Centralized Control with Alternate Tunnel for Data Figure 3: Centralized Control with Alternate Tunnel for Data
The WTP may support widely used encapsulation types such as L2TP, The WTP may support widely used encapsulation types such as L2TP,
L2TPv3, IP-in-IP, IP/GRE, etc. The WTP advertises the different L2TPv3, IP-in-IP, IP/GRE, etc. The WTP advertises the different
alternate tunnel encapsulation types it can support. The AC alternate tunnel encapsulation types it can support. The AC
configures one of the advertised types. As shown in the figure there configures one of the advertised types. As shown in the figure there
is a CAPWAP control and data channel between the WTP and AC. The is a CAPWAP control and data channel between the WTP and AC. The
CAPWAP data channel carries the stations' management traffic as in CAPWAP data channel carries the stations' management traffic as in
the case of the locally bridged system. The main reason to maintain the case of the locally bridged system. The main reason to maintain
a CAPWAP data channel is to maintain similarity with the locally a CAPWAP data channel is to maintain similarity with the locally
bridged system. The WTP maintains three tunnels: CAPWAP Control, bridged system. The WTP maintains three tunnels: CAPWAP Control,
CAPWAP Data, and another alternate tunnel for the data frame. The CAPWAP Data, and another alternate tunnel for the data frames. The
data frames are transported by an alternate tunnel between the WTP data frames are transported by an alternate tunnel between the WTP
and a tunnel termination point such as an Access Router. This and a tunnel termination point such as an Access Router. This
specification describes how the alternate tunnel can be established. specification describes how the alternate tunnel can be established.
The specification defines message elements for the WTP to advertise The specification defines message elements for the WTP to advertise
support for alternate tunnel encapsulation, the AC to configure support for alternate tunnel encapsulation, for the AC to configure
alternate tunnel encapsulation, and for the WTP to report failure of alternate tunnel encapsulation, and for the WTP to report failure of
the alternate tunnel. the alternate tunnel.
The alternate tunnel encapsulation also supports the third-party WLAN The alternate tunnel encapsulation also supports the third-party WLAN
service provider scenario (i.e. Virtual Network Operator, VNO). service provider scenario (i.e. Virtual Network Operator, VNO).
Under this scenario, the WLAN provider owns the WTP and AC resources, Under this scenario, the WLAN provider owns the WTP and AC resources,
while the VNOs can rent the WTP resources from the WLAN provider for while the VNOs can rent the WTP resources from the WLAN provider for
network access. The AC belonging to the WLAN service provider network access. The AC belonging to the WLAN service provider
manages the WTPs in the centralized mode. manages the WTPs in the centralized mode.
As shown in Figure 4, VNO 1&2 don't possess the network access As shown in Figure 4, VNO 1&2 don't possess the network access
resources, however they provide services by acquiring resources from resources, however they provide services by acquiring resources from
the WLAN provider. Since a WTP is capable of supporting up to 16 the WLAN provider. Since a WTP is capable of supporting up to 16
Service Set Identifiers (SSIDs), the WLAN provider may provide Service Set Identifiers (SSIDs), the WLAN provider may provide
network access service for different providers with different SSIDs. network access service for different providers with different SSIDs.
For example, SSID1 is advertised by the WTP for VNO1; while SSID2 is For example, SSID1 is advertised by the WTP for VNO1; while SSID2 is
advertised by the WTP for VNO2. Therefore the data traffic from the advertised by the WTP for VNO2. Therefore the data traffic from the
user can be directly steered to the corresponding access router of user can be directly steered to the corresponding access router of
the VNO who owns that user. AC can notify multiple AR addresses for the VNO who owns that user. As shown in Figure 4, AC can notify
load balancing or redundancy. multiple AR addresses for load balancing or redundancy.
+----+ +----+
| AC | | AC |
+--+-+ +--+-+
CAPWAP-CTL | CAPWAP-CTL |
+-----------------+ +-----------------+
| CAPWAP-DATA: IEEE 802.11 Mgmt traffic | CAPWAP-DATA: IEEE 802.11 Mgmt traffic
| |
WLAN Provider| VNO 1 WLAN Provider| VNO 1
+-----+ CAPWAP-DATA (SSID1) +---------------+ +-----+ CAPWAP-DATA (SSID1) +---------------+
skipping to change at page 8, line 24 skipping to change at page 8, line 24
Channel only transports IEEE 802.11 management frames and not the Channel only transports IEEE 802.11 management frames and not the
data plane (user traffic). data plane (user traffic).
1.3. History of the document 1.3. History of the document
This document was started to accommodate Service Provider's need of a This document was started to accommodate Service Provider's need of a
more flexible deployment mode with alternative tunnels [RFC7494]. more flexible deployment mode with alternative tunnels [RFC7494].
Experiments and tests have been done for this alt-tunnel network Experiments and tests have been done for this alt-tunnel network
infrastructure. However important, the deployment of relevant infrastructure. However important, the deployment of relevant
technology is yet to complete. This experimental document is technology is yet to complete. This experimental document is
intended to serve as a historical reference for any future work as to intended to serve as an archival record for any future work as to the
the operational and deployment requirements.. operational and deployment requirements.
