Internet-Draft LDP Extensions for PLE October 2024
Schmutzer Expires 23 April 2025 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-schmutzer-pals-ple-signaling-02
Published:
Intended Status:
Standards Track
Expires:
Author:
C. Schmutzer, Ed.
Cisco Systems, Inc.

LDP Extensions to Support Private Line Emulation (PLE)

Abstract

This document defines extension to the Pseudowire Emulation Edge-to-Edge (PWE3) control protocol [RFC4447] required for the setup of Private Line Emulation (PLE) pseudowires in MPLS networks.

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/.

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This Internet-Draft will expire on 23 April 2025.

Table of Contents

1. Introduction and Motivation

[RFC5287] has already specified extensions to the Label Distribution Protocol (LDP) for the setup of structure-agnostic TDM pseudowires specified in [RFC4533], structure-aware pseudowires specified in [RFC5086] and SONET/SDH Circuit Emulation over Packet (CEP) pseudowires in [RFC4842].

Private Line Emulation pseudowires are specified in [I-D.ietf-pals-ple]. This document focuses on the LDP definitions and extensions required for the setup of PLE pseudowires taking [RFC5287] and Section 12 of [RFC4842] as a starting point.

2. Requirements Notation

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 BCP14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

3. Terminology

to be added

4. Service Types

The following sections list all possible service types that are supported by PLE and the proposed signalling mechanisms.

4.1. Ethernet Service Types

Table 1: Ethernet Service Types
Service Type PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
1000Base-X TBD1 0x3 1,250,000
10GBASE-R TBD1 0x3 10,312,500
25GBASE-R TBD1 0x3 25,791,300
40GBASE-R TBD1 0x3 41,250,000
50GBASE-R TBD1 0x3 51,562,500
100GBASE-R TBD1 0x3 103,125,000
200GBASE-R TBD1 0x3 212,500,000
400GBASE-R TBD1 0x3 425,000,000

4.2. Fibre Channel Service Types

Table 2: Fibre Channel Service Types
Service Type PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
1GFC TBD1 0x3 1,062,500
2GFC TBD1 0x3 2,125,000
4GFC TBD1 0x3 4,250,000
8GFC TBD1 0x3 8,500,000
10GFC TBD1 0x3 10,518,750
16GFC TBD1 0x3 14,025,000
32GFC TBD1 0x3 28,050,000
64GFC TBD1 0x3 57,800,000
128GFC TBD1 0x3 112,200,000

4.3. OTN Service Types

Table 3: OTN Service Types
Service Type PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
ODU0 TBD1 0x4 1,244,160
ODU1 TBD1 0x4 2,498,775
ODU2 TBD1 0x4 10,037,273
ODU2e TBD1 0x4 10,399,525
ODU3 TBD1 0x4 40,319,218
ODU4 TBD1 0x4 104,794,445

4.4. SONET/SDH Service Types

Table 4: Ethernet Service Types
Service Type PW Type PLE/CEP Type PLE/CEP/TDM Bit-rate
OC3/STM1 TBD1 0x3 155,520
OC12/STM4 TBD1 0x3 622,080
OC48/STM16 TBD1 0x3 2,488,320
OC192/STM64 TBD1 0x3 9,953,280
OC768/STM256 TBD1 0x3 39,813,120

5. PW FEC for Setup of PLE Pseudowires

[RFC4447] does define two types of PW Forwarding Equivalent Classes (FECs)

The Group ID and the Interface Parameters are contained in separate TLVs, called the PW Grouping TLV and the Interface Parameters TLV.

Either of these types of PW FEC MAY be used for the setup of PLE PWs with the PW type TBD1 and appropriate interface parameters.

Using the generalized PW FEC allows for uniquely identifying both PW endpoints and misconnection detection.

The two endpoints MUST agree on the PW type, as both directions of the PW are required to be of the same type.

The Control bit MUST be set as PLE PW encapsulation uses a control word.

6. Interface Parameters for PLE Pseudowires

6.1. Overview

The interface parameters that are relevant for the setup of PLE pseudowires are listed in Table 5

Table 5: Relevant Interface Parameters
Interface Parameter Sub-TLV Length Description
PLE/CEP/TDM Payload Bytes 0x04 4 Section 6.2
PLE/CEP/TDM Bit-Rate 0x07 6 Section 6.3
PLE/CEP Options 0x05 4 Section 6.4

6.2. PLE/CEP/TDM Payload Bytes

The payload byte sub-TLV already defined in [RFC5287] does also apply to PLE and MAY be included if a non-default payload size is to be used. If this TLV is omitted then the default payload size defined in [I-D.ietf-pals-ple] MUST be assumed. The format of the PLE/CEP/TDM Payload Bytes sub-TLV is shown in Figure 1.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Sub-TLV Type |     Length    |  PLE/CEP/TDM Payload Bytes    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: PLE/CEP/TDM Payload Bytes sub-TLV

Type : 4

Length : 4

  • The total length in octets of the value portion of the TLV.

PLE/CEP/TDM Payload Bytes :

  • A two byte field denoting the desired payload size to be used.

6.3. PLE/CEP/TDM Bit-Rate

The bit-rate sub-TLV already defined in [RFC5287] is MANDATORY for PLE pseudowires in order to unambiguously indicate the attachment circuit type. The format of the PLE/CEP/TDM Bit-Rate sub-TLV is shown in Figure 2.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Sub-TLV Type |     Length    |      PLE/CEP/TDM Bit-rate     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     PLE/CEP/TDM Bit-rate      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: PLE/CEP/TDM Bit-Rate sub-TLV

Type : 7

Length : 6

  • The total length in octets of the value portion of the TLV.

