TEAS Working Group A.Wang Internet Draft China Telecom Quintin Zhao Boris Khasanov Huawei Technologies Penghui Mi Tencent Company Raghavendra Mallya Juniper Networks Shaofu Peng ZTE Corporation Intended status: Standard Track March 13, 2017 Expires: September 12, 2017 PCE in Native IP Network draft-wang-teas-pce-native-ip-03.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, and it may not be published except as an Internet-Draft. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. it for publication as an RFC or to translate it into languages other than English. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt Expires September 23, 2017 [Page 1] Internet-Draft PCE in Native IP Network March 13, 2017 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on September 13, 2017. Copyright Notice Copyright (c) 2017 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 (http://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. Abstract This document defines the scenario and solution for traffic engineering within Native IP network, using Dual/Multi-BGP session strategy and PCE-based central control architecture. The proposed central mode control solution conforms to the concept that defined in draft [I-D.draft-ietf-teas-pce-control-function]. And together with draft [I-D.draft-ietf-teas-pcecc-use-cases], the solution portfolio for traffic engineering in MPLS and Native IP network is almost completed. Table of Contents 1. Introduction ................................................ 3 2. Conventions used in this document............................ 3 3. Dual-BGP solution for simple topology........................ 3 4. Dual-BGP in large Scale Topology............................. 5 5. Multi-BGP for Extended Traffic Differentiation .............. 6 6. PCE based solution for Multi-BGP strategy deployment......... 6 7. PCEP extension for key parameters delivery................... 8 8. Deployment Consideration..................................... 8 9. Security Considerations..................................... 10 10. IANA Considerations........................................ 10 11. Conclusions ............................................... 10 12. References ................................................ 10 12.1. Normative References.................................. 10 12.2. Informative References................................ 10 13. Acknowledgments ........................................... 11 Expires September 12, 2017 [Page 2] Internet-Draft PCE in Native IP Network March 13, 2017 1. Introduction Currently, PCE based traffic assurance requires the underlying network devices support MPLS and the network must deploy multiple LSPs to assure the end-to-end traffic performance. LDP/RSVP-TE or Segment Routing should be enabled within the network to establish various MPLS paths. Such solution will certainly work but they does not cover the needs in legacy Native IP network, which demands less signaling protocol and less complex traffic steering policy. Within Native IP network, the solution for traffic engineering is generally hop-by-hop differentiate treatment. To achieve the end2end QoS performance assurance, one can only deploy some dedicated links statically, but such solution is not feasible in the service provider network, because the complexity of underlying network and the variation of application traffic from time to time. In summary, the requirements for traffic engineering in Native IP network are the following: 1) No complex MPLS signaling procedure. 2) End to End traffic assurance, determined QoS behavior. 3) Flexible deployment and automation control. This document defines the solution for traffic engineering within Native IP network, using Dual/Multi-BGP session strategy and PCE- based central control architecture, to meet the above requirements in dynamical and central control mode. Future PCEP protocol extensions to transfer the key parameters between PCE and the underlying network devices(PCC) are provided in draft [draft-wang-pcep-extension-native- IP] 2. Conventions used in this document 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. Dual-BGP solution for simple topology. This section introduces the dual-BGP solution for simple topology that illustrated in Fig.1, which is comprised by SW1, SW2, R1, R2. There are multiple physical links between R1 and R2. Let's assume traffic between IP11 and IP21 is normal traffic, traffic between IP12 Expires September 12, 2017 [Page 3] Internet-Draft PCE in Native IP Network March 13, 2017 and IP22 is priority traffic that should be treated differently. Only Native IGP/BGP protocol is deployed between R1 and R2. The traffic between each address pair may change timely and the corresponding source/destination addresses of the traffic may also change dynamically. The key idea of the Dual-BGP solution for this simple topology is the following: 1) Build two BGP sessions between R1 and R2, via the different loopback address lo0, lo1 on these routers. 2) Send different prefixes via the two BGP sessions. (For example, IP11/IP21 via the BGP pair 1 and IP12/IP22 via the BGP pair 2). 