Internet Engineering Task Force Q. Wang, Ed. Internet-Draft X. Niu, Ed. Intended status: Informational ZTE Corporation Expires: May 7, 2020 Y. Xu CAICT November 4, 2019 Analysis for FlexE control draft-wang-ccamp-flexe-control-analysis-03 Abstract This document gives some analysis about the control of FlexE. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on May 7, 2020. Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Wang, et al. Expires May 7, 2020 [Page 1] Internet-Draft FlexE control November 2019 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 3. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. General Introduction of FlexE . . . . . . . . . . . . . . 3 3.1.1. FlexE Group . . . . . . . . . . . . . . . . . . . . . 3 3.1.2. FlexE Client . . . . . . . . . . . . . . . . . . . . 4 3.1.3. Encapsulation of FlexE Client into FlexE Group . . . 4 3.1.4. MAC Frame . . . . . . . . . . . . . . . . . . . . . . 5 3.1.5. Encapsulation of MAC frames into FlexE Client . . . . 5 3.2. General requirements . . . . . . . . . . . . . . . . . . 5 3.2.1. Configuration Mode for FlexE client . . . . . . . . . 6 3.2.2. Configuration of FlexE group . . . . . . . . . . . . 6 3.2.3. Allocate Resources for FlexE Client . . . . . . . . . 7 3.3. Control Requirements Derived . . . . . . . . . . . . . . 8 4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.1. Normative References . . . . . . . . . . . . . . . . . . 9 8.2. Informative References . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction OIF published the first version of FlexE Implementation Agreement in March 2016, aiming to provide a generic mechanism for supporting a variety of Ethernet MAC rates that may or may not correspond to any existing Ethernet PHY rate. ITU-T SG15 has endorsed the OIF FlexE data plane as parts of [ITU-T G.872], [ITU-T G.709], [ITU-T G.798] and [ITU-T G.8023]. The Recommendations depend on or are based on the FlexE data plane. This draft is intended to trigger discussion of the FlexE control requirements. What kind of models should we use when configuring FlexE capable equipment, how to configure the FlexE group and FlexE client, and what kind of parameters do we need to take into consideration when configuring FlexE group and FlexE client. The analysis is based on the description in section 7 and 8 of [ITU-T G.8023] and FlexE IA 2.0. Wang, et al. Expires May 7, 2020 [Page 2] Internet-Draft FlexE control November 2019 2. Terminology 2.1. Requirements Language 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 RFC 2119 [RFC2119]. 3. Analysis 3.1. General Introduction of FlexE The FlexE shim is built into the Ethernet PCS (physical coding sublayer). If a FlexE group is configured, a corresponding n*100G (or n*50G, n*200G, n*400G) PCS module which may support multiple FlexE clients is created as well. The difference between the FlexE and the traditional Ethernet is that the traditional Ethernet PCS has a 1:1 relationship with the client MAC flow, while with FlexE one bonded huge PCS module can be used to transport more than one FlexE client i.e., the relationship is 1:n. 3.1.1. FlexE Group A FlexE Group is consisted of from 1 to n 100G FlexE instances, which are carried over from 1 to m 100G, 200G or 400G Ethernet PHYs. A FlexE group can also consisted of from 1 to n 50G FlexE instances, which are carried over from 1 to m 50G Ethernet PHYs. All PHYs in the group must operate at the same rate. A FlexE Instance is a unit of information consisting of 50G or 100G of capacity, which is able to carry FlexE Client data, together with its associated overhead. Section monitoring overhead is added/ extracted as one 66B block at the FlexE group source and destination (i.e., trail termination) to determine the status of the FlexE group. Currently, only RPF (Remote PHY Fault) indication is used to report the status of one FlexE group. The set of FlexE Instances in the FlexE Group (not necessarily consecutive FlexE Instance numbers) are indicated in the "FlexE Map" field of the FlexE overhead. The full FlexE map is sent on all FlexE Instances of the FlexE Group so that it is possible for the FlexE demux to verify that the same FlexE Instance numbers are configured at the FlexE mux as at the FlexE demux, and can tell whether all expected FlexE Instances are being received. Wang, et al. Expires May 7, 2020 [Page 3] Internet-Draft FlexE control November 2019 3.1.2. FlexE Client A FlexE Client is an Ethernet flow based on