--- 1/draft-ietf-teas-pce-native-ip-10.txt 2020-08-25 02:13:52.223666945 -0700 +++ 2/draft-ietf-teas-pce-native-ip-11.txt 2020-08-25 02:13:52.339668491 -0700 @@ -1,23 +1,23 @@ TEAS Working Group A. Wang Internet-Draft China Telecom Intended status: Experimental B. Khasanov -Expires: February 11, 2021 Huawei Technologies +Expires: February 26, 2021 Huawei Technologies Q. Zhao Etheric Networks H. Chen Futurewei - August 10, 2020 + August 25, 2020 PCE in Native IP Network - draft-ietf-teas-pce-native-ip-10 + draft-ietf-teas-pce-native-ip-11 Abstract This document defines the architecture for traffic engineering within native IP network, using multiple BGP sessions strategy and PCE -based central control mechanism. It uses the Central Control Dynamic Routing (CCDR) procedures described in this document, and the Path Computation Element Communication Protocol (PCEP) extension specified in draft ietf-pce-pcep-extension-native-ip. @@ -29,21 +29,21 @@ 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 February 11, 2021. + This Internet-Draft will expire on February 26, 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 @@ -110,27 +110,27 @@ path computations within and across PCEP sessions. Furthermore, [RFC8281] specifies a mechanism to dynamically instantiate LSPs on a PCC based on the requests from a stateful PCE or a controller using stateful PCE. [RFC8283] introduces the architecture for PCE as a central controller as an extension of the architecture described in [RFC4655] and assumes the continued use of PCEP as the protocol used between PCE and PCC.[RFC8283] further examines the motivations and applicability for PCEP as a Southbound Interface (SBI), and introduces the implications for the protocol. - This document defines the framework for traffic engineering within + This document defines the architecture for traffic engineering within native IP network, using multiple BGP session strategy, to meet the above criteria in dynamical and centrally control mode. The - framework is referred as CCDR framework. It depends on the central - control (PCE) element to compute the optimal path for selected - traffic, and utilizes the dynamic routing behavior of traditional - IGP/BGP protocols to forward such traffic. + architecture is referred as CCDR architecture. It depends on the + central control (PCE) element to compute the optimal path for + selected traffic, and utilizes the dynamic routing behavior of + traditional IGP/BGP protocols to forward such traffic. The control messages between PCE and underlying network node are transmitted via Path Computation Element Communications Protocol (PCEP) protocol. The related PCEP extensions are provided in draft [I-D.ietf-pce-pcep-extension-native-ip]. 2. Terminology This document uses the following terms defined in [RFC5440]: @@ -160,22 +160,22 @@ normal traffic, traffic between prefix PF12(on SW1) and prefix PF22(on SW2) is priority traffic that should be treated with priority. In Intra-AS scenario, IGP and BGP are deployed between R1 and R2. In inter-AS scenario, only native BGP protocol is deployed. The traffic between each address pair may change in real time and the corresponding source/destination addresses of the traffic may also change dynamically. - The key ideas of the CCDR framework for this simple topology are the - followings: + The key ideas of the CCDR architecture for this simple topology are + the followings: o Build two BGP sessions between R1 and R2, via the different loopback addresses on these routers. o Send different prefixes via the established BGP sessions. For example, PF11/PF21 via the BGP session 1 and PF12/PF22 via the BGP session 2. o Set the explicit peer route on R1 and R2 respectively for BGP next hop to different physical link addresses between R1 and R2. Such @@ -216,33 +216,34 @@ | | | BGP Session 2(lo12/lo22)| +-------------------------+ PF12 | | PF22 PF11 | | PF21 +---+ +-----+-----+ +-----+-----+ +---+ |SW1+---------+(lo11/lo12)+-------------+(lo21/lo22)+--------------+SW2| +---+ | R1 +-------------+ R2 | +---+ +-----------+ +-----------+ - Figure 1: CCDR framework in simple topology + Figure 1: CCDR architecture in simple topology 4. CCDR Architecture in Large Scale Topology When the assured traffic spans across the large scale network, as that illustrated in Figure 2, the multiple BGP sessions cannot be established hop by hop, especially for the iBGP within one AS. For such scenario, we should consider using the Route Reflector (RR) [RFC4456] to achieve the similar effect. Every edge router will establish two BGP sessions with the RR via different loopback addresses respectively. The other steps for traffic differentiation - are same as that described in the CCDR framework for simple topology. + are same as that described in the CCDR architecture for simple + topology. As shown in Figure 2, if we select R3 as the RR, every edge router(R1 and R7 in this example) will build two BGP session with the RR. If the PCE selects the dedicated path as R1-R2-R4-R7, then the operator should set the explicit peer routes via PCEP protocol on these routers respectively, pointing to the BGP next hop (loopback addresses of R1 and R7, which are used to send the prefix of the assured traffic) to the selected forwarding address. +-----+ @@ -255,21 +256,21 @@ PF12 | +--+ | PF22 PF11 | | PF21 +---+ ++-+ +--+ +--+ +-++ +---+ |SW1+-------+R1+----------+R5+----------+R6+---------+R7+--------+SW2| +---+ ++-+ +--+ +--+ +-++ +---+ | | | | | +--+ +--+ | +------------+R2+----------+R4+-----------+ +--+ +--+ - Figure 2: CCDR framework in large scale network + Figure 2: CCDR architecture in large scale network 5. CCDR Multiple BGP Sessions Strategy In general situation, different applications may require different QoS criteria, which may include: o Traffic that requires low latency and is not sensitive to packet loss. o Traffic that requires low packet loss and can endure higher @@ -301,21 +302,21 @@ It is almost impossible to provide an End-to-End (E2E) path efficiently with latency, jitter, packet loss constraints to meet the above requirements in large scale IP-based network via the distributed routing