Network Working Group M. Chen Internet-Draft H. Liu Intended status: Informational Y. Yin Expires: August 21, 2013 Huawei February 17, 2013 Coloring based IP Flow Performance Measurement Framework draft-chen-coloring-based-ipfpm-framework-00 Abstract By setting one unused bit of the IP header of packets to "color" the packets into different color blocks, it naturally gives a way to measure the real packet loss and delay without inserting any extra OAM packets. This is called coloring based IP performance measurement. This document specifies a framework and protocol for this "coloring" based IP performance measurement. 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 RFC 2119 [RFC2119]. 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 August 21, 2013. Copyright Notice Copyright (c) 2013 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 Chen, et al. Expires August 21, 2013 [Page 1] Internet-Draft Colouring based IP FPM Framework February 2013 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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview and Concept . . . . . . . . . . . . . . . . . . . . . 4 4. Reference Model and Functional Components . . . . . . . . . . 5 4.1. Reference Model . . . . . . . . . . . . . . . . . . . . . 5 4.2. Measurement Control Point . . . . . . . . . . . . . . . . 6 4.3. Data Collecting Point . . . . . . . . . . . . . . . . . . 7 4.4. Target Logical Port . . . . . . . . . . . . . . . . . . . 8 5. Colouring based Performance Measurement Protocol . . . . . . . 8 5.1. Common Message Header . . . . . . . . . . . . . . . . . . 8 5.2. Open Message . . . . . . . . . . . . . . . . . . . . . . . 8 5.3. KeepAlive Message . . . . . . . . . . . . . . . . . . . . 9 5.4. Configure Message . . . . . . . . . . . . . . . . . . . . 9 5.5. Report Message . . . . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 9.1. Normative References . . . . . . . . . . . . . . . . . . . 12 9.2. Informative References . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Chen, et al. Expires August 21, 2013 [Page 2] Internet-Draft Colouring based IP FPM Framework February 2013 1. Introduction Performance Measurement (PM) is an important tool that can not only provide Service Level Agreement (SLA) verification but facilitate in trouble shooting (e.g., fault localization or fault delimitation) and network visualization. There are two types of performance measurement: one is active performance measurement, and the other is passive performance measurement. In active performance measurement the receiver measures the injected packets to evaluate the performance of a path. The active measurement measures the performance of the extra injected packets, the rate, numbers and interval of the injected packets will largely affect the accuracy of the results. In addition, it also requires that the injected packets have to follow the same path as the real traffic; this normally cannot be guaranteed in the pure IP network. The One-Way Active Measurement Protocol (OWAMP) [RFC4656] and Two-Way Active Measurement Protocol (TWAMP) [RFC5357] are tools to enable active performance measurement. In passive performance measurement, no artificial traffic is injected into the flow and measurements are taken to record the performance metrics of the real traffic. The Multiprotocol Label Switching (MPLS) PM protocol [RFC6374] for packet loss is an example of passive performance measurement. By periodically inserting auxiliary Operations, Administration, and Maintenance (OAM) packets, the traffic is delimited by the OAM packets into consecutive blocks, and the receivers count the packets and calculate the packets loss each block. But, when the OAM channel is in-band, solutions like [RFC6374] are not pure passive measurement as the OAM packets are inserted into the data stream. Furthermore because solutions like [RFC6374] depend on the fixed positions of the delimiting OAM packets for packets counting, they are vulnerable to out-of-order arrival of packets. This could happen particularly with out-of-band OAM channels, but might also happen with in-band OAM because of the presence of multipath forwarding within the network. Out of order delivery of data and the delimiting OAM can give rise to inaccuracies in the performance measurement figures. The scale of these inaccuracies will depend on data speeds and the variation in delivery, but with out-of-band OAM, this could result in significant differences between real and reported performance. This document describes a mechanism where data packets are marked or "colored" so that they form blocks of data. No additional delimiting Chen, et al. Expires August 21, 2013 [Page 3] Internet-Draft Colouring based IP FPM Framework February 2013 OAM is needed and the performance can be measured in-service without the insertion of additional traffic. Furthermore, because coloring based IP performance measurement does not require extra OAM packets for traffic delimitation, it can be used in situations where there is packets re-ordering. This document specifies a framework and protocol for the "coloring" based IP performance measurement. 