Network Working Group YF. Ji Internet-Draft WW. Bian Intended status: Informational HX. Wang Expires: April 21, 2011 SG. Huang BUPT GY. Zhang CATR October 18, 2010 Performance Measurement Metrics of Label Switched Path (LSP) Establishment in Multi-Layer and Multi-Domain Networks draft-jiyf-ccamp-lsp-00 Abstract As the increment of network scale and the variety of user request, traditional networks are to be partitioned into multi-layer and multi-domain networks for the purpose of better management. In multi-layer and multi-domain networks, various user requests are mapped into different LSPs, and the performance of a LSP is of great importance for the users. Therefore, the LSP is necessary to be evaluated as soon as it is established. For the purpose of judging whether a LSP establishment meets a user requirement or not, typical performance measurement metrics need to be proposed. In this document, LSP establishment delay and bit error ratio (BER) which are serving as the typical performance measurement metrics are illustrated, and the definition and methodologies are proposed. 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 http://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 April 21, 2011. Copyright Notice Ji, et al. Expires April 21, 2011 [Page 1] Internet-Draft LSP Performance October 2010 Copyright (c) 2010 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. 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 . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2. Overview of the Performance Measurement Metrics of LSP Establishment . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Overview of LSP Establishment Delay . . . . . . . . . . . 4 2.2. Overview of LSP Establishment BER . . . . . . . . . . . . 5 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. LSP Establishment Delay in Multi-Layer and Multi-Domain Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Measurement Metric Parameters . . . . . . . . . . . . . . 6 4.2. Definition . . . . . . . . . . . . . . . . . . . . . . . . 7 4.2.1. A Definition in Single Layer and Multi-Domain Networks . . . . . . . . . . . . . . . . . . . . . . . 7 4.2.2. A Definition in Multi-Layer and Multi-Domain Networks . . . . . . . . . . . . . . . . . . . . . . . 8 4.2.3. A Definition in Other Networks . . . . . . . . . . . . 9 4.3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . 10 5. LSP Establishment BER in Multi-Domain Networks . . . . . . . . 10 5.1. General Assumptions . . . . . . . . . . . . . . . . . . . 10 5.2. Definition . . . . . . . . . . . . . . . . . . . . . . . . 10 6. Methodologies . . . . . . . . . . . . . . . . . . . . . . . . 11 6.1. Definition . . . . . . . . . . . . . . . . . . . . . . . . 11 6.2. Methodologies . . . . . . . . . . . . . . . . . . . . . . 11 6.2.1. LSP Establishment Delay . . . . . . . . . . . . . . . 11 6.2.2. LSP Establishment BER . . . . . . . . . . . . . . . . 12 7. Protocol Extension Requirements . . . . . . . . . . . . . . . 12 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 10.1. Normative References . . . . . . . . . . . . . . . . . . . 13 10.2. Informative References . . . . . . . . . . . . . . . . . . 14 Ji, et al. Expires April 21, 2011 [Page 2] Internet-Draft LSP Performance October 2010 Appendix A. Other Authors . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 Ji, et al. Expires April 21, 2011 [Page 3] Internet-Draft LSP Performance October 2010 1. Introduction As the increment of network scale and the variety of user request, traditional networks are to be partitioned into multi-layer and multi-domain networks for the purpose of better management. User requests are mapped into various LSPs in multi-layer and multi-domain networks. Different users have different requirements, thus, LSP establishment is also different in order to satisfy different user requirements. To measure whether a LSP establishment meets a user requirement or not, objective performance measurement metrics and methodologies should be proposed. In this document, LSP establishment delay and BER are considered as the objective performance measurement metrics. This document defines the performance measurement metrics and methodologies that can be used to measure the LSP establishment quality in multi-layer and multi-domain networks. 1.1. Requirements Language 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 [RFC2119]. 1.2. Terminology BER: Bit Error Ratio. BRPC: Backward-Recursive PCE-Based Computation. GMPLS: Generalized Multiprotocol Label Switching. LID: Local Information Database. LSP: Label Switched Path. PCE: Path Computation Element. VSPT: Virtual Shortest Path Tree. 2. Overview of the Performance Measurement Metrics of LSP Establishment 2.1. Overview of LSP Establishment Delay In the process of LSP establishment, delay is considered as one of the main performance measurement metrics. In the background of GMPLS networks, LSPs that have different granularities are established. Ji, et al. Expires April 21, 2011 [Page 4] Internet-Draft LSP Performance October 2010 Two typical LSP establishment methods are explained here: LSP nesting and LSP stitching. LSP nesting corresponds to the LSP establishment in the multi-layer networks, while LSP stitching corresponds to the LSP establishment in the same layer networks. LSP establishment delay in above two methods is divided into two parts: path computation delay and LSP setup delay. In multi-layer and multi-domain networks, owing to the complexity of path computation, PCE-based path computation scheme is considered. Furthermore, optimal inter-domain LSP can not be got on a per-domain basis, so BRPC method is considered to complete inter-domain path computation in this document. Path computation delay is approximately defined from the time that source node sends the path computation request to the time that source node receives the optimal path computation result. In multi-layer and multi-domain networks, end-to-end LSP setup is mainly considered in this document. LSP setup delay is approximately defined from the time that source node sends the LSP setup message to the time that source node receives the confirm message of successful reservation. 