Information Model of Control-Plane and User-Plane separation BNG

Briefly, a CU separation BNG is made up of a centralized CP and a set of UPs. The CP is a user control management component which supports to manage UP’s resources such as the user entry and forwarding policy, for example, the access bandwidth and priority management. And the UP is a network edge and user policy implementation component. It can support the forwarding plane functions on traditional BNG devices, such as traffic forwarding, QoS, and traffic statistics collection, and it can also support the control plane functions on traditional BNG devices, such as routing, multicast, etc. The following figure describes the architecture of CU separation BNG

+-----+ +-----+ +-----+ +-----+ |EMS | |DHCP | |AAA | |policy | | |server |server |server +----|+ +---|-+ +--|--+ +--|--+ | | | | | | | | | | | | | | | | +----|---------|---------|---------|----+ | +--|----+ +--|--+ +---|--+ +----|--+ | | |address| | sub | | AAA | |service| | | |mgt | | Mgt | | | |control| | | +-------+ +-----+ +------+ +-------+ | | | Control Plane | +--------------------------------+ | | | User plane management | | | | | | | +-------------|------------------+ | +-----------------|---------------------+ | | | |----------------|-----------------| | | | | | | +--------|-----+ +------|-------+ +------|------+ | +---------+ | | +---------+ | |+-----|----+ | | | routing | | | | routing | | || routing | | | | control | | | | control | | || control | | | +---------+ | | +---------+ | |+----------+ | | +----------+ | | +----------+ | |+----------+ | User Plane | |forwarding| | | |forwarding| | ||forwarding| | | |plane | | | |plane | | ||plane | | | +----------+ | | +----------+ | |+----------+ | +--------------+ +--------------+ +-------------+ The CU separated BNG is shown in above figure. The BNG Control Plane could be virtualized and centralized, which provides significant benefits such as centralized session management, flexible address allocation, high scalability for subscriber management capacity, and cost-efficient redundancy, etc. The functional components inside the BNG Service Control Plane can be implemented as VNFs and hosted in a NFVI. The User Plane Management module in the BNG control plane centrally manages the distributed BNG User Planes (e.g. load balancing), as well as the setup, deletion, maintenance of channels between Control Planes and User Planes. Other modules in the BNG control plane, such as address management, AAA, and etc., are responsible for the connection with outside subsystems in order to fulfill the service. The routing control and forwarding Plane in the BNG User Plane (local) could be distributed across the infrastructure.

The idea of the information model is to propose a set of generic and abstract information models. The models are intended to be used in both Control Plane and User Planes. A typical scenario would be that this model can be used as a compendium for the interface between Control Plane and User Planes of CU separation BNG, that corresponding data model or TLVs can be defined to realize the communication between the Control Plane and User Planes.

----------------- //// \\\\ //// \\\\ // Cloud \\ | | | | | | | | | +-----------------+ | | | Control Plane | | \\ | | // \\\\ +---------+-------+ //// \\\\ | //// ------------------ | +------------------+-----------+-----+ | | | | User's information IP address QoS: ....... May Including: ...... CIR; | User ID; | PIR; | User MAC; | CBS; | Access method(PPPoE, | PBS; | IPoE, etc) ...... | ...... | | | | | +------------------V-----------+-----+ | +----+ | ------- | /// \\\ +------+ +-------v---------+ +--------+ | | | OTL | | User Plane | | Core | | Internet | | +-------+ +-------+ Routing|-----| | +------+ +-----------------+ +--------+ \\\ /// ------- CU Separation BNG As shown in above figure, when users access to the BNG network, the control plane solicits these users’ information (such as user’s ID, user’s MAC, user’s access methods, for example via PPPoE/IPoE), associates them with available bandwidth which are reported by User planes, and based on the service’s requirement to generate a set of tables, which may include user’s information, user’s IP address, and QoS, etc. Then the control plane can transmit these tables to the User planes. User planes receive these tables, parses it, matches these rules, and then performs corresponding actions.

This section specifies the information model in Routing Backus-Naur Form . This grammar intends to help readers better understand the English text description in order to derive a data model. However it may not provide all the details provided by the English text. When there is a lack of clarity in grammar the English text will take precedence. This section describes information model that represents the concept of the interface of CU separation BNG which is languages and protocols neutral. The following figure describes the Overview of Information Model for CU separation BNG.

