Routing Area Working Group G. Mirsky Internet-Draft Ericsson Intended status: Informational E. Nordmark Expires: September 22, 2016 Arista Networks C. Pignataro N. Kumar D. Kumar Cisco Systems, Inc. M. Chen Huawei Technologies D. Mozes Mellanox Technologies Ltd. S. Pallagatti March 21, 2016 Operations, Administration and Maintenance (OAM) for Overlay Networks: Gap Analysis draft-ooamdt-rtgwg-oam-gap-analysis-01 Abstract This document provides an overview of the Operations, Administration, and Maintenance (OAM) for overlay networks. The OAM toolset includes set of fault management and performance monitoring capabilities (operating in the data plane) that comply with the Overlay OAM Requirements. Insufficient functional coverage of existing OAM protocols also noted in this document. The protocol definitions for each of the Overlay OAM tools to be defined in separate documents. 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 September 22, 2016. Mirsky, et al. Expires September 22, 2016 [Page 1] Internet-Draft OAM for Overlays: Gap Analysis March 2016 Copyright Notice Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 4 1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 4 1.1.2. Requirements Language . . . . . . . . . . . . . . . . 4 2. Working Group Overview . . . . . . . . . . . . . . . . . . . 5 2.1. BIER . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. NVO3 . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3. SFC . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Overlay OAM Toolset . . . . . . . . . . . . . . . . . . . . . 5 3.1. Overlay OAM Fault Management . . . . . . . . . . . . . . 5 3.1.1. Proactive Continuity Check and Connectivity Verification . . . . . . . . . . . . . . . . . . . . 5 3.1.2. On-demand Continuity Check and Connectivity Verification . . . . . . . . . . . . . . . . . . . . 7 3.1.3. Alarm Indication Signal . . . . . . . . . . . . . . . 8 3.2. Overlay OAM Performance Measurement . . . . . . . . . . . 8 3.2.1. Overlay OAM PM Active . . . . . . . . . . . . . . . . 8 3.2.2. Overlay OAM PM Passive . . . . . . . . . . . . . . . 8 3.3. Telemetry in Overlay OAM . . . . . . . . . . . . . . . . 9 3.4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . 9 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . 9 7.2. Informative References . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 Mirsky, et al. Expires September 22, 2016 [Page 2] Internet-Draft OAM for Overlays: Gap Analysis March 2016 1. Introduction Operations, Administration, and Maintenance (OAM) toolset provides methods for fault management and performance monitoring in each layer of the network, in order to improve their ability to support services with guaranteed and strict Service Level Agreements (SLAs) while reducing operational costs. [RFC7276] provided detailed analysis of OAM protocols. Since its completion several new protocols that define data plane encapsulation were introduced. That presented both need to re-evaluate existing set of OAM tools and opportunity to build it into set of tools that can be used and re-used for different data plane protocols. Overlay OAM Requirements define the set of requirements for OAM in Overlay networks. The OAM solution for Overlay networks, developed by the design team, has two objectives: o The Overlay OAM toolset should be developed based on existing IP and IP/MPLS architecture, technology, and toolsets. o The Overlay OAM operational experience should be similar to that in other, e.g. IP and IP/MPLS, networks. The Overlay OAM toolset may use some or all of the following OAM protocols designed at IETF: o proactive continuity check: * Bidirectional Forwarding Detection (BFD) for point-to-point as defined in [RFC5880], [RFC5882], [RFC5883], [RFC5884], [RFC5885], [RFC6428] and [RFC7726]; * BFD for multipoint network as defined in [I-D.ietf-bfd-multipoint] and [I-D.ietf-bfd-multipoint-active-tail]; * S-BFD as defined in [I-D.ietf-bfd-seamless-base] and [I-D.ietf-bfd-seamless-ip]; o on-demand continuity check