2. Alternate Tunnel Encapsulation Overview 2. Alternate Tunnel Encapsulation Overview
+-+-+-+-+-+-+ +-+-+-+-+-+-+ +-+-+-+-+-+-+ +-+-+-+-+-+-+
| WTP | | AC | | WTP | | AC |
+-+-+-+-+-+-+ +-+-+-+-+-+-+ +-+-+-+-+-+-+ +-+-+-+-+-+-+
|Join Request[Supported Alternate Tunnel | |Join Request [ Supported Alternate |
| Encapsulations ] | | Tunnel Encapsulations ] |
|---------------------------------------->| |---------------------------------------->|
| | | |
|Join Response | |Join Response |
|<----------------------------------------| |<----------------------------------------|
| | | |
|IEEE 802.11 WLAN Config. Request [ | |IEEE 802.11 WLAN Configuration Request [ |
| IEEE 802.11 Add WLAN, | | IEEE 802.11 Add WLAN, |
| Alternate Tunnel Encapsulation ( | | Alternate Tunnel Encapsulation ( |
| Tunnel Type, Tunnel Info Element) | | Tunnel Type, Tunnel Info Element) |
| ] | | ] |
|<----------------------------------------| |<----------------------------------------|
| | | |
| | | |
+-+-+-+-+-+-+ | +-+-+-+-+-+-+ |
| Setup | | | Setup | |
| Alternate | | | Alternate | |
| Tunnel | | | Tunnel | |
+-+-+-+-+-+-+ | +-+-+-+-+-+-+ |
| | |IEEE 802.11 WLAN Configuration Response |
|IEEE 802.11 WLAN Config. Response | |[ Alternate Tunnel Encapsulation ( |
| Tunnel Type, Tunnel Info Element) ] |
|---------------------------------------->| |---------------------------------------->|
| | | |
| | | |
+-+-+-+-+-+-+ | +-+-+-+-+-+-+ |
| Tunnel | | | Tunnel | |
| Failure | | | Failure | |
+-+-+-+-+-+-+ | +-+-+-+-+-+-+ |
|WTP Alternate Tunnel Failure Indication | |WTP Alternate Tunnel Failure Indication |
|(report failure (AR address(es))) | |(report failure (AR address(es))) |
|---------------------------------------->| |---------------------------------------->|
skipping to change at page 10, line 20 skipping to change at page 10, line 20
the alternate tunnel encapsulation message element containing the the alternate tunnel encapsulation message element containing the
tunnel type and a tunnel-specific information element. The tunnel- tunnel type and a tunnel-specific information element. The tunnel-
specific information element, for example, may contain information specific information element, for example, may contain information
like the IP address of the tunnel termination point. The WTP sets up like the IP address of the tunnel termination point. The WTP sets up
the alternate tunnel using the alternate tunnel encapsulation message the alternate tunnel using the alternate tunnel encapsulation message
element. element.
Since AC can configure a WTP with more than one AR available for the Since AC can configure a WTP with more than one AR available for the
WTP to establish the data tunnel(s) for user traffic, it may be WTP to establish the data tunnel(s) for user traffic, it may be
useful for the WTP to communicate the selected AR. To enable this, useful for the WTP to communicate the selected AR. To enable this,
the IEEE 802.11 WLAN Configuration Response may contain the AR list the IEEE 802.11 WLAN Configuration Response may carry the alternate
element containing the selected AR. tunnel encapsulation message element containing the AR list element
corresponding to the selected AR as shown in Figure 5.
On detecting a tunnel failure, WTP SHALL forward data frames to the On detecting a tunnel failure, WTP SHALL forward data frames to the
AC and discard the frames. In addition, WTP may dissociate existing AC and discard the frames. In addition, WTP may dissociate existing
clients and refuse association requests from new clients. Depending clients and refuse association requests from new clients. Depending
on the implementation and deployment scenario, the AC may choose to on the implementation and deployment scenario, the AC may choose to
reconfigure the WLAN (on the WTP) to a local bridging mode or to reconfigure the WLAN (on the WTP) to a local bridging mode or to
tunnel frames to the AC. When the WTP detects an alternate tunnel tunnel frames to the AC. When the WTP detects an alternate tunnel
failure, the WTP informs the AC using a message element, WTP failure, the WTP informs the AC using a message element, WTP
Alternate Tunnel Fail Indication (defined in this specification). It Alternate Tunnel Fail Indication (defined in this specification). It
MAY be carried in the CAPWAP Station Configuration Request message MAY be carried in the WTP Event Request message which is defined in
which is defined in [RFC5415]. [RFC5415].
The WTP also needs to notify the AC of which AR(s) are unavailable. The WTP also needs to notify the AC of which AR(s) are unavailable.
Particularly, in the VNO scenario, the AC of the WLAN service Particularly, in the VNO scenario, the AC of the WLAN service
provider needs to maintain the association of the AR addresses of the provider needs to maintain the association of the AR addresses of the
VNOs and SSIDs, and provide this information to the WTP for the VNOs and SSIDs, and provide this information to the WTP for the
purpose of load balancing or master-slave mode. purpose of load balancing or master-slave mode.
