ALTO WG D. Lachos Internet-Draft C. Rothenberg Intended status: Informational Unicamp Expires: January 14, 2021 Q. Xiang Y. Yang Yale University B. Ohlman Ericsson Research S. Randriamasy Nokia Bell Labs F. Boten Sprint LM. Contreras Telefonica J. Zhang Tongji University K. Gao Sichuan University July 13, 2020 Multi-domainn Information Exposure using ALTO draft-lachos-alto-md-info-exposure-00 Abstract A common setting in emerging applications (e.g., data-intensive science applications, flexible inter-domain routing, multi-domain service function chaining) is that the traffic from a source to a destination traverses multiple networks domains. Such multi-domain applications can benefit from network information exposure using ALTO. This document summarizes the benefits of using such multi- domain information and discusses the ALTO design issues for gathering it. Besides, it also presents key design requirements to be addressed in order to realize the proposal of providing multi-domain information by ALTO services. Finally, another important objective of this document is to begin discussions into the ALTO WG concerning potential new items to be considered for the re-charter. 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/. Lachos, et al. Expires January 14, 2021 [Page 1] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 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 14, 2021. Copyright Notice Copyright (c) 2020 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. What does "multi-domain information exposure" mean? . . . . . 3 3. What Information do Multi-domain applications need? . . . . . 5 3.1. Basic Formulation . . . . . . . . . . . . . . . . . . . . 6 4. What are the ALTO issues of gathering multi-domain information? . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Communication Mechanisms . . . . . . . . . . . . . . . . 8 4.1.1. Server-to-Client ALTO communication . . . . . . . . . 8 4.1.2. Domain connectivity discovery . . . . . . . . . . . . 8 4.1.3. ALTO server discovery . . . . . . . . . . . . . . . . 8 4.2. Conceptual Query Interfaces and Data Representation . . . 8 4.2.1. Single-domain composition . . . . . . . . . . . . . . 8 4.2.2. Simple resource query language . . . . . . . . . . . 9 4.3. Computation Model . . . . . . . . . . . . . . . . . . . . 9 4.3.1. Scalability . . . . . . . . . . . . . . . . . . . . . 9 4.3.2. Security and Privacy . . . . . . . . . . . . . . . . 9 5. How to design a whole ALTO framework? . . . . . . . . . . . . 9 5.1. ALTO servers communication . . . . . . . . . . . . . . . 10 5.2. Multi-domain Connectivity discovery . . . . . . . . . . . 10 5.3. Multi-domain ALTO Server discovery . . . . . . . . . . . 11 5.4. Unified resource representation . . . . . . . . . . . . . 11 5.5. Flexible/Generic query language . . . . . . . . . . . . . 11 5.6. Computation complexity optimization . . . . . . . . . . . 12 5.7. Security/Privacy Preserving . . . . . . . . . . . . . . . 12 Lachos, et al. Expires January 14, 2021 [Page 2] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 1. Introduction Many multi-domain applications are emerging with the development of new technologies, such as SDN, NFV, and 5G. Examples of such applications include data-intensive science applications [CMS][LCLS][LHC][SKA], multi-domain service function chaining [NGMN-5G][SFC-MD][MD-ORCH-NFV][ETSI-ZSM], and flexible inter-domain routing [SFP][SDX][RFC5575]. Such cross-domain applications can benefit substantially from exposure of network information to improve both applications performance and resource consumption. The Application-Layer Optimization Protocol (ALTO) [RFC7285] already introduces basic mechanisms (e.g., modularity, dependency) and abstractions (e.g., map services) for applications to take optimized actions based on network information. However, exposing network information to support multi-domain use cases introduces issues to be considered in the current ALTO design. This document provides a definition of multi-domain information exposure (Section 2) and identifies the benefits of using it in applications traversing multiple domains (Section 3). Next, it elaborates key design requirements of ALTO for exposing multi-domain information (Section 4). It then lists a set of mechanisms to design a multi-domain ALTO framework (Section 5). The overall rationale of this document is to arouse a discussion about potential rechartering topics to handle multi-domain with ALTO. 2. What does "multi-domain