and connectivity verification: * MPLS Echo Request/Reply, a.k.a. LSP Ping, as defined in [RFC4379] and its numerous extensions; * LSP Self-ping, as defined in [RFC7746]; Mirsky, et al. Expires September 22, 2016 [Page 3] Internet-Draft OAM for Overlays: Gap Analysis March 2016 * [I-D.kumarzheng-bier-ping] is a good example of generic troubleshooting and defect localization tool that can be extended and suited for more specific requirements of the particular type of an overlay network; o performance measurement: * packet loss and delay measurement in MPLS networks, as defined in [RFC6374] with ability to export measurement results for post-processing [I-D.ietf-mpls-rfc6374-udp-return-path]; * Two-Way Active Measurement Protocol (TWAMP), as defined in [RFC5357], [RFC6038], and [RFC7750]; * use of the Marking Method [I-D.tempia-ippm-p3m] that, if accordingly supported by the overlay layer, can behave as close as technically possible to a passive method to measure performance, e.g. [I-D.mirsky-bier-pmmm-oam]. 1.1. Conventions used in this document 1.1.1. Terminology Term "Overlay OAM" used in this document interchangeably with longer version "set of OAM protocols, methods and tools for Overlay networks". BFD Bidirectional Forwarding Detection FM Fault Management OAM Operations, Administration, and Maintenance PM Performance Measurement SLA Service Level Agreement TWAMP Two-Way Active Measurement Protocol 1.1.2. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Mirsky, et al. Expires September 22, 2016 [Page 4] Internet-Draft OAM for Overlays: Gap Analysis March 2016 2. Working Group Overview 2.1. BIER The BIER working group has some WG documents on OAM which are discussed further in this document. 2.2. NVO3 The NVO3 encapsulations (Geneve [I-D.ietf-nvo3-geneve], GUE [I-D.ietf-nvo3-gue], and GPE [I-D.ietf-nvo3-vxlan-gpe]) all have some notion of a OAM bit or flag. In Geneve this is defined to not apply to intermediate (underlay) routers and that the setting of the bit doesn't affect the ECMP hash. The other proposals do not have as succinct constraints on their OAM bit/flag. There are currently no NVO3 working group OAM protocol specifications. The OAM documents that have been discussed are individual drafts such as [I-D.ashwood-nvo3-oam-requirements], [I-D.nordmark-nvo3-transcending-traceroute], [draft-pang-nvo3-vxlan- path-detection], [I-D.saum-nvo3-pmtud-over-vxlan], and [I-D.singh-nvo3-vxlan-router-alert]. 2.3. SFC TBD 3. Overlay OAM Toolset 3.1. Overlay OAM Fault Management Protocols that enable Fault Management functions of OAM toolset are comprised of protocols that perform proactive and on-demand defect detection and failure localization. 3.1.1. Proactive Continuity Check and Connectivity Verification Bidirectional Forwarding Detection (BFD) [RFC5880] is the protocol of choice for proactive Continuity Check and Connectivity Verification [RFC6428]. 3.1.1.1. Proactive CC/CV in BIER . Bit-Indexed Explicit Replication (BIER) provides the multicast service. For that BFD over multipoint network [I-D.ietf-bfd-multipoint] and [I-D.ietf-bfd-multipoint-active-tail] are the most suitable of BFD family Figure 1 presents IP/UDP format of BFD over BIER in MPLS network. Mirsky, et al. Expires September 22, 2016 [Page 5] Internet-Draft OAM for Overlays: Gap Analysis March 2016 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label Stack Element | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label Stack Element | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BIER-MPLS label | |1| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 1 0 1| Ver | Len | Entropy | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitString (first 32 bits) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ BitString (last 32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |OAM| Reserved | Proto | BFIR-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ IP Header ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Source Port | Destination Port (3784) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ BFD control packet ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: BFD over BIER with IP/UDP format Proto field MUST be set to IPv4 or IPv6 vlalue. Note that IP Destination address in Figure 1 must follow Section 7 [RFC5884], i.e. ?the destination IP address MUST be randomly chosen from the 127/8 range for IPv4 and from the 0:0:0:0:0:FFFF:7F00/104 range for IPv6.? BFD packets in the reverse direction of the BFD session will be transmitted on IP network to the IP address mapped to the BFIR-id and the destination UDP port number set as source UDP port number of the received BFD packet. IP/UDP format presents overhead, particularly in case of IPv6 address family. Thus option to avoid use of extra headers for OAM seems attractive. Figure 2 presents G-ACh format of BFD over BIER in MPLS network. Proto field of the BIER header MUST be set to OAM value. BFD control packet follows the BIER OAM header as defined in [I-D.kumarzheng-bier-ping]. According to the Section 3.1 of [I-D.kumarzheng-bier-ping], Ver is set to 1; BFD control packet over multi-point without or with active tail accordingly identified in Mirsky, et al. Expires September 22, 2016 [Page 6] Internet-Draft OAM for Overlays: Gap Analysis March 2016 Message Type Field. The Proto field ?is used to define if there is any data packet immediately following the OAM payload?. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label Stack Element | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Label Stack Element | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BIER-MPLS label | |1| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 1 0 1| Ver | Len | Entropy | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BitString (first 32 bits) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ BitString (last 32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |OAM| Reserved | Proto | BFIR-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ver | Message Type | Proto | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ BFD control packet ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: BFD over BIER with G-ACh format 3.1.1.2. Proactive CC/CV in NVO3 There is currently no WG document on proactive CC/CV. The individual requirements document [I-D.ashwood-nvo3-oam-requirements] covers this and there is a related proposal for BFD over VXLAN in [I-D.spallagatti-bfd-vxlan]. 3.1.1.3. Proactive CC/CV over SFP 3.1.2. On-demand Continuity Check and Connectivity Verification 3.1.2.1. On-demand CC/CV in BIER [I-D.kumarzheng-bier-ping] defines format of Echo Request/Reply control packet and set of TLVs that can be used to perform failure detection and isolation in BIER domain over MPLS network. Mirsky, et al. Expires September 22, 2016 [Page 7] Internet-Draft OAM for Overlays: Gap Analysis March 2016 3.1.2.2. On-demand CC/CV in NVO3 There is currently no WG document for on-demand CC/CV. Individual documents exist for tracing such as [draft-pang-nvo3- vxlan-path-detection] and [I-D.nordmark-nvo3-transcending-traceroute]. 3.1.2.3. On-demand CC/CV over SFP 3.1.3. Alarm Indication Signal 3.1.3.1. AIS in BIER 3.1.3.2. AIS in NVO3 There is currently no WG document on Alarm Indication Signal. The individual draft [I-D.nordmark-nvo3-transcending-traceroute] suggests reusing ICMP errors for error indications. 3.1.3.3. AIS over SFP 3.2. Overlay OAM Performance Measurement 3.2.1. Overlay OAM PM Active 3.2.1.1. Active PM in BIER 3.2.1.2. Active PM in NVO3 Performance management has been discussed in NVO3 but there is currently no draft in the WG. 3.2.1.3. Active PM over SFP 3.2.2. Overlay OAM PM Passive 3.2.2.1. Passive PM in BIER [I-D.mirsky-bier-pmmm-oam] describes how the Marking Method can be used in BIER domain over MPLS networks. 