2. Terminology SLA: Service Level Agreement OAM: Operations Administration and Maintenance MCP: Measurement Control Point MP: Measurement Point DCP: Data Collecting Point TLP: Target Logical Port MPLS: Multiprotocol Label Switching CSG: Cell Site Gateway RNC: Radio Network Controller RSG: RNC Site Gateway 3. Overview and Concept The concept of "coloring" IP packets for performance measurement is described in [I-D.tempia-opsawg-p3m]. By "coloring" the packets of a specific IP flow to different colors, it naturally splits the IP flow into deferent consecutive blocks. For packet loss measurement, there are two ways to color packets: fixed packet numbers or fixed time period for each color block. This document only talks about the way of fixed time period. The sender and receiver nodes count the transmitted and received packets/octets based on each color block. By collecting and comparing the transmitted and received packets/octets, it can easily detect whether there is packet loss and how many packets/octets get lost. For packet delay measurement, there are two solutions. One is similar to packet loss, it still colors the IP flow to different Chen, et al. Expires August 21, 2013 [Page 4] Internet-Draft Colouring based IP FPM Framework February 2013 color blocks and uses the time when color changing as the reference time for delay calculation. This solution requires that there must not be any out-of-order packets, otherwise, the result will not be accurate. Because it uses the first packet of each color block for delay measurement, if there is packet reordering, the first packet of each block at the sender will be probably different from the first packet of the block at the receiver. The other way is to periodically color a single packet of the IP flow. Within a time period, there is only one packet can be colored. The sender records the timestamp when the colored packet is transmitted, the receiver records the timestamp when detecting the colored packet. With the two timestamps, the packet delay can be computed. To make the above solutions work, two conditions are required. The first one is that there have to be a way to collect the packet counts and timestamps from the senders and receivers to a centralized calculation element. The second is that the centralized calculation element has to know what exactly a pair of packet counts(one from the sender and the other is from the receiver) are based on the same color block and a pair of timestamps (one from the sender and the other is from the receiver) are based on the same colored packet. 4. Reference Model and Functional Components 4.1. Reference Model An Multipoint-to-Multipoint (MP2MP) reference model (as shown in Figure 1) is introduced in this document. For a specific IP flow, there may be one or more upstream and downstream Measurement Points (MPs). An IP flow can be identified by the Source IP (SIP) and Destination IP (DIP) addresses, and it may combine the SIP and DIP with any or all of the Protocol number, the Source port, the Destination port, and the Type of Service (TOS) to identify an IP flow. An MP is a network node. From the measurement point of view, it consists of two parts (as shown in Figure 2): Data Collecting Point (DCP), and Target Logical Port (TLP). For an MP, there is only one DCP and may be one or more TLPs. The Measurement Control Point (MCP) is a centralized calculation element, MPs periodically report their measurement data to the MCP for final performance calculation. The report protocol is defined Section 5 of this document. The reason for choosing MP2MP model is that it can satisfy all the scenarios that include Point-to-Point (P2P), Point-to-Multipoint (P2MP), Multipoint-to-Point (MP2P), and MP2MP. P2P scenario is obvious and can be used anywhere. P2MP and MP2P are very common in Chen, et al. Expires August 21, 2013 [Page 5] Internet-Draft Colouring based IP FPM Framework February 2013 mobile backhaul networks. For example, a Cell Site Gateway (CSG) multi-homing to two Radio Network Controller (RNC) Site Gateways (RSGs) is a typical network design. When there is a failure, there is a requirement to monitor the flows between the CSG and the two RSGs hence to determine whether the fault is in the transport network or in the wireless network(this is normally called "fault delimitation"). This is especially useful in the situation where the transport network belongs to one service provider and wireless network belongs to other service providers. +-----+ +------| MCP |------+ | +-----+ | +-----+ | +---/ \---+ | +-----+ | MP1 |---+ | | +---| MP3 | +-----+ | | +-----+ +-----+ | | +-----+ | MP2 |------+ +------| MP4 | +-----+ +-----+ Figure 1: MP2MP based Model +----------------------+ | +--------+ | | | DCP | | Control Plane | +--------+ | ----------|-----/----------\-----|-------------- | +--+--+ +--+--+ | | | TLP1| | TLP2| | Data plane | +-----+ +-----+ | +----------------------+ Figure 2: Measurement Point 4.2. Measurement Control Point The MCP is responsible for calculating the final performance metrics according to the received measurement data from the MPs (actually from the DCPs). For packet loss, based on each color block, the difference between the total counts received from all upstream MPs and the total counts received from all downstream MPs are the lost packet numbers. The MCP must make sure that the counts from the upstream MPs and downstream MPs are related to the same color block. For packet delay (e.g., one way delay), the difference between the timestamps from the downstream MP and upstream MP is the packet delay. Similarly to packet loss, the MCP must make sure the two timestamps are based on the same colored packet. Chen, et al. Expires August 21, 2013 [Page 6] Internet-Draft Colouring based IP FPM Framework February 2013 This document introduces a Period Number (PN) based synchronization mechanism to help the MCP to determine whether any two or more packet counts (from distributed MPs) are related to the same color block or any two timestamps are related to the same colored packet. The PN is generated each time a DCP reads the packet counts and timestamps from the TLP, and is equal to the modulo of the local time (when the counts and timestamps are read) and the interval of the color time period. Each packet count and timestamp has a PN when reported to the MCP, and the same PN means that they are related to the same color block or colored packet. This requires that the upstream and downstream MPs having a certain time synchronization capability (e.g., supporting the Network Time Protocol (NTP) [RFC5905], or the IEEE 1588 Precision Time Protocol (PTP) [IEEE1588].) and assumes that the upstream and downstream MPs have already time synchronized. Since is the intention to measure packet delay, this requirement for time synchronization is already present. 4.3. Data Collecting Point The DCP is responsible for periodically collecting the measurement data from the TLPs and for reporting the data to the MCP. In addition, when to change the color, when to color a packet (for packet delay measurement), and when to read the packet counts and timestamps are also controlled by DCP. Each DCP will maintain two timers, one (C-timer, used at upstream DCP) is for color changing, the other (R-timer, used at downstream DCP) is for reading the packet counts and timestamps. The two timers have the same time interval but are started at different times. A DCP can be either an upstream or a downstream DCP: the role is specific to an IP flow. For a specific IP flow, the upstream DCP will change the color and read the packet counts and timestamps when the C-timer expires, the downstream DCP just reads the packets counts and timestamps when the R-timer expires. In order to allow for a certain degree of packets re- ordering, the R-timer should be started later than a defined period of time after the C-timer is started (e.g., 1/3 or 2/3 T, where T is the interval of the C-timer). It recommends that: for packet loss measurement, the R-timer should be started at 1/3 T after the C-Timer is started, and for packet delay measurement, the R-timer should be started at 2/3 T after the C-Timer is started. To make the implementation simple, the C-timer should be started at the beginning of each time period. This document recommends the implementation to support at least these time periods (1s, 10s, 1min, 10min and 1h). So, if the time period is 10s, the C-timer should be started at the time of any multiples of 10 in seconds (e.g., 0s, 10s, 20s, etc.), then the R-timer should be started, for example, at the time of T+1/3 or 2/3 T. With this method, each DCP can independently start its C-timer and R-timer given that the clocks have been Chen, et al. Expires August 21, 2013 [Page 7] Internet-Draft Colouring based IP FPM Framework February 2013 synchronized. 4.4. Target Logical Port The TLP is a logical entity that actually executes the final measurement actions (e.g., colors the packets, counts the packets, records the timestamps, etc.). Normally, a physical interface corresponds to a TLP, and the TLP resides in the data plane. For a measurement instance (corresponding to an IP flow), a TLP will maintain a pairs of packet counters and a timestamp counter for each color block. One packet counter is for counting packets and the other is for counting octets. 5. Colouring based Performance Measurement Protocol This section is a preliminary documentation of CPMP. More details will be supplied in a future version of this document. The Coloring-based Performance Measurement Protocol (CPMP) is defined for communication between DCP and MCP. An MCP may use it to enable/ disable a measurement instance on DCPs, and DCPs use it to periodically report measurement data to the MCP. The CPMP uses TCP as the transport protocol, a dedicated TCP port is required. The MCP listens on the port and accept the connect request from DCPs. So, DCPs must know where the MCP is, this could be done by configuration when creating a measurement instance. 