information exposure" mean? For the purposes of this document, a domain is considered to be a separate administrative environment. Specifically, the multi-domain approach involves multiple networks managed by different administrative domains. Examples of such domains include, among others, science networks, mobile operators, cloud service providers, and transport network providers. In multi-domain information exposure, multiple networks perform exchange of information to handle applications traversing multiple domains. For example, consider a collaboration network composed of Lachos, et al. Expires January 14, 2021 [Page 3] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 three-member domains, as shown in Figure 1. An application (e.g., a large data analysis system) wants to reserve bandwidth for two flows f1: (S1, D1) and f2: (S2, D2). In this example, the traffic from a source to a destination traverses multiple domains (A, B, and C), and hence the application needs to retrieve multi-domain information about topology and resources to take optimized allocation/placement decisions. .------------. | Domain B | .-------------. | 30 Gbps | | Domain A | _____o............o---D1 S1 | | / '------------' \ | 100 Gbps | / \ o*************o/ .------------. / | | \ | Domain C | / | | \ | 30 Gbps | S2 | | \____o............|---D2 '-------------' '------------' ---- 1 Tbps link Figure 1: A collaboration network composed of three member domains. The current ALTO base protocol is not designed for a multi-domain setting of exposing network information. For example, consider P2P applications (the first and main use case for the development of ALTO [RFC7971]). Figure 2 depicts a tracker-based P2P application with a global tracker (ALTO client) in domain A accessing ALTO servers at two ISPs (domains B and C). The ALTO server in each domain will provide only local information to ALTO clients, i.e., the tracker will receive topology-/policy-related information of a single domain (domain B or domain C). Due to the lack of information exchange between different domains, ALTO servers will not be able to expose information across multiple domains, i.e., the tracker will not receive merged topology-/policy-related information from domain B and domain C. Lachos, et al. Expires January 14, 2021 [Page 4] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 ,-------. ,---. ,-' `-. +-----------+ ,-' `-. / domain B \ | Peer 1 |******** / \ / +-------------+ \ | | * / domain A \ ++====>| ALTO Server | )+-----------+ * / \ || \ +------^------+ / +-----------+ * ; +-----------+ : || \ # / | Peer 2 | * | | Tracker |<====++ `-. # ,-' | |****** * | |ALTO Client| | `---#---' +-----------+ * * | +-----------+<====++ ,---#---. * * : * ; || ,-' # `-. +-----------+ * * \ * / || / # \ | Peer 3 | * * \ * / || / +------v------+ \ | |**** * * \ * / ++====>| ALTO Server | )+-----------+ * * * `-. * ,-' \ +-------------+ / +-----------+ * * * `-*-' \ / | Peer 4 |** * * * * `-. domain C,-' | | * * * * * `-------' +-----------+ * * * * * * * * * * * * * * ********************************************************* Legend: *** Application protocol === ALTO protocol ### Multi-domain ALTO protocol (NOT EXISTS) Figure 2: Global Tracker Accessing ALTO Server at Various Domains (Adapted from [RFC7971]). 3. What Information do Multi-domain applications need? Many types of network information are needed by cross-domain applications to improve their performances, including network state (e.g., loss, delay, ECN bit [RFC3168], INT [INT]), performance metrics (e.g., throughput, max reservable Bandwidth), capability information (e.g., delivery/acquisition protocol), locality (e.g., servers/domains location and paths), among others. In our previous example (See Figure 1), before the application can run a resource allocation algorithm to execute such submitted flows, it needs to gather some information from the network domains: o End-to-End cost across multiple domains This cost may be expressed in terms of resource availability and sharing (e.g., network bandwidth) for the set of requested flows to be reserved. In our presented scenario, for example, both Lachos, et al. Expires January 14, 2021 [Page 5] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 flows f1 and f2 are sharing the same network path in domain A. It means that they share a common resource, the network bandwidth. o Sequence of domains and candidate paths In multi-domain use cases, each flow will consume networking resources of multiple domains (if source node and destination node are located in different domains). Therefore, the application needs to discover a sequence of domains and candidate paths between source nodes and destination nodes, i.e., which domains are involved for the different traffic flows. In our example, the multi-domain network paths for f1 and f2 are [A , B], and [A, C], respectively. 