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This section describes information model for the Control-Plane (CP). As mentioned in section 3, the Control Plane is a user control management component which manages the user’s information, User-Plane's resources and forwarding policy, etc. The control plane can generate several tables which contain a set of rules based on the resources and specific requirements of user's service. After that, the control plane sends the tables to User Planes, and User planes receive the tables, parse them, match the rules, and then perform corresponding actions. The Routing Backus-Naur Form grammar below illustrates the Information model for Control-Plane:

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user-related-infor-model: present the attributes which can describe the user’s profile, such as user’s basic information, qos, and IP address, etc. interface-related-infor-model: present the attributes which relate to some physical/virtual interface. This model can be used to indicate which kinds of service can be supported by interfaces. device-related-infor-model: present the attributes which relate to specific device. For example the control plane can manage and distribute the users, which belong to same subnet, to some specific devices. And the user plane’s devices provide corresponding service for these users.

The user related information are a bunch of attributes which may bind to specific users. For example, the control plane can use a unified ID to distinguish different users and distribute the IP address and QoS rules to a specific user. In this section, the user related information models are presented. The user related information models include the user information model, IPv4/IPv6 information model, QoS information model, etc. The Routing Backus-Naur Form grammar below illustrates the user related information model:

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The User Basic Information model contains a set of attributes to describe the basic information of a specific user, such as user’s mac address, access type (via PPPoE, IPoE, etc), inner vlan ID, outer vlan ID, etc. The Routing Backus-Naur Form grammar below illustrates the user basic information model:

:: = [][] [][] ]]> USER_ID (4 bytes): is the identifier of user. This parameter is a unique and mandatory, it can be used to distinguish different users. MAC_ADDRESS (6 bytes): is the MAC address of the user. ACCESS_TYPE (2 bytes): This attribute is an optional parameter. It can be used to indicate the protocol be used for user’s accessing, such as PPPoE, IPoE, etc. SESSION_ID (4 bytes): This attribute is an optional parameter. It can be used as the identifier of PPPoE session. INNER_VLAN-ID (2 bytes): The identifier of user’s inner VLAN. OUTER_VLAN_ID (2 bytes): The identifier of user’s outer VLAN. USER_INTERFACE (4 bytes): This attribute specifies the binding interface of a specific user. The ifIndex of the interface MAY be included. This is the 32-bit ifIndex assigned to the interface by the device as specified by the Interfaces Group MIB . The ifIndex can be utilized within a management domain to map to an actual interface, but it is also valuable in public applications . The ifIndex can be used as an opaque token to discern which interface of User-Plane is providing corresponding service for specific user.

The IPv4 information model presents the user’s IPv4 parameters. It is an optional constructs. The Routing Backus-Naur Form grammar below illustrates the user’s IPv4 information model:

::= ]]> USER_ID (4 bytes): is the identifier of user. This parameter is unique and mandatory. This attribute is used to distinguish different users. And it collaborates with other IPv4 parameters to present the user’s IPv4 information. USER_IPV4 (4 bytes): This attribute specifies the user’s IPv4 address, and it's usually used in user plane discovery and ARP reply message. MASK_LENGTH (4 bytes): This attribute specifies the user’s subnet masks lengths which can identify a range of IP addresses that are on the same network. GATEWAY (4 bytes): This attribute specifies the user’s gateway, and it's usually used in User Plane discovery and ARP reply message. VRF (4 bytes): is the identifier of VRF instance.

