SPRING Working Group F. Yang Internet-Draft T. Zhou Intended status: Standards Track Y. Wang Expires: January 13, 2022 Huawei Technologies July 12, 2021 ACH6 for OAM in Segment Routing draft-yang-spring-ach6-oam-sr-00 Abstract This document defines an OAM toolset encapsulated in ACH6 to provide the functions of performance measurement, continuity check and verification to an SRv6 path. 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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 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 https://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 January 13, 2022. Copyright Notice Copyright (c) 2021 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 Yang, et al. Expires January 13, 2022 [Page 1] Internet-Draft ACH6 for OAM in SR July 2021 (https://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 . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. ACH6 OAM for SRv6 . . . . . . . . . . . . . . . . . . . . . . 3 3.1. ACH6 OAM Message . . . . . . . . . . . . . . . . . . . . 3 3.2. ACH6 On-Demand Echo Request/Reply . . . . . . . . . . . . 3 3.3. ACH6 Proactive Continuity Check . . . . . . . . . . . . . 5 3.4. ACH6 Performance Measurement . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . 9 7.2. Informative References . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction ACH6 [I-D.yang-spring-ach6-sr] provides a method of supporting an OAM toolset with a unified TLV format in Segment Routing over IPv6 network. There are several advantages: o An Associated Channel ID in ACH6 provides a unified identifier to OAM sessions for a specific SRv6 path. o In Segment Routing networks, ACH6 TLV is proposed to be encapsulated in IPv6 Destination Options Header. Together with IPv6 Segment Routing Header, OAM functions like continuity check and performance management can be monitored either hop-by-hop on every SR endpoint or end-to-end from the first endpoint to the last. o By leveraging native semantics of IPv6 extension headers, ACH6 OAM messages target to be processed in fast path to improve OAM accuracy and efficiency. o By leveraging native semantics of IPv6 extension headers, ACH6 OAM can help network nodes reduce OAM configurations and session management. Yang, et al. Expires January 13, 2022 [Page 2] Internet-Draft ACH6 for OAM in SR July 2021 In this method, ACH6 OAM categorizes OAM functionalities into three types of messages, including On-demand Echo Request/Reply, Proactive Continuity Check and Performance Measurement. 2. Terminology This document uses the following terms: OAM: Operations, Administration, and Maintenance ACH6: Associated CHannel over IPv6 3. ACH6 OAM for SRv6 3.1. ACH6 OAM Message Figure 1 defines the format of ACH6 OAM message. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Channel Type = TBA | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Associated Channel ID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ~ ~ OAM Message Body (Variable) ~ ~ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1 ACH6 OAM Message Format ACH6 Channel Type indicates which type of OAM message is encapsulated in the following OAM message body, and OAM message body contains the OAM messages. Three types of OAM messages are defined: o TBA 1 = On-demand Echo Request/Reply o TBA 2 = Proactive Continuity Check o TBA 3 = Performance Measurement 3.2. ACH6 On-Demand Echo Request/Reply On-demand Echo Request/Reply provides a method of on-demand continuity check and connectivity verification. Figure 2 defines ACH6 OAM format of On-demand Echo Request/Reply message. Yang, et al. Expires January 13, 2022 [Page 3] Internet-Draft ACH6 for OAM in SR July 2021 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Channel Type = TBA1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Associated Channel ID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Echo Req/Rep | Reply Mode | Return Code | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ sub-TLVs (optional) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2 ACH6 OAM On Demand Echo Request/Reply Message Associated Channel ID: indicates the identifier of OAM session. Message Type: o 1 = Echo Request o 2 = Echo Reply Reply Mode: o 1 = Do not reply o 2 = Reply via an IPv6 UDP packet o 3 = Reply via an IPv6 packet without payload o 4 = Reply via application-level control channel Return code: o 0 = No return code o 1 = Malformed echo request received o 2 = One or more of the TLVs was not understood o 3 = Packet-rorward-success o 4 = No route to destination o 5 = Communication with destination administratively prohibited Yang, et al. Expires January 13, 2022 [Page 4] Internet-Draft ACH6 for OAM in SR July 2021 o 6 = Beyond scope of source address o 7 = Address unreachable o 8 = Port unreachable o 9 = Source address failed ingress/egress policy o 10 = Reject route to destination o 11 = Exceeding the minimum IPv6 MTU o 12 = Hop limit exceeded in transit o 13 = Fragment reassembly time exceeded o 14 = Erroneous header field encountered o 15 = Unrecognized Next Header type encountered o 16 = Unrecognized IPv6 option encountered Sequence number: is allocated by the sender of echo request to detect whether the reply packet is lost. 3.3. ACH6 Proactive Continuity Check Proactive Continuity Check provides a method of proactive continuity check to continuously detect the path status and fault. Figure 3 defines ACH6 OAM format of Proactive Continuity Check message. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Channel Type = TBA2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Associated Channel ID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Diag |Sta| Flag | Reserved | Detect Multi | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Desired Min TX Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Required Min TX Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Required Min Echo RX Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 ACH6 OAM ProCC Message Yang, et al. Expires January 13, 2022 [Page 5] Internet-Draft ACH6 for OAM in SR July 2021 Associated Channel ID: indicates the identifier of OAM session. Diag: o 0 = no diagnostic o 1 = control detection time expired o 2 = echo function failed o 3 = neighbor signaled session down o 4 = forwarding plane reset o 5 = path down o 6 = concatenated path down o 7 = administratively down o 8 = reverse concatenated path down o 9-31 = reserved for future use State: o 0 = adminDown o 1 = down o 2 = Init o 3 = up Flag: o P flag: if set, the transmitting node is requesting verification of connectivity, or of a parameter change, and is expecting a packet with the F bit in reply. If clear, the transmitting node is not requesting verification. o F flag: if set, the transmitting node is responding to a received Proactive Continuity Check packet that had the P bit set. If clear, the transmitting node is not responding to a requesting packet that had the P bit set. o D flag: if set, Demand mode is active in the transmitting node. The node wishes to operate in Demand mode and direct the remote Yang, et al. Expires January 13, 2022 [Page 6] Internet-Draft ACH6 for OAM in SR July 2021 node to cease the periodic transmission of Proactive Continuity Check packets. If clear, Demand mode is not active in the transmitting node. o M flag: this bit is reserved for future point-to-multipoint extensions to ACH6 Proactive Continuity Check. It MUST be zero on both transmit and receipt. Detect Mult: detection time multiplier. Desired Min TX Interval: this is the minimum interval, in microseconds, that the local system would like to use when transmitting ACH6 Proactive Continuity Check packets. Required Min RX Interval: this is the minimum interval, in microseconds, between received ACH6 Proactive Continuity Check packets that this system is capable of supporting, less any jitter applied by the sender. Required Min Echo RX Interval: this is the minimum interval, in microseconds, between received Echo packets that this system is capable of supporting, less any jitter applied by the sender. 3.4. ACH6 Performance Measurement Performance Measurement provides a method of measuring packet loss and delay. Figure 4 defines ACH6 OAM format of Performance Measurement message. Yang, et al. Expires January 13, 2022 [Page 7] Internet-Draft ACH6 for OAM in SR July 2021 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Channel Type = TBA3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Associated Channel ID ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reflector Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ TimeStamp1 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ TimeStamp2 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ TimeStamp3 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ TimeStamp4 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Padding (MBZ, variable) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4 ACH6 OAM Performance Measurement Message Associated Channel ID: indicates the identifier of OAM session. Sender Sequence Number: the counter of performance measurement test packets sent from sender Reflector Sequence Number: the counter of performace measurement test packets set by reflector Timestamp 1-4: When a query is sent from A, timestamp 1 is set to T1, timestamp 2-4 fields are set to 0. When the query is received at B, timestamp 2 is set to T2. In this case, B copies timestamp 1 to timestamp 3, copies timestamp 2 to timestamp 4, and initializes timestamp 1 and timestamp 2 to 0. When B sends a response, timestamp 1 is set to T3. When a response is received at A, timestamp 2 is set to T4. 4. IANA Considerations o This document requests IANA to assign a codepoint of On-demand Echo Request/Reply of ACH6 Channel Types. o This document requests IANA to assign a codepoint of Proactive Continuity Check of ACH6 Channel Types. Yang, et al. Expires January 13, 2022 [Page 8] Internet-Draft ACH6 for OAM in SR July 2021 o This document requests IANA to assign a codepoint of Performance Measurement of ACH6 Channel Types. 5. Security Considerations TBD 6. Acknowledgements 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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 7.2. Informative References [I-D.yang-spring-ach6-sr] Yang, F. and T. Zhou, "ACH6 in Segment Routing", draft- yang-spring-ach6-sr-00 (work in progress), July 2021. Authors' Addresses Fan Yang Huawei Technologies Beijing China Email: shirley.yangfan@huawei.com Tianran Zhou Huawei Technologies Beijing China Email: zhoutianran@huawei.com Yang, et al. Expires January 13, 2022 [Page 9] Internet-Draft ACH6 for OAM in SR July 2021 Yali Wang Huawei Technologies Beijing China Email: wangyali11@huawei.com Yang, et al. Expires January 13, 2022 [Page 10]