TRILL Working group Tissa Senevirathne Internet Draft Norman Finn Intended status: Standard Track Samer Salam Deepak Kumar CISCO Donald Eastlake Sam Aldrin Yizhou Li Huawei January 12, 2014 Expires: July 2014 TRILL Fault Management draft-ietf-trill-oam-fm-01.txt 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), 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 The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on July 13, 2014. Copyright Notice Copyright (c) 2014 IETF Trust and the persons identified as the document authors. All rights reserved. Senevirathne Expires July 12, 2014 [Page 1] Internet-Draft TRILL Fault Management January 2014 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. Abstract This document specifies TRILL OAM Fault Management. Methods in this document follow the IEEE 802.1 CFM framework and reuse OAM tools where possible. Additional messages and TLVs are defined for TRILL specific applications or where a different set of information is required other than IEEE 802.1 CFM. Table of Contents 1. Introduction ............................................... 4 2. Conventions used in this document .......................... 4 3. General Format of TRILL OAM frames ......................... 5 3.1. Identification of TRILL OAM frames ....................... 7 3.2. Use of TRILL OAM Flag .................................... 7 3.2.1. Handling of TRILL frames with the "A" Flag ............. 8 3.3. OAM Capability Announcement .............................. 8 4. TRILL OAM Layering vs. IEEE Layering ....................... 9 4.1. Processing at ISS Layer ................................. 11 4.1.1. Receive Processing .................................... 11 4.1.2. Transmit Processing ................................... 11 4.2. End Station VLAN and Priority Processing ................ 11 4.2.1. Receive Processing .................................... 11 4.2.2. Transmit Procession ................................... 11 4.3. TRILL Encapsulation and De-capsulation Layer ............ 11 4.3.1. Receive Processing for Unicast packets ................ 11 4.3.2. Transmit Processing for unicast packets ............... 12 4.3.3. Receive Processing for Multicast packets .............. 13 4.3.4. Transmit Processing of Multicast packets .............. 14 4.4. TRILL OAM Layer Processing .............................. 15 5. Maintenance Associations (MA) in TRILL .................... 16 6. MEP Addressing ............................................ 17 6.1. Use of MIP in TRILL ..................................... 20 7. Continuity Check Message (CCM) ............................ 22 8. TRILL OAM Message Channel ................................. 24 8.1. TRILL OAM Message header ................................ 24 Senevirathne Expires July 13, 2014 [Page 2] Internet-Draft TRILL Fault Management January 2014 8.2. TRILL OAM Opcodes ....................................... 25 8.3. Format of TRILL OAM TLV ................................. 25 8.4. TRILL OAM TLVs .......................................... 26 8.4.1. Common TLVs between 802.1ag and TRILL ................. 26 8.4.2. TRILL OAM Specific TLVs ............................... 27 8.4.3. TRILL OAM Application Identifier TLV .................. 27 8.4.4. Out Of Band Reply Address TLV ......................... 28 8.4.5. Diagnostics Label TLV ................................. 29 8.4.6. Original Data Payload TLV ............................. 31 8.4.7. RBridge scope TLV ..................................... 31 8.4.8. Previous RBridge nickname TLV ......................... 32 8.4.9. Next Hop RBridge List TLV ............................. 33 8.4.10. Multicast Receiver Port count TLV .................... 33 8.4.11. Flow Identifier (flow-id) TLV ........................ 34 8.4.12. Reflector Entropy TLV ................................ 35 9. Loopback Message .......................................... 36 9.1. Loopback OAM Message format ............................. 36 9.2. Theory of Operation ..................................... 36 9.2.1. Actions by Originator RBridge ......................... 36 9.2.2. Intermediate RBridge .................................. 37 9.2.3. Destination RBridge ................................... 37 10. Path Trace Message ....................................... 38 10.1. Theory of Operation .................................... 39 10.1.1. Action by Originator RBridge ......................... 39 10.1.2. Intermediate RBridge ................................. 39 10.1.3. Destination RBridge .................................. 41 11. Multi-Destination Tree Verification (MTV) Message ........ 41 11.1. Multi-Destination Tree Verification (MTV) OAM Message Format ....................................................... 41 11.2. Theory of Operation .................................... 42 11.2.1. Actions by Originator RBridge ........................ 42 11.2.2. Receiving RBridge .................................... 43 11.2.3. In scope RBridges .................................... 43 12. Application of Continuity Check Message (CCM) in TRILL ... 44 12.1. CCM Error Notification ................................. 45 12.2. Theory of Operation .................................... 46 12.2.1. Actions by Originator RBridge ........................ 46 12.2.2. Intermediate RBridge ................................. 47 12.2.3. Destination RBridge .................................. 47 13. Fragmented Reply ......................................... 47 14. Security Considerations .................................. 48 15. IEEE Allocation Considerations ........................... 48 16. IANA Considerations ...................................... 48 17. References ............................................... 48 17.1. Normative References ................................... 48 17.2. Informative References ................................. 49 18. Acknowledgments .......................................... 50 Senevirathne Expires July 13, 2014 [Page 3] Internet-Draft TRILL Fault Management January 2014 Appendix A. Backwards Compatibility .......................... 51 Appendix B. Base Mode for TRILL OAM .......................... 54 Appendix C. Unicast MAC Request .............................. 56 1. Introduction The general structure of TRILL OAM messages is presented in [TRLOAMFRM]. According to [TRLOAMFRM], TRILL OAM messages consist of five parts: link header, TRILL header, flow entropy, OAM message channel, and link trailer. The OAM message channel allows defining various control information and carrying OAM related data between TRILL switches, also known as RBridges or Routing Bridges. A common OAM message channel representation can be shared between different technologies. This consistency between different OAM technologies promotes nested fault monitoring and isolation between technologies that share the same OAM framework. This document uses the message format defined in IEEE 802.1ag Connectivity Fault Management (CFM) [8021Q] as the basis for the TRILL OAM message channel. The ITU-T Y.1731 [Y1731] standard utilizes the same messaging format as [8021Q] and OAM messages where applicable. This document takes a similar stance and reuse [8021Q] in TRILL OAM. It is assumed readers are familiar with [8021Q] and [Y1731]. Readers who are not familiar with these documents are encouraged to review them. 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]. Acronyms used in the document include the following: MP - Maintenance Point [TRLOAMFRM] MEP - Maintenance End Point [TRLOAMFRM] [8021Q] MIP - Maintenance Intermediate Point [TRLOAMFRM] [8021Q] MA - Maintenance Association [8021Q] [TRLOAMFRM] Senevirathne Expires July 13, 2014 [Page 4] Internet-Draft TRILL Fault Management January 2014 MD - Maintenance Domain [8021Q] CCM - Continuity Check Message [8021Q] LBM - Loop Back Message [8021Q] PTM - Path Trace Message MTV - Multi-destination Tree Verification Message OAM - Operations, Administration, and Maintenance [RFC6291] TRILL - Transparent Interconnection of Lots of Links [RFC6325] FGL - Fine Grained Label [RFCfgl] ECMP - Equal Cost Multipath ISS - Internal Sub Layer Service [8021Q] 3. General Format of TRILL OAM frames The TRILL forwarding paradigm allows an implementation to select a path from a set of equal cost paths to forward a unicast TRILL Data packet. For multi-destination TRILL Data packets, a distribution tree is chosen by the TRILL switch that ingresses or creates the packet. Selection of the path of choice is implementation dependent at each hop for unicast and at the ingress for multi-destination. However, it is a common practice to utilize Layer 2 through Layer 4 information in the frame payload for path selection. For accurate monitoring and/or diagnostics, OAM Messages are required to follow the same path as corresponding data packets. [TRLOAMFRM] presents the high-level format of the OAM messages. The details of the TRILL OAM frame format are defined in this document. Senevirathne Expires July 13, 2014 [Page 5] Internet-Draft TRILL Fault Management January 2014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Link Header . (variable) | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + TRILL Header + 8 or more bytes | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Flow Entropy . 