Network Working Group S. Iino Internet-Draft S. Govindan Expires: September 30, 2005 M. Sugiura H. Cheng Panasonic March 29, 2005 Wireless LAN Control Protocol (WiCoP) draft-iino-capwap-wicop-00.txt Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 30, 2005. Copyright Notice Copyright (C) The Internet Society (2005). Abstract The popularity of wireless local area networks (WLANs) has led to wide spread deployments across different establishments. It has also translated in to increasing scale of the WLANs. Large-scale deployments made of large numbers of wireless termination points Iino, et al. Expires September 30, 2005 [Page 1] Internet-Draft WiCoP March 2005 (WTPs) and covering substantial areas are increasingly common. The Wireless LAN Control Protocol (WiCoP) described in this document allows for the control and provisioning of large-scale WLANs. It enables central management of these networks and realizes the objectives set forth for the control and provisioning of wireless access points (CAPWAP). Table of Contents 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 7 5. WiCoP Format . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.1 WiCoP Header . . . . . . . . . . . . . . . . . . . . . . . 9 5.2 WiCoP Control Packet . . . . . . . . . . . . . . . . . . . 11 5.2.1 WiCoP Control Messages . . . . . . . . . . . . . . . . 12 5.2.2 WiCoP Control Message Elements . . . . . . . . . . . . 13 5.2.3 WiCoP Control Message Description . . . . . . . . . . 25 5.3 WiCoP Data Packet . . . . . . . . . . . . . . . . . . . . 34 5.4 WiCoP Timers . . . . . . . . . . . . . . . . . . . . . . . 35 5.4.1 Active Presence Timer . . . . . . . . . . . . . . . . 35 5.4.2 Feedback Interval . . . . . . . . . . . . . . . . . . 35 5.4.3 Response Timer . . . . . . . . . . . . . . . . . . . . 35 5.4.4 Wireless Connectivity Timer . . . . . . . . . . . . . 36 6. WiCoP Processes . . . . . . . . . . . . . . . . . . . . . . . 37 6.1 Initialization . . . . . . . . . . . . . . . . . . . . . . 37 6.2 Capabilities Exchange . . . . . . . . . . . . . . . . . . 37 6.3 Connection . . . . . . . . . . . . . . . . . . . . . . . . 37 6.4 Configuration . . . . . . . . . . . . . . . . . . . . . . 38 6.4.1 Logical Groups . . . . . . . . . . . . . . . . . . . . 38 6.4.2 Resource Control . . . . . . . . . . . . . . . . . . . 38 6.5 Operation . . . . . . . . . . . . . . . . . . . . . . . . 39 6.5.1 Updates . . . . . . . . . . . . . . . . . . . . . . . 39 6.5.2 Feedback and Statistics . . . . . . . . . . . . . . . 39 6.5.3 Non-periodic Events . . . . . . . . . . . . . . . . . 40 6.5.4 Firmware Trigger . . . . . . . . . . . . . . . . . . . 40 6.5.5 Wireless Terminal Management . . . . . . . . . . . . . 40 6.5.6 Key Configuration . . . . . . . . . . . . . . . . . . 41 7. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 43 8. Security Considerations . . . . . . . . . . . . . . . . . . . 44 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 45 Intellectual Property and Copyright Statements . . . . . . . . 47 Iino, et al. Expires September 30, 2005 [Page 2] Internet-Draft WiCoP March 2005 1. Requirements notation 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 [RFC2119]. Iino, et al. Expires September 30, 2005 [Page 3] Internet-Draft WiCoP March 2005 2. Terminology This document follows the terminologies of [I-D.ietf-capwap-arch] and [I-D.ietf-capwap-objectives]. Iino, et al. Expires September 30, 2005 [Page 4] Internet-Draft WiCoP March 2005 3. Introduction The popularity of wireless local area networks (WLANs) has led to numerous but incompatible designs and solutions. The CAPWAP Architecture Taxonomy [I-D.ietf-capwap-arch] describes major variations of these designs. Among them, the local-MAC and split-MAC architecture designs are notable categories. Wireless LAN Control Protocol (WiCoP) recognizes the major architecture designs and presents a common platform on which WLAN entities of different designs can be accommodated. This enables interoperability among wireless termination points (WTPs) and WLAN access controllers (ACs) of distinct architecture designs. WiCoP therefore allows for cost-effective WLAN expansions. It can also accommodate future developments in WLAN technologies. Figure 1 illustrates the WiCoP opertional structure in which distinct control elements are utilized for local-MAC and split-MAC WTPs. WiCoP also addresses the increasing trend in shared infrastructure WLANs. Here, WLAN management needs to distinguish and isolate control for the different logical groups sharing a single physical WLAN. WiCoP manages WLANs through a series of tunnels that separate traffic based on logical groups. The WiCoP operational structure in Figure 1 shows that each WTP uses a number of tunnels to distinguish and separate traffic for control and for each logical group. The protocol allows for managing WLANs in a manner consistent with the logical groups that share the physical infrastructure. Iino, et al. Expires September 30, 2005 [Page 5] Internet-Draft WiCoP March 2005 Local-MAC WTP +-------+ +-------+ | | | | Logical Groups | (=====Control Tunnel======) | | | | | ~~~~~~~ | | | | / / | <=====Logical Group A=====> | / A /~~~~ | | | | / / / | <=====Logical Group B=====> | ~~~~~~~ /~~~~ | | | | / B / / | <=====Logical Group C=====> | ~~~~~~~ / | | | | / C / | | +-------+ ~~~~~~~ | | | | | AC | | | | | Split-MAC WTP | | | | +-------+ Logical Groups | | | | | [=====Control Tunnel======] | ~~~~~~~ | | | | / / | | | | / 1 /~~~~ | <=====Logical Group 1=====> | / / / | | | | ~~~~~~~ / | <=====Logical Group 2=====> | / 2 / | | | | ~~~~~~~ +-------+ +-------+ Figure 1 WiCoP enables collective management of WTPs and its operations include; i. WTP configuration ii. Firmware distribution iii. WLAN monitoring and statistics iv. Terminal data management v. Traffic tunneling Iino, et al. Expires September 30, 2005 [Page 6] Internet-Draft WiCoP March 2005 4. Protocol Overview The Wireless LAN Control Protocol (WiCoP) focuses on enabling interoperability in shared infrastructure WLANs. It is designed for use with different wireless technologies. This document provides both the general operations of WiCoP and also specific use-cases with respect to IEEE 802.11 based systems. The state machine for WiCoP is illustrated in Figure 2. Each state represents a major process in WiCoP operation. +-------------------------------------------+ | \ | \ V \ +-------------+ +-------------+ +-------------+ | |<--------| | | | | Initial- | | Capabilities| | Connection |<----+ | ization | | Exchange | | | | | |-------->| |-------->| | | +-------------+ +-------------+ +-------------+ | | | | | | | | | V | +-------------+ | | | | +---->| Configur- | | | | ation | | | | | | | +-------------+ | | | | | | | | | | | | / | V / | +--------------+ / | | | / +-----| |/ | Operation | | | +--------------+ Figure 2 Iino, et al. Expires September 30, 2005 [Page 7] Internet-Draft WiCoP March 2005 The Capabilities Exchange state combines discovery of WTPs together with inspection of their respective capabilities. This enables the AC to determine if a communicating WTP is of local-MAC or split-MAC design variant. Security associations between WTPs and the AC are established within the Connection state of WiCoP. The specific security mechanism is not covered by WiCoP. WiCoP configures WTPs within the Configuration state. This state involves operations whose effects are primarily long-term. The active operation of WTPs occurs in the Operation state. The Operation state involves active control of WTPs and the WLAN. Iino, et al. Expires September 30, 2005 [Page 8] Internet-Draft WiCoP March 2005 5. WiCoP Format WiCoP uses separate packets for control and data transfer between the AC and WTPs. A common header is used for both types of packets in which a single-bit flag distinguishes between them. 5.1 WiCoP Header Figure 3 illustrates the WiCoP common header for control and data packets. 