a MAC data rate that may or may not correspond to any Ethernet PHY rate. The FlexE Client MAC rates supported by a FlexE Groups could be 10Gb/s, 40Gb/s, or m*25Gb/ s. The FlexE Client MAC rates supported by FlexE Groups may support all, or only a subset of these FlexE Client rates. Each FlexE Client is presented to the FlexE Shim as a 64B/66B encoded bit stream according to clause 82 of [IEEE 802.3]. The FlexE client has the semantics of an Ethernet PHY and there is no new layer network defined for FlexE client, as both FlexE group and FlexE client are processed in Ethernet PHY layer. From the network management point of view, the FlexE client can be created accordingly and the corresponding calendar slots of one FlexE group are allocated to one FlexE client. The FlexE client could be generated internally within a system, or created from a traditional Ethernet PHY. What kind of FlexE clients will be created depends on the operator's needs. According to the description in clause 8.1 of [ITU-T G.8023], there is no overhead defined for monitoring a FlexE client, so the concept of network connection for FlexE client in the equipment does not exist. It is not correct to treat FlexE client as a network layer. One FlexE client can be generated internally within one system, it can also be formed by converting from the standard Ethernet signal, e.g, a 10GBASE-R signal could be converted to a 10G FlexE Client format by performing idle insertion/deletion. FlexE Clients do not need to be produced or received in the same manner at both ends of the connection. 3.1.3. Encapsulation of FlexE Client into FlexE Group In order to distribute the FlexE client over PHYs of one FlexE group, a number of management information command should be sent to the processing function which performs the encapsulation of FlexE client over FlexE group. [ITU-T G.8023] specifies the equipment function blocks for Flex Ethernet interface, which are between equipment management function and atomic function within one network element. According to the description in clause 7.2 of [ITU-T G.8023], the management information commands sent to the source adaptation function from equipment management function are listed below: TxCC, TxCCA, TxCCB, TxCR, TxCA TxGID, TxPHYMAP Wang, et al. Expires May 7, 2020 [Page 4] Internet-Draft FlexE control November 2019 The TxCC, TxCCA and TxCCB are used to configure the calendar for use, which could be type A or type B calendar configuration, slots allocated for a specific FlexE client and FlexE client number. TxCR and TxCA are used to coordinate the switch of calendar configuration between the FlexE source and destination node. The TxGID is used to configure the FlexE group identifier. The TxPHYMAP is used to configure the set of PHYs in the FlexE group. If 200G and 400G are used, the 100G FlexE instance should be used in the case of PHYMAP. The built-in function multiplexer performs the action of assigning the individual FlexE Client to specific calendar slots of the FlexE group according to the input management information. At the destination side, the Demultiplexer function could use activate the FlexE Client and assigns the calendar slots of the FlexE group payload area to the individual FlexE client accordng to external configuration or the client calendar information carried in the overhead. Expected group ID, PHYMAP and calendar allocation information are needed sometimes to help verify the correctness of FlexE configuration. However, not all of the management information listed in [ITU-T G.8023] need to be exposed to the external management system, as some of them may be inferred, e.g., Calendar configuration(CC), which could be inferred by comparing the original and new configuration. 3.1.4. MAC Frame Defined in IEEE. 3.1.5. Encapsulation of MAC frames into FlexE Client The external management information commands used as input to the encapsulation/adaptation function are defined by [IEEE 802.3], according to the description in [ITU-T G.8023]. The [IEEE 802.3] process mainly includes the 64B/66B encoding, as well as MAC frame check sequence generation and frame counting. The FlexE client stream is generated at the determined FlexE Client MAC rate and 64B/66B encoded. 