PLE/CEP/TDM Bit-rate :

  • A four byte field denoting the data rate in units of 1-kbps

6.4. PLE/CEP Options

The options sub-TLV already defined in Section 12.3 of [RFC4842] MUST be present when signaling PLE pseudowires. The format of the PLE/CEP options sub-TLV is shown in Figure 3.

 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Sub-TLV Type |     Length    |         PLE/CEP Options       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: PLE/CEP Options sub-TLV

Type : 5

Length : 4

  • The total length in octets of the value portion of the TLV.

PLE/CEP Options :

  • A two byte field with the format as shown in Figure 4

 0                                       1
 0   1   2   3   4   5   6   7   8   9   0   1   2   3   4   5
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
|AIS|UNE|RTP|EBM|      Reserved [0:6]       |  PLE/CEP  | Async |
|   |   |   |   |                           |    Type   |T3 |E3 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Figure 4: PLE/CEP Options

AIS, UNE, RTP, EBM :

  • These bits MUST be set to zero and ignored by the receiver.

Reserved :

  • 7-bit field for future use. MUST be set to ZERO and ignored by receiver.

CEP/PLE Type :

  • Indicates the connection type for CEP and PLE. CEP connection types are defined in [RFC4842]. Two new values for PLE are defined in this document:

    • 0x3 - Basic PLE payload

    • 0x4 - Byte aligned PLE payload

Async :

  • These bits MUST be set to zero and ignored by the receiver.

7. LDP Status Codes

Per [RFC4447] in case of incompatible bit-rate the LDP status code 0x00000026 (incompatible bit-rate) and in case of incompatible PLE options the LDP status code 0x00000027 (CEP-TDM mis-configuration) has to be used to indicate the reason of failure to establish the pseudowire.

Setting of the Control bit to zero MUST result in an LDP status of 0x00000024 (Illegal C-Bit).

8. Using the PW Status TLV

The PLE PW control word carries status indications for both attachment circuits (L bit) and the PSN (R bit) indication (see [I-D.ietf-pals-ple]). Similar functionality is available via use of the PW Status TLV (see Section 5.4.2 of [RFC4447]). If the latter mechanism is employed, the signaling PE sends its peer a PW Status TLV for this PW, setting the appropriate bits (see Section 3.5 of [RFC4446]):

As long as the TDM PW interworking function is operational, usage of the Status TLV is NOT RECOMMENDED in order to avoid contention between status indications reported by the data and control plane. However, if the TDM PW interworking function (IWF) itself fails while the PWE3 control plane remains operational, a Status TLV with all of the above bits set SHOULD be sent.

9. Security Considerations

This document does not have any additional impact on the security of PWs above that of basic LDP-based setup of PWs specified in [RFC4447].

10. IANA Considerations

As already indicated in section 10 of [I-D.schmutzer-bess-bitstream-vpws-signalling], IANA is requested to assign a PW type (value TBD1) for PLE pseudowires from the "MPLS Pseudowire Types" registry.

11. Acknowledgements

to be added

12. References

12.1. Normative References

[I-D.ietf-pals-ple]
Gringeri, S., Whittaker, J., Leymann, N., Schmutzer, C., and C. Brown, "Private Line Emulation over Packet Switched Networks", Work in Progress, Internet-Draft, draft-ietf-pals-ple-09, , <https://datatracker.ietf.org/doc/html/draft-ietf-pals-ple-09>.
[I-D.schmutzer-bess-bitstream-vpws-signalling]
Gringeri, S., Whittaker, J., Schmutzer, C., Vasudevan, B., and P. Brissette, "Ethernet VPN Signalling Extensions for Bit-stream VPWS", Work in Progress, Internet-Draft, draft-schmutzer-bess-bitstream-vpws-signalling-02, , <https://datatracker.ietf.org/doc/html/draft-schmutzer-bess-bitstream-vpws-signalling-02>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC4447]
Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and G. Heron, "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", RFC 4447, DOI 10.17487/RFC4447, , <https://www.rfc-editor.org/rfc/rfc4447>.
[RFC4842]
Malis, A., Pate, P., Cohen, R., Ed., and D. Zelig, "Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Circuit Emulation over Packet (CEP)", RFC 4842, DOI 10.17487/RFC4842, , <https://www.rfc-editor.org/rfc/rfc4842>.
[RFC5287]
Vainshtein, A. and Y. Stein, "Control Protocol Extensions for the Setup of Time-Division Multiplexing (TDM) Pseudowires in MPLS Networks", RFC 5287, DOI 10.17487/RFC5287, , <https://www.rfc-editor.org/rfc/rfc5287>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.

12.2. Informative References

[RFC1925]
Callon, R., "The Twelve Networking Truths", RFC 1925, DOI 10.17487/RFC1925, , <https://www.rfc-editor.org/rfc/rfc1925>.
[RFC4446]
Martini, L., "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)", BCP 116, RFC 4446, DOI 10.17487/RFC4446, , <https://www.rfc-editor.org/rfc/rfc4446>.
[RFC4533]
Zeilenga, K. and J.H. Choi, "The Lightweight Directory Access Protocol (LDAP) Content Synchronization Operation", RFC 4533, DOI 10.17487/RFC4533, , <https://www.rfc-editor.org/rfc/rfc4533>.
[RFC5086]
Vainshtein, A., Ed., Sasson, I., Metz, E., Frost, T., and P. Pate, "Structure-Aware Time Division Multiplexed (TDM) Circuit Emulation Service over Packet Switched Network (CESoPSN)", RFC 5086, DOI 10.17487/RFC5086, , <https://www.rfc-editor.org/rfc/rfc5086>.

Author's Address

Christian Schmutzer (editor)
Cisco Systems, Inc.
Austria