The IPv6 information model presents the user’s IPv6 parameters. It is an optional constructs. The Routing Backus-Naur Form grammar below illustrates the user’s IPv6 information model:

::=( )|() ]]> USER_ID (4 bytes): is the identifier of user. This parameter is unique and mandatory. This attribute is used to distinguish different users. And it collaborates with other IPv6 parameters to present the user’s IPv4 information. USER_IPV6 (2 bytes): This attribute specifies the user’s IPv6 address, and it usually be used in neighbor discovery (ND discovery). PREFIX_LEN (4 bytes): This attribute specifies the user’s subnet prefix lengths which can identify a range of IP addresses that are on the same network. PD_ADDRESS (4 bytes): In IPv6 networking, DHCPv6 prefix delegation is used to assign a network address prefix and automate configuration and provisioning of the public routable addresses for the network. This attribute specifies the user’s DHCPv6 prefix delegation address, and it's usually used in neighbor discovery (ND discovery). PD_PREFIX_LEN (4 bytes): This attribute specifies the user’s DHCPv6 delegation prefix length, and it's usually used in neighbor discovery (ND discovery). VRF (4 bytes): is the identifier of VRF instance

In CU separation BNG, the Control-Plane (CP) generates the QoS table base on UP's bandwidth resources and specific QoS requirements of user's services. This table contains a set of QoS matching rules such as user’s committed information rate, peak information rate, committed burst size, etc. And it is an optional constructs. The Routing Backus-Naur Form grammar below illustrates the user’s qos information model:

::= () [] ]]> USER_ID (4 bytes): is the identifier of user. This parameter is unique and mandatory. This attribute is used to distinguish different users. And it collaborates with other qos parameters to present the user’s qos information. CIR (4 bytes): In BNG network, the Committed Information Rate (CIR) is the bandwidth for a user guaranteed by an internet service provider to work under normal conditions. This attribute is used to indicate the user’s committed information rate, and it usually collaborates with other qos attributes (such as PIR, CBS, PBS, etc) to present the user’s QoS profile. PIR (4 bytes): Peak Information Rate (PIR) is a burstable rate set on routers and/or switches that allows throughput overhead. This attribute is used to indicate the user’s peak information rate, and it usually collaborate with other QoS attributes (such as CIR, CBS, PBS, etc) to present the user’s QoS profile. CBS (4 bytes): The Committed Burst Size (CBS) specifies the relative amount of reserved buffers for a specific ingress network's forwarding class queue or egress network's forwarding class queue. This attribute is used to indicate the user’s committed burst size, and it usually collaborates with other qos attributes (such as CIR, PIR, PBS, etc) to present the user’s QoS profile. PBS (4 bytes): The Peak Burst Size (PBS) sepcifies the maximum size of the first token bucket. This attribute is used to indicate the user’s peak burst size, and it usually collaborate with other qos attributes (such as CIR, PIR, CBS, etc) to present the user’s QoS profile. QOS_PROFILE (4 bytes): This attribute specifies the standard profile provided by the operator. It can be used as a QoS template which is defined as a list of classes of services and associated properties. The properties may include: o Rate-limit: used to rate-limit the class of service. The value is expressed as a percentage of the global service bandwidth. o latency: used to define the latency constraint of the class. The latency constraint can be expressed as the lowest possible latency or a latency boundary expressed in milliseconds. o jitter: used to define the jitter constraint of the class. The jitter constraint can be expressed as the lowest possible jitter or a jitter boundary expressed in microseconds. o bandwidth: used to define a guaranteed amount of bandwidth for the class of service. It is expressed as a percentage.

This model contains the necessary information for the interface. It is used to indicate which kind of service can be supported by this interface. The Routing Backus-Naur Form grammar below illustrates the interface related information model:

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The interface model mentioned here is a logical construct that identifies a specific process or a type of network service. In CU separation BNG network, the Control-Plane (CP) generates the Interface-Infor table based on the available resources, which are received from the User-Plane (UP), and the specific requirements of user's services. The Routing Backus-Naur Form grammar below illustrates the interface information model:

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IFINDEX (4 bytes): The IfIndex is the 32-bit index assigned to the interface by the device as specified by the Interfaces Group MIB . The ifIndex can be utilized within a management domain to map to an actual interface, but it is also valuable in public applications. The ifIndex can be used as an opaque token to discern which interface of User-Plane is providing corresponding service for specific user. BAS_ENABLE (2 bytes): This is a flag, and if it is TRUE, the BRAS is enabled on this interface. PPP_Only (2 bytes): This is a flag, and if it is TRUE, the interface only supports PPP user. IPV4_TRIG (2 bytes): This is a flag, and if it is TRUE, the interface supports that the user can be triggered to connect the internet by using IPv4 message. IPV6_TRIG (2 bytes): This is a flag, and if it is TRUE, the interface supports that the user can be triggered to connect the internet by using IPv6 message. ND-TRIG (2 bytes): This is a flag, and if it is TRUE, the interface supports that the user can be triggered to connect the internet by using neighbor discovery message. ARP_PROXY (2 bytes): This is a flag, and if it is TRUE, the ARP PROXY is enabled on this interface.

