nmrg X. Li Internet Draft L. Zhang Intended status: Informational J. Wei Expires: May 2021 Y. Tang S. Huang BUPT November 2, 2020 Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks draft-li-nmrg-control-slicing-00.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. 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Abstract Optical networks which support a large number of emerging applications, such as 5G, Cloud Computing, Big Data, Internet of things, autonomous driving, etc., play an increasingly important role in the current world. All the time spectrum resources in optical networks have been treated equally. All spectrum resources form a resource pool which is allocated to applications bit by bit until it is all used up. Although this pattern reduces the complexity of resource maintenance, it has poor flexibility and high operation complexity for different types of applications. This draft proposes a framework of centralized control and distributed function slicing for fast connection establishment and fault recovery in optical networks. The proposed framework divides all spectrum resources into four functional areas, i.e., optical channel area, fault recovery area, resource pool area, and the reserved functional area. A functional area is responsible for a specific network function. This framework improves the flexibility of optical networks and can achieve fast connection establishment and fault recovery for the request with a highest service level. Table of Contents 1. Introduction...................................................3 2. Conventions used in this document..............................4 3. Motivation of Centralized Control and Distributed Function Slicing...........................................................5 Li, et al. Expires May 2, 2021 [Page 2] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 4. Centralized Control and Distributed Function Slicing Framework.5 4.1. Framework.................................................6 4.2. Optical Channel Area......................................7 4.3. Fault Recovery Area.......................................8 4.4. Resource Pool Area........................................8 4.5. Reserved Functional Area..................................8 5. Security Considerations........................................8 6. IANA Considerations............................................8 7. References.....................................................9 7.1. Normative References......................................9 7.2. Informative References....................................9 1. Introduction This document describes the framework of centralized control and distributed function slicing for fast connection establishment and fault recovery in optical networks. Recently, a large number of emerging applications, such as 5G, Cloud Computing, Big Data, Internet of things, autonomous driving, etc., are emerging. Optical networks which take advantages of large-capacity, high-speed, and low energy consumption play an increasingly important role while accommodating these applications. Meanwhile, optical networks have been developed gradually from the point-to-point transmission to multi-layer and multi-domain networking. In the process of development, some important architectures and protocols have been proposed, such as automatically switched optical network (ASON), generalized multiprotocol label switching (GMPLS), path computation element (PCE), software defined optical network (SDON), etc. ASON is to facilitate fast configuration of both switched and soft permanent connections. The GMPLS protocol is proposed to realize the control plane. The PCE is proposed to conduct the constraint-based light- path computation in multi-domain and multi-layer optical networks [Pao2013]. SDON adopts the centralized control mode and supports multiple novel applications such as bandwidth on demand (BoD), virtual optical network (VON), dynamic path protection, etc [Thy2016]. These architectures and protocols help to reduce the operation complexity of optical networks. However, all the time spectrum resources for these architectures and protocols have been treated equally. For example, when a user request arrives, spectrum resources are equally allocated whether this request has a high service level or not. No matter the request has a high service level or a low high service level, the control plane equally conducts the process of routing and spectrum allocation. In other words, all spectrum resources form a resource pool which is equally allocated to applications bit by bit until it is all used up. Although this Li, et al. Expires May 2, 2021 [Page 3] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 pattern reduces the complexity of resource maintenance, it has poor flexibility and high operation complexity for different types of applications. For example, the establishment and removal of an end- to-end light-path is implemented by the centralized controller in SDONs. When a user request arrives at an optical network, the controller needs to compute the path and distribute the cross connection message by southbound protocol for optical networks. The process will consume a lot of time and is difficult to achieve the fast connection establishment. For some user requests with the highest service level, this time consumption may be intolerable. If some light-paths or