0 31 | 7 15 23 | |-------|-------|-------|-------|-------|-------|-------|-------| | | +---------------+-+-+-+-+-+-+-+-+-------------------------------+ | Version |M|D|C|R|E|F|L| | Reserve | +---------------+-+-+-+-+-+-+-+-+-------------------------------+ | Fragment ID | Fragment No. | Length | +---------------+---------------+-------------------------------+ Figure 3 Version Field This field indicates the protocol version. 'M' Field The MAC-type field, 'M', distinguishes between local-MAC WTPs and split-MAC WTPs. This field is used for interoperability between WTPs of the two different designs. A '0' value indicates WiCoP exchanges with a split-MAC WTP while a '1' value indicates WiCoP exchanges with a local-MAC WTP. 'D' Field The differentiator field, 'D', is used to distinguish between WTP variants within a type of WTP design. The CAPWAP Architecture Taxonomy [I-D.ietf-capwap-arch] illustrates that the split-MAC design allows encryption/decryption to be performed at either the WTP or the AC. The Architecture Taxonomy also indicates that the local-MAC design allows authentication to take place at either the WTP or the Iino, et al. Expires September 30, 2005 [Page 9] Internet-Draft WiCoP March 2005 AC. WiCoP acknowledges these major variants and accommodates them using the 'D' field in conjunction with the 'M' field. So for a split-MAC WTP, the 'D' field is used to indicate location of encryption/decryption while for a local-MAC WTP, the 'D' field is used to indicate location of authentication. The following table highlights their usage. 'M' 'D' Description 0 0 Split-MAC WTP - Encryption/decryption is performed at WTP 0 1 Split-MAC WTP - Encryption/decryption is performed at AC 1 0 Local-MAC WTP - Authentication is performed by WTP 1 1 Local-MAC WTP - Authentication is performed by AC 'C' Field This field distinguishes between a WiCoP control and WiCoP data packet. Each type of information is tunneled separately across the WiCoP interface between WTPs and the AC. A '0' value for the 'C' field indicates a data packet while a '1' value indicates a control packet. 'R' Field The retransmission field, 'R', is used to differentiate between first and subsequent transmission of WiCoP packets. The 'R' field is used for critical WiCoP packets such as those relating to security key exchanges. A '0' value for the 'R' field indicates the first transmission of a WiCoP packet while a '1' value indicates a retransmission. 'E' Field The encryption field, 'E', is used to indicate if the WiCoP packet is encrypted between the AC and WTPs. The 'E' field is used for those WiCoP packets that are exchanged during initialization. A '0' value indicates the WiCoP packet is unencrypted while a '1' value indicates the packet is encrypted. Iino, et al. Expires September 30, 2005 [Page 10] 'F' Field The fragmentation field indicates if the packet is a fragment of a larger packet. A '0' value indicates a non-fragmented packet while a '1' value indicates a fragmented packet. The 'F', 'L', 'Fragment ID' and 'Fragment No.' fields are used together. 'L' Field This field is used to indicate the last fragment of a larger packet. It is only valid when the 'F' field has a '1' value. A '0' value for the 'L' field indicates the last fragment of a larger packet while a '1' value indicates an intermediate fragment of a larger packet. The 'F', 'L', 'Fragment ID' and 'Fragment No.' fields are used together. Fragment ID Field The Fragment ID identifies the larger packet which has been fragmented. It is used to distinguish between fragments of different large packets. This field is valid only when the 'F' field has a '1' value. The 'F', 'L', 'Fragment ID' and 'Fragment No.' fields are used together. Fragment No. Field The fragment number field identifies the sequence of fragments of a larger packet. The value of the Fragment No. field is incremented for each fragment of a larger packet so as to show the order of fragments. This field is valid only when the 'F' field has a '1' value. The 'F', 'L', 'Fragment ID' and 'Fragment No.' fields are used together. Length Field This field specifies the length of the WiCoP payload following the header. 5.2 WiCoP Control Packet The WiCoP control header follows the WiCoP common header. It is highlighted in Figure 5. Iino, et al. Expires September 30, 2005 [Page 11] Internet-Draft WiCoP March 2005 0 31 | 7 15 23 | |-------|-------|-------|-------|-------|-------|-------|-------| | | +---------------+---------------+-------------------------------+ | Msg Type | Reserve | Seq Num | +---------------+---------------+-------------------------------+ | Msg Element Length | +-------------------------------+ Figure 5 The control packet adds four additional fields to the common header. These are described below; Msg Type Field The message type field specifies the type of control message transported in the packet. The list of control messages is presented below. Seq Num Field The sequence number field is used to map WiCoP request and response sequences. The initiator of a WiCoP request message increments the Seq Num field for each new request message. The responder then uses these values of the Seq Num fields in its corresponding response messages. Msg Element Length Field This field specifies the length in bytes of the subsequent WiCoP control message element. 5.2.1 WiCoP Control Messages The list of WiCoP control messages is shown below; Iino, et al. Expires September 30, 2005 [Page 12] Internet-Draft WiCoP March 2005 Message Msg Type ------------------------------------------------------------ Capabilities 1 Capabilities Response 2 Connection 3 Connection Response 4 Configuration Request 5 Configuration Response 6 Configuration Data 7 Configuration Data Response 8 Configuration Trigger 9 Configuration Trigger Response 10 Feedback 11 Feedback Response 12 Reset 13 Reset Response 14 Firmware Trigger 15 Firmware Trigger Response 16 Terminal Addition 17 Terminal Additiona Response 18 Terminal Deletion 19 Terminal Deletion Response 20 Key Configuration 21 Key Configuration Response 22 Notification 23 Notification Response 24 5.2.2 WiCoP Control Message Elements WiCoP control messages each include a control message header followed by one or more message elements. The message elements are shown in the following table. Iino, et al. Expires September 30, 2005 [Page 13] Internet-Draft WiCoP March 2005 +-----------------+-----------+-------------------------------------+ | Message Element | Type | Description | +-----------------+-----------+-------------------------------------+ | WTP Info | 1 | Information regarding WTPs, such as | | | | manufacturer ID, MAC address, etc. | | | | | | Cap from WTP | 2 | QoS abilities (WME) and security | | | | abilities (IEEE 802.11i) are | | | | included | | | | | | Conf If Data | 3 | PHY information for each wireless | | | | interface | | | | | | Conf WTP Data | 4 | Information regarding logical | | | | groups on