NFVRG S. Jeon Internet-Draft Y. Kim Intended status: Informational Soongsil University Expires: January 4, 2019 July 3, 2018 Use Cases and Requirements for Dynamic Slice Stitching draft-sijeon-nfvrg-slice-stitching-00.txt Abstract This document describes use cases and requirements for dynamic slice stitching. 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 January 4, 2019. Copyright Notice Copyright (c) 2018 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. Jeon & Kim Expires January 4, 2019 [Page 1] Internet-Draft Dynamic Slice Stitching July 2018 Table of Contents 1. Overview and Use Cases . . . . . . . . . . . . . . . . . . . 2 2. Requirements for Dynamic Slice Stitching . . . . . . . . . . 5 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 5. Informative References . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Overview and Use Cases Network slicing means that a communication network is divided into multiple, logical end-to-end networks (slices), all sharing the same physical network infrastructure [_3GPP.23.501]. Multiple services belonging to different service categories such as eMBB, massive IoT, mission-critical IoT can be supported by different slices. Network slicing does not remain multiple services support with virtualization effect but the potential is with beyond regional domain boundary for global vertical industry service. A vertical industry service may remain in a single operator domain or require multiple domains operated by the same network/service providers. In the multiple domain scenario, network slices created from each domain should be federated and associated. We call it 'slice stitching'. In the design phase, slice stitching can be treated and handled by network slice description that defines overall characteristics of the network slice with types of service function, link connectivity between network functions, resource of each service function and link, etc. The need of slice stitching could be found in load balancing, differentiated WAN services with more bandwidth and advanced middlebox support, security-enhanced purpose on demand, which can be provided by dynamic instantiation of a new slice and interconnection among the existing ones. In addition, one very interesting use case can be found in providing virtualized home domain service support with low latency in a visited roaming domian. The dynamic slice stitching can be illustrated and explained by high-level operations in Figs. 1 and 2. (a), (b), (c) in Figs. 1 and 2 denote the order of the operations in each figure. Jeon & Kim Expires January 4, 2019 [Page 2] Internet-Draft Dynamic Slice Stitching July 2018 ========== ========== = = = = -- = A = -------------------------------- = B = -- = = = = ========== ========== (a) Slices A and B interconnected ========== ========== = = = = -- = A = -------------------------------- = B = -- = = ========== = = ========== = = ========== = C = = = ========== (b) Slices A and B interconnected, and Slice C is created but not interconnected with Slices A and B ========== ========== = = = = -- = A = --+--------------------------+-- = B = -- = = \ ========== / = = ========== \ = = / ========== +-- = C = --+ = = ========== (c) Slices A and C interconnected with Slice B Figure 1: High-Level Operation Scenario of Dynamic Slice Stitching for New Slice Stitching Fig. 1 describes an operation operation for new slice stitching. In Fig. 1 (a), Slices A and B are connected, where each slice is instantiated at different domains operated by the same operator. In Fig. 1 (b), Slice C is created and instantiated for differentiated WAN service support with high availability and reliability by following one of the needs explained above. One thing to notice here is, Slice C is not connected with Slice A and Slice B. In Fig. 1 (c), Slice C is interconnected with Slices A and B, so a tenant with premium connection demand/subscription can be served by Slices A, C, B, while Slice A and Slice B serve on-going service sessions. Jeon & Kim Expires January 4, 2019 [Page 3] Internet-Draft Dynamic Slice Stitching July 2018 ========== ========== ========== = = = = = = -- = A = -------- = B = -------- = C = -- = = = = = = ========== ========== ========== (a) Slices A and C interconnected with Slice B ========== = = +-- = B = --+ ========== / = = \ ========== = = / ========== \ = = -- = A = --+ +-- = C = -- = = ========== = = ========== = = ========== = B' = = = ========== (b) Slices A and C interconnected with Slice B, and newly created Slice B' but not interconnected with other slices ========== = = +-- = B = --+ ========== / = = \ ========== = = / ========== \ = = -- = A = --+ +-- = C = -- = = \ ========== / = = ========== \ = = / ========== +-- = B' = --+ = = ========== (c) Slices A and C interconnected with Slice B and Slice B' Figure 2: High-Level Operation Scenario of Dynamic Slice Stitching for Additional Slice Stitching Another operation scenario for dynamic slice stitching can be found in additional slice creation and interconnection illustrated in Fig. 2. In Fig. 2 (a), Slices A, B, C are interconnected, where each slice is instantiated at different domains operated by the same Jeon & Kim Expires January 4, 2019 [Page 4] Internet-Draft Dynamic Slice Stitching July 2018 operator. In Fig. 2 (b), Slice B' is created for security-enhanced support by following one of the needs explained above. One thing to notice here is, Slices A and C are not interconnected each other. In Fig. 2 (c), Slice B' is federated with Slices A and C, so a tenant with premium connection demand/subscription can be served by Slices A, B', C. This document describes requirements for dynamic slice stitching explained in Figs. 1 and 2. From the requirements, we check current available approaches and measures. 2. Requirements for Dynamic Slice Stitching Dynamic slice stitching basically requires interconnection between Slice A and B(B'), Slice B(B') and C. The interconnection should be made at network resource level to meet required connectivity demand in the end-to-end connection perspective. The interconnection also includes function level, so chaining of service functions between Slice A and B(B'), Slice B(B') and C should dynamically be made. 1) Resource stitching between slices Suppose that Slice A and Slice B in Fig. 1 were configured with 100 Mbps bandwidth and 100 ms latency in end-to-end connection. When Slice C is interconnected with Slice A and Slice B, to meet the same or better performance for service sessions going through Slice A, Slice C, Slice B in order, dynamic adjustment such as scaling up/down of existing resouce assigned in Slice A to Slice B could be required. The resource adjustment and reconfiguration may also happen in Fig. 2. 2) Service function stitching between slices Suppose that each slice is composed of one or more service functions and the service functions in each slice need to be stitched for end- to-end service. Service functions should dynamically chained. When it comes Service Function Chaining (SFC) with the Network Service Header (NSH) approach or routing controller, dynamic calculation of chaining should be orchestrated by the multi-domain slice orchestrator and configuration should be made at proper entity such as NSH classifier or dataplane node. However, such approach may bring about chaining scalability issue with chaining burden. Isolating SF chaining list per slice with such as hierarchical SFC (hSFC) could be effective and efficient for smooth operation support in the function stitching [I-D.ietf-sfc-hierarchical]. Jeon & Kim Expires January 4, 2019 [Page 5] Internet-Draft Dynamic Slice Stitching July 2018 3. IANA Considerations This document does not require any IANA actions. 4. Security Considerations This document does not have security considerations. 5. Informative References [_3GPP.23.501] 3GPP, "System Architecture for the 5G System", 3GPP TS 23.501 15.0.0, December 2018, . [I-D.ietf-sfc-hierarchical] Dolson, D., Homma, S., Lopez, D., and M. Boucadair, "Hierarchical Service Function Chaining (hSFC)", draft- ietf-sfc-hierarchical-11 (work in progress), June 2018. Authors' Addresses Seil Jeon Soongsil University 369 Sangdo-ro, Dongjak-gu Seoul Korea Email: sijeon@dcn.ssu.ac.kr Younghan Kim Soongsil University 369 Sangdo-ro, Dongjak-gu Seoul Korea Email: younghak@ssu.ac.kr Jeon & Kim Expires January 4, 2019 [Page 6]