3.2. General requirements It can be derived from section 2.1.2 and section 2.1.5 that process involved when producing the FlexE Client from MAC frames is 64b/66b encoding, and this encoding has already been defined by [IEEE 802.3]. Wang, et al. Expires May 7, 2020 [Page 5] Internet-Draft FlexE control November 2019 as no extra overhead is added during this process. Therefore, configuration for mapping MAC frames into FlexE client from external management system is not needed. In addition to the above analysis, this draft also consider other aspects of requirements for FlexE control/management. Configuration mode for FlexE Configuration of FlexE group Creation of FlexE client and allocation of one or more FlexE group calendar slot resources to a FlexE client. 3.2.1. Configuration Mode for FlexE client There are two different configuration modes for bring one FlexE client into service. The first one is static model, which is to use external management system to configure the FlexE client and resources allocated for the FlexE client at source and destination FlexE shims. In this case, the CR/CA mechanism does not work. Verification of configuration consistency at FlexE source and destination site by comparing the in-band FlexE overhead with the configuration at FlexE destination are needed; The other one is MASTER/SLAVE mode, which is to use the FlexE overhead to coordinate the resource configuration between FlexE source and destination, the external resource configuration information is only sent the source node. 3.2.2. Configuration of FlexE group It can be concluded from the above analysis that external configuration tools should be involved to bring one FlexE group into service. The initial configuration commands could be from external management system, SDN controller etc. A FlexE group must be configured first before any client signals are carried over it. When a new FlexE Group is brought into service, the initial configuration must be provisioned for both ends, and the initial configuration must be the same for both direction. The group is configured to be consist of from 1 to n 100G FlexE Instances carried over from 1 to m PHYs of the same rate (100GBASE-R, 200GBASE- R, or 400GBASE-R). The group could also be configured to be consist of from 1 to n 50G FlexE Instances carried over from 1 to m PHYs of the same rate (50GBASE-R). A PHY number may correspond to the physical port ordering on equipment, but the FlexE Shim at each end of the group must identify each PHY in the group using the same PHY number, and each FlexE Instance with the same FlexE Instance number. In certain cases, it may be desirable not to populate all 100G FlexE Wang, et al. Expires May 7, 2020 [Page 6] Internet-Draft FlexE control November 2019 instances on a 200G or 400G PHY, and these so-called unequipped FlexE instance should also be configured. Unequipped instances must always be the highest numbered instance(s) on a PHY of the FlexE Group, and there must always be at least one equipped 100G FlexE Instance on every PHY. If aware case is needed to be considered, unavailable slot information should be configured at FlexE aware node to discard unavailable slot first, so as to put the rest of available slots onto the lower rate physical port. Unavailable slots are placed at the end of each relevant sub-calendar (the highest numbered slots). 3.2.3. Allocate Resources for FlexE Client The FlexE client MAC flows are encapsulated in one or more FlexE calendar slots. According to the analysis in section 3.2.1, there are two different configuration modes. For the first one, static mode, after the FlexE group is configured, the FlexE client resource allocation information are sent both to FlexE souce and destination to help create the FlexE client. A number of expected configuration parameters are sent to FlexE destination to help verify the correctness of configuration at both sides. Information sent can be found in [draft-xiaobn-ccamp- flexe-yang-mod]. For the Master/slave mode, the FlexE client resource allocation information are only sent to the FlexE source site. The FlexE source site first create the FlexE clients, and then the built-in multiplexer at the FlexE source site allocates the calendar slots to a specific FlexE client according to the input from external management system, and insert these configuration information into the FlexE overhead. When these overheads arrives at the destination site, the demultiplexer function at the destination site extracts FlexE overhead first and get the information of calendar slot allocation information. Based on these information, the FlexE destination site finish the configuration of FlexE