5.1. Common Message Header There are 4 messages defined in this document, which include Open Message, KeepAlive Message, Configure Message and Report Message. Each message has a common header as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| Rev | Message Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 5.2. Open Message After a TCP session between a DCP and MCP is established, the Open Message is the first message sent by the MCP to the DCP or the DCP to the MCP hence to establish a CPMP session. The format of Open Message is as follows: Chen, et al. Expires August 21, 2013 [Page 8] Internet-Draft Colouring based IP FPM Framework February 2013 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| Res | Message Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DCP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MCP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hold Time | Keep Alive | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Optional | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ More detail in the future version. 5.3. KeepAlive Message A Keepalive message is sent by a DCP or a MCP in order to keep the CPMP session in active state. The Keepalive message is also used in response to an Open message to acknowledge that an Open message has been received and that the CPMP session characteristics are acceptable. The format of Keepalive message is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| Rev | Message Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ More detail in the future version. 5.4. Configure Message Configure Message is a message that a MCP uses to configure parameters of the measurement instances on DCP and to enable/disable the instances. Chen, et al. Expires August 21, 2013 [Page 9] Internet-Draft Colouring based IP FPM Framework February 2013 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version|R| Rev | Message Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DCP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MCP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Instance ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Configure TLV ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Configure Message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Instance ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Configure TLV More detail in the future version. 5.5. Report Message Report Message is a message that a DCP uses it to report measurement data to MCP. Chen, et al. Expires August 21, 2013 [Page 10] Internet-Draft Colouring based IP FPM Framework February 2013 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| Rev | Message Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DCP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MCP-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Instance TLV ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Report Message 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Instance ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Period Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Count1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Count1(cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Count2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Count2(cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Timestamp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Timestamp(cont.) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure, Instance TLV More detail in the future version. 6. IANA Considerations TBD. Chen, et al. Expires August 21, 2013 [Page 11] Internet-Draft Colouring based IP FPM Framework February 2013 7. Security Considerations TBD. 8. Acknowledgements The authors would like to thank Adrian Farrel for his review, suggestion and comments to this document. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 9.2. Informative References [I-D.tempia-opsawg-p3m] Bonda, A., Capello, A., Cociglio, M., and L. Castaldelli, "A packet based method for passive performance monitoring", draft-tempia-opsawg-p3m-02 (work in progress), July 2012. [IEEE1588] IEEE, "1588-2008 IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems", March 2008. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protocol (OWAMP)", RFC 4656, September 2006. [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, October 2008. [RFC5905] Mills, D., Martin, J., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, June 2010. [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay Measurement for MPLS Networks", RFC 6374, September 2011. Chen, et al. Expires August 21, 2013 [Page 12] Internet-Draft Colouring based IP FPM Framework February 2013 Authors' Addresses Mach(Guoyi) Chen Huawei Email: mach.chen@huawei.com Hongming Liu Huawei Email: liuhongming@huawei.com Yuanbin Yin Huawei Email: yinyuanbin@huawei.com Chen, et al. Expires August 21, 2013 [Page 13]