3.1. Basic Formulation Consider different services, for each domain, providing previous information. Each service is defined as an object fi with a set of network properties, such as: o Path (fi.path): representing the sequence of network devices that packets of flow fi will traverse. o Available bandwidth (fi.abw): representing the bandwidth that flow fi can request. o Delay (fi.delay): representing the average delay of packets of flow fi. In our example, consider each ALTO server providing the bandwidth property using a set of linear inequalities (See Figure 3). Where x1 and x2 represent the available bandwidth that can be reserved for (S1, D1 ), and (S2, D2), respectively. +-----------+---------------------- --------+ | DOMAIN | LINEAR INEQUALITIES | +-----------+-------------------------------+ | Domain A | x1 + x2 <= 100 ....... (le11) | +-----------+-------------------------------+ | Domain B | x1 <= 30 ....... (le21) | +-----------+-------------------------------+ | Domain C | x2 <= 30 ........ (le31) | +-----------+-------------------------------+ Figure 3: Bandwidth properties for the reservation request from Figure 1. Lachos, et al. Expires January 14, 2021 [Page 6] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 Each linear inequality represents a constraint on the reservable bandwidths over different shared resources by the two flows. For example, the inequality le11 indicates that both flows share a common resource and that the sum of their bandwidths can not exceed 100 Gbps. In a multi-domain setting, a network property to a flow fi may involve properties of multiple networks, e.g.,: o fi.md-abw: min(fi.abw[A] + fi.abw[B] + fi.abw[C]) o fi.md-path: fi.path[A] . fi.path[B] . fi.path[C] o fi.md-delay: fi.delay[A] + fi.delay[B] + fi.delay[C] The involved domains may exchange such multi-domain properties. They also may apply composition mechanisms to create a unified representation to reveal a compact multi-domain network resource information. For example, taking a look at the set of previous linear inequalities (See Figure 3), one can conclude that the constraint le21 at domain B (x1 <= 30) and the constraint le31 at domain C (x2 <= 30) can eliminate that at domain A (X1 + x2 <= 100). ALTO servers may compose this information and remove the cross-domain redundancy (e.g., using a classic compression algorithm [TELGEN83]). Therefore, the compressed multi-domain set of linear inequalities is reduced to two linear inequalities (i.e., le21 and le31). 4. What are the ALTO issues of gathering multi-domain information? ALTO provides a generic framework to expose network information for applications to improve their performance. In particular, ALTO introduces generic mechanisms such as: (i) information resource directory (IRD), (ii) information consistency (tag, dependency, multi-info resources [ALTO-MULTIPART]), and (iii) information update model (e.g., incremental update with server-sent events [ALTO-SSE]). ALTO also introduces abstractions exposing network information to the applications: (i) network and cost maps, (ii) a multi-cost map [RFC8189], (iii) the path vector abstraction [ALTO-PATH], and (iv) capability maps (e.g., CDNI [ALTO-CDNI] and unified property Map [ALTO-PROP]). Another generic concept introduced is "filter", so that information resources can be filtered (e.g., filtered network/ cost map). Besides, each individual information resource is provided as a RESTful service with a very simple, but well-working grammar (essentially JSON grammar [RFC7159]). However, the multi-domain settings of exposing network information arise key issues to be considered in the current ALTO design. Next, we list several design issues of using ALTO to provide multi-domain Lachos, et al. Expires January 14, 2021 [Page 7] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 information. Such issues can be roughly categorized in three aspects: (i) communication mechanisms, (ii) conceptual query interfaces and data representation, and (iii) computation model. 