3.2.2.2. Passive PM in NVO3 Marking has been discussed in NVO3 sessions, but there is no draft in the working group. Mirsky, et al. Expires September 22, 2016 [Page 8] Internet-Draft OAM for Overlays: Gap Analysis March 2016 3.2.2.3. Passive PM over SFP 3.3. Telemetry in Overlay OAM Excessive use of the in-band OAM channel may affect user flow and thus change network behavior. For example, if operator uses passive measurement exporting massive amount of data over the OAM channel may affect network. I think that a management channel should be used in such case. Obviously it may traverse the same nodes and links but may not require the same QoS. We can refer to LMAP Reference Model [RFC7594] with Controller, Measurement Agent and Data Collector. [I-D.lapukhov-dataplane-probe] proposes transport independent generic telemetry probe structure. 3.4. Conclusions 4. IANA Considerations This document does not propose any IANA consideration. This section may be removed. 5. Security Considerations This document list the OAM requirement for BIER-enabled domain and does not raise any security concerns or issues in addition to ones common to networking. 6. Acknowledgement TBD 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 7.2. Informative References Mirsky, et al. Expires September 22, 2016 [Page 9] Internet-Draft OAM for Overlays: Gap Analysis March 2016 [I-D.ashwood-nvo3-oam-requirements] Chen, H., Ashwood-Smith, P., Xia, L., Iyengar, R., Tsou, T., Sajassi, A., Boucadair, M., Jacquenet, C., Daikoku, M., Ghanwani, A., and R. Krishnan, "NVO3 Operations, Administration, and Maintenance Requirements", draft- ashwood-nvo3-oam-requirements-04 (work in progress), October 2015. [I-D.ietf-bfd-multipoint] Katz, D., Ward, D., and J. Networks, "BFD for Multipoint Networks", draft-ietf-bfd-multipoint-07 (work in progress), August 2015. [I-D.ietf-bfd-multipoint-active-tail] Katz, D., Ward, D., and J. Networks, "BFD Multipoint Active Tails.", draft-ietf-bfd-multipoint-active-tail-01 (work in progress), November 2015. [I-D.ietf-bfd-seamless-base] Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J. Networks, "Seamless Bidirectional Forwarding Detection (S-BFD)", draft-ietf-bfd-seamless-base-08 (work in progress), February 2016. [I-D.ietf-bfd-seamless-ip] Akiya, N., Pignataro, C., and D. Ward, "Seamless Bidirectional Forwarding Detection (S-BFD) for IPv4, IPv6 and MPLS", draft-ietf-bfd-seamless-ip-03 (work in progress), February 2016. [I-D.ietf-mpls-rfc6374-udp-return-path] Bryant, S., Sivabalan, S., and S. Soni, "RFC6374 UDP Return Path", draft-ietf-mpls-rfc6374-udp-return-path-04 (work in progress), August 2015. [I-D.ietf-nvo3-geneve] Gross, J. and I. Ganga, "Geneve: Generic Network Virtualization Encapsulation", draft-ietf-nvo3-geneve-01 (work in progress), January 2016. [I-D.ietf-nvo3-gue] Herbert, T., Yong, L., and O. Zia, "Generic UDP Encapsulation", draft-ietf-nvo3-gue-02 (work in progress), December 2015. Mirsky, et al. Expires September 22, 2016 [Page 10] Internet-Draft OAM for Overlays: Gap Analysis March 2016 [I-D.ietf-nvo3-vxlan-gpe] Quinn, P., Manur, R., Kreeger, L., Lewis, D., Maino, F., Smith, M., Agarwal, P., Yong, L., Xu, X., Elzur, U., Garg, P., and D. Melman, "Generic Protocol Extension for VXLAN", draft-ietf-nvo3-vxlan-gpe-01 (work in progress), November 2015. [I-D.kumarzheng-bier-ping] Kumar, N., Pignataro, C., Akiya, N., Zheng, L., Chen, M., and G. Mirsky, "BIER Ping and Trace", draft-kumarzheng- bier-ping-02 (work in progress), December 2015. [I-D.lapukhov-dataplane-probe] Lapukhov, P., "Data-plane probe for in-band telemetry collection", draft-lapukhov-dataplane-probe-00 (work in progress), March 2016. [I-D.mirsky-bier-pmmm-oam] Mirsky, G., Zheng, L., Chen, M., and G. Fioccola, "Performance Measurement (PM) with Marking Method in Bit Index Explicit Replication (BIER) Layer", draft-mirsky- bier-pmmm-oam-01 (work in progress), March 2016. [I-D.nordmark-nvo3-transcending-traceroute] Nordmark, E., Appanna, C., and A. Lo, "Layer-Transcending Traceroute for Overlay Networks like VXLAN", draft- nordmark-nvo3-transcending-traceroute-02 (work in progress), March 2016. [I-D.saum-nvo3-pmtud-over-vxlan] Dikshit, S. and N. A, "PMTUD Over Vxlan", draft-saum-nvo3- pmtud-over-vxlan-02 (work in