96 bytes . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OAM Ether Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . OAM Message Channel . Variable . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link Trailer | Variable +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 Format of TRILL OAM Messages Link Header: Media-dependent header. For Ethernet, this includes Destination MAC, Source MAC, VLAN (optional) and EtherType fields. TRILL Header: Fixed size of 8 bytes when the Extended Header is not included [RFC6325] Flow Entropy: This is a 96-byte fixed size field. The least significant bits of the field MUST be padded with zeros, up to 96 bytes, when the flow entropy is less than 96 bytes. Flow entropy enables emulation of the forwarding behavior of the desired data packets. The Flow Entropy field starts with the Inner.MacDA. The offset of the Inner.MacDA depends on whether extensions are included or not as specified in [TRILLEXT] and [RFC6325]. OAM Ether Type: OAM Ether Type is 16-bit EtherType that identifies the OAM Message channel that follows. This document Senevirathne Expires July 13, 2014 [Page 6] Internet-Draft TRILL Fault Management January 2014 specifies using the EtherType allocated for 802.1ag for this purpose. Identifying the OAM Message Channel with a dedicated EtherType allows the easy identification of the beginning of the OAM message channel across multiple standards. OAM Message Channel: This is a variable size section that carries OAM related information. The message format defined in [8021Q] will be reused for TRILL OAM. Link Trailer: Media-dependent trailer. For Ethernet, this is the FCS (Frame Check Sequence). 3.1. Identification of TRILL OAM frames TRILL, as originally specified in [RFC6325], did not have a specific flag or a method to identify OAM frames. This document updates [RFC6325] to include specific methods to identify TRILL OAM frames. Section 3.2. below explains the details of the method. 3.2. Use of TRILL OAM Flag The TRILL Header, as defined in [RFC6325], has two reserved bits. This document specifies use of the reserved bit next to Version field in the TRILL header as the Alert flag. Alert flag will be denoted by "A". Implementations that comply with this document MUST utilize "A" flag and CFM etherType to identify TRILL OAM frames. The "A" flag MUST NOT BE utilized for forwarding decisions such as the selection of which ECMP path or multi-destination tree to use. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | V |A|R|M|Op-Length| Hop Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Egress RBridge Nickname | Ingress RBridge Nickname | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options... +-+-+-+-+-+-+-+-+-+-+-+- Figure 2 TRILL Header with the "A" Flag A (1 bit) - Indicates this is a possible OAM frame and is subject to specific handling as specified in this document. Senevirathne Expires July 13, 2014 [Page 7] Internet-Draft TRILL Fault Management January 2014 All other fields carry the same meaning as defined in RFC6325. 3.2.1. Handling of TRILL frames with the "A" Flag Value "1" in the A flag indicates TRILL frames that may qualify as OAM frames. Implementations are further REQUIRED to validate such frames by comparing the value at the OAM Ether Type (Figure 1) location with the CFM EtherType "0x8902" [8021Q]. If the value matches, such frames are identified as TRILL OAM frames and SHOULD be processed as discussed in Section 4. Frames with the "A" flag set that do not contain CFM EtherType are not considered as OAM frames. Such frames MUST be discarded. 3.3. OAM Capability Announcement Any given TRILL RBridge can be (1) OAM incapable or (2) OAM capable with new extensions or (3) OAM capable with backwards- compatible method. The OAM request originator, prior to origination of the request is required to identify the OAM capability of the target and generate the appropriate OAM message. Capability flags defined in TRILL version sub-TLV (TRILL-VER) [rfc6326bis] will be utilized for announcing OAM capabilities. The following OAM related Flags are defined: O - OAM Capable B - Backwards Compatible. A capability announcement, with O Flag set to 1 and B flag set to 1, indicates that the implementation is OAM capable but utilize backwards compatible method defined in Appendix A. A capability announcement, with O Flag set to 1 and B flag set to 0, indicates that the implementation is OAM capable and utilizes the method specified in section 3.2. When O Flag is set to 0, the announcing implementation is considered not capable of OAM and in this case the B flag is ignored. Senevirathne Expires July 13, 2014 [Page 8] Internet-Draft TRILL Fault Management January 2014 +-+-+-+-+-+-+-+-+ | Type | (1 byte) +-+-+-+-+-+-+-+-+ | Length | (1 byte) +-+-+-+-+-+-+-+-+ | Max-version | (1 byte) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+ |A|O|B|Other Capabilities and Header Flags| (4 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+ 0 1 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 0 1 Figure 3 TRILL-VER sub-TLV [rfc6326bis] with O and B flags NOTE: Bit position of O and B flags in the TRILL-VER sub-TLV are presented above as an example. Actual positions of the flags will be determined by TRILL WG and IANA and future revision of this document will be updated to include the allocations. 4. TRILL OAM Layering vs. IEEE Layering This section presents the placement of the TRILL OAM shim within the IEEE 802.1 layers. The processing of both the Transmit and Receive directions is explained. Senevirathne Expires July 13, 2014 [Page 9] Internet-Draft TRILL Fault Management January 2014 +-+-+-+-+-+-+-+-+-+-+ | RBridge Layer | | Processing | +-+-+-+-+-+-+-+-+-+-+ | | +-+-+-+-+-+-+ | TRILL OAM | UP MEP | Layer | MIP +-+-+-+-+-+-+ Down MEP | | +-+-+-+-+-+-+ (3)--------> | TRILL | | Encap/Decap +-+-+-+-+-+-+ | +-+-+-+-+-+-+ (2)--------> |End station| | VLAN & priority Processing +-+-+-+-+-+-+ | +-+-+-+-+-+-+ (1)--------> |ISS | |Processing | +-+-+-+-+-+-+ | | | Figure 4 Placement of TRILL MP within IEEE 802.1 [RFC6325] Section 4.6 as updated by [RFCclcorrect] provides a detailed explanation of frame processing. Please refer to [RFC6325] for processing scenarios not covered herein. Sections 4.1 and 4.2 below apply to links using a broadcast LAN technology such as Ethernet. On links using an inherently point-to-point technology, such as PPP [RFC6361], there is no Outer.MacDA, Outer.MacSA, our Outer.VLAN because these are part of the link header for Ethernet. Point-to-point links typically have link headers Senevirathne Expires July 13, 2014 [Page 10] Internet-Draft TRILL Fault Management January 2014 without these fields. These fields are primarily significant for native frames from and/or to end stations. 4.1. Processing at ISS Layer 4.1.1. Receive Processing The ISS Layer receives an indication from the port. It extracts DA, SA and marks the remainder of the payload as M1. ISS Layer passes on (DA,SA,M1) as an indication to the higher layer. For TRILL Ethernet frames, this is Outer.MacDA and Outer.MacSA. M1 is the remainder of the packet. 4.1.2. Transmit Processing The ISS layer receives an indication from the higher layer that contains (DA, SA, M1). It constructs an Ethernet frame and passes down to the port. 4.2. End Station VLAN and Priority Processing 4.2.1. Receive Processing Receives (DA, SA, M1) indication from ISS Layer. Extracts the VLAN ID an priority from the M1 part of the received indication (or derive them from the port defaults or the like) and constructs (DA, SA, VLAN, PRI, M2). VLAN+PRI+M2 map to M1 in the received indication. Pass (DA, SA, VLAN, PRI, M2) to the TRILL encap/decap procession layer. 4.2.2. Transmit Procession Receive (DA, SA, VLAN, PRI, M2) indication from TRILL encap/decap processing layer. Merge VLAN, PRI, M2 to form M1. Pass down (DA, SA, M1) to the ISS processing Layer. 