The message element has a status field that indicates whether the The message element has a status field that indicates whether the
message denotes reporting a failure or the clearing of the previously message denotes reporting a failure or the clearing of the previously
reported failure. reported failure.
skipping to change at page 11, line 16 skipping to change at page 11, line 16
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 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel-Type1 | Tunnel-Type [2...N] | Tunnel-Type 1 | Tunnel-Type 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | Tunnel-Type N |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Supported Alternate Tunnel Encapsulations Figure 6: Supported Alternate Tunnel Encapsulations
o Type: <IANA-1> for Supported Alternate Tunnel Encapsulations o Type: <IANA-1> for Supported Alternate Tunnel Encapsulations
o Length: The length in bytes, two bytes for each Alternative tunnel o Length: The length in bytes, two bytes for each Alternative tunnel
type that is included type that is included
o Tunnel-Type: This is identified by value defined in Section 3.2. o Tunnel-Type: This is identified by value defined in Section 3.2.
There may be one or more Tunnel-Types as shows in Figure 6.
3.2. Alternate Tunnel Encapsulations Type 3.2. Alternate Tunnel Encapsulations Type
This message element is sent by the AC. This message element allows This message element can be sent by the AC. This message element
the AC to select the alternate tunnel encapsulation. This message allows the AC to select the alternate tunnel encapsulation. This
element may be provided along with the IEEE 802.11 Add WLAN message message element may be provided along with the IEEE 802.11 Add WLAN
element. When the message element is present the following fields of message element. When the message element is present, the following
the IEEE 802.11 Add WLAN element SHALL be set as follows: MAC mode is fields of the IEEE 802.11 Add WLAN element SHALL be set as follows:
set to 0 (Local MAC) and Tunnel Mode is set to 0 (Local Bridging). MAC mode is set to 0 (Local MAC) and Tunnel Mode is set to 0 (Local
Bridging). Besides, the message element can also be sent by the WTP
to communicate the selected AR(s).
The message element contains the following fields: The message element contains the following fields:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel-Type | Info Element Length | | Tunnel-Type | Info Element Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Info Element | Info Element
+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+
skipping to change at page 12, line 30 skipping to change at page 12, line 34
parameters to enable the WTP to setup the alternate tunnel. This parameters to enable the WTP to setup the alternate tunnel. This
specification provides details for this elements for CAPWAP, specification provides details for this elements for CAPWAP,
PMIPv6, and GRE. This specification reserves the tunnel type PMIPv6, and GRE. This specification reserves the tunnel type
values for the key tunnel types and defines the most common values for the key tunnel types and defines the most common
message elements. It is anticipated that message elements for the message elements. It is anticipated that message elements for the
other protocols (like L2TPv3, etc.) will be defined in other other protocols (like L2TPv3, etc.) will be defined in other
specifications in the future. specifications in the future.
3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication 3.3. IEEE 802.11 WTP Alternate Tunnel Failure Indication
The Alternate Tunnel Failure Indication message element is sent by The WTP MAY include the Alternate Tunnel Failure Indication message
the WTP to inform the AC about the status of the Alternate Tunnel. in a WTP Event Request message to inform the AC about the status of
It MAY be included in the CAPWAP Station Configuration Request the Alternate Tunnel. For the case where WTP establishes data
message. For the case where WTP establishes data tunnels with tunnels with multiple ARs (e.g., under VNO scenario), the WTP needs
multiple ARs (e.g., under VNO scenario), the WTP needs to notify the to notify the AC of which AR(s) are unavailable. The message element
AC of which AR(s) are unavailable. The message element contains the contains the following fields:
following fields:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| WLAN ID | Status | Reserved | | WLAN ID | Status | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. Access Router Information Element . . Access Router Information Element .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: IEEE 802.11 WTP Alternate Tunnel Failure Indication Figure 8: IEEE 802.11 WTP Alternate Tunnel Failure Indication
skipping to change at page 14, line 33 skipping to change at page 14, line 33
Proxy Mobile IPv6 (PMIPv6) (defined in [RFC5213]) based user plane Proxy Mobile IPv6 (PMIPv6) (defined in [RFC5213]) based user plane
can also be used as alternate tunnel encapsulation between the WTP can also be used as alternate tunnel encapsulation between the WTP
and the AR. In this scenario, a WTP acts as the Mobile Access and the AR. In this scenario, a WTP acts as the Mobile Access
Gateway (MAG) function that manages the mobility-related signaling Gateway (MAG) function that manages the mobility-related signaling
for a station that is attached to the WTP IEEE 802.11 radio access. for a station that is attached to the WTP IEEE 802.11 radio access.
The Local Mobility Anchor (LMA) function is at the AR. If PMIPv6 UDP The Local Mobility Anchor (LMA) function is at the AR. If PMIPv6 UDP
encapsulation is selected by the AC and configured by the AC to a encapsulation is selected by the AC and configured by the AC to a
WTP, the Info Element field defined in Section 3.2 SHOULD contain the WTP, the Info Element field defined in Section 3.2 SHOULD contain the
following information: following information:
o Access Router (acts as LMA) Information: IPv4 or IPv6 address for o Access Router (acting as LMA) Information: IPv4 or IPv6 address
the alternate tunnel endpoint. for the alternate tunnel endpoint.