2.2. Overview of LSP Establishment BER To measure the performance of LSP establishment, physical impairment parameter is one of the main performance measurement metrics, and BER is the main embodiment among all of physical impairment parameters, so BER is considered as one of the performance measurement metrics in the process of LSP establishment. In the measurement process of LSP establishment BER, BRPC method is used for the path computation and end-to-end way is used for the LSP setup, and BER is evaluated in the LSP setup process. The approximate procedure is as follows: the signaling collects some physical parameter information from source node to destination node, and destination node evaluates the LSP performance combining corresponding physical parameter information, then destination node returns Resv message to establish LSP if the LSP performance meets the user request, otherwise, LSP establishment fails. 3. Motivation LSP establishment delay in multi-layer and multi-domain networks is useful for several reasons: o Average LSP establishment delay is an important performance measurement metric that MAY reflect the scalability ability of a Ji, et al. Expires April 21, 2011 [Page 5] Internet-Draft LSP Performance October 2010 multi-layer and multi-domain network. Longer LSP establishment delay with the increasing numbers of domains and nodes or traffic volumes will most likely show that the network scalability is not good, especially when the LSP establishment delay surpasses linearity curve. o LSP establishment delay is an important performance measurement metric that MAY reflect the quality of LSP establishment in multi- layer and multi-domain networks. Longer LSP establishment delay will most likely show that the quality of LSP establishment is not good. o The values in the samples of LSP establishment delay MAY serve as an early indicator to provide references on whether to accept a service request that has stringent establishment delay requirement or not. LSP establishment BER in multi-domain networks is useful for several reasons: o LSP establishment BER is an important performance measurement metric that MAY reflect the quality of LSP establishment in multi- domain networks. Higher LSP establishment BER will most likely show that the quality of LSP establishment is not good. o The values in the samples of LSP establishment BER MAY serve as an early indicator to provide references on whether to accept a service request that has stringent establishment BER requirement or not. 4. LSP Establishment Delay in Multi-Layer and Multi-Domain Networks This section integrally defines a performance measurement metric named LSP establishment delay in multi-layer and multi-domain networks. 4.1. Measurement Metric Parameters o ID0, the source node ID. o ID1, the destination node ID. o T0, a time when the path computation is attempted. o T1, a time when the LSP setup is attempted. Ji, et al. Expires April 21, 2011 [Page 6] Internet-Draft LSP Performance October 2010 4.2. Definition 4.2.1. A Definition in Single Layer and Multi-Domain Networks In single layer and multi-domain networks, LSP can be established using LSP stitching method. In this method, the LSP establishment delay is collected from two parts: path computation delay and LSP setup delay. The path computation from source node ID0 to destination node ID1 mainly includes following process: source node ID0 sends a path computation Req message to the PCE responsible for the source domain. This request is forwarded between PCEs, domain-by-domain, to the PCE responsible for the destination domain. The PCE in the destination domain creates a set of optimal paths from all of the domain ingress nodes to the destination node. This set is represented as a tree of potential paths called a VSPT, and the PCE passes it back to the previous PCE in a Rep message. Each PCE in turn adds to the VSPT and passes it back until the PCE in the source domain uses the VSPT to select an optimal end-to-end path from the tree, and returns the path to the source node. The BRPC procedure above makes an assumption that the sequence of domains is known in advance. The path computation delay from source node ID0 to destination node ID1 at T0 is dT means that source node ID0 sends the path computation Req message to the PCE responsible for the source domain at time T0, and that source node receives the path computation results from the PCE responsible for the source domain at time T0+dT. The LSP setup from source node ID0 to destination node ID1 mainly includes following process: source node ID0 firstly sends the LSP setup message, which includes two procedures: determining if service layer exist and sending Path message. The detailed procedures are as follows: source node ID0 firstly determine if service