a per-logical group basis | | | | (e.g. per-virtual AP) | | | | | | Cap to WTP | 5 | Setup data sent to WTPs by AC on a | | | | per-logical group basis | | | | | | QoS Value | 6 | QoS setup (access categories) | | | | | | Timer Init | 7 | Initial values of timers such as | | Value | | aging, echo interval etc. | | | | | | Terminal Data | 8 | Information relevant to wireless | | | | terminals - BSSID, association ID, | | | | etc. | | | | | | BSSID | 9 | BSSID, and terminal MAC address | | | | | | Encryption Data | 10 | Details of the security framework - | | | | cipher suit, operation mode etc. | | | | | | EAP Frame | 11 | EAP frame | | | | | | Statistics | 12 | Various statistics information - | | | | transmission attempts, FCS errors | | | | etc. | | | | | | Interface Error | 13 | Type of wireless interface failure | | | | | | FROM Error | 14 | Flash ROM Error information | | | | | | QoS Capability | 15 | Network congestion information | | | | | | TFTP Data | 16 | Firmware related details | | | | | Iino, et al. Expires September 30, 2005 [Page 14] Internet-Draft WiCoP March 2005 | Result | 17 | Result of protocol operations - | | | | success or failure | | | | | | OID | 18 | SNMP OIDs | | | | | | MIC Flag | 19 | Location of KeyMIC calculation | +-----------------+-----------+-------------------------------------+ Each message element comprises a number of information items that are detailed below. The length of each information item is specified in bytes. WTP Info: Information included in the WTP Info message element is provided on a per-WTP basis. So each WTP exchanges one WTP Info message element. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | Manufacturer | 8 | DisplayString | Manufacturer ID | | ID | | | | | | | | | | MAC Address | 6 | PhyAddress | WTP MAC Address | | | | | | | Firmware | 8 | DisplayString | Firmware version of | | Version | | | WTP | | | | | | | Start Time | 4 | TimeTicks | Starting time of WTP | | | | | (UNIX Time) | +--------------+----------+----------------+------------------------+ Cap from WTP: Information included in the Cap from WTP message element is provided on a per-WTP basis. So each WTP exchanges one Cap from WTP message element. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | 802.11e Cap | 2 | Integer | Length of 802.11e | | Length | | | Capabilities | | | | | | | 802.11e | Variable | OCTETString | 802.11e capabilities | | Capabilities | | | of WTP. If WTP does | Iino, et al. Expires September 30, 2005 [Page 15] Internet-Draft WiCoP March 2005 | | | | not have such | | | | | capabilities, this | | | | | field is filled with | | | | | '0' | | | | | | | 802.11i Cap | 2 | Integer | Length of 802.11i | | Length | | | Capabilities | | | | | | | 802.11i | Variable | OCTETString | 802.11i capabilities | | Capabilities | | | of WTP. If WTP does | | | | | not have such | | | | | capabilities,this | | | | | field is filled with | | | | | '0' | | | | | | | AuthType | 2 | OCTETString | Type of authentication | | | | | mechanism used between | | | | | WTP and AC | +--------------+----------+----------------+------------------------+ Conf If Data The Conf If Data message element relates to the wireless interface. So a WTP with many interfaces will include corresponding numbers of Conf If Data message elements within the WiCoP control messages. Conf If Data message elements are indexed by the If ID information item. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | If ID | 1 | Integer | Denotes identification | | | | | of a wireless | | | | | interface | | | | | | | Current | 1 | Integer | Current Power Level | | Power | | | ('1' = Max; '2' = 1/2; | | | | | '3' = 1/4; '4' = 1/8 | | | | | | | Radio | 1 | Integer | Radio channel of | | Channel | | | operation | | | | | | | 2Dot4Mode | 1 | Integer | Interface mode in | | | | | 2.4GHz. ('1' = IEEE | | | | | 802.11b; '2' = IEEE | | | | | 802.11g; '3' = Both) | +--------------+----------+----------------+------------------------+ Iino, et al. Expires September 30, 2005 [Page 16] Internet-Draft WiCoP March 2005 Conf WTP Data Configuration information is provided on the basis of logical groups or BSSIDs. So there are multiple Conf WTP Data message elements to address the many logical groups within a WLAN managed by WiCoP. Conf WTP Data message elements are indexed by the BSSID information item. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | BSSID | 6 | OCTETString | BSSID | | | | | | | ESSID | 32 | OCTETString | ESSID | | | | | | | BSSID - | 32 | OCTETString | Mapping for logical | | TunnelID | | | groups across BSSID | | | | | and WiCoP tunnels | | | | | | | Beacon | 1 | Integer | Time interval between | | Period | | | Beacon transmissions | | | | | | | DTIM Period | 1 | Integer | DTIM period of Beacon | | | | | transmissions | | | | | | | AnyRejectFla | 1 | Integer | Flag indicating WTP | | g | | | rejection of any Probe | | | | | Request within any | | | | | SSID - ('1' = | | | | | Rejected; '2' = Not | | | | | Rejected) | | | | | | | SSID Stealth | 1 | Integer | Flag indicating | | Flag | | | inclusion of ESSID | | | | | within Beacon Frames | | | | | ('1' = ESSID included; | | | | | '2' = ESSID not | | | | | included) | | | | | | | Operation | 2 | Integer | Data rates supported | | Rate Set | | | by WTP for terminal | | | | | being added using 12 | | | | | bit format for 1.1, | | | | | 2.2, 3.55, 4.6, 5.9, | | | | | 6.11, 7.12, 8.18, | | | | | 9.24, 10.36, 11.48 and | | | | | 12.54 Mbps | | | | | | Iino, et al. Expires September 30, 2005 [Page 17] Internet-Draft WiCoP March 2005 | Encryption | 1 | Integer | Encryption Type - | | Type | | | '1' = OFF; '2' = | | | | | WEP40; '3' = WEP104; | | | | | '4' = WEP128) | | | | | | | Encryption | 16 | OCTETString | Static Encryption Key | | Key | | | | +--------------+----------+----------------+------------------------+ Cap to WTP: Capabilities information is provided on the basis of logical groups or virtual APs. So there are multiple Cap to WTP message elements to address the many logical groups within a WLAN managed by WiCoP. Conf to WTP message elements are indexed by the BSSID information item. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | BSSID | 6 | OCTETString | BSSID | | | | | | | 802.11e Cap | 2 | Integer | Length of 802.11e | | Length | | | Capabilities | | | | | | | 802.11e | Variable | OCTETString | 802.11e capabilities | | Capabilities | | | of WTP. If WTP does | | | | | not have such | | | | | capabilities, this | | | | | field is filled with | | | | | '0' | | | | | | | 802.11i Cap | 2 | Integer | Length of 802.11i | | Length | | | Capabilities | | | | | | | 802.11i | Variable | OCTETString | 802.11i capabilities | | Capabilities | | | of WTP. If WTP does | | | | | not have such | | | | | capabilities,this | | | | | field is filled with | | | | | '0' | +--------------+----------+----------------+------------------------+ QoS Value: QoS parameters are assigned for each logical groups to address their respective individual conditions and requirements. QoS Value message Iino, et al. Expires September 30, 2005 [Page 18] Internet-Draft WiCoP March 2005 elements are provided on a per-logical group basis. QoS Value message elements are indexed by the BSSID information item. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | BSSID | 6 | OCTETString | BSSID | | | | | | | WTP AC_BE | 2 | Integer | AC Parameters Record | | | | | AC_BE in WTP | | | | | | | WTP AC_BK | 2 | Integer | AC Parameters Record | | | | | AC_BK in WTP | | | | | | | WTP AC_VI | 2 | Integer | AC Parameters Record | | | | | AC_VI in WTP | | | | | | | WTP AC_VO | 2 | Integer | AC Parameters Record | | | | | AC_VO in WTP | | | | | | | TE AC_BE | 2 | Integer | AC Parameters Record | | | | | AC_BE in terminals | | | | | | | TE AC_BK | 2 | Integer | AC Parameters Record | | | | | AC_BK in terminals | | | | | | | TE AC_VI | 2 | Integer | AC Parameters Record | | | | | AC_VI in terminals | | | | | | | TE AC_VO | 2 | Integer | AC Parameters Record | | | | | AC_VO in terminals | +--------------+----------+----------------+------------------------+ Timer Init Value: WiCoP timers are used for the WTP as a whole. So the Timer Init Value message element is provided on a per-WTP basis. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | BSSID | 6 | OCTETString | BSSID | | | | | | | Response | 4 | Integer | Initial value of | | Timer | | | Response Timer | | | | | | | Active | 4 | Integer | Initial value of | Iino, et al. Expires September 30, 2005 [Page 19] Internet-Draft WiCoP March 2005 | Presence | | | Active Presence Timer | | Timer | | | | | | | | | | Feedback | 4 | Integer | Initial value of | | Interval | | | Feedback Interval | | Timer | | | Timer | +--------------+----------+----------------+------------------------+ Terminal Data: The Terminal Data message element is applicable for both local-MAC and split-MAC WTP designs. In the case of local-MAC, Terminal Data is sent from WTPs to the AC. In the case of split-MAC, Terminal Data is sent from the AC to WTPs. So the direction of usage depends on the type of WTP at which wireless terminal operations are performed. Some information items may be optional for use with specific WTP designs. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | BSSID | 6 | PhyAddress | BSSID in which | | | | | terminal is being | | | | | added | | | | | | | MAC Address | 6 | PhyAddress | MAC address of | | | | | terminal being added | | | | | | | Association | 2 | Integer | Association ID of | | ID | | | terminal being added | | | | | | | Operation | 2 | Integer | Data rates supported | | Rate Set | | | by WTP for terminal | | | | | being added using 12 | | | | | bit format for 1.1, | | | | | 2.2, 3.55, 4.6, 5.9, | | | | | 6.11, 7.12, 8.18, | | | | | 9.24, 10.36, 11.48 and | | | | | 12.54 Mbps | | | | | | | Listen | 2 | Integer | Listen period | | Period | | | | +--------------+----------+----------------+------------------------+ BSSID: Iino, et al. Expires September 30, 2005 [Page 20] Internet-Draft WiCoP March 2005 +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | BSSID | 6 | PhyAddress | BSSID in which | | | | | terminal is being | | | | | added | | | | | | | MAC Address | 6 | PhyAddress | MAC address of | | | | | terminal being added | +--------------+----------+----------------+------------------------+ Encryption Data: +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | MAC Address | 6 | PhyAddress | MAC address of | | | | | terminal | | | | | | | Operation | 1 | Integer | Operational Mode ('1' | | | | | = Set Key; '2' = | | | | | Delete Key) | | | | | | | Key Index | 1 | Integer | Key Index - valid when | | | | | Operational Mode = Set | | | | | Key | | | | | | | Key Flag | 1 | Integer | Key Flag ('1' = | | | | | Unicast Key or PTK; | | | | | '2' = Broadcast Key or | | | | | GTK) - valid only when | | | | | Operational Mode = Set | | | | | Key | | | | | | | Cipher Suit | 1 | Integer | Encryption Type ('1' = | | | | | WEP40; '2' = WEP104; | | | | | '3' = WEP128; '4' = | | | | | TKIP; '5' = AES) - | | | | | valid only when | | | | | Operational Mode = Set | | | | | Key | | | | | | | Key | 32 | OCTESTString | Key body - valid only | | | | | when Operational Mode | | | | | = Set Key | +--------------+----------+----------------+------------------------+ Iino, et al. Expires September 30, 2005 [Page 21] Internet-Draft WiCoP March 2005 EAP Frame: +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | MAC Address | 6 | PhyAddress | MAC address of | | | | | terminal | | | | | | | EAP | Variable | OCTETString | EAP Frames | +--------------+----------+----------------+------------------------+ Statistics: Statistics information covers all aspects of WTPs. As such, this message element is provided on a per-WTP basis. +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | OutOctet | 4 | Counter 32 | Octet number of frame | | | | | WTP transmits | | | | | | | Transmit | 4 | Counter 32 | Total number of frames | | Count | | | transmitted by WTP | | | | | | | Successful | 4 | Counter 32 | Total number of ACKs | | Transmit | | | received | | Count | | | | | | | | | | ACK Failure | 4 | Counter 32 | Total number of failed | | Count | | | ACKs | | | | | | | InOctets | 4 | Counter 32 | Octet number of frame | | | | | WTP receives | | | | | | | Receive | 4 | Counter 32 | Total number of frames | | Count | | | received by WTP | | | | | | | Receive | 4 | Counter 32 | Total number of | | Discard | | | received frames that | | | | | are discarded | | | | | | | Retransmissi | 4 | Counter 32 | Number of WTP | | on Count | | | retransmission | | | | | attempts" | | | | | | Iino, et al. Expires September 30, 2005 [Page 22] Internet-Draft WiCoP March 2005 | Duplicate | 4 | Counter 32 | Number of duplicate | | Recieve | | | frames received by WTP | | Count | | | | | | | | | | FCS Error | 4 | Counter32 | Number to frames | | Receive | | | received with FCS | | Count | | | errors | | | | | | | Unknown | 4 | Counter 32 | Number of unknown | | Frame | | | protocol frames | | Receive | | | received | | Count | | | | | | | | | | Beacon | 4 | Counter 32 | Number of transmitted | | Transmit | | | Beacon frames | | Count | | | | | | | | | | Probe | 4 | Counter 32 | Number of transmitted | | Transmit | | | Probe Response frames | | Count | | | | | | | | | | Probe | 4 | Counter 32 | Number of received | | Receive | | | Probe Response frames | | Count | | | | | | | | | | Decrypt CRC | 4 | Counter 32 | Number of received | | Error Count | | | frames that cannot | | | | | decrypt | +--------------+----------+----------------+------------------------+ Interface Error: +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | Interface | 1 | Integer | Interface ID | | Index | | | | | | | | | | Error Type | 1 | Integer | Type of error ('1' = | | | | | Unrecoverable; '2' = | | | | | Recoverable) | +--------------+----------+----------------+------------------------+ FROM Error: Iino, et al. Expires September 30, 2005 [Page 23] Internet-Draft WiCoP March 2005 +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | FROM Index | 1 | Integer | FROM ID | | | | | | | Error Type | 1 | Integer | Type of error ('1' = | | | | | Unrecoverable; '2' = | | | | | Recoverable) | +--------------+----------+----------------+------------------------+ QoS Capability: +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | EDCA | 1 | Integer | EDcA Capability ('1' = | | | | | Capable; '2' = Not | | | | | capable) | | | | | | | HCCA | 1 | Integer | HCcA Capability ('1' = | | | | | Capable; '2' = Not | | | | | capable) | +--------------+----------+----------------+------------------------+ TFTP Data: +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | TFTP Data | Variable | OCTETString | Details of TFTP | +--------------+----------+----------------+------------------------+ Result: +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | Result