The message element structure for PMIPv6 encapsulation is shown in The message element structure for PMIPv6 encapsulation is shown in
Figure 10: Figure 10:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tunnel-Type=4 | Info Element Length | | Tunnel-Type=4 | Info Element Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. Access Router (LMA) Information Element . . Access Router Information Element .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Alternate Tunnel Encapsulation - PMIPv6 Figure 10: Alternate Tunnel Encapsulation - PMIPv6
4.3. GRE based Alternate Tunnel 4.3. GRE based Alternate Tunnel
Generic Routing Encapsulation (defined in [RFC2784]) mode based user Generic Routing Encapsulation (defined in [RFC2784]) mode based user
plane can also be used as alternate tunnel encapsulation between the plane can also be used as alternate tunnel encapsulation between the
WTP and the AR. In this scenario, a WTP and the access routers WTP and the AR. In this scenario, a WTP and the access router
represent the two end points of the GRE tunnel. If GRE encapsulation represent the two end points of the GRE tunnel. If GRE encapsulation
is selected by the AC and configured by the AC to a WTP, the Info is selected by the AC and configured by the AC to a WTP, the Info
Element field defined in Section 3.2 SHOULD contain the following Element field defined in Section 3.2 SHOULD contain the following
information: information:
o Access Router Information: IPv4 or IPv6 address for the alternate o Access Router Information: IPv4 or IPv6 address for the alternate
tunnel endpoint. tunnel endpoint.
o GRE Key Information: The Key field is intended to be used for o GRE Key Information: The Key field is intended to be used for
identifying an individual traffic flow within a tunnel [RFC2890]. identifying an individual traffic flow within a tunnel [RFC2890].
skipping to change at page 15, line 40 skipping to change at page 15, line 40
. GRE Key Element . . GRE Key Element .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: Alternate Tunnel Encapsulation - GRE Figure 11: Alternate Tunnel Encapsulation - GRE
5. Alternate Tunnel Information Elements 5. Alternate Tunnel Information Elements
This section defines the various elements described in Section 4.1, This section defines the various elements described in Section 4.1,
Section 4.2, and Section 4.3. Section 4.2, and Section 4.3.
These information elements can only be inluded in the Alternate These information elements can only be included in the Alternate
Tunnel Encapsulations Type message element, and the IEEE 802.11 WTP Tunnel Encapsulations Type message element, and the IEEE 802.11 WTP
Alternate Tunnel Failure Indication message element as their sub- Alternate Tunnel Failure Indication message element as their sub-
elements. elements.
5.1. Access Router Information Elements 5.1. Access Router Information Elements
The Access Router Information Elements allow the AC to notify a WTP The Access Router Information Elements allow the AC to notify a WTP
of which AR(s) are available for establishing a data tunnel. The AR of which AR(s) are available for establishing a data tunnel. The AR
information may be IPv4 address, or IPv6 address.This information information may be IPv4 address, or IPv6 address.This information
element SHOULD be contained whatever the tunnel type is. element SHOULD be contained whatever the tunnel type is.
If the Alternate Tunnel Encapsulations Type message element is sent
by the WTP to communicate the selected AR(s), this Access Router
Information Element SHOULD be contained.
The following are the Access Router Information Elements defined in The following are the Access Router Information Elements defined in
this specification. The AC can use one of them to notify the this specification. The AC can use one of them to notify the
destination information of the data tunnel to the WTP. The Elements destination information of the data tunnel to the WTP. The Elements
containing the AR IPv4 address MUST NOT be used if an IPv6 data containing the AR IPv4 address MUST NOT be used if an IPv6 data
channel with IPv6 transport is used. channel with IPv6 transport is used.
5.1.1. AR IPv4 List Element 5.1.1. AR IPv4 List Element
This Element (see Figure 12) is used by the AC to configure a WTP This Element (see Figure 12) is used by the AC to configure a WTP
with the AR IPv4 address available for the WTP to establish the data with the AR IPv4 address available for the WTP to establish the data
skipping to change at page 16, line 36 skipping to change at page 16, line 40
. AR IPv4 Address-N . . AR IPv4 Address-N .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: AR IPv4 List Element Figure 12: AR IPv4 List Element
Type: 0 Type: 0
Length: This refers to the total length in octets of the element Length: This refers to the total length in octets of the element
excluding the Type and Length fields. excluding the Type and Length fields.
AR IPv4 Address: IPv4 address of the AR. At least one IPv4 address AR IPv4 Address: The IPv4 address of the AR. At least one IPv4
SHALL be present. Multiple addresses may be provided for load address SHALL be present. Multiple addresses may be provided for
balancing or redundancy. load balancing or redundancy.