4.3. TRILL Encapsulation and De-capsulation Layer 4.3.1. Receive Processing for Unicast packets Receive indication (DA, SA, VLAN, PRI, M2) from End Station VLAN and Priority Processing Layer. o If DA matches port Local DA and Frame is of TRILL EtherType Senevirathne Expires July 13, 2014 [Page 11] Internet-Draft TRILL Fault Management January 2014 . Discard DA, SA, VLAN, PRI. From M2, derive (TRILL-HDR, iDA, iSA, i-VL, M3) . If TRILL nickname is Local and TRILL-OAM Flag is set Pass on to OAM processing . Else pass on (TRILL-HDR, iDA, iSA, i-VL, M3) to RBridge Layer o If DA matches port Local DA and EtherType is RBridge-Channel [Channel] . Process as a possible unicast native RBridge Channel packet o If DA matches port Local DA and EtherType is neither TRILL nor RBridge-Channel . Discard packet o If DA does not match and port is Appointed Forwarder for VLAN and EtherType is not TRILL or RBridge-Channel . Insert TRILL-Hdr and send (TRILL-HDR, iDA, iSA,i-VL, M3) indication to RBridge Layer <- This is the ingress function 4.3.2. Transmit Processing for unicast packets o Receive indication (TRILL-HDR, iDA, iSA, iVL, M3) from RBridge Layer o If egress TRILL nickname is local o If port is Appointed Forwarder for iVL and the port is not configured as a trunk or p2p port and (TRILL Alert Flag set and OAM EtherType present) then . Strip TRILL-HDR and construct (DA, SA, VLAN, M2) o Else . Discard packet o If egress TRILL nickname is not local Senevirathne Expires July 13, 2014 [Page 12] Internet-Draft TRILL Fault Management January 2014 o Insert Outer.MacDA, Outer.MacSA, Outer.VLAN, TRILL EtherType and construct (DA, SA, VLAN, M2). Where M2 is (TRILL-HDR, iDA, iSA, iVL, M) o Forward (DA, SA, V, M2) to the VLAN End Station processing Layer. 4.3.3. Receive Processing for Multicast packets o Receive (DA, SA, V, M2) from VLAN aware end station processing layer o If the DA is All-RBridges and the EtherType is TRILL o Strip DA, SA and V. From M2, extract (TRILL-HDR, iDA, iSA, iVL and M3). o If TRILL OAM Flag is set and OAM EtherType is present at the end of Flow entropy . Perform OAM Processing o Else extract the TRILL header, inner MAC addresses and inner VLAN and pass indication (TRILL-HDR, iDA, iSA, iVL and M3) to TRILL RBridge Layer o If the DA is All-IS-IS-RBridges and the Ethertype is L2-IS- IS then pass frame up to TRILL IS-IS processing o If the DA is All-RBridges or All-IS-IS-RBridges but Ethertype is not TRILL or L2-IS-IS respectively o Discard the packet o If the EtherType is TRILL but the multicast DA is not All- RBridge or if the EtherType is L2-IS-IS but the multicast Da is not All-IS-IS-RBridges o Discard the packet o If DA is All-Edge-RBridges and EtherType is RBridge-Channel [Channel] o Process as a possible multicast native RBridge Channel packet Senevirathne Expires July 13, 2014 [Page 13] Internet-Draft TRILL Fault Management January 2014 o If the DA is in the initial bridging/link protocols block (01-80-C2-00-00-00 to 01-80-C2-00-00-0F) or is in the TRILL block and not assigned for Outer.MacDA use (01-80-C2-00-00- 42 to 01-80-C2-00-00-4F) then o The frame is not propagated through an RBridge although some special processing may be done at the port as specified in [RFC6325] and the frame may be dispatched to Layer 2 processing at the port if certain protocols are supported by that port (examples: Link Aggregation Protocol, Link Layer Discovery Protocol). o If the DA is some other multicast value o Insert TRILL-HDR and construct (TRILL-HDR, iDA, iSA, IVL, M3) o Pass the (TRILL-HDR, iDA, iSA, IVL, M3) to RBridge Layer 4.3.4. Transmit Processing of Multicast packets The following ignores the case of transmitting TRILL IS-IS packets. o Receive indication (TRILL-HDR, iDA, iSA, iVL, M3) from RBridge layer. o If TRILL-HDR multicast flag set and TRILL-HDR Alert flag set and OAM EtherType present then: o (DA, SA, V, M2) by inserting TRILL Outer.MacDA of All- RBridges, Outer.MacSA, Outer.VL and TRILL EtherType. M2 here is (Ethertype TRILL, TRILL-HDR, iDA, iSA, iVL, M) NOTE: Second copy of native format is not made. o Else If TRILL-HDR multicast flag set and Alert flag not set o If the port is appointed Forwarder for iVL and the port is not configured as a trunk port or a p2p port, Strip TRILL-HDR, iSA, iDA, iVL and construct (DA, SA, V, M2) for native format. o Make a second copy (DA, SA, V, M2) by inserting TRILL Outer.MacDA, Outer.MacSA, Outer.VL and TRILL EtherType. M2 here is (EtherType TRILL, TRILL-HDR, iDA, iSA, iVL, M) Senevirathne Expires July 13, 2014 [Page 14] Internet-Draft TRILL Fault Management January 2014 o Pass the indication (DA, SA, V, M2) to End Station VLAN processing layer. 4.4. TRILL OAM Layer Processing TRILL OAM Processing Layer is located between the TRILL Encapsulation / De-capsulation layer and RBridge Layer. It performs 1. Identification of OAM frames that need local processing and 2. performs OAM processing or redirect to the CPU for OAM processing. o Receive indication (TRILL-HDR, iDA, iSA, iVL, M3) from RBridge layer. o If the TRILL Multicast Flag is set and TRILL Alert Flag is set and TRILL OAM EtherType is present then o If MEP or MIP is configured on the Inner.VLAN of the packet then . discard packets that have MD-LEVEL Less than that of the MEP or packets that do not have MD-LEVEL present (e.g., due to packet truncation). . If MD-LEVEL matches MD-LEVEL of the MEP then . Re-direct to OAM Processing (Do not forward further) . If MD-LEVEL matches MD-LEVEL of MIP then . Make a Copy for OAM processing and continue o Else if TRILL Alert Flag is set and TRILL OAM EtherType is present then o If MEP or MIP is configured on the Inner.VLAN of the packet then . discard packets that have MD-LEVEL not present or MD-LEVEL is Less than that of the MEP. . If MD-LEVEL matches MD-LEVEL of the MEP then . Re-direct to OAM Processing (Do not forward further) . If MD-LEVEL matches MD-LEVEL of MIP then . Make a Copy for OAM processing and continue o Else // Non OAM l Packet o Continue o Pass the indication (DA, SA, V, M2) to End Station VLAN processing layer. Senevirathne Expires July 13, 2014 [Page 15] Internet-Draft TRILL Fault Management January 2014 NOTE: In the Received path, processing above compares against Down MEP and MIP Half functions. In the transmit processing it compares against Up MEP and MIP Half functions. Appointed Forwarder is a Functionality that TRILL Encap/De-Cap layer performs. The TRILL Encap/De-cap Layer is responsible for prevention of leaking of OAM packets as native frames. 5. Maintenance Associations (MA) in TRILL [8021Q] defines a maintenance association as a logical relationship between a group of nodes. Each Maintenance Association (MA) is identified with a unique MAID of 48 bytes [8021Q]. CCM and other related OAM functions operate within the scope of an MA. The definition of MA is technology independent. Similarly it is encoded within the OAM message, not in the technology dependent portion of the packet. Hence the MAID as defined in [8021Q] can be utilized for TRILL OAM, without modifications. This also allows us to utilize CCM and LBM messages defined in [8021Q], as is. In TRILL, an MA may contain two or more RBridges (MEPs). For unicast, it is likely that the MA contains exactly two MEPs that are the two end-points of the flow. For multicast, the MA may contain two or more MEPs. For TRILL, in addition to all of the standard 802.1ag MIB definitions, each MEP's MIB contains one or more flow entropy definitions corresponding to the set of flows that the MEP monitors. [8021Q] MIB is augmented to add the TRILL specific information. Figure 5, below depicts the augmentation of the CFM MIB to add the TRILL specific Flow Entropy. Senevirathne Expires July 13, 2014 [Page 16] Internet-Draft TRILL Fault Management January 2014 MA--- | --- MEP | . - Remote MEP List . | --- MEP-A | --- MEP-B . | . - Flow Entropy List { Augments IEEE8021-CFM-MIB} | --- (Flow Entropy-1) | --- (Flow-entropy-2) | . --- (Flow Entropy n) | Other MIB entries Figure 5 Correlation of TRILL augmented MIB 6. MEP Addressing In IEEE 802.1ag [8021Q], OAM messages address the target MEP by utilizing a unique MAC address. In TRILL a MEP is addressed by combination of the egress RBridge nickname and the Inner VLAN/FGL. At the MEP, OAM packets go through a hierarchy of op-code de- multiplexers. The op-code de-multiplexers channel the incoming OAM packets to the appropriate message processor (e.g. LBM) The reader may refer to Figure 6 below for a visual depiction of these different de-multiplexers. 1. Identify the packets that need OAM processing at the Local RBridge as specified in Section 4. Senevirathne Expires July 13, 2014 [Page 17] Internet-Draft TRILL Fault Management January 2014 a. Identify the MEP that is associated with the Inner.VLAN. 2. The MEP first validates the MD-LEVEL and then a. Redirect to MD-LEVEL De-multiplexer 3. MD-LEVEL de-multiplexer compares the MD-Level of the packet against the MD level of the local MEPs of a given MD-Level on the port (Note: there can be more than one MEP at the same MD- Level but belonging to different MAs) a. If the packet MD-LEVEL is equal to the configured MD- LEVEL of the MEP, then pass to the Opcode de-multiplexer b. If the packet MD-LEVEL is less than the configured MD- LEVEL of the MEP, discard the packet c. If the packer MD-LEVEL is greater than the configured MD-LEVEL of the MEP, then pass on to the next higher MD- LEVEL de-multiplexer, if available. Otherwise, if no such higher MD-LEVEL de-multiplexer exists, then forward the packet as normal data. 4. Opcode De-multiplexer compares the opcode in the packet with supported opcodes a. If Op-code is CCM, LBM, LBR, PTM, PTR, MTVM, MTVR, then pass on to the correct Processor b. If Op-code is Unknown, then discard. Senevirathne Expires July 13, 2014 [Page 18] Internet-Draft TRILL Fault Management January 2014 | .CCM LBM PTM MTV | | | | +-+-+-+-+-+-+-+-+-+-+-+-+ | OP Code DE-Mux |--- Unknown +-+-+-+-+-+-+-+-+-+-+-+-+ ^ ^ ^ MD==Li | | | +-+-+ +-+-+ +-+-+ | L |-->|L2 |-.- |Ln |---- > +-+-+ +-+-+ +-+-+ | | ^ | | | MD
