Export of Gigabit Passive Optical Network Encapsulation Mode in IP Flow Information Export (IPFIX)

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Table of Contents

1. Introduction

The G-PON Encapsulation Method (GEM) data plane header defined in Section 8.3.1 of [itu-g984-3] facilitates the framing, error control, payload type identification and payload separation in the Optical Distribution Network. It is being used in the Optical Distribution Network between the Optical Line Termination (OLT) at the network operator and the Optical Network Unit (ONU), Optical Network Terminal (ONT) at the end user in the passive optical transport within the broadband access domain.¶

IPFIX is widely applied in the broadband access domain to gain visibility into the forwarding and data plane. However, that visibility is today constraint to the ethernet, IP and application transport properties of the data plane.¶

This document specifies two IPFIX Information Elements (IEs) to facilitate visibility in the GEM data plane.¶

Figure 1 shows the GEM frame, the GEM header and its properties.¶

                            GEM Frame
     |<------------------------------------------------------>|
     |                                                        |
     +--------------+-----------------------------------------+
     |  GEM Header  |              GEM Payload                |
     +--------------+-----------------------------------------+
    /               |
   /                 --------------\
  /                                 --------------\
 /                                                 -----------\
v                                                              v
+----------------+----------------+---------+------------------+
| PLI            | Port-ID        | PTI     |  HEC             |
| (12-bits)      | (12-bits)      | (3-bits)|  (13-bits)       |
+----------------+----------------+---------+------------------+

  Figure 1: G.984.3 GEM header and frame structure

These IEs are used to export the GEM Port-ID and PTI to enable the distinction between user service and user and OAM application frames.¶

Some examples are provided in Appendix A.¶

2. Terminology

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.¶

This document makes use of the terms defined in [RFC7011], [itu-g984-1] and [itu-g984-3].¶

The following terms are used as defined in [RFC7011]:¶

• IPFIX¶

• IPFIX Information Elements¶

• Template¶

• Template Record¶

• Options Template¶

• Options Template Record¶

• Data Record¶

• Data Set¶

The following terms are used as defined in [itu-g984-1]:¶

• Optical Access Network (OAN)¶

• Optical Distribution Network (ODN)¶

• Optical Line Termination (OLT)¶

• Optical Network Termination (ONT)¶

• Optical Network Unit (ONU)¶

The following terms are used as defined in [itu-g984-3]:¶

• G-PON Encapsulation Method (GEM)¶

• GEM Port¶

• Gigabit-capable Passive Optical Network (G-PON)¶

3. New IPFIX G-PON GEM Elements

This section specifies the new IPFIX G-PON GEM IEs.¶

gponGemPti

3-bit GEM PTI content type field defined in Section 8.3.1 of [itu-g984-3]. The values are encoded in the 3 least significant bits of the IE.¶

gponGemPortId

12-bit GEM Port-ID field defined in Section 8.3.1 of [itu-g984-3].¶

4. Sample Use Cases

The IPFIX IEs gponGemPti (TBD1) or gponGemPortId (TBD2), sourceMacAddress (56), destinationMacAddress (80), ingressInterface (10), egressInterface (14) and forwardingStatus (89)[RFC5102] [RFC7270] [IANA-IPFIX], and some existing counter informations [IANA-IPFIX] providing answers to the following questions (amongst others):¶

• How many user or OAM frames are forwarded or dropped to which ONU on which egress interface and GEM Port-ID?¶

• If dropped, for which reasons?¶

The received ONU frames on an OLT are mapped and forwarded depending on GEM Port-ID to a dot1qVlanId (243) and dot1qPriority (244) upstream to the provider network.¶

5. IANA Considerations

Note to the RFC-Editor:¶

• Please replace TBD1 - TBD2 with the values allocated by IANA¶

• Please replace the [RFC-to-be] with the RFC number assigned to this document¶

     +-------+--------------------------------+
     |Element|              Name              |
     |   ID  |                                |
     +-------+--------------------------------+
     | TBD1  | gponGemPti                     |
     |       |                                |
     +-------+--------------------------------+
     | TBD2  | gponGemPortId                  |
     |       |                                |
     +-------+--------------------------------+

Table 1: New G-PON GEM IEs in the "IPFIX Information Elements" Registry

+-------+----------------------------------------------------------+
| Value |       GEM PTI Content Type Meaning         | Additional  |
|       |                                            | Information |
+-------+----------------------------------------------------------+
|  000  | User data fragment, not the end of a frame | [RFC-to-be] |
+-------+----------------------------------------------------------+
|  001  | User data fragment, end of a frame         | [RFC-to-be] |
+-------+----------------------------------------------------------+
|  010  | Reserved                                   | [RFC-to-be] |
+-------+----------------------------------------------------------+
|  011  | Reserved                                   | [RFC-to-be] |
+-------+----------------------------------------------------------+
|  100  | GEM OAM, not the end of a frame            | [RFC-to-be] |
+-------+----------------------------------------------------------+
|  101  | GEM OAM, end of a frame                    | [RFC-to-be] |
+-------+----------------------------------------------------------+
|  110  | Reserved                                   | [RFC-to-be] |
+-------+----------------------------------------------------------+
|  111  | Reserved                                   | [RFC-to-be] |
+-------+----------------------------------------------------------+

        Table 2: "IPFIX G-PON Encapsulation Method PTI" Subregistry

6. Acknowledgements

The authors would like to thank Paul Aitken for their review and valuable comments, and xxx for the implementation and validation.¶

7. Implementation Status

Note to the RFC-Editor: Please remove this section before publishing.¶

8. Security Considerations

There exists no extra security considerations regarding allocation of these new IPFIX IEs compared to [RFC7012].¶

The IEs described in this document export provider plane data metrics on how frames are being forwarded within an Optical Access Network. Applications and operators using the IEs described in this document must evaluate the sensitivity of this information in their implementation context, and apply the data-at-rest storage guidance in Section 11.8 of [RFC7011] as appropriate.¶

Appendix A. IPFIX Encoding Examples

TBD.¶

Authors' Addresses