layers exist. If service layer exists, source node needs to finishes the switch reversing function, then sends Path message to the next node to reserve resource, and the next node carries out the same function like source node until Path message arrives at destination node ID1. Subsequently, destination node returns Resv message to the previous node until source node receives the Resv message. If service layer does not exist, source node firstly establishes a service layer using signaling, then source node sends Path message to determine an available wavelength set until Path message arrives at destination node. If the available wavelength set exists, then destination node sends Resv message to source node to reserve available resources, and the switch reversing function of corresponding nodes are also finished simultaneously, otherwise, PathErr message is returned to the source node. In the circumstance of service layer exists, any node which Path message traverses detects the unavailable service Ji, et al. Expires April 21, 2011 [Page 7] Internet-Draft LSP Performance October 2010 layer, then PathErr message is also returned to the source node. The LSP setup delay from source node ID0 to destination node ID1 at T1 is dT means that source node ID0 sends the LSP setup message at time T1, and that source node receives the corresponding Resv message from destination node ID1 at time T1+dT. The value of LSP establishment delay in single layer and multi-domain networks is a real number of milliseconds. There is another case in which source node does not receive the optimal path computation result or the LSP confirm message of successful reservation within a reasonable period of time, and the value of LSP establishment delay in this case is marked undefined. 4.2.2. A Definition in Multi-Layer and Multi-Domain Networks In multi-layer and multi-domain networks, LSP can be established using LSP nesting method. In this method, the LSP establishment delay is collected from two parts: path computation delay and LSP setup delay. The path computation from source node ID0 to destination node ID1 mainly includes following process: source node ID0 sends a path computation Req message to the PCE responsible for the source domain. This request is forwarded between PCEs, domain-by-domain, to the PCE responsible for the destination domain. The PCE in the destination domain creates a set of optimal paths from all of the domain ingress nodes to the destination node. This set is represented as a tree of potential paths called a VSPT, and the PCE passes it back to the previous PCE in a Rep message. Each PCE in turn adds to the VSPT and passes it back until the PCE in the source domain uses the VSPT to select an optimal end-to-end path from the tree, and returns the path to the source node. The BRPC procedure above makes an assumption that the sequence of domains is known in advance. The path computation delay from source node ID0 to destination node ID1 at T0 is dT means that source node ID0 sends the path computation Req message to the PCE responsible for the source domain at time T0, and that source node receives the path computation results from the PCE responsible for the source domain at time T0+dT. The LSP setup from source node ID0 to destination node ID1 mainly includes following process: source node ID0 firstly sends the LSP setup message, which includes two procedures: determining if service layer exist and sending Path message. The detailed procedures are as follows: source node ID0 firstly determine if service layers exist. If service layer exists, source node needs to finishes the switch reversing function, then sends Path message to the next node to reserve resource, and the next node carries out the same function Ji, et al. Expires April 21, 2011 [Page 8] Internet-Draft LSP Performance October 2010 like source node until Path message arrives at destination node ID1. Subsequently, destination node returns Resv message to the previous node until source node receives the Resv message. If the capacity of existing service layer is not fully occupied, then fine granularity service that capacity is no more than remaining capacity of existing service layer can still be accepted in this service layer. If service layer does not exist, source node firstly establishes a service layer using signaling, then source node sends Path message to determine an available wavelength set until Path message arrives at destination node. If the available wavelength set exists, then destination node sends Resv message to source node to reserve available resources, and the switch reversing function of corresponding nodes are also finished simultaneously, otherwise, PathErr message is returned to the source node. In the circumstance of service layer exists, any node which Path message traverses detects the unavailable service layer, then PathErr message is also returned to the source node. If the capacity of new established service layer is not fully occupied, then fine granularity service that capacity is no more than remaining capacity of new established service layer can still be accepted in this service layer. The LSP setup delay from source node ID0 to destination node ID1 at T1 is dT means that source node ID0 sends the LSP setup message at time T1, and that source node receives the corresponding Resv message from destination node ID1 at time T1+dT. The value of LSP establishment delay in multi-layer and multi-domain networks is a real number of milliseconds. There is another case in which source node does not receive the optimal path computation result or the LSP confirm message of successful reservation within a reasonable period of time, and the value of LSP establishment delay in this case is marked undefined. 