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

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Copyright Notice

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Table of Contents

• 1. Introduction
• 1.1. Conventions used in this document
• 1.1.1. Terminology
• 1.1.2. Requirements Language
• 2. Working Group Overview
• 2.1. BIER
• 2.2. NVO3
• 2.3. SFC
• 3. Overlay OAM Toolset
• 3.1. Overlay OAM Fault Management
• 3.1.1. Proactive Continuity Check and Connectivity Verification
• 3.1.2. On-demand Continuity Check and Connectivity Verification
• 3.1.3. Alarm Indication Signal
• 3.2. Overlay OAM Performance Measurement
• 3.2.1. Overlay OAM PM Active
• 3.2.2. Overlay OAM PM Passive
• 3.3. Telemetry in Overlay OAM
• 3.4. Conclusions
• 4. IANA Considerations
• 5. Security Considerations
• 6. Acknowledgement
• 7. References
• 7.1. Normative References
• 7.2. Informative References
• Authors' Addresses

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:

• The Overlay OAM toolset should be developed based on existing IP and IP/MPLS architecture, technology, and toolsets.
• 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:

• 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];

• 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];
  • [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;

• 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].

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.

    
 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                           ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    
 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                           ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+