light-trees are pre-established, then these light-paths can be used directly. This new mechanism can save a lot of path computation time for some services with the highest level. This draft proposes a framework of centralized control and distributed function slicing for fast connection establishment and fault recovery in optical networks. The proposed framework divides all spectrum resources into four functional areas. A functional area is a range of spectrum in the resource pool. Some particular pre- configured functions have been reserved in each functional area. A functional area or multiple functional areas can be allocated to an application. The first functional area is the optical channel area in which a group of light-paths or light-trees have already been established and can be used directly. The second functional area is the fault recovery area in which all interrupted light-paths or light-trees are recovered in this area. The third functional area is the resource pool area where spectrum resources are allocated to applications equally. The fourth functional area is the reserved functional area where new function can be explored in this area. This framework improves the flexibility of optical networks and can achieve fast connection establishment and fault recovery. 2. Conventions used in this document This document makes use of the following acronyms: SDON: Software-Defined Optical Networks GMPLS: Generalized Multi-Protocol Label Switching PCE: Path Calculation Element ASON: Automatically Switched Optical Network VON: Virtual Optical Network Li, et al. Expires May 2, 2021 [Page 4] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 BoD: Bandwidth on Demand 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]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying significance described in RFC 2119. In this document, the characters ">>" preceding an indented line(s) indicates a statement using the key words listed above. This convention aids reviewers in quickly identifying or finding the portions of this RFC covered by these keywords. 3. Motivation of Centralized Control and Distributed Function Slicing All the time spectrum resources in optical networks have been treated equally. All spectrum resources form a resource pool which is used in the same way. Although this pattern reduces the complexity of resource maintenance, it has poor flexibility and high operation complexity for different types of applications. It is difficult to achieve fast connection establishment and fault recovery based on this organization form of spectrum resources. The disadvantage of SDON is decoupling the control function from physical optical devices. The next research will focus on how to make better use of all spectrum resources. Therefore, in order to resolve this problem, this draft proposes a framework of centralized control and distributed function slicing for fast connection establishment and fault recovery in optical networks. It divides all spectrum resources into four functional areas, i.e., optical channel area, fault recovery area, resource pool area, and the reserved functional area. A functional area is responsible for a specific network function, especially for fast connection establishment and fault recovery. This framework improves the flexibility of optical networks and can achieve fast connection establishment and fault recovery for the request with a highest service level. From the perspective of time consuming of connection establishment and fault recovery, the centralized control and distributed function slicing framework will get enormous benefits. 4. Centralized Control and Distributed Function Slicing Framework This section first gives an overview of the framework of centralized control and distributed function slicing. Li, et al. Expires May 2, 2021 [Page 5] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 4.1. Framework +------------------------------------------------------------+ | | | Centralized Controller | | | +------------------------------------------------------------+ | | | | | | | | V V V V +------------+ +------------+ +------------+ +------------+ | Lightweight| | Lightweight| | Normal | | Lightweight| | Operating | | Operating | | Operating | | Operating | +------------+ +------------+ +------------+ +------------+ | | | | | | | |Control Plane -------------------------------------------------------------------- | | | |Physical Plane V V V V +------------+ +-------------+ +------------+ +-------------+ | Optical | | Fault | | Resource | | Reserved | |Channel Area| |Recovery Area| | Pool Area | |Function Area| +------------+ +-------------+ +------------+ +-------------+ -------------------------------------------------------------------> Distributed Function Slicing Figure 1 Centralized Control and Distributed Function Slicing Figure 1 shows the framework of centralized control and distributed function slicing. It contains two parts, i.e., control plane and physical plane. Control plane is realized by a centralized controller. Being different from conventional controller, this controller supports the lightweight operating on some functional areas. Therefore, conventional complex operations can be simplified. All spectrum resources in physical plane are divided into four functional areas, i.e., optical channel area, fault recovery area, resource pool area, and the reserved functional