Code | 1 | Integer | '1' = OK; '2' = NG | +--------------+----------+----------------+------------------------+ OID: Iino, et al. Expires September 30, 2005 [Page 24] Internet-Draft WiCoP March 2005 +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | Length | 1 | Integer | Length of OID String | | | | | and OID Value | | | | | | | OID String | Variable | OCTETString | Object Indentifier | | | | | that is assigned | | | | | according to Basic | | | | | Encoding Rules (BER) | | | | | | | Value | Variable | OCTETString | Value | +--------------+----------+----------------+------------------------+ MIC Flag: +--------------+----------+----------------+------------------------+ | Item | Length | Syntax | Description | +--------------+----------+----------------+------------------------+ | MIC Flag | 1 | Integer | Determines the entity | | | | | calculating MIC ('1' = | | | | | AC; '2' = WTP) | +--------------+----------+----------------+------------------------+ 5.2.3 WiCoP Control Message Description Message: Capabilities Type: Request Description: WTPs broadcast Capabilities message when they are powered on. The message serves to discover and identify the controlling AC and to provide it with information regarding the capabilities of the WTP. This includes specifying whether the WTP is of local-MAC or split-MAC design and radio capabilities. In the IEEE 802.11 use-case, Capabilities also specifies whether the WTP can perform encryption and authentication. TLV: The Capabilities message includes message elements of types 1 and 2. +----------------+ | Capabilities | +----------------+ | WTP Info | Iino, et al. Expires September 30, 2005 [Page 25] Internet-Draft WiCoP March 2005 | | | Cap from WTP | +----------------+ Message: Capabilities Response Type: Response Description: This message is sent by an AC after examining the compatibility of the WTP and its capabilities. The compatibility is with respect to the MAC architecture that can be supported. If the WTP is determined to be compatible, the Capabilities Response message also contains information on the capabilities of the AC. TLV: The Capabilities Response message includes message elements of types 5 and 17. +-----------------------+ | Capabilities Response | +-----------------------+ | Cap to WTP 1 | | | | Cap to WTP ... | | | | Cap to WTP n | | | | Result | +-----------------------+ Message: Connection Type: Request Description: The Connection message initiates the mutual security association between AC and WTPs. The specific security mechanism for the authentication is out of scope of the WiCoP specifications. TLV: The Connection message includes message elements of type 2. +----------------+ | Connection | +----------------+ | Cap from WTP | +----------------+ Iino, et al. Expires September 30, 2005 [Page 26] Internet-Draft WiCoP March 2005 Message: Connection Response Type: Response Description: This message indicates the result of the WTP-AC security association. If successful, it also represents the admission of the WTP into the WLAN. TLV: Type 17 message element is included. +---------------------+ | Connection Response | +---------------------+ | Result | +---------------------+ Message: Configuration Request Type: Request Description: This message starts the Configuration state of WiCoP. It is a request for configuration information from the WTPs to the AC. Message: Configuration Response Type: Response Description: This is an acknowledgement for the Configuration Request message. TLV: Type 17 message element is included. +------------------------+ | Configuration Response | +------------------------+ | Result | +------------------------+ Message: Configuration Data Type: Request Description: Configuration information including operational parameters is sent using the Configuration Data message. This Iino, et al. Expires September 30, 2005 [Page 27] Internet-Draft WiCoP March 2005 message is also used for configuration updates in the Operation state of WiCoP. TLV: This message includes message elements of type 3, 4, 5, 6 and 7. +---------------------+ | Configuration Data | +---------------------+ | Conf If Data 1 | | | | Conf If Data ... | | | | Conf If Data n | | | | Conf WTP DATA 1 | | | | Conf WTP DATA ... | | | | Conf WTP DATA n | | | | Cap to WTP 1 | | | | Cap to WTP ... | | | | Cap to WTP n | | | | QoS Value 1 | | | | QoS Value ... | | | | QoS Value n | | | | Timer Init Value | +---------------------+ Message: Configuration Data Response Type: Response Description: This is an acknowledgement for the Configuration Data message. TLV: Type 17 message element is included. +-----------------------------+ | Configuration Data Response | +-----------------------------+ Iino, et al. Expires September 30, 2005 [Page 28] Internet-Draft WiCoP March 2005 | Result | +-----------------------------+ Message: Configuration Trigger Type: Request Description: This message is used to trigger the activation of the configuration information sent in earlier Configuration messages. Message: Configuration Trigger Response Type: Response Description: This is an acknowledgement of the Configuration Trigger. This response message is sent before activation of the configuration information. TLV: Message elements of type 17 are included. +--------------------------------+ | Configuration Trigger Response | +--------------------------------+ | Result | +--------------------------------+ Message: Reset Type: Request Description: This message from the AC instructs the WTP to clear registers and revert to initial conditions. Message: Reset Response Type: Response Description: This is an acknowledgement for the Reset message to the AC. TLV: Message elements of type 17 are included. +----------------+ | Reset Response | Iino, et al. Expires September 30, 2005 [Page 29] Internet-Draft WiCoP March 2005 +----------------+ | Result | +----------------+ Message: Feedback Type: Request Description: This message is used to send regular statistics information from WTPs to the AC. Additionally, it acts as a keepalive indicator for WTPs that is used to update the Active Presence Timer. Feedback is also used by the AC to determine the active state of WTPs. TLV: This message includes message elements of type 12. +--------------+ | Feedback | +--------------+ | Statistics | +--------------+ Message: Feedback Response Type: Response Description: This is an acknowledgement for Feedback messages. TLV: Message elements of type 17 are included. +-------------------+ | Feedback Response | +-------------------+ | Result | +-------------------+ Message: Firmware Download Type: Request Description: This message is used to instruct WTPs to update their firmware. The message element contains information regarding the new firmware. TLV: Message elements of type 16 are included. Iino, et al. Expires September 30, 2005 [Page 30] Internet-Draft WiCoP March 2005 +-------------------+ | Firmware Download | +-------------------+ | TFTP Data | +-------------------+ Message: Firmware Download Response Type: Request Response Description: This is an acknowledgement for the Firmware Download message. TLV: Message elements of type 17 are included. +----------------------------+ | Firmware Download Response | +----------------------------+ | Result | +----------------------------+ Message: Notification Type: Request Description: This message is used to indicate non-periodic events. It may