Application of FlexE Configuration Model

Flex Ethernet (FlexE) implementation agreement version 1.1 , 2.0 , 2.1 and 2.2 have been published by OIF. FlexE provides a generic mechanism for supporting a variety of Ethernet MAC rates that may or may not correspond to any existing Ethernet PHY rate. This includes MAC rates that are both greater than (through bonding) and less than (through sub-rate and channelization) the Ethernet PHY rates used to carry FlexE. In ITU-T, Recommendation specifies the functions required to insert and extract information to/from an Ethernet physical layer (PHY) as defined in IEEE 802.3, including the FlexE shim as defined in the FLEXE IA (currently based on version 1.1 ). Recommendation specifies the rates and formats for use in metro transport network (MTN) digital layer networks, and the MTNS frame format is specified in a way that maximizes reuse of OIF FLEXE IA ( version 2.1 at present) implementation logic, including support for bonding homogenous groups of 50GBASE-R, 100GBASE-R, 200GBASE-R, 400GBASE-R interfaces. In IETF, some drafts discussed FlexE framework, controls, and configurations. The draft defines a FlexE configuration YANG model for the configuration and management of FlexE devices. Based on current FlexE standards above and the FlexE configuration model, applications of FlexE configuration model, including the configuration of the FlexE group and the FlexE client are illustrated, and it is useful for the deployment of FlexE configuration model in related network devices.

A simplified graphical representation of the data model is used in this document. The meaning of the symbols in the YANG data tree presented later in this document is defined in . They are provided below for reference. o Brackets "[" and "]" enclose list keys. o Abbreviations before data node names: "rw" means configuration (read-write) and "ro" state data (read-only). o Symbols after data node names: "?" means an optional node, "!" means a presence container, and "*" denotes a list and leaf-list o Parentheses enclose choice and case nodes, and case nodes are also marked with a colon (":"). o Ellipsis ("...") stands for contents of subtrees that are not shown. o Some of the key terms used in this document are listed as follow. The terminology for describing YANG data models is found in [RFC7950].

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

FlexE Group: A FlexE group is composed of from 1 to m bonded Ethernet PHYs. FlexE Client: An Ethernet flow based on a MAC data rate that may or may not correspond to any Ethernet PHY rate. FlexE Calendar: The total capacity of a FlexE group is represented as a collection of slots which have a granularity of 5G or 25G. The calendar for a FlexE group composed of n 100G PHYs is represented as an array of 20n slots (each representing 5G of bandwidth). This calendar is partitioned into sub-calendars, with 20 slots per 100G PHY. Detailed description of these terms can be found in .

To model the FlexE YANG model, it need some analysis of the requirements of FlexE configuration, and give more priority to the fundamental configuration. Based on that, proper augments and extensions can be made in future. In following sections, the requirements are summarized according to the descriptions in OIF FlexE and ITU-T FlexE related standards. In and , some MI (Management Information), such as MI_TxGID, MI_TxFlexEMAP, are defined for specific network atomic functions in order to configure the functions. Some MIs are reported from the atomic functions which are useful for monitoring the real states and verifying the consistency between the configuration and the real states. Here configuration requirements of FlexE groups, FlexE clients, FlexE calendar and calendar slots are summarized and illustrated.

Requirements of the FlexE group include, R-Group-01 The model SHALL support the management of the FlexE group, consisting of one or more Ethernet PHY(s). R-Group-02 The model SHOULD be able to verify that the collection of Ethernet PHY(s) included in a FlexE group have the same characteristics (e.g. number of PHYs, rate of PHYs, etc.) at the local FlexE shims. If inconsistency exists, notifications (e.g. errors) SHOULD be invoked. Requirements of the calendar slot include, R-Calendar-01 The model SHALL support the updates of usage of calendar slots in the FlexE calendar, and support the notification of the usage. R-Calendar-02 The model SHALL support the verification of assignment of calendar slots in the FlexE calendar. If inconsistency exists, notifications (e.g. errors) SHOULD be invoked. R-Calendar-03 The model MAY support the configuration of calendar A and B. R-Calendar-04 The model MAY support the switching of a calendar configuration between calendar A and B. Requirements of the FlexE client include, R-Client-01 The model SHALL support to assign required calendar slots to transport the FlexE clients. The assigned calendar slots MAY be in different FlexE calendars with different ETH PHYs. R-Client-02 The model SHALL support to add FlexE client(s) into or remove FlexE client(s) from the FlexE group, without affecting the other existing FlexE clients whose size and calendar slot assignments are not changed.