  • | T |----------------- >| M |--- > + TRILL OAM ---- + pass through OAM ---- Figure 6 OAM De-Multiplexers at MEP for active SAP T : Denotes Tap, that identifies OAM frames that need local processing. These are the packets with OAM flag set AND OAM Ether type is present after the flow entropy of the packet M : Is the post processing merge, merges data and OAM messages that are passed through. Additionally, the Merge component ensures, as explained earlier, that OAM packets are not forwarded out as native frames. L : Denotes MD-Level processing. Packets with MD-Level less than the Level will be dropped. Packets with equal MD-Level are passed on to the opcode de-multiplexer. Others are passed on to the next level MD processors or eventually to the merge point (M). NOTE: LBM, MTV and PT are not subject to MA de-multiplexers. These packets do not have an MA encoded in the packet. Adequate response can be generated to these packets, without loss of functionality, by any of the MEPs present on that interface or an entity within the RBridge. Senevirathne Expires July 13, 2014 [Page 19] Internet-Draft TRILL Fault Management January 2014 6.1. Use of MIP in TRILL Maintenance Intermediate Points (MIP) are mainly used for fault isolation. Link Trace Messages in [8021Q] utilize a well-known multicast MAC address and MIPs generate responses to Link Trace messages. Response to Link Trace messages or lack thereof can be used for fault isolation in TRILL. As explained in section 10. , a hop-count expiry approach will be utilized for fault isolation and path tracing. The approach is very similar to the well-known IP trace-route approach. Hence, explicit addressing of MIPs is not required for the purpose of fault isolation. Any given RBridge can have multiple MIPs located within an interface. As such, a mechanism is required to identify which MIP should respond to an incoming OAM message. Similar approach as presented above for MEPs can be used for MIP processing. It is important to note that "M", the merge block of a MIP, does not prevent OAM packets leaking out as native frames. On edge interfaces, MEPs MUST be configured to prevent the leaking of TRILL OAM packets out of the TRILL Campus. Senevirathne Expires July 13, 2014 [Page 20] Internet-Draft TRILL Fault Management January 2014 PT MTV | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OP Code De-Mux |-> Unknown +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ^ ^ ^ MD==Li | | | +-+-+ +-+-+ +-+-+ | L |- >|L2 |-.- |Ln |------+ +-+-+ +-+-+ +-+-+ | ^ | | | Drop | | MD not --- |TRILL OAM | Present | | | v TRILL Data ---- TRILL Data ----- ------- >| T |------------------ >| M |---- > + TRILL OAM ---- ---- Figure 7 OAM De-Multiplexers at MIP for active SAP T: TAP processing for MIP. All packets with OAM flag set are captured. L : MD Level Processing, Packet with matching MD Level are "copied" to the Opcode de-multiplexer and original packet is passed on to the next MD level processor. Other packets are simply passed on to the next MD level processor, without copying to the OP code de-multiplexer. M : Merge processor, merge OAM packets to be forwarded along with the data flow. Packets that carry Path Trace Message (PTM) or Multi-destination Tree Verification (MTV) OpCodes are passed on to the respective processors. Packets with unknown OpCodes are counted and discarded. Senevirathne Expires July 13, 2014 [Page 21] Internet-Draft TRILL Fault Management January 2014 7. Continuity Check Message (CCM) CCMs are used to monitor connectivity and configuration errors. [8021Q] monitors connectivity by listening to periodic CCM messages received from its remote MEP partners in the MA. An [8021Q] MEP identifies cross-connect errors by comparing the MAID in the received CCM message with the MEP's local MAID. The MAID [8021Q] is a 48-byte field that is technology independent. Similarly, the MEPID is a 2-byte field that is independent of the technology. Given this generic definition of CCM fields, CCM as defined in [8021Q] can be utilized in TRILL with no changes. TRILL specific information may be carried in CCMs when encoded using TRILL specific TLVs or sub-TLVs. This is possible since CCMs may carry optional TLVs. Unlike classical Ethernet environments, TRILL contains multipath forwarding. The path taken by a packet depends on the payload of the packet. The Maintenance Association identifies the interested end-points (MEPs) of a given monitored path. For unicast there are only two MEPs per MA. For multicast there can be two or more MEPs in the MA. The entropy values of the monitored flows are defined within the MA. CCM transmit logic will utilize these flow entropy values when constructing the CCM packets. Please see section 12. below for the theory of operation of CCM. The MIB of [8021Q] is augmented with the definition of flow- entropy. Please see [TRILLOAMMIB] for definition of these and other TRILL related OAM MIB definitions. The below Figure depicts the correlation between MA, CCM and the flow-entropy. Senevirathne Expires July 13, 2014 [Page 22] Internet-Draft TRILL Fault Management January 2014 MA--- | --- MEP | . - Remote MEP List . | --- MEP-A | --- MEP-B . | . - Flow Entropy List {Augments IEEE8021-CFM-MIB} | --- (Flow Entropy-1) {note we have to define | destination nickname with --- (Flow-entropy-2) the flow entropy discuss} | . ---(Flow Entropy n) | . - CCM | --- (standard 8021ag entries) | --- (hop-count) { Augments IEEE8021-CFM-MIB} | --- (Other TBD TRILL OAM specific entries) {Augmented} | . | - Other MIB entries Figure 8 Augmentation of CCM MIB in TRILL In a multi-pathing environment, a Flow - by definition - is unidirectional. A question may arise as to what flow entropy should be used in the response. CCMs are unidirectional and have no explicit reply; as such, the issue of the response flow entropy does not arise. In the transmitted CCM, each MEP reports local status using the Remote Defect Indication (RDI) flag. Senevirathne Expires July 13, 2014 [Page 23] Internet-Draft TRILL Fault Management January 2014 Additionally, a MEP may raise SNMP TRAPs [TRILLOAMMIB] as Alarms when a connectivity failure occurs. 8. TRILL OAM Message Channel The TRILL OAM Message Channel can be divided into two parts: TRILL OAM Message header and TRILL OAM Message TLVs. Every OAM Message MUST contain a single TRILL OAM message header and a set of one or more specified OAM Message TLVs. 8.1. TRILL OAM Message header As discussed earlier, a common messaging framework between [8021Q], TRILL, and other similar standards such as Y.1731 can be accomplished by re-using the OAM message header defined in [8021Q]. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |MD-L | Version | OpCode | Flags |FirstTLVOffset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Opcode Specific Information . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . TLVs . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9 OAM Message Format o MD-L: Maintenance Domain Level (3 bits). Identifies the maintenance domain level. For TRILL, in general, this field is set to zero. However, extension of TRILL, for example to support multilevel, may create different MD-LEVELs and MD-L field must be appropriately set in those scenarios. (Please refer to [8021Q] for the definition of MD-Level) o Version: Indicates the version (5 bits). As specified in [8021Q]. This document does not require changing the Version defined in [8021Q]. Senevirathne Expires July 13, 2014 [Page 24] Internet-Draft TRILL Fault Management January 2014 o Flags: Includes operational flags (1 byte). The definition of flags is Opcode-specific and is covered in the applicable sections. o FirstTLVOffset: Defines the location of the first TLV, in bytes, starting from the end of the FirstTLVOffset field (1 byte). (Refer to [8021Q] for the definition of the FirstTLVOffset.) MD-L, Version, Opcode, Flags and FirstTLVOffset fields collectively are referred to as the OAM Message Header. The Opcode specific information section of the OAM Message may contain Session Identification number, time-stamp, etc. 8.2. TRILL OAM Opcodes The following Opcodes are defined for TRILL. Each of the Opcodes indicates a separate type of TRILL OAM message. Details of the messages are presented in the related sections. TRILL OAM Message Opcodes: TBD-64 : Path Trace Reply TBD-65 : Path Trace Message TBD-66 : Multicast Tree Verification Reply TBD-67 : Multicast Tree Verification Message 8.3. Format of TRILL OAM TLV The same TLV format as defined in section 21.5.1 of [8021Q] is used for TRILL OAM. The following figure depicts the general format of a TRILL OAM TLV: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Value(variable) . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 10 TRILL OAM TLV Senevirathne Expires July 13, 2014 [Page 25] Internet-Draft TRILL Fault Management January 2014 Type (1 octet): Specifies the Type of the TLV (see sections 8.4. for TLV types). Length (2 octets): Specifies the length of the 'Value' field in octets. Length of the 'Value' field can be either zero or more octets. Value (variable): The length and the content of this field depend on the type of the TLV. Please refer to applicable TLV definitions for the details. Semantics and usage of Type values allocated for TRILL OAM purpose are defined by this document and other future related documents. 8.4. TRILL OAM TLVs TRILL related TLVs are defined in this section. [8021Q] defined TLVs are reused, where applicable. Types 32-63 are reserved for ITU-T Y.1731. We propose to reserve Types 64-95 for TRILL OAM TLVs. 8.4.1. Common TLVs between 802.1ag and TRILL The following TLVs are defined in [8021Q]. We propose to re-use them where applicable. The format and semantics of the TLVs are as defined in [8021Q]. Type Name of TLV in [8021Q] ---- ------------- 0 End TLV 1 Sender ID TLV 2 Port Status TLV 3 Data TLV 4 Interface Status TLV 5 Reply Ingress TLV 6 Reply Egress TLV 7 LTM Egress Identifier TLV 8 LTR Egress Identifier TLV 9-30 Reserved 31 Organization Specific TLV Senevirathne Expires July 13, 2014 [Page 26] Internet-Draft TRILL Fault Management January 2014 8.4.2. TRILL OAM Specific TLVs As indicated above, Types 64-95 will be requested to be reserved for TRILL OAM purposes. Listed below is a summary of TRILL OAM TLVs and their corresponding codes. Format and semantics of TRILL OAM TLVs are defined in subsequent sections. Type TLV Name ----------- ---------------------- TBD-TLV-64 TRILL OAM Application Identifier TBD-TLV-65 Out of Band IP Address TBD-TLV-66 Original Payload TBD-TLV-67 Diagnostic VLAN TBD-TLV-68 RBridge scope TBD-TLV-69 Previous RBridge Nickname TBD-TLV-70 TRILL Next Hop RBridge List (ECMP) TBD-TLV-71 Multicast Receiver Availability TBD-TLV-72 Flow Identifier TBD-TLV-73 Reflector Entropy TBD-TLV-74 to TBD-TLV-95 Reserved 8.4.3. TRILL OAM Application Identifier TLV TRILL OAM Application Identifier TLV carries TRILL OAM application specific information. The TRILL OAM Application Identifier TLV MUST always be present and MUST be the first TLV in TRILL OAM messages. Messages that do not include the TRILL OAM Application Identifier TLV as the first TLV MUST be discarded by an RBridge, unless that RBridge is also running Ethernet CFM. 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 | Version | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Return Code |Return sub-code| Reserved |F|C|O|I| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 11 TRILL OAM Application Identifier TLV Type (1 octet) = TBD-TLV-64 indicate that this is the TRILL OAM Application Identifier TLV Length (2 octets) = 6 Senevirathne Expires July 13, 2014 [Page 27] Internet-Draft TRILL Fault Management January 2014 TRILL OAM Version (1 Octet), currently set to zero. Indicates the TRILL OAM version. TRILL OAM version can be different than the [8021Q] version. Return Code (1 Octet): Set to zero on requests. Set to an appropriate value in response messages. Return sub-code (1 Octet): Return sub-code is set to zero on transmission of request message. Return sub-code identifies categories within a specific Return code. Return sub-code MUST be interpreted within a Return code. Reserved: set to zero on transmission and ignored on reception. F (1 bit): Final flag, when set, indicates this is the last response. C (1 bit): Label error (VLAN/Label mapping error), if set indicates that the label (VLAN/FGL) in the flow entropy is different than the label included in the diagnostic TLV. This field is ignored in request messages and MUST only be interpreted in response messages. O (1 bit): If set, indicates, OAM out-of-band response requested. I (1 bit): If set, indicates, OAM in-band response requested. NOTE: When both O and I bits are set to zero, indicates that no response is required (silent mode). User MAY specify both O and I or one of them or none. When both O and I bits are set response is sent both in-band and out-of-band. 8.4.4. Out Of Band Reply Address TLV Out of Band Reply Address TLV specifies the address to which an out of band OAM reply message MUST be sent. When O bit in the TRILL Version TLV is not set, Out of Band Reply Address TLV is ignored. Senevirathne Expires July 13, 2014 [Page 28] Internet-Draft TRILL Fault Management January 2014 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 | Address Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Addr Length | | +-+-+-+-+-+-+-+-+ | | | . Reply Address . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 12 Out of Band IP Address TLV Type (1 octet) = TBD-TLV-65 Length (2 octets) = Variable. Minimum length is 2. Address Type (1 Octet): 0 - IPv4. 1 - IPv6. 2 - TRILL RBridge nickname. All other values reserved. Addr Length (1 Octet). 4 - IPv4. 16 - IPv6, 2 - TRILL RBRidge nickname. Reply Address (variable): Address where the reply needed to be sent. Length depends on the address specification. 8.4.5. Diagnostics Label TLV Diagnostic label specifies the data label (VLAN or FGL) in which the OAM messages are generated. Receiving RBridge MUST compare the data label of the Flow entropy to the data label specified in the Diagnostic Label TLV. Label Error Flag in the response (TRILL OAM Message Version TLV) MUST be set when the two VLANs do not match. Senevirathne Expires July 13, 2014 [Page 29] Internet-Draft TRILL Fault Management January 2014 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 | L-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + | Reserved | Label(VLAN) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + Figure 13 Diagnostic VLAN TLV Type (1 octet) = TBD-TLV-66 indicates that this is the TRILL Diagnostic VLAN TLV Length (2 octets) = 5 L-Type (Label type, 1 octet) 0- indicate 802.1Q 12 bit VLAN. 1 - indicate TRILL 24 bit fine grain label Label (24 bits): Either 12 bit VLAN or 24 bit fine grain label. RBridges do not perform Label error checking when Label TLV is not included in the OAM message. In certain deployments intermediate devices may perform label translation. In such scenarios, originator should not include the diagnostic Label TLV in OAM messages. Inclusion of diagnostic TLV will generate unwanted label error notifications. Senevirathne Expires July 13, 2014 [Page 30] Internet-Draft TRILL Fault Management January 2014 8.4.6. Original Data Payload TLV 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 | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | | . Original Payload . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 14 Original Data Payload TLV Type (1 Octet) = TBD-TLV-67 Length (2 octets) = variable 8.4.7. RBridge scope TLV RBridge scope TLV identifies nicknames of RBridges from which a response is required. The RBridge scope TLV is only applicable to Multicast Tree Verification messages. This TLV SHOULD NOT be included in other messages. Receiving RBridges MUST ignore this TLV on messages other than Multicast Verification Message. Each TLV can contain up to 255 nicknames of in scope RBridges. A Multicast Verification Message may contain multiple "RBridge scope TLVs", in the event that more than 255 in scope RBridges need to be specified. Absence of the "RBridge scope TLV" indicates that a response is needed from all the RBridges. Please see section 11. for details. Senevirathne Expires July 13, 2014 [Page 31] Internet-Draft TRILL Fault Management January 2014 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 | nOfnicknames | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | nickname-1 | nickname-2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | nickname-n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 15 RBridge Scope TLV Type (1 octet) = TBD-TLV-68 indicates that this is the "RBridge scope TLV" Length (2 octets) = variable. Minimum value is 2. Nickname (2 octets) = 16 bit RBridge nickname. 8.4.8. Previous RBridge nickname TLV "Previous RBridge nickname TLV" identifies the nickname or nicknames of the upstream RBridge. [RFC6325] allows a given RBridge to hold multiple nicknames. "Upstream RBridge nickname TLV" is an optional TLV. Multiple instances of this TLV MAY be included when an upstream RBridge is represented by more than 255 nicknames (highly unlikely). 