progress), December 2015. [I-D.singh-nvo3-vxlan-router-alert] Singh, K., Jain, P., Rio, D., Henderickx, W., Shekhar, R., and R. Rahman, "VxLAN Router Alert Option", draft-singh- nvo3-vxlan-router-alert-02 (work in progress), September 2015. [I-D.spallagatti-bfd-vxlan] Networks, J., Basil, B., Paragiri, S., Govindan, V., Mudigonda, M., and G. Mirsky, "BFD for VXLAN", draft- spallagatti-bfd-vxlan-02 (work in progress), October 2015. Mirsky, et al. Expires September 22, 2016 [Page 11] Internet-Draft OAM for Overlays: Gap Analysis March 2016 [I-D.tempia-ippm-p3m] Capello, A., Cociglio, M., Fioccola, G., Castaldelli, L., and A. Bonda, "A packet based method for passive performance monitoring", draft-tempia-ippm-p3m-03 (work in progress), March 2016. [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", RFC 4379, DOI 10.17487/RFC4379, February 2006, . [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, DOI 10.17487/RFC5357, October 2008, . [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, . [RFC5882] Katz, D. and D. Ward, "Generic Application of Bidirectional Forwarding Detection (BFD)", RFC 5882, DOI 10.17487/RFC5882, June 2010, . [RFC5883] Katz, D. and D. Ward, "Bidirectional Forwarding Detection (BFD) for Multihop Paths", RFC 5883, DOI 10.17487/RFC5883, June 2010, . [RFC5884] Aggarwal, R., Kompella, K., Nadeau, T., and G. Swallow, "Bidirectional Forwarding Detection (BFD) for MPLS Label Switched Paths (LSPs)", RFC 5884, DOI 10.17487/RFC5884, June 2010, . [RFC5885] Nadeau, T., Ed. and C. Pignataro, Ed., "Bidirectional Forwarding Detection (BFD) for the Pseudowire Virtual Circuit Connectivity Verification (VCCV)", RFC 5885, DOI 10.17487/RFC5885, June 2010, . [RFC6038] Morton, A. and L. Ciavattone, "Two-Way Active Measurement Protocol (TWAMP) Reflect Octets and Symmetrical Size Features", RFC 6038, DOI 10.17487/RFC6038, October 2010, . Mirsky, et al. Expires September 22, 2016 [Page 12] Internet-Draft OAM for Overlays: Gap Analysis March 2016 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay Measurement for MPLS Networks", RFC 6374, DOI 10.17487/RFC6374, September 2011, . [RFC6428] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed., "Proactive Connectivity Verification, Continuity Check, and Remote Defect Indication for the MPLS Transport Profile", RFC 6428, DOI 10.17487/RFC6428, November 2011, . [RFC7276] Mizrahi, T., Sprecher, N., Bellagamba, E., and Y. Weingarten, "An Overview of Operations, Administration, and Maintenance (OAM) Tools", RFC 7276, DOI 10.17487/RFC7276, June 2014, . [RFC7594] Eardley, P., Morton, A., Bagnulo, M., Burbridge, T., Aitken, P., and A. Akhter, "A Framework for Large-Scale Measurement of Broadband Performance (LMAP)", RFC 7594, DOI 10.17487/RFC7594, September 2015, . [RFC7726] Govindan, V., Rajaraman, K., Mirsky, G., Akiya, N., and S. Aldrin, "Clarifying Procedures for Establishing BFD Sessions for MPLS Label Switched Paths (LSPs)", RFC 7726, DOI 10.17487/RFC7726, January 2016, . [RFC7746] Bonica, R., Minei, I., Conn, M., Pacella, D., and L. Tomotaki, "Label Switched Path (LSP) Self-Ping", RFC 7746, DOI 10.17487/RFC7746, January 2016, . [RFC7750] Hedin, J., Mirsky, G., and S. Baillargeon, "Differentiated Service Code Point and Explicit Congestion Notification Monitoring in the Two-Way Active Measurement Protocol (TWAMP)", RFC 7750, DOI 10.17487/RFC7750, February 2016, . Authors' Addresses Greg Mirsky Ericsson Email: gregory.mirsky@ericsson.com Mirsky, et al. Expires September 22, 2016 [Page 13] Internet-Draft OAM for Overlays: Gap Analysis March 2016 Erik Nordmark Arista Networks Email: nordmark@acm.org Carlos Pignataro Cisco Systems, Inc. Email: cpignata@cisco.com Nagendra Kumar Cisco Systems, Inc. Email: naikumar@cisco.com Deepak Kumar Cisco Systems, Inc. Email: dekumar@cisco.com Mach Chen Huawei Technologies Email: mach.chen@huawei.com David Mozes Mellanox Technologies Ltd. Email: davidm@mellanox.com Santosh Pallagatti Email: santosh.pallagatti@gmail.com Mirsky, et al. Expires September 22, 2016 [Page 14]