A FlexE group must be configured first before any client signals are carried over it. The initial configuration commands could be from external management system, SDN controller etc. Currently, the FlexE configuration model shows the necessary parameters about the FlexE group and the FlexE client. That is the base model for further augments or extensions. In this section, more details about parameters in the model are elaborated, and some examples are illustrated based on following figure.

Following YANG tree is an excerpt from the FlexE-cm YANG model.

More explanations for the flexe-group data node include, The leaf index provides an index to the FlexE group. The value of the index may be generated by local network device or network management system, so the values in FlexE mux and demux may be different. The leaf group-num is transported between FlexE mux and FlexE demux. The leaf negotiation-mode includes dynamic mode and static mode, and the fault value is dynamic mode. For the dynamic mode, the calendar slot information for the FlexE client is only sent to the FlexE mux. While for the static mode, the calendar slot information for the FlexE client is configured both to the FlexE mux and demux. The leaf sync-phy-number is used for the synchronization management channel. The list flexe-phys includes all the PHYs bonded in a FlexE group. Each of the PHYs is identified by the port-name and phy-number in the group. Both ends of each PHY in the FlexE group should use the same PHY number.

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]]> While in the FlexE demux, part of the configuration for FlexE group is shown as follows,

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]]> Based on the configuration above, the running states in the FlexE device can be gotten by using NETCONF Get command. To FlexE group, the running states include total-bandwidth and free-bandwidth of the FlexE group, and free-timeslot-list and used-timeslot-list of each PHY in the FlexE group.

Following YANG tree is an excerpt from the FlexE-cm YANG model.

More explanations for the flexe-client data node include, The leaf client-index provides an index to the FlexE client. The value of the client-index may be configured by the network device or network management system or controller, and the values in FlexE mux and demux may be different. The leafref group-index references the FlexE group with the specific group index. It means that the FlexE group should be created before configuring the FlexE client, and the FlexE client will be transported by the specific FlexE group. The leaf client-num is used to indicate the FlexE client. The value of the client-num should be configured by the network management system or controller, and the values in FlexE mux and demux should be the same. The container timeslot-lists shows all the calendar slots assigned to the FlexE client. In the list timeslot-list, the total assignment of slots in each PHY, which is indicated by the leaf port-name, are indicated by the slots in the leaf time-slot. For example, two FlexE clients are configured to be transported by the FlexE group in section 4.1. The bandwidth of the first FlexE client is 10Gb/s, and the assigned calendar slots include two 5G slots. The bandwidth of the second FlexE client is 200Gb/s, and the assigned calendar slots include 40 5G slots, exactly located in two 100G PHYs. This configuration shows the capability of FlexE bonding. Part of the configuration for the first and second FlexE client in FlexE mux is shown as follows,

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]]> Part of the configuration for the first and second FlexE client in FlexE demux is shown as follows,

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Minxue Wang China Mobile No.32 Xuanwumen west street Beijing, China Email: wangminxue@chinamobile.com Liuyan Han China Mobile No.32 Xuanwumen west street Beijing, China Email: hanliuyan@chinamobile.com Xiaobing Niu (editor) ZTE Beijing, China Email: niu.xiaobing@zte.com.cn Qilei Wang (editor) ZTE Nanjing, China Email: wang.qilei@zte.com.cn

This memo includes no request to IANA.

TBD.