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | nickname | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 16 Previous RBridge nickname TLV Type (1 octet) = TBD-TLV-69 indicates that this is the "Upstream RBridge nickname" Length (2 octets) = 4. Senevirathne Expires July 13, 2014 [Page 32] Internet-Draft TRILL Fault Management January 2014 Nickname (2 octets) = 16 bit RBridge nickname. 8.4.9. Next Hop RBridge List TLV "Next Hop RBridge List TLV" identifies the nickname or nicknames of the downstream next hop RBridges. [RFC6325] allows a given RBridge to have multiple Equal Cost Paths to a specified destination. Each next hop RBridge is represented by one of its nicknames. "Next Hop RBridge List TLV" is an optional TLV. Multiple instances of this TLV MAY be included when there are more than 255 Equal Cost Paths to the destination. 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 | nOfnicknames | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | nickname-1 | nickname-2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | nickname-n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 17 Next Hop RBridge List TLV Type (1 octet) = TBD-TLV-70 indicates that this is the "Next nickname" Length (2 octets) = variable. Minimum value is 2. Nickname (2 octets) = 16 bit RBridge nickname. 8.4.10. Multicast Receiver Port count TLV "Multicast Receiver Port Count TLV" identifies the number of ports interested in receiving the specified multicast stream within the responding RBridge on the label (VLAN or FGL) specified by the Diagnostic Label TLV. Multicast Receiver Port count is an Optional TLV. Senevirathne Expires July 13, 2014 [Page 33] Internet-Draft TRILL Fault Management January 2014 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | number of Receivers | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 18 Multicast Receiver Availability TLV Type (1 octet) = TBD-TLV-71 indicates that this is the "Multicast Availability TLV" Length (2 octets) = 5. Number of Receivers (4 octets) = Indicates the number of Multicast receivers available on the responding RBridge on the label specified by the diagnostic label. 8.4.11. Flow Identifier (flow-id) TLV Flow Identifier (flow-id) uniquely identifies a specific flow. The flow-id value is unique per MEP and needs to be interpreted as such. 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MEP-ID | flow-id | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 19 Flow Identifier TLV Type (1 octet) = TBD-TLV-72 Length (2 octets) = 5. Reserved (1 octet) set to 0 on transmission and ignored on reception. MEP-ID (2 octets) = MEP-ID of the originator [8021Q]. Senevirathne Expires July 13, 2014 [Page 34] Internet-Draft TRILL Fault Management January 2014 Flow-id (2 octets) = uniquely identifies the flow per MEP. Different MEPs may allocate the same flow-id value. The {MEP-ID, flow-id} pair is globally unique. Inclusion of the MEP-ID in the flow-id TLV allows inclusion of MEP-ID for messages that do not contain MEP-ID in OAM header. Applications may use MEP-ID information for different types of troubleshooting. 8.4.12. Reflector Entropy TLV Reflector Entropy TLV is an optional TLV. This TLV, when present, tells the responder to utilize the Reflector Entropy specified within the TLV as the flow-entropy of the response message. 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 | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . Reflector Entropy . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 20 Reflector Entropy TLV Type (1 octet) =TBD-TLV-73 Reflector Entropy TLV. Length (1 octet) =97. Reserved (1 octet) = set to zero on transmission and ignored by the recipient. Reflector Entropy (96-octet) = Flow Entropy to be used by the responder. May be padded with zero if the desired flow entropy is less than 96 octets. Senevirathne Expires July 13, 2014 [Page 35] Internet-Draft TRILL Fault Management January 2014 9. Loopback Message 9.1. Loopback OAM Message format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |MD-L | Version | OpCode | Flags |FirstTLVOffset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Loopback Transaction Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | . TLVs . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 21 Loopback OAM Message Format The above figure depicts the format of the Loopback Request and response messages as defined in [8021Q]. The Opcode for Loopback Message is set to 65 and the Opcode for the Reply Message is set to 64. The Session Identification Number is a 32-bit integer that allows the requesting RBridge to uniquely identify the corresponding session. Responding RBridges, without modification, MUST echo the received "Loopback Transaction Identifier" number.. 9.2. Theory of Operation 9.2.1. Actions by Originator RBridge Identifies the destination RBridge nickname based on user specification or based on the specified destination MAC or IP address. Constructs the flow entropy based on user specified parameters or implementation specific default parameters. Constructs the TRILL OAM header: sets the opcode to Loopback message type (3). Assign applicable Loopback Transaction Identifier number for the request. The TRILL OAM Version TLV MUST be included and with the flags set to applicable values. Senevirathne Expires July 13, 2014 [Page 36] Internet-Draft TRILL Fault Management January 2014 Include following OAM TLVs, where applicable o Out-of-band Reply address TLV o Diagnostic Label TLV o Sender ID TLV Specify the Hop count of the TRILL data frame per user specification or utilize an applicable Hop count value. Dispatch the OAM frame for transmission. RBridges may continue to retransmit the request at periodic intervals, until a response is received or the re-transmission count expires. At each transmission Session Identification number MUST be incremented. 9.2.2. Intermediate RBridge Intermediate RBridges forward the frame as a normal data frame and no special handling is required. 9.2.3. Destination RBridge If the Loopback message is addressed to the local RBridge and satisfies the OAM identification criteria specified in section 3.1. then, the RBridge data plane forwards the message to the CPU for further processing. The TRILL OAM application layer further validates the received OAM frame by checking for the presence of OAM-Ethertype at the end of the flow entropy and the MD Level. Frames that do not contain OAM-Ethertype at the end of the flow entropy MUST be discarded. Construction of the TRILL OAM response: TRILL OAM application encodes the received TRILL header and flow entropy in the Original payload TLV and includes it in the OAM message. Set the Return Code and Return sub code to applicable values. Update the TRILL OAM opcode to 2 (Loopback Message Reply) Senevirathne Expires July 13, 2014 [Page 37] Internet-Draft TRILL Fault Management January 2014 Optionally, if the VLAN/FGL identifier value of the received flow entropy differs from the value specified in the diagnostic Label, set the Label Error Flag on TRILL OAM Application Identifier TLV. Include the sender ID TLV (1) If in-band response was requested, dispatch the frame to the TRILL data plane with request-originator RBridge nickname as the egress RBridge nickname. If out-of-band response was requested, dispatch the frame to the IP forwarding process. 10. Path Trace Message The primary use of the Path Trace Message is for fault isolation. It may also be used for plotting the path taken from a given RBridge to another RBridge. [8021Q] accomplishes the objectives of the TRILL Path Trace Message using Link Trace Messages. Link Trace Messages utilize a well-known multicast MAC address. This works for [8021Q], because for 802.1 both the unicast and multicast paths are congruent. However, TRILL is multicast and unicast incongruent. Hence, TRILL OAM uses a new message format: the Path Trace message. The Path Trace Message has the same format as Loopback Message. Opcode for Path Trace Reply Message is 65 and Request 64 Operation of the Path Trace message is identical to the Loopback message except that it is first transmitted with a TRILL Hop count field value of 1. The sending RBridge expects a Time Expiry Return-Code from the next hop or a successful response. If a Time Expiry Return-code is received as the response, the originator RBridge records the information received from intermediate node that generated the Time Expiry message and resends the message by incrementing the previous Hop count value by 1. This process is continued until, a response is received from the destination RBridge or Path Trace process timeout occur or Hop count reaches a configured maximum value. Senevirathne Expires July 13, 2014 [Page 38] Internet-Draft TRILL Fault Management January 2014 10.1. Theory of Operation 10.1.1. Action by Originator RBridge Identify the destination RBridge based on user specification or based on location of the specified MAC address. Construct the flow entropy based on user specified parameters or implementation specific default parameters. Construct the TRILL OAM header: Set the opcode to Path Trace Request message type (65). Assign an applicable Session Identification number for the request. Return-code and sub-code MUST be set to zero. The TRILL OAM Application Identifier TLV MUST be included and set the flags to applicable values. Include following OAM TLVs, where applicable o Out-of-band IP address TLV o Diagnostic Label TLV o Include the Sender ID TLV Specify the Hop count of the TRILL data frame as 1 for the first request. Dispatch the OAM frame to the TRILL data plane for transmission. An RBridge may continue to retransmit the request at periodic intervals, until a response is received or the re-transmission count expires. At each new re-transmission, the Session Identification number MUST be incremented. Additionally, for responses received from intermediate RBridges, the RBridge nickname and interface information MUST be recorded. 