be sent by either WTPs or the AC. Notification messages indicate failures, non-periodic changes etc. TLV: Message elements of types 13 and 14 are included. +-------------------+ | Notification | +-------------------+ | Interface Error | | | | FROM Error | +-------------------+ Message: Notification Response Type: Response Description: This is an acknowledgement for the Notification message. It may be followed by Configuration messages to rectify errors. Iino, et al. Expires September 30, 2005 [Page 31] Internet-Draft WiCoP March 2005 TLV: Message elements of type 17 are included. +-----------------------+ | Notification Response | +-----------------------+ | Result | +-----------------------+ Message: Terminal Addition Type: Request Description: This message can be sent from WTPs or the AC. In both cases it is sent in response to an IEEE 802.11 association frame. For split-MAC WTPs, Terminal Addition is sent from the AC to the WTPs and includes information on the wireless terminal relevant to the WTP. For local-MAC WTPs, Terminal Addition is sent from a WTP to the AC and contains information on the wireless terminal relevant to the AC. TLV: Message elements of type 8 are included. +-------------------+ | Terminal Addition | +-------------------+ | Terminal Data | +-------------------+ Message: Terminal Addition Response Type: Response Description: This is an acknowledgement sent from either WTPs or the AC depending on the WiCoP interface. TLV: Message elements of type 17 are included. +----------------------------+ | Terminal Addition Response | +----------------------------+ | Result | +----------------------------+ Iino, et al. Expires September 30, 2005 [Page 32] Internet-Draft WiCoP March 2005 Message: Terminal Deletion Type: Request Description: This message is sent in response to a disconnection of a wireless terminal. It can be sent from WTPs of the AC. In both cases, Terminal Deletion instructs the recipient to remove any state information relating to the specific wireless terminal. The message is sent in response to an IEEE 802.11 disassociation frame, IEEE 802.11 deauthentication frame or due to the expiration of the Active Presence Timer. For split-MAC WTPs, Terminal Deletion is sent from the AC to the WTPs. For local-MAC WTPs, Terminal Deletion is sent from the WTPs to the AC. TLV: Message elements of type 9 are included. +-------------------+ | Terminal Deletion | +-------------------+ | BSSID | +-------------------+ Message: Terminal Deletion Response Type: Response Description: This is an acknowledgement sent from either WTPs or the AC depending on the WiCoP interface. TLV: Message elements of type 17 are included. +----------------------------+ | Terminal Addition Response | +----------------------------+ | Result | +----------------------------+ Message: Key Configuration Type: Request Description: This message is used when 'M' = 0 and 'D' = 1. It is Iino, et al. Expires September 30, 2005 [Page 33] Internet-Draft WiCoP March 2005 used to configure security key information from the AC to the WTPs. TLV: The following message elements are included for Key Configuration. +-------------------+ | Key Configuration | +-------------------+ | MIC Flag | | | | Encryption Data | | | | EAP Frame | +-------------------+ Message: Key Configuration Response Type: Response Description: This is an acknowledgement for the Key Configuration message. TLV: Message elements of type 17 are included. +----------------------------+ | Key Configuration Response | +----------------------------+ | Result | +----------------------------+ 5.3 WiCoP Data Packet WiCoP data packets include the WiCoP common header followed by a payload. Data packets are used to distinguish traffic from control when both control and data paths are identical. Such a scenario would involve data traffic of the WTPs traversing the AC. However, given the diversity of large-scale WLAN deployments, there are scenarios in which data and control paths are distinct. WiCoP can be used in both cases. The WiCoP data packet format is illustrated below in Figure 7 together with the WiCoP common header. Iino, et al. Expires September 30, 2005 [Page 34] Internet-Draft WiCoP March 2005 0 31 | 7 15 23 | |-------|-------|-------|-------|-------|-------|-------|-------| | | +---------------+-+-+-+-+-+-+-+-+-------------------------------+ | Version |M|D|C|R|E|F|L| | Reserve | +---------------+-+-+-+-+-+-+-+-+-------------------------------+ | Fragment ID | Fragment No. | Length | +---------------+---------------+-------------------------------+ | Paylaod | +---------------------------------------------------------------+ Figure 7 5.4 WiCoP Timers WiCoP uses a number of timers to determine WLAN status and maintain system performance. Timers are maintained by all WiCoP entities. The timers are described in this section. 5.4.1 Active Presence Timer The Active Presence Timer is used by each WiCoP entity AC and WTPs - to verify the presence of each other. The absence of a reply to the Feedback message within the expiration of the Active Presence Timer indicates the corresponding entity is inactive. Contingency operations such as reset are used in this case. The value of the Active Presence Timer ranges from 10 to 300 seconds with a default value of 30 seconds. 5.4.2 Feedback Interval Feedback messages are periodic with the frequency defined by the Feedback Interval. The interval is set during WTP configuration. It has a value ranging from 1 to 100 seconds and a default value of 10 seconds. 5.4.3 Response Timer This is a general purpose timer used to limit the elapsed time between transmission of a request message and receipt of a corresponding response message. The value of this timer ranges from 1 to 3 seconds with a default value of 1 second. Iino, et al. Expires September 30, 2005 [Page 35] Internet-Draft WiCoP March 2005 5.4.4 Wireless Connectivity Timer This timer triggers any changes in wireless connectivity. WiCoP uses this timer to send Notification and other messages relating to wireless conditions. It is also used to trigger the disconnection of mobile terminals without disassociation. The value of the Wireless Connectivity Timer ranges from 1 minute to 86,400 minutes with a default value of 10 minutes. Iino, et al. Expires September 30, 2005 [Page 36] Internet-Draft WiCoP March 2005 6. WiCoP Processes The processes of the Wireless LAN Control Protocol are described in this section with respect to the operational state in which they occur. 6.1 Initialization The initialization state represents the initial state of WiCoP entities. Hardware is initialized and the WiCoP entities remain in their respective base system conditions. 6.2 Capabilities Exchange WiCoP is designed to control WLANs with both local-MAC and split-MAC WTPs. Since there are differences in the functional characteristics these two types of WTPs, WiCoP first determines their specific capabilities. So in the Capabilities Exchange state, a WTP first broadcasts a Capabilities message to find its AC. The AC receiving the message examines the compatibility of the WTPs capabilities and responds with an appropriate Capabilities Response message. A WTP continues to send Capabilities messages at an interval specified by the Response Timer until it receives a Capabilities Response message. In the Capabilities Exchange state, there is a limit of connection attempts after which the AC ignores the WTP. This is to ensure that rogue WTPs which are not compatible with the AC do not repeatedly attempt connections. The limit of connection attempts is 3 within 60 seconds. 