This module manages Cisco's WiMAX ASN Gateway (ASN-GW). A WiMAX network supports wireless data communication through WiMAX radio (802.16) technology. The high level architecture of a first generation WiMAX network with the respective protocols for each interface is shown below: + | R2 | + | | R1 | | R6 | | | | MS | | | | | | | + | | | R3 | R8 | R4 | | | | | | + | | R1 | | R6 | | | MS | | | | | | | | + | | + The diagram below depicts the relation of the subscriber to the session and flows: + | ASN-GW | - Subscriber -Session -Flow (connected via data path) + | -Flow (connected via data path) | + A subscriber initiates a call from a MS. A session is created between the BS and the ASN-GW for that call. Multiple flows can be created for the session with different QOS parameters. For example one flow can created for a voice stream and another for data. Data paths are created between the BS and ASN-GW to forward the data packets of the created flows. When the first subscriber from any MS connected to a BS initiates a call via the BS to the ASN-GW, a signaling path is created between the BS and the ASN-GW. There is only one signaling path between each BS and ASN-GW. Signaling paths and base stations can be used interchangeably. The signaling and data paths remains active as long as there are subscribers connected to the ASN-GW from any MS connected to the BS. If a path has no session/flow connected, it will be purged after a certain period of time. This situation can occur when all subscribers on a certain path are disconnected. A subscriber disconnecting from a certain path does not indicate that the subscriber has left the network, it could simply be handing off to a different path. The IP addresses of the signaling and data paths can be the same or different both in the BS side and in the ASN-GW side. + | Base | | ASN-GW | | Station| | | | | SigPath | | | IP(B1)|<............>|IP(A1) | | | | | | | | | | | DataPath 1 | | | IP(B2)|<............>|IP(A2) | | | | | | | DataPath 2 | | | IP(B3)|<............>|IP(A3) | + Relationships: Base Station 1 to many Mobile Stations ASN-GW 1 to many Base Stations Subscriber 1 to 1 Sessions Session 1 to many Flows Datapath 1 to many Flows Signaling Path 1 to 1 Base Station Acronyms and terms: AAA AAA refers to a framework that specifies the protocols procedures for authentications, authorizatitin and accounting associated with the user, MS and subscribed serviced. AGW ASN-GW ASN ASN (Access Service network) is defined as a complete set of network functions needed to provide radio access to a WiMAX subscriber. ASN-GW ASN-Gateway is a logical entity that represents an aggregation of Control Plane functional entities that are either paired with a corresponding function in the ASN (for e.g BS instance) a resident function is the CSN or another functions in the ASN. For every MS, a BS is associated with exactly one default ASN-GW. However, ASN-GW functions for every MS may be distributes amongst multiple ASN-GWs located in one or more ASNs. The ASN-GW utilizes Session Redudancy to ensure a backup ASN-GW is available in case the primary ASN-GW goes down. BS Base Station is a logical entity that represents an aggregation of Control Plane functional entities that are either paired with a corresponding function in the ASN (e.g. BS instance), a resident function in the CSN or a function in another ASN. The ASN-GW may also perform Bearer Plane routing or bridging function. BSID The Base Station Identifier is a global unique identifier for a WiMAX base station. CPE Customer Premise Equipment. CSN CSN (Connectivity Service Network) is defined as a set of network functions that provide IP connectivity services to the WiMAX subscribers. Data Path Corresponding to each subscriber, data paths are created to foward packets between the ASN-GW and the subscribers. DPID Data Path ID is used to identify the tunnel carrying MS traffic between ASN gateways or between the ASN gateway and base station. As of 8/28/07, only the GRE key is to be used as the DPID. Flow A service flow is a unidirectional logical flow between the network and the Subscriber Station. A service flow is created to handle a different QoS over the connection oriented MAC. A subscriber can have multiple service flows associated and each service flow is associcated with an uplink and downlink classifier. GRE Generic Routing Encapsulation. Refer to RFC 1701 for more details. LB Load Balancing Messages Messages are packets exchanged on the signaling paths. MS The Mobile Station is a generalized mobile equipment set providing connectivity between subscriber equipment and a base station (BS) The Mobile Station may be a host or a CPE type of device that can support multiple hosts. MSID The Mobile Station Identifier is the 802.16 identifier used for all subscriber stations, and is used in all the messages over R6. The identifier associates all requests from a mobile to the ASN-GW. Packets Packets are datagrams fowarded over the data paths. R1 Communication protocol between mobile and BS as per the air interface (PHY and MAC) specifications (IEEE P802.16d/e). R1 may include additional protocols related to the management plane. R2 The interface between the MS and CSN associated with Authentication, Services Authorization, IP Host Configuration management, and mobility management. This is a logical interface thus does not reflect a direct protocol interface between MS and CSN. R3 The interface between the ASN and the CSN to support AAA, policy enforcement and mobility management capabilities. It also encompasses the bearer plane methods (e.g., tunneling) to transfer IP data between the ASN and the CSN. R4 Communication protocol between ASN-GWs. R4 consists of a set of control and bearer plane protocols originating/terminating in various entities within the ASN that coordinate MS mobility between ASNs. In Release 1, R4 is the only interoperable interface between heterogeneous or dissimilar ASNs. R5 Consists of a set of control plane and bearer plane protocols for internetworking between CSNs operated by either the home or visited NSP. R6 Communication protocol between ASN-GW and BS R6 consists of a set of control and bearer plane protocols for communication between the BS and the ASN GW. The bearer plane consists of intra-ASN data path or inter-ASN tunnels between the BS and ASN-GW. The control plane includes protocols for IP tunnel management (establish, modify, and release) in accordance with the MS mobility events. R6 may also serve as a conduit for exchange of MAC states information between neighboring BSs. R8 Communication protocol between base stations. R8 consists of a set of control plane message flows and, in some situations, bearer plane data flows between the base stations to ensure fast and seamless handover. Bearer plane consists of protocols that allow the data transfer between Base Stations involved in handover of a certain MS. Control plane consists of the inter-BS communication protocol defined in IEEE 802.16 and additional set of protocols that allow controlling the data transfer between the Base Stations involved in handover of a certain MS. Session Session is a connection between one or more MS and a network element in order to exchange link-level frames or packets. SFID The service flow is identified using a SFID (Service Flow Identifier). Signaling Path A signaling path exists between the BS and ASN-GW, and is used for all signaling such as creating, dleteing, authenticating, as we as additional functions related to the subscriber. SR Session Redundancy Subscriber The 802.16 subscriber entity connects over the 802.16 airlink, and eventually results in the creation of the subscriber object at the ASN-GW. UHO Unpredicitive Handoff PMIP Proxy Mobile Internet Protocol HA Home Agent REFERENCE [1] WIMAX Forum Network Architecture, (Stage 3: Detailed Protocols and Procedures) Release 1.1.1 September 14, 2007.