5.1.2. AR IPv6 List Element 5.1.2. AR IPv6 List Element
This Element (see Figure 13) is used by the AC to configure a WTP This Element (see Figure 13) is used by the AC to configure a WTP
with the AR IPv6 address available for the WTP to establish the data with the AR IPv6 address available for the WTP to establish the data
tunnel for user traffic. tunnel for user traffic.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 17, line 24 skipping to change at page 17, line 24
. AR IPv6 Address-N . . AR IPv6 Address-N .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: AR IPv6 List Element Figure 13: AR IPv6 List Element
Type: 1 Type: 1
Length: This refers to the total length in octets of the element Length: This refers to the total length in octets of the element
excluding the Type and Length fields. excluding the Type and Length fields.
AR IPv6 Address: IPv6 address of the AR. At least one IPv6 address AR IPv6 Address: The IPv6 address of the AR. At least one IPv6
SHALL be present. Multiple addresses may be provided for load address SHALL be present. Multiple addresses may be provided for
balancing or redundancy. load balancing or redundancy.
5.2. Tunnel DTLS Policy Element 5.2. Tunnel DTLS Policy Element
The AC distributes its DTLS usage policy for the CAPWAP data tunnel The AC distributes its DTLS usage policy for the CAPWAP data tunnel
between a WTP and the AR. There are multiple supported options, between a WTP and the AR. There are multiple supported options,
represented by the bit field below as defined in AC Descriptor represented by the bit field below as defined in AC Descriptor
message elements. The WTP MUST abide by one of the options for message elements. The WTP MUST abide by one of the options for
tunneling user traffic with AR. The Tunnel DTLS Policy Element obeys tunneling user traffic with AR. The Tunnel DTLS Policy Element obeys
the definition in [RFC5415]. If there are more than one ARs the definition in [RFC5415]. If, for reliability reasons, the AC has
information provided by the AC for reliability reasons, the same provided more than one AR address in the Access Router Information
Tunnel DTLS Policy (see Figure 14) is generally applied for all Element, the same Tunnel DTLS Policy (the last one in Figure 14) is
tunnels associated with the ARs. Otherwise, Tunnel DTLS Policy MUST generally applied for all tunnels associated with those ARs.
be bonding together with each of the ARs, then WTP will enforce the Otherwise, Tunnel DTLS Policy MUST be bonded together with each of
the Access Router Information Elements, and the WTP will enforce the
independent tunnel DTLS policy for each tunnel with a specific AR. independent tunnel DTLS policy for each tunnel with a specific AR.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Tunnel DTLS Policy Element Type| Length | |Tunnel DTLS Policy Element Type| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |A|D|C|R| | Reserved |D|C|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information (optional) . . AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |D|C|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |D|C|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: Tunnel DTLS Policy Element Figure 14: Tunnel DTLS Policy Element
Type: 2 Type: 2
Length: This refers to the total length in octets of the element Length: This refers to the total length in octets of the element
excluding the Type and Length fields. excluding the Type and Length fields.
Reserved: A set of reserved bits for future use. All implementations Reserved: A set of reserved bits for future use. All implementations
complying with this protocol MUST set to zero any bits that are complying with this protocol MUST set to zero any bits that are
reserved in the version of the protocol supported by that reserved in the version of the protocol supported by that
implementation. Receivers MUST ignore all bits not defined for the implementation. Receivers MUST ignore all bits not defined for the
version of the protocol they support. version of the protocol they support.
A: If A bit is set, there is an AR information associated with the
DTLS policy. There may be an array of pairs binding DTLS policy
information and AR information contained in the Tunnel DTLS Policy
Element. Otherwise, the same Tunnel DTLS Policy (see Figure 14) is
generally applied for all tunnels associated with the ARs configured
by the AC.
D: DTLS-Enabled Data Channel Supported (see [RFC5415]). D: DTLS-Enabled Data Channel Supported (see [RFC5415]).
C: Clear Text Data Channel Supported (see [RFC5415]). C: Clear Text Data Channel Supported (see [RFC5415]).
R: A reserved bit for future use (see [RFC5415]). R: A reserved bit for future use (see [RFC5415]).
AR Information: This means Access Router Information Element. In
this context, each address in AR information MUST be one of
previously specified AR addresses.
The last element having no AR Information in Figure 14 is the default
tunnel DTLS policy, and provides options for any address not
previously mentioned. Therefore, the AR information field here is
optional. If all ARs share the same tunnel DTLS policy, in this
element, there will not be AR information field and its specific
tunnel DTLS policy.
5.3. IEEE 802.11 Tagging Mode Policy Element 5.3. IEEE 802.11 Tagging Mode Policy Element
In 802.11 networks, IEEE 802.11 Tagging Mode Policy Element is used In 802.11 networks, IEEE 802.11 Tagging Mode Policy Element is used
to specify how the WTP apply the QoS tagging policy when receiving to specify how the WTP applies the QoS tagging policy when receiving
the packets from stations on a particular radio. When the WTP sends the packets from stations on a particular radio. When the WTP sends
out the packet to data channel to the AR(s), the packets have to be out the packet to data channel to the AR(s), the packets have to be
tagged for QoS purposes (see [RFC5416]). tagged for QoS purposes (see [RFC5416]).