protocol, but these requirements can be solved with the assistance of PCE, as that described in [RFC4655] and [RFC8283] because the PCE has the overall network view, can collect real network topology and network performance information about the underlying network, select the appropriate path to meet various network performance requirements of different traffics. - The framework to implement the CCDR Multiple BGP sessions strategy + The architecture to implement the CCDR Multiple BGP sessions strategy are the followings. Here PCE is the main component of the Software Definition Network (SDN) controller and is responsible for optimal path computation for priority traffic. o SDN controller gets topology via BGP-LS[RFC7752] and link utilization information via existing Network Monitor System (NMS) from the underlying network. o PCE calculates the appropriate path upon application's requirements, sends the key parameters to edge/RR routers(R1, R7 @@ -355,21 +356,21 @@ PF12 | +--+ | PF22 PF11 | | PF21 +---+ +v-+ +--+ +--+ +-v+ +---+ |SW1+-------+R1+----------+R5+----------+R6+---------+R7+--------+SW2| +---+ ++-+ +--+ +--+ +-++ +---+ | | | | | +--+ +--+ | +------------+R2+----------+R4+-----------+ - Figure 3: CCDR framework for Multi-BGP deployment + Figure 3: CCDR architecture for Multi-BGP deployment 6. PCEP Extension for Key Parameters Delivery The PCEP protocol needs to be extended to transfer the following key parameters: o Peer addresses pair that is used to build the BGP session o Advertised prefixes and their associated BGP session. @@ -391,45 +392,45 @@ [RFC8231] and PCECC [RFC8283] mechanism. Details of communications between PCEP and BGP subsystems in router's control plane are out of scope of this draft and will be described in separate draft [I-D.ietf-pce-pcep-extension-native-ip] . 7. Deployment Consideration 7.1. Scalability - In CCDR framework, PCE needs only influence the edge routers for the - prefixes advertisement via the multiple BGP sessions deployment. The - route information for these prefixes within the on-path routers were - distributed via the BGP protocol. + In CCDR architecture, PCE needs only influence the edge routers for + the prefixes advertisement via the multiple BGP sessions deployment. + The route information for these prefixes within the on-path routers + were distributed via the BGP protocol. For multiple domains deployment, the PCE or the pool of PCEs that reponsible for these domains need only control the edge router to build multiple EBGP sessions, all other procedures are the same that in one domain. Unlike the solution from BGP Flowspec, the on-path router need only keep the specific policy routes to the BGP next-hop of the differentiate prefixes, not the specific routes to the prefixes themselves. This can lessen the burden from the table size of policy based routes for the on-path routers, and has more expandability when comparing with the solution from BGP flowspec or Openflow. For example, if we want to differentiate 1000 prefixes from the normal traffic, CCDR needs only one explicit peer route in every on-path router, but the BGP flowspec or Openflow needs 1000 policy routes on them. 7.2. High Availability - The CCDR framework is based on the distributed IP protocol. If the - PCE failed, the forwarding plane will not be impacted, as the BGP + The CCDR architecture is based on the distributed IP protocol. If + the PCE failed, the forwarding plane will not be impacted, as the BGP session between all devices will not flap, and the forwarding table will remain unchanged. If one node on the optimal path is failed, the priority traffic will fall over to the best-effort forwarding path. One can even design several assurance paths to load balance/hot-standby the priority traffic to meet the path failure situation. For high availability of PCE/SDN-controller, operator should rely on existing high availability solutions for SDN controller, such as @@ -445,34 +446,34 @@ first, and then the traffic can be assured between different domains. Within each domain, the traffic will be forwarded along the best- effort path. Service provider can selectively upgrade the routers on each domain in sequence. 8. Security Considerations A PCE needs to assure calculation of E2E path based on the status of network and the service requirements in real-time. - The PCE need consider the explicit route deployment order (for + The PCE needs consider the explicit route deployment order (for example, from tail router to head router) to eliminate the possible transient traffic loop. The setup of BGP session, prefix advertisement and explicit peer route establishment are all controlled by the PCE. To prevent the bogus PCE to send harmful messages to the network nodes, the network devices should authenticate the validity of PCE and keep secures communication channel between them. Mechanism described in [RFC8253] should be used to avoid such situation. - CCDR framework does not require the change of forward behavior on the - underlay devices, then there will no additional security impact on - the devices. + CCDR architecture does not require the change of forward behavior on + the underlay devices, then there will no additional security impact + on the devices. 9. IANA Considerations This document does not require any IANA actions. 10. Acknowledgement The author would like to thank Deborah Brungard, Adrian Farrel, Vishnu Beeram, Lou Berger, Dhruv Dhody, Raghavendra Mallya , Mike Koldychev, Haomian Zheng, Penghui Mi, Shaofu Peng and Jessica Chen @@ -535,21 +536,21 @@ [RFC8735] Wang, A., Huang, X., Kou, C., Li, Z., and P. Mi, "Scenarios and Simulation Results of PCE in a Native IP Network", RFC 8735, DOI 10.17487/RFC8735, February 2020, . 11.2. Informative References [I-D.ietf-pce-pcep-extension-native-ip] Wang, A., Khasanov, B., Fang, S., and C. Zhu, "PCEP Extension for Native IP Network", draft-ietf-pce-pcep- - extension-native-ip-05 (work in progress), February 2020. + extension-native-ip-06 (work in progress), August 2020. Authors' Addresses Aijun Wang China Telecom Beiqijia Town, Changping District Beijing 102209 China Email: wangaj3@chinatelecom.cn