6.3 Connection A Connection message from WTP to the AC indicates a transition to the Connection state and triggers the mutual security association. At this point, the AC and WTPs first authenticate each other. Here, authentication information such as EAP messages are transported in WiCoP Connection messages. At the end of successful mutual authentication, subsequent WiCoP exchanges are secured based on the type of underlying transport. Given the predominance of IP, WiCoP exchanges are secured by IPSEC. Successful establishment of the security association results in the AC admitting the WTP in the WLAN with a successful Connection Iino, et al. Expires September 30, 2005 [Page 37] Internet-Draft WiCoP March 2005 Response message. Failure of the security association results in a transition back to the Initialization state. During the security association setup, the AC monitors the receipt of WiCoP control messages to prevent replay attacks. The security association between AC and WTPs covers mutual authentication and also protection for integrity, confidentiality and modification protection for subsequent traffic exchanges. 6.4 Configuration The Configuration state is triggered by the Configuration Request message from a WTP. In this state, the WiCoP interface with respect to the WTP architecture is established. So the differences between local-MAC and split-MAC designs are accommodated by means of the interface setup. The AC acknowledges the Configuration Request with a Configuration Response message, after which it sends configuration information in Configuration messages. Where appropriate, WiCoP includes MIB objects as the message element of Configuration messages. The use of MIB objects simplifies WTP configuration. A number of Configuration messages are sent for which each is acknowledged with a Configuration Response message. 6.4.1 Logical Groups Configuration messages are used to establish logical groups in the WLAN and also to separate traffic among them. In the IEEE 802.11 use-case, logical groups are established on the basis of BSSIDs and are separated over the WiCoP interface using tunnels. The BSSID-TunnelID parameter in the Configuration message maps logical groups across the wireless and WiCoP interfaces. Tunnels may be based on VLANs, IP tunnels or other technologies. WiCoP enables traffic separation by establishing links between the tunnels and logical groups. 6.4.2 Resource Control The Configuration messages are also used to establish operational QoS information at WTPs. In particular, the EDCA related message elements are used to specify QoS information to be configured at the wireless terminals in each logical group. WiCoP enables the central AC to supervise QoS settings in the entire WLAN. The EDCA message elements also include QoS information necessary at the WTPs. Iino, et al. Expires September 30, 2005 [Page 38] Internet-Draft WiCoP March 2005 6.5 Operation The Operation state of WiCoP commences after the exchange of all relevant Configuration information and when the AC sends a Configuration Trigger message to the WTP. This message informs the WTP to begin operations based on the configuration information sent earlier. After activating the configuration information, the WTP replies with a Configuration Trigger Response message. 6.5.1 Updates The dynamic nature of WLAN systems requires regular updates to network operations. So in the Operation state, WiCoP allows the AC to exchange additional configuration information with the Configuration message. The WTP activates configuration update information upon receiving the Configuration Trigger message from the AC. Configuration updates can be used to clear statistics information by reflecting initial values. An extreme case of configuration update involves use of the Reset message from the AC, which instructs the WTP to revert to initial conditions. The WTP replies with a Reset Response message before reverting to its initial state. 6.5.2 Feedback and Statistics The Operation state also sees regular feedback being sent by WTPs to the AC. The WTPs use Feedback messages to send statistics information that have been gathered. Feedback messages are sent with a frequency defined by the Feedback Interval. In addition to statistics, the Feedback message also serves as a WTP keepalive indicator to the AC. So Feedback messages combine statistics information together with WTP status information. Feedback messages also contain information on the state of congestion at mobile terminals and WTPs. So it includes parameters specifying the channel interference and queue levels. This information enables the AC to adapt its downstream transmissions so as to relieve congestion. One example is for the AC to schedule transmissions away from the congested WTPs. The AC additionally uses the Feedback message to randomly determine the active state of WTPs. An active WTP replies with a corresponding Feedback Response message. Iino, et al. Expires September 30, 2005 [Page 39] Internet-Draft WiCoP March 2005 6.5.3 Non-periodic Events The Notification message is used for non-periodic events. It is used to indicate error conditions or drastic changes in congestion state. It can be sent from either WTPs or the AC. A Notification Response message is sent in reply to this. The response may contain information on rectifying the error or may simply be an acknowledgement of the Notification. 6.5.4 Firmware Trigger The Firmware Download message is used to trigger WTPs to to update their firmware to the most recent version available. This message contains TFTP information which the WTP uses to receive firmware. WTPs reply with the Firmware Download Response message before activating the new firmware. 6.5.5 Wireless Terminal Management The Operation state of WiCoP also involves configuration of WTPs and the AC with wireless terminal specific information. Here the Terminal Addition message is used in response to a new wireless terminal entering the WLAN. This message may be sent by either the WTPs or the AC depending on the WiCoP interface being used. The recipient of this message replies with the Terminal Addition Response message. The Terminal Deletion message is used when a wireless terminal leaves the WLAN. This is used to delete state information that was maintained by either the WTPs or the AC. It is acknowledged with the Terminal Deletion Response message. Figure 8 below illustrates the exchange of Terminal Addition and Terminal Deletion messages for both local-MAC and split-MAC based WiCoP interfaces. Here the WiCoP Terminal Addition message is triggered as a response to IEEE 802.11 Association message. In the case of local-MAC architecture, the WTP sends the message to the AC. However, in the split-MAC architecture, Terminal Addition is sent from AC to the WTP. +----------+ +---------------+ +------+ | Terminal | | Local-MAC WTP | | AC | +----------+ +---------------+ +------+ | | | | | | Iino, et al. Expires September 30, 2005 [Page 40] Internet-Draft WiCoP March 2005 | IEEE 802.11 Association | WiCoP | |-------------------------)| Terminal Addition | | |===========================)| | | | | | WiCoP Terminal | | |(===========================| | IEEE 802.11 Association | Addition Response | |(-------------------------| | | Response | | | | | | | | | | | | | | | +---------------+ | | | Split-MAC WTP | | | +---------------+ | | | | | | | | IEEE 802.11 Association | | |-------------------------)| | | | IEEE 802.11 Association | | |===========================)| | | (Over WiCoP) | | | | | | | | | WiCoP | | | Terminal Addition | | |(===========================| | | | | | | | | WiCoP Terminal | | |===========================)| | IEEE 802.11 Association | Addition Response | |(-------------------------| | | Response | | | | | Figure 8 6.5.6 Key Configuration One of the differences between split-MAC and local-MAC WTPs is the location of the over-the-air encryption. Some split-MAC and local-MAC WTPs perform encryption locally while others leave it to the AC. WiCoP accommodates these differences by enabling security Iino, et al. Expires September 30, 2005 [Page 41] Internet-Draft WiCoP March 2005 key configuration in those cases where encryption is performed at the WTP. The encryption setup process is therefore contingent on the WiCoP protocol interface. When dynamic WEP is used, the WiCoP Key Configuration message is used to notify WTPs of encryption keys for each associated wireless terminal. Here, the EAPoL Key frame is encapsulated in the Key Configuration message and sent to a WTP. Upon receiving the Key Configuration message, the WTP sets the encryption key in its local security table, decapsulates the EAPOL Key frame and forwards it to the wireless terminal. When WPA or IEEE 802.11i is used in WLAN architectures in which the authenticator is located at the AC and encryption points at WTPs, the exchanges of the 4-way handshake are managed distinctly. This is because the AC is no longer in a position to calculate the KeyMIC as it is not aware of the KeyRSC sequence counter. So here, WiCoP Key Configuration message is used to transport the 3rd message of the 4-way handshake - containing the EAPoL-Key - with unassigned KeyRSC and KeyMIC fields. When the WTP receives the WiCoP Key Configuration message, it first assigns the sequnce number value to the KeyRSC field. Then, the WTP calculates the KeyMIC value using the PTK and 3rd message of 4-way handshake with assigned sequence counter value. So the WiCoP Key Configuration message allows the KeyMIC to be calculated at the WTPs instead of the AC. The 1st, 2nd and 4th messages of the 4-way handshake are transported in WiCoP data packets that are assigned priorities similar to that of WiCoP control packets. Similarly, for the group key handshake in WPA and IEEE 802.11i, the 1st message of the handshake is transported using the WiCoP Key Configuration message with unassigned KeyRSC. The WTP again assigns the sequence number value to the KeyRSC and then calculates the KeyMIC. The 2nd message of the handshake however is transported in WiCoP data packets with priorities similar to that of WiCoP control packets. The Key Configuration Response message is used by the WTP to notify the AC of the encryption setup process. Iino, et al. Expires September 30, 2005 [Page 42] Internet-Draft WiCoP March 2005 7. Summary and Conclusion The Wireless LAN Control Protocol presents a solution for managing large-scale WLANs with diverse elements. It addresses the challenges presented in the CAPWAP Problem Statement [I-D.ietf-capwap-problem-statement] and realizes the requirements of the CAPWAP Objectives [I-D.ietf-capwap-objectives]. WiCoP enables integral control of split-MAC and local-MAC WTPs by defining appropriate differentiators within the protocol message exchanges and processes. It addresses architecture designs in which the authenticator and encryption points are located on distinct entities. And in doing so, WiCoP realizes the interoperability objective and its benefits. WiCoP also addresses shared WLAN deployments by configuring and managing WTPs on a logical group basis. It is futher provisioned to separate control and data traffic within WLANs. So the protocol addresses the objectives of logical groups and traffic separation. Overall, the specifications presented in this document allows for an effective WLAN control and provisioning protocol. Iino, et al. Expires September 30, 2005 [Page 43] Internet-Draft WiCoP March 2005 8. Security Considerations Illegitimate WTPs and ACs pose a significant threat to WLAN security. This can be mitigated by requiring all WiCoP entities to be mutually authenticated before initiating critical protocol exchanges. WiCoP includes a trigger for a suitable authentication mechanism. This is to accommodate different security mechanism that may be used between WTPs and AC depending on the nature of the deployment. In extension to mutual authentication, the subsequent exchange of protocol information between WTPs and AC need to be protected. The exchanges have to be protected against alterations of any sort and DoS attacks. Also, the information should not be accessible to any third party. Encryption of protocol exchanges is therefore necessary. WiCoP includes appropriate procedures to select and establish a security association between WTPs and AC in the Connection state. Architecture designs in which authentication is performed at the AC and encryption at the WTPs can be exposed to the threat of replay attacks. Since the AC will not be aware of the exact value of the sequence counter, it will not make the corresponding assignment within the 4-way handshake. This leaves the wireless terminal to accept all incoming frames including illegitimate frames as it cannot verify the sequence counter value. Such a threat needs to protected against by allowing the WTP to assign the correct value of the sequence counter. WiCoP accomplishes this by sending the 3rd message of the 4-way handshake within a control message to the WTP, which then updates the sequence counter field before forwarding to the wireless terminals. 9. References [I-D.ietf-capwap-arch] Yang, L., Zerfos, P. and E. Sadot, "Architecture Taxonomy for Control and Provisioning of Wireless Access Points(CAPWAP)", Internet-Draft draft-ietf-capwap-arch-06, November 2004. [I-D.ietf-capwap-objectives] Govindan, S., "Objectives for Control and Provisioning of Wireless Access Points (CAPWAP)", Internet-Draft draft-ietf-capwap-objectives-01, March 2005. [I-D.ietf-capwap-problem-statement] Calhoun, P., "CAPWAP Problem Statement", Internet-Draft draft-ietf-capwap-problem-statement-02, Iino, et al. Expires September 30, 2005 [Page 44] Internet-Draft WiCoP March 2005 September 2004. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Authors' Addresses Satoshi Iino Panasonic Mobile Communications 600, Saedo-cho Tsuzuki-ku Yokohama 224 8539 Japan Phone: +81 45 938 3789 Email: iino.satoshi@jp.panasonic.com Saravanan Govindan Panasonic Singapore Laboratories Block 1022, Tai Seng Industrial Estate #06-3530, Tai Seng Avenue Singapore 534 415 Singapore Phone: +65 6550 5441 Email: sgovindan@psl.com.sg Mikihito Sugiura Panasonic Mobile Communications 600, Saedo-cho Tsuzuki-ku Yokohama 224 8539 Japan Phone: +81 45 938 3789 Email: sugiura.mikihito@jp.panasonic.com Iino, et al. Expires September 30, 2005 [Page 45] Internet-Draft WiCoP March 2005 Hong Cheng Panasonic Singapore Laboratories Block 1022, Tai Seng Industrial Estate #06-3530, Tai Seng Avenue Singapore 534 415 Singapore Phone: +65 6550 5447 Email: hcheng@psl.com.sg Iino, et al. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Iino, et al. Expires September 30, 2005 [Page 47]