4.1. Communication Mechanisms 4.1.1. Server-to-Client ALTO communication In multi-domain scenarios is not possible to optimize the traffic with only locally available network information (i.e., server-to- client ALTO communication). For example, compute costs for source/ destination pairs correctly if a source and/or a destination is outside the domain it belongs to. Therefore, it also necessary multi-ALTO server communication to allow exchanging detailed network information from multiple domains. The ALTO protocol specification states (See Section 3.1 of [RFC7285]) that "It may also be possible for an ALTO server to exchange network information with other ALTO servers (either within the same administrative domain or another administrative domain with the consent of both parties) in order to adjust exported ALTO". However, such a protocol is outside the scope of the specification. 4.1.2. Domain connectivity discovery The connectivity information is the reachability between source nodes and the destination nodes. In order to find the resources sharing between different source/destination pair, an application needs to know which domains are involved in the data movement of each node pair. Besides, a set of candidate paths needs to be computed in order to know how to reach a remote destination node. The current ALTO extensions do not have this feature. 4.1.3. ALTO server discovery Once the multi-domain connectivity discovery is performed, an application (as an ALTO client) needs to be aware of the presence and the location of ALTO servers in order to get appropriate guidance. These ALTO servers will be located in different network domains, so that multi-domain ALTO server discovery mechanisms are needed. 4.2. Conceptual Query Interfaces and Data Representation 4.2.1. Single-domain composition In the current ALTO framework, each domain can have its own representation of the same network information. For example, suppose that the path cost for member domain B (See Figure 1) is utilization charge instead of available bandwidth. In this case, both values are Lachos, et al. Expires January 14, 2021 [Page 8] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 not comparable together. Even, if all the member domains have the same utilization charge property, there would not necessarily a uniform form of billing because each member domain is autonomous. Member domain A may charge using dollar, member domain B may charge using euros, while member domain C may use some form of local units. 4.2.2. Simple resource query language Applications need to express their objectives and requirements in a query. For example, find the bandwidth the network can provide for flow f1 (S1, D1) subject to reachability requirements (e.g., from S1 to D1), bi-direction symmetry (e.g., data traffic from S1 to D1 and from D1 to S1), waypoint traversal (e.g., f2 must traverse one middlebox m1), blacklist of devices (e.g., f1 should not pass a certain device m2), link/node disjointness (e.g., f1 and f2 flows being transmitted along two link-disjoint paths), and QoS metrics (e.g., the bandwidth of the flow f1 needs to be at least 30 Gbps). The current query interface in ALTO (e.g., filtered network/cost map) can not express such flexible queries. 4.3. Computation Model 4.3.1. Scalability The optimization problems specified by the applications can be computationally expensive and time-consuming. For example, the number of available paths for each flow is increased exponentially with the number of domains involved. As such, the number of available configurations for a set of flows would also increase exponentially with both the network size and the number of flows. 4.3.2. Security and Privacy The information provided by the ALTO base protocol is considered coarse-grained in several recent multi-domain use cases. New ALTO extensions have been designed to provide fine-grained network information to the application. Using these ALTO extension services for multi-domain scenarios would raise new security and privacy concerns. 