4.2.3. A Definition in Other Networks There are two types of other networks: single layer and single domain networks and multi-layer and single domain networks. The definition in single layer and single domain networks is similar to the definition in single layer and multi-domain networks, and the difference is that inter-domain LSP establishment process in single layer and single domain networks is not considered. Accordingly, the definition in multi-layer and single domain networks is similar to the definition in multi-layer and multi-domain networks, and the difference is that inter-domain LSP establishment process in multi- layer and single domain networks is not considered. The value of LSP establishment delay in single layer and single domain networks and multi-layer and single domain networks is a real Ji, et al. Expires April 21, 2011 [Page 9] Internet-Draft LSP Performance October 2010 number of milliseconds. There is another case in which source node does not receive the optimal path computation result or the LSP confirm message of successful reservation within a reasonable period of time, and the value of LSP establishment delay in this case is marked undefined. 4.3. Discussion The reason that LSP establishment delay is set to undefined not only lies in source node never receives the corresponding reply message within a reasonable period of time , but also consists in that source node receives the PathErr message. There are many possible reasons for receiving the PathErr message: for example, network does not have enough resources to establish the service layer for the user requests or network element failure occurs. 5. LSP Establishment BER in Multi-Domain Networks This section integrally defines a performance measurement metric named LSP establishment BER in multi-domain networks. 5.1. General Assumptions o Every node has a LID which stores the node physical information. o Destination node has a performance evaluation module which can evaluate the established LSP performance combining corresponding physical parameter information. 5.2. Definition In the measurement process of LSP establishment BER, no matter that the network is single domain or multi-domain, the evaluation method is the same, and only the wavelength lightpath has physical parameters, so single layer network is considered. In multi-domain networks, as physical parameters are collected and measured in the process of LSP setup, so only the LSP setup process is considered. The LSP setup from source node to destination node mainly includes following process: source node firstly determine if service layers exist. If service layer exists, source node sends Path message to the next node to reserve resource and collects physical information of nodes and links, and the next node carries out the same function like source node until Path message arrives at destination node, then Ji, et al. Expires April 21, 2011 [Page 10] Internet-Draft LSP Performance October 2010 destination node evaluates the LSP performance combining corresponding physical parameter information. If computed BER is within the tolerable range, then destination node returns Resv message to the previous node until source node receives the Resv message, otherwise, destination node returns PathErr message to the previous node until source node receives the PathErr message, and LSP setup fails. If service layer does not exist, source node firstly establishes a service layer using signaling, then source node sends Path message to determine an available wavelength set until Path message arrives at destination node. Meanwhile, signaling collects physical information of nodes and links. If the available wavelength set exists and BER that is computed by destination node is within the tolerable range, then destination node sends Resv message to source node to reserve available resources, otherwise, PathErr message is returned to the source node and LSP setup fails. In the circumstance of service layer exists, any node which Path message traverses detects the unavailable service layer, then PathErr message is also returned to the source node and LSP setup fails. 6. Methodologies 6.1. Definition o T0, a time when the path computation is attempted. o T1, a time when the LSP setup is attempted. o T2, a time when the optimal path computation result is returned. o T3, a time when the LSP confirm message of successful reservation is returned. 6.2. Methodologies 6.2.1. LSP Establishment Delay o Make sure that the PCE has enough computation ability to compute the path that conforms to user request. o Make sure that the network has enough resources to establish the requested path. o At the source node, form the path computation Req message. A timestamp (T0) may be stored locally on the source node when the path computation Req message is sent towards the PCE responsible for the source domain, and a timestamp (T1) may be stored locally on the source node when source node ID0 sends the LSP setup Ji, et al. Expires April 21, 2011 [Page 11] Internet-Draft LSP Performance October 2010 message. o If the corresponding end-to-end path computation results and Resv message arrive at source node within a reasonable period of time, take the timestamp (T2) and timestamp (T3) upon receipt of the messages. By subtracting the two timestamps, an estimate of path computation delay (T2-T0) and LSP setup delay (T3-T1) can be computed. o If the corresponding end-to-end path computation results and Resv message fails to arrive at source node within a reasonable period of time, the path computation delay and LSP setup delay are considered to be undefined. o If the corresponding response is a PathErr message, then the path computation delay and LSP setup delay are considered to be undefined. 