3) Set the explicit peer route on R1 and R2 respectively for BGP next hop of lo0, lo1 to different physical link address between R1 and R2. So, the traffic between the IP11 and IP21, and the traffic between IP12 and IP22 will go through different physical links between R1 and R2, each type of traffic occupy the different dedicated physical links. If there is more traffic between IP12 and IP22 that needs to be assured , one can add more physical links on R1 and R2 to reach the loopback address lo1(also the next hop for BGP Peer pair2). In this cases the prefixes that advertised by two BGP peer need not be changed. If, for example, there is traffic from another address pair that needs to be assured (for example IP13/IP23), but the total volume of assured traffic does not exceed the capacity of the previous appointed physical links, then one need only to advertise the newly added source/destination prefixes via the BGP peer pair2, then the traffic between IP13/IP23 will go through the assigned dedicated physical links as the traffic between IP12/IP22. Such decouple philosophy gives the network operator more flexible control ability on the network traffic, get the determined QoS assurance effect to meet the application's requirement. No complex MPLS signal procedures is introduced, the router need only support native IP protocol. Expires September 12, 2017 [Page 4] Internet-Draft PCE in Native IP Network March 13, 2017 | BGP Peer Pair2 | +------------------+ |lo1 lo1 | | | | BGP Peer Pair1 | +------------------+ IP12 |lo0 lo0 | IP22 IP11 | | IP21 SW1-------R1-----------------R2-------SW2 Links Group Fig.1 Design Philosophy for Dual-BGP Solution 4. Dual-BGP in large Scale Topology When the assured traffic spans across one large scale network, as that illustrated in Fig.2, the dual BGP sessions cannot be established hop by hop especially for the iBGP within one AS. For such scenario, we should consider to use the Route Reflector (RR) to achieve the similar Dual-BGP effect, that is to say, select one router which performs the role of RR (for example R3 in Fig.2 - Dual- BGP Solution using Route Reflector for large scale network), every other edge router will establish two BGP peer sessions with the RR, using their different loopback addresses respectively(the inner router will establish one BGP session with RR). The other two steps for traffic differentiation are same as one described in the Dual-BGP simple topology usage case. For the example shown in Fig.2, if we select the R1-R2-R4-R7 as the dedicated path, then we should set the explicit peer routes 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 actual address of the physical link +------------R3--------------+ | | SW1-------R1-------R5---------R6-------R7--------SW2 | | | | +-------R2---------R4--------+ Fig.2 Dual-BGP solution for large scale network Expires September 12, 2017 [Page 5] Internet-Draft PCE in Native IP Network March 13, 2017 5. Multi-BGP for Extended Traffic Differentiation In general situation, several additional traffic differentiation criteria exist, including: o Traffic that requires low latency links and is not sensitive to packet loss o Traffic that requires low packet loss but can endure higher latency o Traffic that requires lowest jitter path o Traffic that requires high bandwidth links These different traffic requirements can be summarized in the following table: +----------+-------------+---------------+-----------------+ | Flow No. | Latency | Packet Loss | Jitter | +----------+-------------+---------------+-----------------+ | 1 | Low | Normal | Don't care | +----------+-------------+---------------+-----------------+ | 2 | Normal | Low | Dont't care | +----------+-------------+---------------+-----------------+ | 3 | Normal | Normal | Low | +----------+-------------+---------------+-----------------+ Table 1. Traffic Requirement Criteria For Flow No.1, we can select the shortest distance path to carry the traffic; for Flow No.2, we can select the idle links to form its end to end path; for Flow No.3, we can let all the traffic pass one single path, no ECMP distribution on the parallel links is required. It is difficult and almost impossible to provide an end-to-end (E2E) path with latency, latency variation, packet loss, and bandwidth utilization constraints to meet the above requirements in large scale IP-based network via the traditional distributed routing protocol, but these requirements can be solved using the PCE-based architecture since 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 the various network performance requirements of different traffic type. 6. PCE based solution for Multi-BGP strategy deployment. With the advent of SDN concepts towards pure IP networks, it is Expires September 12, 2017 [Page 6] Internet-Draft PCE in Native IP Network March 13, 2017 possible to deploy the PCE related technology into the underlying native IP network, to accomplish the central and dynamic control of network traffic according to the application's various requirements. The procedure to implement the dynamic deployment of Multi-BGP strategy is the following: 1) PCE gets topology and link utilization information from the underlying network, calculate the appropriate link path upon application's requirements. 2) PCE sends the key parameters to edge/RR routers(R1, R7 and R3 in Fig.3) to build multi-BGP peer relations and advertise different prefixes via them. 3) PCE sends the route information to the routers (R1,R2,R4,R7 in Fig.3) on forwarding path via PCEP, to build the path to the BGP next-hop of the advertised prefixes. 4) If the assured traffic prefixes were changed but the total volume of assured traffic does not exceed the physical capacity of the previous end-to-end path, then PCE needs only change the related information on edge routers (R1,R7 in Fig.3). 5) If volume of the assured traffic exceeds the capacity of previous calculated path, PCE must recalculate the appropriate path to accommodate the exceeding traffic via some new end-to-end physical link. After that PCE needs to update on-path routers to build such path hop by hop. +----+ ***********+PCE +************* * +--*-+ * * / * \ * * * * PCEP* *BGP-LS/SNMP *PCEP * * * * * \ * / \ * / * \ */ \*/-----------R3--------------* | | | | SW1-------R1-------R5---------R6-------R7--------SW2 | | | | | | | | +-------R2---------R4--------+ Fig.3 PCE based solution for Multi-BGP deployment Expires September 12, 2017 [Page 7] Internet-Draft PCE in Native IP Network March 13, 2017 7. PCEP extension for key parameters delivery. We need to extend the PCEP protocol to transfer the following key parameters: 1) BGP peer address and advertised prefixes. 