5. How to design a whole ALTO framework? In order to address the aforementioned issues, this section summarizes envisioned solutions and on-going efforts to allow ALTO to expose network information across multiple domains. See Table 1 to identify the relationship between the key design issues and their corresponding mechanisms to consider in a multi-domain ALTO framework. Lachos, et al. Expires January 14, 2021 [Page 9] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 +---------------------------------+---------------------------------+ | FROM | TO | +---------------------------------+---------------------------------+ | Server-to-Client ALTO | ALTO servers communication | | communication | | | ------------------------------- | ------------------------------- | | Domain connectivity discovery | Multi-domain connectivity | | | discovery | | ------------------------------- | ------------------------------- | | ALTO server discovery | Multi-domain ALTO server | | | discovery | | ------------------------------- | ------------------------------- | | Single-domain composition | Unified Resource Representation | | ------------------------------- | ------------------------------- | | Simple resource query language | Generic/Flexible query language | | ------------------------------- | ------------------------------- | | Scalability | Computation complexity | | | optimization | | ------------------------------- | ------------------------------- | | Security & Privacy | Security/Privacy preserving | +---------------------------------+---------------------------------+ Table 1: Issues of applying the current ALTO framework in the multi- domain setting & solutions. 5.1. ALTO servers communication ALTO servers may consider either a hierarchical or mesh architectural deployment design [INTER-ALTO][MD-ANALY][MD-BROKER][MD-SFC]. When a hierarchical architecture is used, ALTO servers in domain partitions gather locally-available network information and send it to central server, which in turn merges data and distributes ALTO services. In a mesh deployment, ALTO servers may be set up in each domain independently, connected to each other, and gathering the network information from other domains. 5.2. Multi-domain Connectivity discovery Multi-domain mechanisms combining domains sequence computation and paths computation need to be defined, or standardized computation protocols could be re-used. In the latter case, the IETF has a set of well defined protocols, such as BGP [RFC4271], PCE ([RFC5441] , [RFC6805]), or BGP-LS [RFC7752]. The BGP protocol, for instance, provides multi-domain sequence computation to know how to reach a destination just identifying the next hop for IP traffic delivery; however, it does not advertise multiple alternative routes. BGP-LS allows visibility of the network topology (real physical or abstracted) and export traffic engineering information with external Lachos, et al. Expires January 14, 2021 [Page 10] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 domains using the BGP routing protocol. Following the PCE-based architecture [RFC4655] for computing optimal multi-domain end-to-end paths, [RFC5441], [RFC6805] define mechanisms where a PCE entity cooperates either with other PCE entities in adjacent domains or with a parent PCE entity, respectively. A mix between BGP-LP and PCE may also be considered, with the first one providing topology/link-state network information, and with the second one making the necessary path computations between domains. 5.3. Multi-domain ALTO Server discovery The ALTO cross-domain server discovery document [RFC8686] specifies a procedure for identifying ALTO servers outside of the ALTO client's own network domain. Other mechanisms could also be leveraged, such as those based on PCE or BGP architectures. For example, [RFC4674] proposes a set of functional requirements to allow a path computation client (PCC) to automatically and dynamically discover the location of PCEs entities (including additional information about supported capabilities) for each controller domain. Inline with those requirements, [PROTO-BGP] is defining extensions to BGP to also carry PCE discovery information. Specifically, this document extends BGP to allow a PCE entities to advertise their location and some useful information to a PCC for the PCE selection. 5.4. Unified resource representation Therefore, multi-domain composition mechanisms are necessaries so that network information from ALTO servers in multiple domains can fit into a single and consistent "virtual" domain abstraction. ALTO information services such as network maps, cost maps, unified entity properties, network capabilities, and routing path abstractions (path vectors) of individual domains need to follow a common semantic as well as be consistently integrated to provide the abstraction of a single, coherent network to the applications. ... design options of multi-domain composition mechanisms [UNI-REPRES][UNICORN][MERCATOR][MERCATOR-2]. 