The IEEE 802.11 Tagging Mode Policy abides the IEEE 802.11 WTP The IEEE 802.11 Tagging Mode Policy abides the IEEE 802.11 WTP
Quality of Service defined in Section 6.22 of [RFC5416]. Quality of Service defined in Section 6.22 of [RFC5416].
If there are more than one ARs information provided by the AC for If, for reliability reasons, the AC has provided more than one AR
reliability reasons, the same IEEE 802.11 Tagging Mode Policy (see address in the Access Router Information Element, the same IEEE
Figure 15) is generally applied for all tunnels associated with the 802.11 Tagging Mode Policy (the last one in Figure 15) is generally
ARs. Otherwise, IEEE 802.11 Tagging Mode Policy MUST be bonding applied for all tunnels associated with those ARs. Otherwise, IEEE
together with each of the ARs, then WTP will enforce the independent 802.11 Tagging Mode Policy MUST be bonded together with each of the
tunnel IEEE 802.11 Tagging Mode Policy for each tunnel with a Access Router Information Elements, and the WTP will enforce the
independent IEEE 802.11 Tagging Mode Policy for each tunnel with a
specific AR. specific AR.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tagging Mode Policy Ele. Type | Length | | Tagging Mode Policy Ele. Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |A|P|Q|D|O|I| | Reserved |P|Q|D|O|I|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information (optional) . . AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |P|Q|D|O|I|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |P|Q|D|O|I|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: IEEE 802.11 Tagging Mode Policy Element Figure 15: IEEE 802.11 Tagging Mode Policy Element
Type: 3 Type: 3
Length: This refers to the total length in octets of the element Length: This refers to the total length in octets of the element
excluding the Type and Length fields. excluding the Type and Length fields.
Reserved: A set of reserved bits for future use. Reserved: A set of reserved bits for future use.
A: If A bit is set, there is an AR information associated with the
Tagging Mode policy. There may be an array of pairs binding Tagging
Mode policy information and AR information contained in the Tagging
Mode Policy Element. Otherwise, the same Tagging Mode Policy (see
Figure 15) is generally applied for all tunnels associated with the
ARs configured by the AC.
P: When set, the WTP is to employ the 802.1p QoS mechanism (see P: When set, the WTP is to employ the 802.1p QoS mechanism (see
[RFC5416]). [RFC5416]).
Q: When the 'P' bit is set, the 'Q' bit is used by the AC to Q: When the 'P' bit is set, the 'Q' bit is used by the AC to
communicate to the WTP how 802.1p QoS is to be enforced. (see communicate to the WTP how 802.1p QoS is to be enforced (see
[RFC5416]). [RFC5416]).
D: When set, the WTP is to employ the DSCP QoS mechanism (see D: When set, the WTP is to employ the DSCP QoS mechanism (see
[RFC5416]). [RFC5416]).
O: When the 'D' bit is set, the 'O' bit is used by the AC to O: When the 'D' bit is set, the 'O' bit is used by the AC to
communicate to the WTP how DSCP QoS is to be enforced on the outer communicate to the WTP how DSCP QoS is to be enforced on the outer
(tunneled) header (see [RFC5416]). (tunneled) header (see [RFC5416]).
I: When the 'D' bit is set, the 'I' bit is used by the AC to I: When the 'D' bit is set, the 'I' bit is used by the AC to
communicate to the WTP how DSCP QoS is to be enforced on the communicate to the WTP how DSCP QoS is to be enforced on the
station's packet (inner) header (see [RFC5416]). station's packet (inner) header (see [RFC5416]).
AR Information: This means Access Router Information Element. In
this context, each address in AR information MUST be one of
previously specified AR addresses.
The last element having no AR Information in Figure 15 is the default
IEEE 802.11 Tagging Mode Policy, and provides options for any address
not previously mentioned. Therefore, the AR information field here
is optional. If all ARs share the same IEEE 802.11 Tagging Mode
Policy, in this element, there will not be AR information field and
its specific IEEE 802.11 Tagging Mode Policy.
5.4. CAPWAP Transport Protocol Element 5.4. CAPWAP Transport Protocol Element
The CAPWAP data tunnel supports both UDP and UDP-Lite (see The CAPWAP data tunnel supports both UDP and UDP-Lite (see
[RFC3828]). When run over IPv4, UDP is used for the CAPWAP data [RFC3828]). When run over IPv4, UDP is used for the CAPWAP data
channels. When run over IPv6, the CAPWAP data channel may use either channels. When run over IPv6, the CAPWAP data channel may use either
UDP or UDP-lite. The AC specifies and configure the WTP for which UDP or UDP-lite. The AC specifies and configures the WTP for which
transport protocol is to be used for the CAPWAP data tunnel. transport protocol is to be used for the CAPWAP data tunnel.
The CAPWAP Transport Protocol Element abides the definition in The CAPWAP Transport Protocol Element abides the definition in
Section 4.6.14 of [RFC5415]. Section 4.6.14 of [RFC5415].
If, for reliability reasons, the AC has provided more than one AR
address in the Access Router Information Element, the same CAPWAP
Transport Protocol (the last one in Figure 16) is generally applied
for all tunnels associated with those ARs. Otherwise, CAPWAP
Transport Protocol MUST be bonded together with each of the Access
Router Information Elements, and the WTP will enforce the independent
CAPWAP Transport Protocol for each tunnel with a specific AR.