The device related information model presents the attributes which related to specific device. For example the control plane can manage and distribute the users, who belong to same subnet, to some specific devices. And then the user plane’s devices can provide corresponding service for these users. The Routing Backus-Naur Form grammar below illustrates the device related information model:

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In CU separation BNG information model, the Control-Plane (CP) generates and sends this Address field distribute table to UP. Based on this table, the user-plane’s devices can be divided into several blocks, and each block is in charge of working for users with the same subnet. The Routing Backus-Naur Form grammar below illustrates the address field distribute information model:

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This section describes information model for the interface of User Plane (UP). As mentioned in section 3, the UP is a network edge and user policy implementation component. It supports: Forwarding plane functions on traditional BNG devices, including traffic forwarding, QoS, and traffic statistics collection and Control plane functions on traditional BNG devices, including routing, multicast, and MPLS. In CU separation BNG information model, the CP generates tables and provides the rules. The UP plays two roles: It receives these tables, parses it, and matches these rules, then performs corresponding actions. It also generates several tables to report the available resources (such as usable interfaces, etc) and statistical information to CP. The Routing Backus-Naur Form grammar below illustrates the User Plane information model:

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The User Plane can generate the network resource table, which contains a bunch of attributes to present the available network resources, for example the usable interfaces. The Figure below illustrates the Port Resources Information Table of User-Plane:

:: ]]> IFINDEX (4 bytes): IfIndex is the 32-bit index assigned to the interface by the device as specified by the Interfaces Group MIB . The ifIndex can be utilized within a management domain to map to an actual interface, but it is also valuable in public applications. The ifIndex can be used as an opaque token to discern which interface of User-Plane is available. IF_NAME (64 bytes): the textual name of the interface. The value of this object should be the name of the interface as assigned by the local device and should be suitable for use in commands entered at the device's `console'. This might be a text name, such as `le0' or a simple port number, such as `1', depending on the interface naming syntax of the device. If several entries in the ifTable together represent a single interface as named by the device, then each will have the same value of ifName. IF_TYPE (4 bytes): the type of interface, such as Ethernet, GE, Eth-Trunk, etc. LINK_TYPE (4 bytes): This attribute specifies the type of link, such as point-to-point, broadcast, multipoint, point-to-multipoint, private and public (accessibility and ownership), etc. MAC_ADDRESS (6 bytes): This attribute specifies the available interface’s MAC address. IF_PHY_STATE (1 bytes): The current operational state of the interface. This is an enumeration type node: 1- Up: ready to pass packets; 2- Down 3- Testing: in some test mode; 4- Unknow: status cannot be determined for some reason; 5- Dormant; 6- Not present: some component is missing. MTU: This attribute specifies the available interface’s MTU (Maximum Transmission Unit).

The user-plane also generates the traffic statistics table to report the current traffic statistics. The Figure below illustrates the Traffic Statistics Infor model of User-Plane:

::= ]]> USER_ID (4 bytes): is the identifier of user. This parameter is unique and mandatory. This attribute is used to distinguish different users. And it collaborates with other statistics parameters such as ingress packets, egress packets, etc, to report the user’s status profile. STATISTICS_TYPE (4 bytes): This attributes specifies the traffic type such as IPv4, IPv6, etc. INGRESS_STATIISTICS_PACKETS (8 bytes): This attribute specifies the Ingress Statistics Packets of specific user. INGRESS STATISTICS_BYTES (8 bytes): This attribute specifies the Ingress Statistics Bytes of specific user. EGRESS_STATISTICS_PACKETS (8 bytes): This attribute specifies the Egress Statistics Packets of specific user. EGRESS_STATISTICS_BYTES (8 bytes): This attribute specifies the Egress Statistics Bytes of specific user.