5.5. Flexible/Generic query language With a flexible/generic query language, the network can filter out a large number of unqualified domains. The language specification could be inspired by standard [GSM][NFV-NSD] or pre- standard [SOCKET-INTENTS][IBN] mechanisms, implemented with a user- friendly grammar (e.g., SQL-style query). Lachos, et al. Expires January 14, 2021 [Page 11] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 5.6. Computation complexity optimization Therefore, ALTO servers need to support mechanisms to improve the scalability and performance (e.g., pre-computation and projection). For example, the ALTO Routing State Abstraction extension document [DRAFT-RSA] describes equivalent transformation algorithms that can effectively reduce the redundancy in the network view as much as possible while still providing the same information. Such algorithms may be integrated with any ALTO service (e.g., path vector extension) as a post-processing step. 5.7. Security/Privacy Preserving ALTO needs mechanisms (with little overhead) that provide accurate sharing network information, and at the same time, protects each member domain. This privacy-preserving interdomain information process may consider, for instance, a secure multi-party computation (SMPC) protocol [MD-ANALY][MERCATOR]. 6. IANA Considerations This document includes no request to IANA. 7. Security Considerations TBD. 8. References 8.1. Normative References [RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, DOI 10.17487/RFC3168, September 2001, . [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI 10.17487/RFC4271, January 2006, . [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, DOI 10.17487/RFC4655, August 2006, . Lachos, et al. Expires January 14, 2021 [Page 12] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 [RFC4674] Le Roux, J., Ed., "Requirements for Path Computation Element (PCE) Discovery", RFC 4674, DOI 10.17487/RFC4674, October 2006, . [RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux, "A Backward-Recursive PCE-Based Computation (BRPC) Procedure to Compute Shortest Constrained Inter-Domain Traffic Engineering Label Switched Paths", RFC 5441, DOI 10.17487/RFC5441, April 2009, . [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., and D. McPherson, "Dissemination of Flow Specification Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009, . [RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the Path Computation Element Architecture to the Determination of a Sequence of Domains in MPLS and GMPLS", RFC 6805, DOI 10.17487/RFC6805, November 2012, . [RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March 2014, . [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S., Previdi, S., Roome, W., Shalunov, S., and R. Woundy, "Application-Layer Traffic Optimization (ALTO) Protocol", RFC 7285, DOI 10.17487/RFC7285, September 2014, . [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, DOI 10.17487/RFC7752, March 2016, . [RFC7971] Stiemerling, M., Kiesel, S., Scharf, M., Seidel, H., and S. Previdi, "Application-Layer Traffic Optimization (ALTO) Deployment Considerations", RFC 7971, DOI 10.17487/RFC7971, October 2016, . [RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost Application-Layer Traffic Optimization (ALTO)", RFC 8189, DOI 10.17487/RFC8189, October 2017, . Lachos, et al. Expires January 14, 2021 [Page 13] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 [RFC8686] Kiesel, S. and M. Stiemerling, "Application-Layer Traffic Optimization (ALTO) Cross-Domain Server Discovery", RFC 8686, DOI 10.17487/RFC8686, February 2020, . 8.2. Informative References [ALTO-CDNI] Seedorf, J., Yang, Y., Ma, K., Peterson, J., and J. Zhang, "Content Delivery Network Interconnection (CDNI) Request Routing: CDNI Footprint and Capabilities Advertisement using ALTO", draft-ietf-alto-cdni-request-routing-alto-11 (work in progress), April 2020. [ALTO-MULTIPART] Zhang, J. and Y. Yang, "Multiple ALTO Resources Query Using Multipart Message", draft-zhang-alto-multipart-03 (work in progress), March 2020. [ALTO-PATH] Gao, K., Randriamasy, S., Yang, Y., and J. Zhang, "ALTO Extension: Path Vector", draft-ietf-alto-path-vector-10 (work in progress), March 2020. [ALTO-PROP] Roome, W., Randriamasy, S., Yang, Y., Zhang, J., and K. Gao, "Unified Properties for the ALTO Protocol", draft- ietf-alto-unified-props-new-10 (work in progress), November 2019. [ALTO-SSE] Roome, W. and Y. Yang, "ALTO Incremental Updates Using Server-Sent Events (SSE)", draft-ietf-alto-incr-update- sse-17 (work in progress), July 2019. [CMS] The CMS Collaboration, "The CMS experiment at the CERN LHC", 2008, . [DRAFT-RSA] Gao, K., xinwang2014@hotmail.com, x., Xiang, Q., Gu, C., Yang, Y., and G. Chen, "Compressing ALTO Path Vectors", draft-gao-alto-routing-state-abstraction-08 (work in progress), March 2018. Lachos, et al. Expires January 14, 2021 [Page 14] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 [ETSI-ZSM] ETSI, "Zero Touch Network and Service Management", 2020, . [GSM] GSM Association, "Generic Network Slice Template", 2019, . [IBN] Clemm, A., Ciavaglia, L., Granville, L., and J. Tantsura, "Intent-Based Networking - Concepts and Definitions", draft-irtf-nmrg-ibn-concepts-definitions-01 (work in progress), March 2020. [INT] Kim, C., Sivaraman, A., Katta, N., Bas, A., Dixit, A., and L. Wobker, "In-band network telemetry via programmable dataplanes", Book Title ACM SIGCOMM, 2015. [INTER-ALTO] Dulinski, Z., Wydrych, P., and R. Stankiewicz, "Inter-ALTO Communication Problem Statement", draft-dulinski-alto- inter-problem-statement-02 (work in progress), July 2015. [LCLS] SLAC National Accelerator Laboratory, "The Linac Coherent Light Source", 2020, . [LHC] CERN: European Council for Nuclear Research, "The Large Hadron Collider (LHC) Experiment", 2020, . [MD-ANALY] Xiang, Q., Zhang, J., Le, F., Yang, Y., and H. Newman, "Resource Orchestration for Multi-Domain, Exascale, Geo- Distributed Data Analytics", draft-xiang-alto-multidomain- analytics-03 (work in progress), March 2020. [MD-BROKER] Perez, D. and C. Rothenberg, "ALTO-based Broker-assisted Multi-domain Orchestration", draft-lachosrothenberg-alto- brokermdo-03 (work in progress), March 2020. [MD-ORCH-NFV] Katsalis, K., Nikaein, N., and A. Edmonds, "Multi-domain orchestration for NFV: Challenges and research directions", focus 189--195, 2016. Lachos, et al. Expires January 14, 2021 [Page 15] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 [MD-SFC] Perez, D., Xiang, Q., Rothenberg, C., and Y. Yang, "Multi- domain Service Function Chaining with ALTO", draft-lachos- sfc-multi-domain-alto-00 (work in progress), March 2020. [MERCATOR] Xiang, Q., Zhang, J., Wang, T., Liu, J., Guok, C., Le, F., MacAuley, J., Newman, H., and R. Yang, "Fine-Grained, Multi-Domain Network Resource Abstraction as a Fundamental Primitive to Enable High-Performance, Collaborative Data Sciences", Publisher IEEE, BookTitle SC18: International Conference for High Performance Computing, Networking, Storage and Analysis, Pages 58-70, 2018. [MERCATOR-2] Xiang, Q., Zhang, J., Wang, T., Liu, J., Guok, C., Le, F., MacAuley, J., Newman, H., and R. Yang, "Toward Fine- Grained, Privacy-Preserving, Efficient Multi-Domain Network Resource Discovery", Publisher IEEE, Journal IEEE Journal on Selected Areas in Communications, Volume 37, Number 8, Pages 1924-1940, 2019. [NFV-NSD] ETSI ISG, "Network functions virtualisation (NFV); management and orchestration; network service templates specification", 2019, . 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Authors' Addresses Danny Alex Lachos Perez University of Campinas Av. Albert Einstein 400 Campinas, Sao Paulo 13083-970 Brazil Email: dlachosp@dca.fee.unicamp.br URI: https://intrig.dca.fee.unicamp.br/danny-lachos/ Lachos, et al. Expires January 14, 2021 [Page 17] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 Christian Esteve Rothenberg University of Campinas Av. Albert Einstein 400 Campinas, Sao Paulo 13083-970 Brazil Email: chesteve@dca.fee.unicamp.br URI: https://intrig.dca.fee.unicamp.br/christian/ Qiao Xiang Yale University 51 Prospect Street New Haven, CT USA Email: qiao.xiang@cs.yale.edu Y. Richard Yang Yale University 51 Prospect St New Haven, CT USA Email: yang.r.yang@gmail.com Borje Ohlman Ericsson Research S-16480 Stockholm Sweden Email: Borje.Ohlman@ericsson.com Sabine Randriamasy Nokia Bell Labs Route de Villejust NOZAY 91460 FRANCE Email: Sabine.Randriamasy@nokia-bell-labs.com Lachos, et al. Expires January 14, 2021 [Page 18] Internet-Draft Multi-domain Info Exposure using ALTO July 2020 Farni Boten Sprint USA Email: farni.weaver@sprint.com Luis M. Contreras Telefonica Ronda de la Comunicacion, s/n Madrid 28050 Spain Email: luismiguel.contrerasmurillo@telefonica.com URI: http://lmcontreras.com/ Jingxuan Jensen Zhang Tongji University 4800 Caoan Road Shanghai 201804 China Email: jingxuan.n.zhang@gmail.com Kai Gao Sichuan University Chengdu 610000 China Email: kaigao@scu.edu.cn Lachos, et al. Expires January 14, 2021 [Page 19]