0 1 2 3 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 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 | | Type=4 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport | | Transport | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transport | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: CAPWAP Transport Protocol Element Figure 16: CAPWAP Transport Protocol Element
Type: 4 Type: 4
Length: 1 Length: 1
Transport: The transport to use for the CAPWAP Data channel. The Transport: The transport to use for the CAPWAP Data channel. The
following enumerated values are supported: following enumerated values are supported:
1 - UDP-Lite: The UDP-Lite transport protocol is to be used for the 1 - UDP-Lite: The UDP-Lite transport protocol is to be used for the
CAPWAP Data channel. Note that this option MUST NOT be used if the CAPWAP Data channel. Note that this option MUST NOT be used if the
CAPWAP Control channel is being used over IPv4 and AR address is IPv4 CAPWAP Control channel is being used over IPv4 and AR address is IPv4
contained in the AR Information Element. contained in the AR Information Element.
2 - UDP: The UDP transport protocol is to be used for the CAPWAP Data 2 - UDP: The UDP transport protocol is to be used for the CAPWAP Data
channel. channel.
AR Information: This means Access Router Information Element. In
this context, each address in AR information MUST be one of
previously specified AR addresses.
The last element having no AR Information in Figure 16 is the default
CAPWAP Transport Protocol, and provides options for any address not
previously mentioned. Therefore, the AR information field here is
optional. If all ARs share the same CAPWAP Transport Protocol, in
this element, there will not be AR information field and its specific
CAPWAP Transport Protocol.
5.5. GRE Key Element 5.5. GRE Key Element
If a WTP receives the GRE Key Element in the Alternate Tunnel If a WTP receives the GRE Key Element in the Alternate Tunnel
Encapsulation message element for GRE selection, the WTP MUST insert Encapsulation message element for GRE selection, the WTP MUST insert
the GRE Key to the encapsulation packet (see [RFC2890]). An AR the GRE Key to the encapsulation packet (see [RFC2890]). An AR
acting as decapsulating tunnel endpoint identifies packets belonging acting as decapsulating tunnel endpoint identifies packets belonging
to a traffic flow based on the Key value. to a traffic flow based on the Key value.
The GRE Key Element field contains a four octet number defined in The GRE Key Element field contains a four octet number defined in
[RFC2890]. [RFC2890].
If, for reliability reasons, the AC has provided more than one AR
address in the Access Router Information Element, a GRE Key Element
MAY be bonded together with each of the Access Router Information
Elements, and the WTP will enforce the independent GRE Key for each
tunnel with a specific AR.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GRE Key Element Type | Length | | GRE Key Element Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GRE Key | | GRE Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| GRE Key |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. ...... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: GRE Key Element Figure 17: GRE Key Element
Type: 5 Type: 5
Length: This refers to the total length in octets of the element Length: This refers to the total length in octets of the element
excluding the Type and Length fields. excluding the Type and Length fields.
GRE Key: The Key field contains a four octet number which is inserted GRE Key: The Key field contains a four octet number which is inserted
by the WTP according to [RFC2890]. by the WTP according to [RFC2890].
AR Information: This means Access Router Information Element. In
this context, it SHOULD be restricted to a single address, and MUST
be the address of one of previously specified AR addresses.
Any address not explicitly mentioned here does not have a GRE key.
5.6. IPv6 MTU Element 5.6. IPv6 MTU Element
If AC has chosen a tunneling mechanism based on IPv6, it SHOULD If AC has chosen a tunneling mechanism based on IPv6, it SHOULD
support the minimum IPv6 MTU requirements [RFC2460]. This issue is support the minimum IPv6 MTU requirements [RFC8200]. This issue is
described in [I-D.ietf-intarea-tunnels]. AC SHOULD inform the WTP described in [I-D.ietf-intarea-tunnels]. AC SHOULD inform the WTP
about the IPv6 MTU information in the "Tunnel Info Element" field. about the IPv6 MTU information in the "Tunnel Info Element" field.
If, for reliability reasons, the AC has provided more than one AR
address in the Access Router Information Element, an IPv6 MTU Element
MAY be bonded together with each of the Access Router Information
Elements, and the WTP will enforce the independent IPv6 MTU for each
tunnel with a specific AR.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 MTU Element Type | Length | | IPv6 MTU Element Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum IPv6 MTU | Reserved | | Minimum IPv6 MTU | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum IPv6 MTU | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. AR Information .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ...... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 18: IPv6 MTU Element Figure 18: IPv6 MTU Element
Type: 6 Type: 6
Length: This refers to the total length in octets of the element Length: This refers to the total length in octets of the element
excluding the Type and Length fields. excluding the Type and Length fields.
Minimum IPv6 MTU: The field contains a two octet number indicate the Minimum IPv6 MTU: The field contains a two octet number indicate the
minimum IPv6 MTU in the tunnel. minimum IPv6 MTU in the tunnel.
AR Information: This means Access Router Information Element. In
this context, each address in AR information MUST be one of
previously specified AR addresses.