10.1.2. Intermediate RBridge Path Trace Messages transit through Intermediate RBridges transparently, unless Hop-count has expired. TRILL OAM application layer further validates the received OAM frame by examining the presence of TRILL OAM Flag and OAM- Senevirathne Expires July 13, 2014 [Page 39] Internet-Draft TRILL Fault Management January 2014 Ethertype at the end of the flow entropy and by examining the MD Level. Frames that do not contain OAM-Ethertype at the end of the flow entropy MUST be discarded. Construction of the TRILL OAM response: TRILL OAM application encodes the received TRILL header and flow entropy in the Original payload TLV and include it in the OAM message. Set the Return Code to (2) "Time Expired" and Return sub code to zero (0). Update the TRILL OAM opcode to 64 (Path Trace Message Reply). If the VLAN/FGL identifier value of the received flow entropy differs from the value specified in the diagnostic Label, set the Label Error Flag on TRILL OAM Application Identifier TLV. Include following TLVs Upstream RBridge nickname TLV (69) Reply Ingress TLV (5) Reply Egress TLV (6) Interface Status TLV (4) TRILL Next Hop RBridge (Repeat for each ECMP) (70) Sender ID TLV (1) If Label error detected, set C flag (Label error detected) in the version. If in-band response was requested, dispatch the frame to the TRILL data plane with request-originator RBRidge nickname as the egress RBridge nickname. If out-of-band response was requested, dispatch the frame to the standard IP forwarding process. Senevirathne Expires July 13, 2014 [Page 40] Internet-Draft TRILL Fault Management January 2014 10.1.3. Destination RBridge Processing is identical to section 10.1.2. With the exception that TRILL OAM Opcode is set to Path Trace Reply (64). 11. Multi-Destination Tree Verification (MTV) Message Multi-Destination Tree Verification messages allow verifying TRILL distribution tree integrity and pruning. TRILL VLAN/FGL and multicast pruning are described in [RFC6325] [RFCclcorrect] and [RFCfgl]. Multi-destination tree verification and Multicast group verification messages are designed to detect pruning defects. Additionally, these tools can be used for plotting a given multicast tree within the TRILL campus. Multi-Destination tree verification OAM frames are copied to the CPU of every intermediate RBridge that is part of the distribution tree being verified. The originator of the Multi- destination Tree verification message specifies the scope of RBridges from which a response is required. Only the RBridges listed in the scope field respond to the request. Other RBridges silently discard the request. Inclusion of the scope parameter is required to prevent receiving an excessive number of responses. The typical scenario of distribution tree verification or group verification, involves verifying multicast connectivity to a selected set of end-nodes as opposed to the entire network. Availability of the scope facilitates narrowing down the focus to only the RBridges of interest. Implementations MAY choose to rate-limit CPU bound multicast traffic. As a result of rate-limiting or due to other congestion conditions, MTV messages may be discarded from time to time by the intermediate RBRidges and the requester may be required to retransmit the request. Implementations SHOULD narrow the embedded scope of retransmission request only to RBRidges that have failed to respond. 11.1. Multi-Destination Tree Verification (MTV) OAM Message Format Format of MTV OAM Message format is identical to that of Loopback Message format defined in section 9. with the exception that the Loopback Transaction Identifier, in section 9.1. , is replaced with the Session Identifier. Senevirathne Expires July 13, 2014 [Page 41] Internet-Draft TRILL Fault Management January 2014 11.2. Theory of Operation 11.2.1. Actions by Originator RBridge The user is required at a minimum to specify either the distribution trees that need to be verified, or the Multicast MAC address and VLAN/FGL, or VLAN/FGL and Multicast destination IP address. Alternatively, for more specific multicast flow verification, the user MAY specify more information e.g. source MAC address, VLAN/FGL, Destination and Source IP addresses. Implementations, at a minimum, must allow the user to specify a choice of distribution trees, Destination Multicast MAC address and VLAN/FGL that needed to be verified. Although, it is not mandatory, it is highly desired to provide an option to specify the scope. It should be noted that the source MAC address and some other parameters may not be specified if the Backwards Compatibility Method of Appendix A is used to identify the OAM frames. Default parameters MUST be used for unspecified parameters. Flow entropy is constructed based on user specified parameters and/or default parameters. Based on user specified parameters, the originating RBridge identifies the nickname that represents the multicast tree. Obtain the applicable Hop count value for the selected multicast tree. Construct TRILL OAM message header and include Session Identification number. Session Identification number facilitate the originator to map the response to the correct request. TRILL OAM Application Identifier TLV MUST be included. Op-Code MUST be specified as Multicast Tree Verification Message (70) Include RBridge scope TLV (67) Optionally, include following TLV, where applicable o Out-of-band IP address o Diagnostic Label o Sender ID TLV (1) Senevirathne Expires July 13, 2014 [Page 42] Internet-Draft TRILL Fault Management January 2014 Specify the Hop count of the TRILL data frame per user specification or alternatively utilize the applicable Hop count value if TRILL Hop count is not being specified by the user. Dispatch the OAM frame to the TRILL data plane to be ingressed for transmission. The RBridge may continue to retransmit the request at a periodic interval until either a response is received or the re- transmission count expires. At each new re-transmission, the Session Identification number MUST be incremented. At each re- transmission, the RBridge may further reduce the scope to the RBridges that it has not received a response from. 11.2.2. Receiving RBridge Receiving RBridges identify multicast verification frames per the procedure explained in sections 3.2. CPU of the RBridge validates the frame and analyzes the scope RBridge list. If the RBridge scope TLV is present and the local RBridge nickname is not specified in the scope list, it will silently discard the frame. If the local RBridge is specified in the scope list OR RBridge scope TLV is absent, the receiving RBridge proceeds with further processing as defined in section 11.2.3. 11.2.3. In scope RBridges Construction of the TRILL OAM response: TRILL OAM application encodes the received TRILL header and flow entropy in the Original payload TLV and includes them in the OAM message. Set the Return Code to (0) and Return sub code to zero (0). Update the TRILL OAM opcode to 66 (Multicast Tree Verification Reply). Include following TLVs: Upstream RBridge nickname TLV (69) Reply Ingress TLV (5) Interface Status TLV (4) Senevirathne Expires July 13, 2014 [Page 43] Internet-Draft TRILL Fault Management January 2014 TRILL Next Hop RBridge (Repeat for each downstream RBridge) (70) Sender ID TLV (1) Multicast Receiver Availability TLV (71) If Label (VLAN or FGL) cross connect error detected, set C flag (Cross connect error detected) in the version. If in-band response was requested, dispatch the frame to the TRILL data plane with request-originator RBridge nickname as the egress RBridge nickname. If out-of-band response was requested, dispatch the frame to the standard IP forwarding process. 