2) Explicit route information to BGP next hop of advertised prefixes. Once the router receives such information, it should establish the BGP session with the peer appointed in the PCEP message, advertise the prefixes that contained in the corresponding PCEP message, and build the end to end dedicated path hop by hop. 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.[draft-wang-pce-extension for native IP] The reason why we selected PCEP as the southbound protocol instead of OpenFlow, is that PCEP is very suitable for the changes in control plane of the network devices, there OpenFlow dramatically changes the forwarding plane. We also think that the level of centralization that requires by OpenFlow is hardly achievable in many today's SP networks so hybrid BGP+PCEP approach looks much more interesting. 8. Deployment Consideration This solution requires the parallel work of 2 subsystems in router's control plane: PCE (PCEP) and BGP as well as coordination between them, so it might require additional planning work before deployment. 8.1 Scalability In current solution, PCE need only to influence the edge routers for the prefixes differentiation via the multi-BGP deployment. The route information for these prefixes within the on-path routers were distributed via the traditional BGP protocol. 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 scalability when comparing with the solution from BGP flowspec or Openflow. Expires September 12, 2017 [Page 8] Internet-Draft PCE in Native IP Network March 13, 2017 8.2 High Availability Current solution is based on the traditional distributed IP protocol, then if the central control 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 the same. If one node on the optimal path is failed, the assurance traffic will fall over to the best-effort forwarding path. One can even design several assurance paths to load balance/hot standby the assurance traffic to meet the path failure situation, as done in MPLS FRR. From PCE/SDN-controller HA side we will rely on existing HA solutions of SDN controllers such as clustering. 8.3 Incremental deployment Not every router within the network support will support the PCEP extension that defined in [draft-wang-pce-extension-native-IP] simultaneously. For such situations, router on the edge of sub domain can be upgraded first, and then the traffic can be assured between different sub domains. Within each sub domain, the traffic will be forwarded along the best-effort path. Service provider can selectively upgrade the routers on each sub-domain in sequence. 8.4 Deployment within Pure IGP network For some small underlying networks where the routers support only the pure IGP protocol, we can use EVPN/VxLAN technology and similar procedures that described within this draft to differentiate the forwarding paths for different applications: 1) PCE instructs the IGP edge router (ABR) build different BGP sessions. 2) PCE instructs the IGP edge router (ABR) redistribute external prefixes via different BGP sessions under the EVPN address family, and then different external prefixes will be associated with different VTEP addresses. 3) PCE calculates the optimal path and instruct the on-path routers to build the explicit peer routes to the different VTEP addresses (also the different loopback addresses on ABR). Expires September 12, 2017 [Page 9] Internet-Draft PCE in Native IP Network March 13, 2017 The traffic will then be forwarded via the VxLAN encapsulation, the route path of them will be determined by the outer tunnel address, which is calculated and programmed by PCE. The detail of deployment scenario and the corresponding PCEP extension will be exploited further later. 9. Security Considerations TBD 10. IANA Considerations TBD 11. Conclusions TBD 12. References 12.1. Normative References [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006,. [RFC5440]Vasseur, JP., Ed., and JL. Le Roux, Ed., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009, . 12.2. Informative References [I-D.draft-ietf-teas-pce-control-function] A.Farrel, Q.Zhao et al. "An Architecture for use of PCE and PCEP in a Network with Central Control" https://datatracker.ietf.org/doc/draft-ietf-teas-pce-central- control/ September, 2016 Expires September 12, 2017 [Page 10] Internet-Draft PCE in Native IP Network March 13, 2017 [I-D. draft-ietf-teas-pcecc-use-cases] Quintin Zhao, Robin Li, Boris Khasanov et al. "The Use Cases for Using PCE as the Central Controller(PCECC) of LSPs https://tools.ietf.org/html/draft-ietf-teas-pcecc-use-cases-00 March,2017 [draft-wang-pcep-extension for native IP] Aijun Wang, Boris Khasanov et al. "PCEP Extension for Native IP Network" https://datatracker.ietf.org/doc/draft-wang-pce-extension- native-ip/ 13. Acknowledgments The authors would like to thank George Swallow, Xia Chen, Jeff Tantsura, Daniele Ceccarelli and Dhruv Dhody for their valuable comments and suggestions. The authors would also like to thank Lou Berger, Adrian Farrel, King Daniel for their suggestions to put forward this draft. Authors' Addresses Aijun Wang China Telecom Beiqijia Town, Changping District Beijing,China Email: wangaj.bri@chinatelecom.cn Expires September 12, 2017 [Page 11] Internet-Draft PCE in Native IP Network March 13, 2017 Quintin Zhao Huawei Technologies 125 Nagog Technology Park Acton, MA 01719 US EMail: quintin.zhao@huawei.com Boris Khasanov Huawei Technologies Moskovskiy Prospekt 97A St.Petersburg 196084 Russia EMail: khasanov.boris@huawei.com Penghui Mi Tencent Tencent Building, Kejizhongyi Avenue, Hi-techPark, Nanshan District,Shenzhen 518057, P.R.China Email kevinmi@tencent.com Raghavendra Mallya Juniper Networks 1133 Innovation Way Sunnyvale, California 94089 USA Email: rmallya@juniper.net Shaofu Peng ZTE Corporation No.68 Zijinghua Road,Yuhuatai District Nanjing 210012 China Email: peng.shaofu@zte.com.cn Expires September 12, 2017 [Page 12]