6. IANA Considerations 6. IANA Considerations
This document requires the following IANA considerations. This document requires the following IANA considerations.
o <IANA-1>. This specification defines the Supported Alternate o <IANA-1>. This specification defines the Supported Alternate
Tunnel Encapsulations Type message element in Section 3.1. This Tunnel Encapsulations Type message element in Section 3.1. This
elements needs to be registered in the existing CAPWAP Message elements needs to be registered in the existing CAPWAP Message
Element Type registry, defined in [RFC5415]. The Type value for Element Type registry, defined in [RFC5415]. The Type value for
this element needs to be between 1 and 1023 (see Section 15.7 in this element needs to be between 1 and 1023 (see Section 15.7 in
[RFC5415]). [RFC5415]).
skipping to change at page 22, line 42 skipping to change at page 24, line 42
CAPWAP 0 [RFC5415],[RFC5416] CAPWAP 0 [RFC5415],[RFC5416]
L2TP 1 [RFC2661] L2TP 1 [RFC2661]
L2TPv3 2 [RFC3931] L2TPv3 2 [RFC3931]
IP-IP 3 [RFC2003] IP-IP 3 [RFC2003]
PMIPv6-UDP 4 [RFC5844] PMIPv6-UDP 4 [RFC5844]
GRE 5 [RFC2784] GRE 5 [RFC2784]
GTPv1-U 6 [3GPP TS 29.281] GTPv1-U 6 [3GPP TS 29.281]
o Alternate Tunnel Sub-elements Registry: This specification defines o Alternate Tunnel Sub-elements Registry: This specification defines
the Alternate Tunnel Sub-elements. Currently, these information the Alternate Tunnel Sub-elements. Currently, these information
elements can only be inluded in the Alternate Tunnel elements can only be included in the Alternate Tunnel
Encapsulations Type message element, and the IEEE 802.11 WTP Encapsulations Type message element, and the IEEE 802.11 WTP
Alternate Tunnel Failure Indication message element as their sub- Alternate Tunnel Failure Indication message element as their sub-
elements. These information elements contains a Type field. The elements. These information elements contains a Type field. The
namespace for the field is 16 bits (0-65535). This specification namespace for the field is 16 bits (0-65535). This specification
defines values, zero (0) through six (6) in Section 5. This defines values, zero (0) through six (6) in Section 5. This
namespace is managed by IANA and assignments require an Expert namespace is managed by IANA and assignments require an Expert
Review. Review.
Type Type Value Type Type Value
AR IPv4 List 0 AR IPv4 List 0
skipping to change at page 23, line 44 skipping to change at page 25, line 44
[RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003, [RFC2003] Perkins, C., "IP Encapsulation within IP", RFC 2003,
DOI 10.17487/RFC2003, October 1996, DOI 10.17487/RFC2003, October 1996,
<https://www.rfc-editor.org/info/rfc2003>. <https://www.rfc-editor.org/info/rfc2003>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <https://www.rfc-editor.org/info/rfc2460>.
[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, DOI 10.17487/RFC2661, August 1999, RFC 2661, DOI 10.17487/RFC2661, August 1999,
<https://www.rfc-editor.org/info/rfc2661>. <https://www.rfc-editor.org/info/rfc2661>.
[RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
DOI 10.17487/RFC2784, March 2000, DOI 10.17487/RFC2784, March 2000,
<https://www.rfc-editor.org/info/rfc2784>. <https://www.rfc-editor.org/info/rfc2784>.
skipping to change at page 24, line 36 skipping to change at page 26, line 31
(CAPWAP) Protocol Specification", RFC 5415, (CAPWAP) Protocol Specification", RFC 5415,
DOI 10.17487/RFC5415, March 2009, DOI 10.17487/RFC5415, March 2009,
<https://www.rfc-editor.org/info/rfc5415>. <https://www.rfc-editor.org/info/rfc5415>.
[RFC5416] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley, [RFC5416] Calhoun, P., Ed., Montemurro, M., Ed., and D. Stanley,
Ed., "Control and Provisioning of Wireless Access Points Ed., "Control and Provisioning of Wireless Access Points
(CAPWAP) Protocol Binding for IEEE 802.11", RFC 5416, (CAPWAP) Protocol Binding for IEEE 802.11", RFC 5416,
DOI 10.17487/RFC5416, March 2009, DOI 10.17487/RFC5416, March 2009,
<https://www.rfc-editor.org/info/rfc5416>. <https://www.rfc-editor.org/info/rfc5416>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>.
9.2. Informative References 9.2. Informative References
[I-D.ietf-intarea-tunnels] [I-D.ietf-intarea-tunnels]
Touch, J. and M. Townsley, "IP Tunnels in the Internet Touch, J. and M. Townsley, "IP Tunnels in the Internet
Architecture", draft-ietf-intarea-tunnels-07 (work in Architecture", draft-ietf-intarea-tunnels-07 (work in
progress), June 2017. progress), June 2017.
[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., [RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
RFC 5213, DOI 10.17487/RFC5213, August 2008, RFC 5213, DOI 10.17487/RFC5213, August 2008,
 End of changes. 56 change blocks. 
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