12. Application of Continuity Check Message (CCM) in TRILL Section 7. provides an overview of CCM Messages defined in [8021Q] and how they can be used within the TRILL OAM. This section, presents the application and Theory of Operations of CCM within the TRILL OAM framework. Readers are referred to [8021Q] for CCM message format and applicable TLV definitions and usages. Only the TRILL specific aspects are explained below. In TRILL, between any two given MEPs there can be multiple potential paths. Whereas in [8021Q], there is always a single path between any two MEPs at any given time. [RFC6905] requires solutions to have the ability to monitor continuity over one or more paths. CCM Messages are uni-directional, such that there is no explicit response to a received CCM message. Connectivity status is indicated by setting the applicable flags (e.g. RDI) of the CCM messages transmitted by an MEP. It is important that the solution presented in this document accomplishes the requirements specified in [RFC6905] within the framework of [8021Q] in a straightforward manner and with minimum changes. Section 8 above defines multiple flows within the CCM object, each corresponding to a flow that a given MEP wishes to monitor. Receiving MEPs do not cross check whether a received CCM belongs to a specific flow from the originating RBridge. Any attempt to track status of individual flows may explode the amount of state information that any given RBridge has to maintain. Senevirathne Expires July 13, 2014 [Page 44] Internet-Draft TRILL Fault Management January 2014 The obvious question arises: How does the originating RBridge know which flow or flows are at fault? This is accomplished with a combination of the RDI flag in the CCM header, flow-id TLV, and SNMP Notifications (Traps). Section 12.1. 12.1. below discuss the procedure. 12.1. CCM Error Notification Each MEP transmits 4 CCM messages per each flow. ([8021Q] detects CCM fault when 3 consecutive CCM messages are lost). Each CCM Message has a unique sequence number and unique flow-identifier. The flow identifier is included in the OAM message via flow-id TLV. When an MEP notices a CCM timeout from a remote MEP ( MEP-A), it sets the RDI flag on the next CCM message it generates. Additionally, it logs and sends SNMP notification that contain the remote MEP Identification, flow-id and the Sequence Number of the last CCM message it received and if available, the flow-id and the Sequence Number of the first CCM message it received after the failure. Each MEP maintains a unique flow-id per each flow, hence the operator can easily identify flows that correspond to the specific flow-id. The following example illustrates the above. Assume there are two MEPs, MEP-A and MEP-B. Assume there are 3 flows between MEP-A and MEP-B. Let's assume MEP-A allocates sequence numbers as follows Flow-1 Sequence={1,2,3,4,13,14,15,16,.. } flow-id=(1) Flow-2 Sequence={5,6,7,8,17,18,19,20,.. } flow-id=(2) Flow-3 Sequence={9,10,12,11,21,22,23,24,.. } flow-id=(3) Let's Assume Flow-2 is at fault. MEP-B, receives CCM from MEP-A with sequence numbers 1,2,3,4, but did not receive 5,6,7,8. CCM timeout is set to 3 CCM intervals in [8021Q]. Hence MEP-B detects the error at the 8'th CCM message. At this time the sequence number of the last good CCM message MEP-B has received from MEP-A is 4 and flow-id of the last good CCM Message is (1). Hence MEP-B will generate a CCM error SNMP Senevirathne Expires July 13, 2014 [Page 45] Internet-Draft TRILL Fault Management January 2014 notification with MEP-A and Last good flow-id (1) and sequence number 4. When MEP-A switches to flow-3 after transmitting flow-2, MEP-B will start receiving CCM messages. In the foregoing example it will be CCM message with Sequence Numbers 9,10,11,12,21 and so on. When in receipt of a new CCM message from a specific MEP, after a CCM timeout, the TRILL OAM will generate an SNMP Notification of CCM resume with remote MEP-ID and the first valid flow-id and the Sequence number after the CCM timeout. In the foregoing example, it is MEP-A, flow-id (1) and Sequence Number 9. The remote MEP list under the CCM MIB Object is augmented to contain "Last Sequence Number", flow-id and "CCM Timeout" variables. Last Sequence Number and flow-id are updated every time a CCM is received from a remote MEP. CCM Timeout variable is set when the CCM timeout occurs and is cleared when a CCM is received. 12.2. Theory of Operation 12.2.1. Actions by Originator RBridge Derive the flow entropy based on flow entropy specified in the CCM Management object. Construct the TRILL CCM OAM header as specified in [8021Q]. TRILL OAM Version TLV MUST be included as the first TLV and set the flags to applicable values. Include other TLVs specified in [8021Q] Include the following optional TRILL OAM TLVs, where applicable o Sender ID TLV Specify the Hop count of the TRILL data frame per user specification or utilize an applicable Hop count value. Dispatch the OAM frame to the TRILL data plane for transmission. An RBridge transmits a total of 4 requests, each at CCM retransmission interval. At each transmission the Session Identification number MUST be incremented by one. Senevirathne Expires July 13, 2014 [Page 46] Internet-Draft TRILL Fault Management January 2014 At the 5'th retransmission interval, flow entropy of the CCM packet is updated to the next flow entropy specified in the CCM Management Object. If current flow entropy is the last flow entropy specified, move to the first flow entropy specified and continue the process. 12.2.2. Intermediate RBridge Intermediate RBridges forward the frame as a normal data frame and no special handling is required. 12.2.3. Destination RBridge If the CCM Message is addressed to the local RBridge or multicast and satisfies OAM identification methods specified in sections 3.2. then the RBridge data plane forwards the message to the CPU for further processing. The TRILL OAM application layer further validates the received OAM frame by examining the presence of OAM-Ethertype at the end of the flow entropy. Frames that do not contain OAM-Ethertype at the end of the flow entropy MUST be discarded. Validate the MD-LEVEL and pass the packet to the Opcode de- multiplexer. The Opcode de-multiplexer delivers CCM packets to the CCM process. The CCM Process performs processing specified in [8021Q]. Additionally the CCM process updates the CCM Management Object with the sequence number of the received CCM packet. Note: The last received CCM sequence number and CCM timeout are tracked per each remote MEP. If the CCM timeout is true for the sending remote MEP, then clear the CCM timeout in the CCM Management object and generate the SNMP notification as specified above. 13. Fragmented Reply The response Message allows Fragmented Replies. In case of Fragmented Replies, all messages MUST follow the procedure defined in this section. All Reply Messages MUST be encoded as described in this document. Senevirathne Expires July 13, 2014 [Page 47] Internet-Draft TRILL Fault Management January 2014 The same session Identification Number MUST be included in all related fragments of the same message. The TRILL OAM Application Identifier TLV MUST be included with the appropriate Final Flag field. The Final Flag, MUST, only be set on the final fragment of the reply. 14. Security Considerations For general TRILL related security considerations, please refer to [RFC6325]. Specific security considerations related methods presented in this document are currently under investigation. 15. IEEE Allocation Considerations The IEEE 802.1 Working Group is requested to allocate a separate opcode and TLV space within 802.1QCFM messages for TRILL purpose. 16. IANA Considerations IANA is requested to do the following: - Assign a multicast MAC address from the block assigned to TRILL [RFC6325] - Set up sub-registry within the TRILL Parameters registry for block of TRILL "OAM OpCodes" (Section 8.2. ) - Set up sub-registry within the TRILL Parameters registry for TRILL "OAM TLV Types" (Section 8.4. ) - Assign a unicast MAC addressed under the IANA OUI, reserved for identification of OAM packets discussed in backward compatibility method (Appendix A) See Appendix C. 17. References 17.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Senevirathne Expires July 13, 2014 [Page 48] Internet-Draft TRILL Fault Management January 2014 [RFC6325] Perlman, R., et.al., "Routing Bridges (RBridges): Base Protocol Specification", RFC 6325, July 2011. [RFCfgl] D. Eastlake, M. Zhang, P. Agarwal, R. Perlman, D. Dutt, "TRILL: Fine-Grained Labeling", draft-ietf-trill-fine- labeling, work in progress. [8021Q] IEEE, "Media Access Control (MAC) Bridges and Virtual Bridged Local Area Networks", IEEE Std 802.1Q-2011, August, 2011. 17.2. Informative References [RFC4379] Kompella, K. et.al, "Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures", RFC 4379, February 2006. [RFC6291] Andersson, L., et.al., "Guidelines f