area. Figure 2 presents four functional areas. Since physical plane contains different types of resources, this draft only focus on spectrum resource slicing. A functional area is responsible for a specific network function. For the optical channel area, some optical channels have been already established. These optical channels can be used directly without routing and spectrum allocation. Therefore, only lightweight operating is required in the optical channel area. Li, et al. Expires May 2, 2021 [Page 6] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 This area supports fast connection establishment. The fault recovery area can continue to be divided into sub-area. When faults occur in the optical networks, all interrupted services can be recovered in these sub-areas in parallel. It avoids the traffic congestion caused by resource competition. This area supports fast fault recovery. For the resource pool area, all spectrum resources are treated equally and can be allocated to applications bit by bit until it is all used up. For the reserved functional area, this area is reserved for developing other novel network functions. |<-------------->|<----------------->|<----------->|<------------->| | | | … | | | | | … | | | | | … | | | | | … | | | | | | … | | | | | … | | | | | … | | | | | … | | | +----------------+-------------------+-------------+--------- -----+ |Optical Channel |Fault Recovery Area|Resource Pool| Reserved | | Area | | | Fuction Area | Figure 2 Four Functional Areas 4.2. Optical Channel Area In the optical channel area, some optical channels have been already established. These optical channels can be used directly. The type and the number of established optical channels are determined by the real network environment. Each established optical channels contain four parts, i.e., source, destination, bandwidth, and path. Table 1 Already Established Optical Channels +------------+--------------+------------+-------------+ | Source | Destinations | Bandwidth | Path | +------------+--------------+------------+-------------+ | A | B | 40G | A->E->F->B | +------------+--------------+------------+-------------+ | C | D | 100G |C->H->G->Q->D| +------------+--------------+------------+-------------+ | … | … | … | … | +------------+--------------+------------+-------------+ Source: the node at which the traffic uploads. Destinations: a set of nodes at which the traffic downloads. Bandwidth: the transmission rate of this optical channel. Path: successive links which connect the source and destinations. Li, et al. Expires May 2, 2021 [Page 7] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 4.3. Fault Recovery Area The fault recovery area is divided into multiple sub-areas. When faults occur in the optical networks, all interrupted services can be recovered in these sub-areas in parallel. It avoids the traffic congestion caused by resource competition. This area supports fast fault recovery. | Fault Recovery Area | |<---------------------------------------------------------------->| | | | … | | | | | … | | | | | … | | | | | | … | | | | | … | | | | | … | | | +----------------------+----------------------+--------------------+ | Sub-Area | Sub-Area | Sub-Area | Figure 3 Multiple Sub-Areas in Fault Recovery Area Once a fault occurs in an optical network, all interrupted services are sorted and organized into several groups. Each group is allocated to a sub-area. These groups can conduct service recovery in parallel. Therefore, the fault recovery area supports fast fault recovery. 4.4. Resource Pool Area In the resource pool area, all spectrum resources are treated equally and can be allocated to applications bit by bit until it is all used up. 4.5. Reserved Functional Area This area is reserved for developing other novel network functions. 5. Security Considerations TBD 6. IANA Considerations This document makes no request of IANA. Li, et al. Expires May 2, 2021 [Page 8] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative References [Pao2013] F. Paolucci, F. Cugini, A. Giorgetti, N. Sambo, and P. Castoldi, "A Survey on the Path Computation Element (PCE) Architecture", IEEE COMMUNICATIONS SURVEYS & TUTORIALS, vol. 15, no. 4, pp. 1819-1841, 2013. [Thy2016] A. Thyagaturu, A. Mercian, M. McGarry, M. Reisslein, and W. Kellerer, "Software Defined Optical Networks (SDONs): A Comprehensive Survey", IEEE COMMUNICATIONS SURVEYS & TUTORIALS, VOL. 18, NO. 4, pp. 2738-2786, 2016. Li, et al. Expires May 2, 2021 [Page 9] Internet-Draft Centralized Control and Distributed Function Slicing for Fast Connection Establishment and Fault Recovery in Optical Networks November 2020 Authors' Addresses Xin Li Beijing University of Posts and Telecommunications 10 Xitucheng Road, Haidian District, Beijing, China Email: xinli@bupt.edu.cn Lu Zhang Beijing University of Posts and Telecommunications 10 Xitucheng Road, Haidian District, Beijing, China Email: luzhang@bupt.edu.cn Jianghua Wei Beijing University of Posts and Telecommunications 10 Xitucheng Road, Haidian District, Beijing, China Email: jhwei@bupt.edu.cn Ying Tang Beijing University of Posts and Telecommunications 10 Xitucheng Road, Haidian District, Beijing, China Email: ytang@bupt.edu.cn Shanguo Huang Beijing University of Posts and Telecommunications 10 Xitucheng Road, Haidian District, Beijing, China Email: shghuang@bupt.edu.cn Li, et al. Expires May 2, 2021 [Page 10]