6.2.2. LSP Establishment BER o Make sure that the PCE has enough computation ability to compute the path that conforms to user request. o Make sure that the network has enough resources to establish the requested path. o In the process of path computation, BRPC is used as the computation method. o In the process of LSP setup, when Path message arrives at destination node, then the destination node computes the BER combining the corresponding physical parameter information which is collected from the traversing nodes and links. If the computed BER is within the tolerable range, then Resv message is returned to source node. o If the computed BER is outside the tolerable range, then PathErr message is returned to source node and LSP establishment fails. 7. Protocol Extension Requirements o In the measurement process of LSP establishment delay, the start time of LSP establishment and the stop time of LSP establishment need to be determined using corresponding protocol. In the process of path computation, a new object that includes timestamp needs to be added in routing protocol in order to record the start time of path computation and the stop time of path computation; In Ji, et al. Expires April 21, 2011 [Page 12] Internet-Draft LSP Performance October 2010 the process of LSP setup, a new object that includes timestamp needs to be added in signaling protocol in order to record the start time of LSP setup and the stop time of LSP setup. o In the measurement process of LSP establishment BER, the physical information of nodes and links needs to be collected using signaling protocol, and BER is evaluated in the destination node combining corresponding physical parameter information, so a new object that includes network physical parameters needs to be added in signaling protocol in order to collect the physical information of nodes and links. 8. Security Considerations This document involves some information collection about network physical parameters. Such information would need to be protected from intentional or unintentional disclosure. 9. Acknowledgments We wish to thank Yongli Zhao, Linna Xia, Haoyuan Lin, Hongrui Han for their comments and help. The RFC text was produced using Marshall Rose's xml2rfc tool. 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFC's to Indicate Requirement Levels", RFC 2119, March 1997. [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. [RFC3945] Eric, M., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006. [RFC5440] Vasseur, J. and JL. Le Roux, "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC 5440, March 2009. Ji, et al. Expires April 21, 2011 [Page 13] Internet-Draft LSP Performance October 2010 [RFC5441] Vasseur, J., 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, April 2009. [RFC5814] Sun, W. and G. Zhang, "Label Switched Path (LSP) Dynamic Provisioning Performance Metrics in Generalized MPLS Networks", RFC 5814, March 2010. 10.2. Informative References [I-D.ietf-ccamp-wson-impairments] Lee, Y., Bernstein, G., Li, D., and G. Martinelli, "The Application of the Path Computation Element Architecture to the Determination of a Sequence of Domains in MPLS & GMPLS", July 2010. [Interdomain-LSP] Aslam, F., Uzmi, ZA., and A. Farrel, "Interdomain Path Computation: Challenges and Solutions for Label Switched Networks", IEEE Communications Magazine, October 2007. [RFC5212] Shiomoto, K., Papadimitriou, D., Le Roux, JL., Vigoureu, M., and D. Brungard, "Requirements for GMPLS-Based Multi- Region and Multi-Layer Networks (MRN/MLN)", RFC 5212, July 2008. Appendix A. Other Authors 1. Min Zhang BUPT No.10,Xitucheng Road,Haidian District Beijing 100876 P.R.China Phone: +8613910621756 Email: mzhang@bupt.edu.cn URI: http://www.bupt.edu.cn/ 2. Yunbin Xu Ji, et al. Expires April 21, 2011 [Page 14] Internet-Draft LSP Performance October 2010 CATR No.52 Hua Yuan Bei Lu,Haidian District Beijing 100083 P.R.China Phone: ++8613681485428 Email: xuyunbin@mail.ritt.com.cn URI: http://www.bupt.edu.cn/ Authors' Addresses Yuefeng Ji BUPT No.10,Xitucheng Road,Haidian District Beijing 100876 P.R.China Phone: +8613701131345 Email: jyf@bupt.edu.cn URI: http://www.bupt.edu.cn Weiwei Bian BUPT No.10,Xitucheng Road,Haidian District Beijing 100876 P.R.China Phone: +8615210837998 Email: bianweiwei2008@163.com URI: http://www.bupt.edu.cn/ Ji, et al. Expires April 21, 2011 [Page 15] Internet-Draft LSP Performance October 2010 Hongxiang Wang BUPT No.10,Xitucheng Road,Haidian District Beijing 100876 P.R.China Phone: +8613683683550 Email: wanghx@bupt.edu.cn URI: http://www.bupt.edu.cn/ Shanguo Huang BUPT No.10,Xitucheng Road,Haidian District Beijing 100876 P.R.China Phone: +86 1062282048 Email: shghuang@bupt.edu.cn URI: http://www.bupt.edu.cn/ Guoying Zhang CATR No.52 Hua Yuan Bei Lu,Haidian District Beijing 100083 P.R.China Phone: +86 1062300103 Email: zhangguoying@mail.ritt.com.cn URI: http://www.catr.cn/ Ji, et al. Expires April 21, 2011 [Page 16]