clients. In order to verify the correctness of the resource configuration, the expected FlexE group ID, PHY number and instance number information, FlexE client number and slot allocation information for a specific FlexE client should also be configured to FlexE destination site. The FlexE client port is an internal port which only perform the function of encapsulating upper layer packets into MAC frames, 64b/66b encoding. The bandwidth capability of these internal ports should be known by external management/control tools in order to be used by the upper layer (e.g., MPLS-TP) flow correctly. Wang, et al. Expires May 7, 2020 [Page 7] Internet-Draft FlexE control November 2019 3.3. Control Requirements Derived a. Using external control/management system to configure FlexE group, which may include the configuration of group number, PHY number and instance number, as well as correlation between logical PHY number and physical port number. A number of expected configuration parameters are also needed to help verify the consistency between FlexE source and destination. b. Using external control/management system to create the FlexE client, which include the FlexE client number, FlexE client type and slots allocation information. Different configuration mode for FlexE client are needed. c. External control command could be provide to trigger the switch of calendar slots. d. Interworking between 5G slot granularity capable node and 25G slot granularity node. e. Configuration of unequipped instance, unavailable slots, which include the number of unequipped instance and number of unavailable slots on each instances f. An interface needs to be defined for a FlexE client in the case that an Ethernet PHY signal (e.g., 40GBASE-R) is directed towards a FlexE client interface or delivered from one FlexE shim to another in the case of equipment which terminates the FlexE group. This interface is used to indicate the conversion of Ethernet PHY signal to FlexE client signal, as only idle insertion/deletion is performed during this process in the former case, while in the latter case, this interface is used to indicate the "switch" of FlexE client. g. Different kinds of alarms should be taken into consideration when modelling FlexE technology, which may include PHY failed, skew exceed threshold, inconsistent configuration between two ends. 4. Summary According to the analysis in section 2, the main control/management requirement for FlexE technology is to configure the FlexE group and FlexE client. Once a FlexE group is configured and the FlexE client ports is created, slots allocation is configured, use of the FlexE technology is the same as that in traditional Ethernet. Wang, et al. Expires May 7, 2020 [Page 8] Internet-Draft FlexE control November 2019 5. Acknowledgements 6. IANA Considerations This memo includes no request to IANA. 7. Security Considerations None. 8. References 8.1. Normative References [ITU-T_G709] ITU-T, "ITU-T G.709: Optical Transport Network Interfaces; 07/2016", http://www.itu.int/rec/T-REC- G..709-201606-P/en, July 2016. [ITU-T_G798] ITU-T, "ITU-T G.798: Characteristics of optical transport network hierarchy equipment functional blocks", August 2018. [ITU-T_G8023] ITU-T, "ITU-T G.8023: Characteristics of equipment functional blocks supporting Ethernet physical layer and Flex Ethernet interfaces", , 2016. [ITU-T_G872] ITU-T, "ITU-T G.872: The Architecture of Optical Transport Networks; 2017", http://www.itu.int/rec/T-REC-G.872/en, January 2017. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 8.2. Informative References [I-D.izh-ccamp-flexe-fwk] Hussain, I., Valiveti, R., Pithewan, K., Wang, Q., Andersson, L., Zhang, F., Chen, M., Dong, J., Du, Z., zhenghaomian@huawei.com, z., Zhang, X., Huang, J., and Q. Zhong, "GMPLS Routing and Signaling Framework for Flexible Ethernet (FlexE)", draft-izh-ccamp-flexe-fwk-00 (work in progress), October 2016. Wang, et al. Expires May 7, 2020 [Page 9] Internet-Draft FlexE control November 2019 [I-D.xiaobn-ccamp-flexe-yang-mod] NIU, X., Wang, Q., Xu, Y., and S. Munagapati, "A YANG Data Model for Flex Ethernet(FlexE)", draft-xiaobn-ccamp-flexe- yang-mod-01 (work in progress), May 2019. Authors' Addresses Qilei Wang (editor) ZTE Corporation Nanjing CN Email: wang.qilei@zte.com.cn Xiaobing Niu (editor) ZTE Corporation Beijing CN Email: niu.xiaobing@zte.com.cn Yunbin Xu CAICT Beijing CN Email: xuyunbin@caict.ac.cn Wang, et al. Expires May 7, 2020 [Page 10]