]> LDP Extensions to Support Private Line Emulation (PLE) Cisco Systems, Inc.
Austria cschmutz@cisco.com
This document defines extension to the Pseudowire Emulation Edge-to-Edge (PWE3) control protocol required for the setup of Private Line Emulation (PLE) pseudowires in MPLS networks.
Introduction and Motivation has already specified extensions to the Label Distribution Protocol (LDP) for the setup of structure-agnostic TDM pseudowires specified in , structure-aware pseudowires specified in and SONET/SDH Circuit Emulation over Packet (CEP) pseudowires in . Private Line Emulation pseudowires are specified in . This document focuses on the LDP definitions and extensions required for the setup of PLE pseudowires taking and as a starting point.
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 when, and only when, they appear in all capitals, as shown here.
Terminology to be added
Service Types The following sections list all possible service types that are supported by PLE and the proposed signalling mechanisms.
Ethernet Service Types 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
Fibre Channel Service Types 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
OTN Service Types 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
SONET/SDH Service Types 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
PW FEC for Setup of PLE Pseudowires does define two types of PW Forwarding Equivalent Classes (FECs)
  • PWId FEC (FEC 128)
  • Generalized PW FEC (FEC 129)
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. 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.
Interface Parameters for PLE Pseudowires
Overview The interface parameters that are relevant for the setup of PLE pseudowires are listed in Relevant Interface Parameters
Interface Parameter Sub-TLV Length Description
PLE/CEP/TDM Payload Bytes 0x04 4
PLE/CEP/TDM Bit-Rate 0x07 6
PLE/CEP Options 0x05 4
Endpoint-ID TBD2 2-82
PLE/CEP/TDM Payload Bytes The payload byte sub-TLV already defined in 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 MUST be assumed. The format of the PLE/CEP/TDM Payload Bytes sub-TLV is shown in .
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.
PLE/CEP/TDM Bit-Rate The bit-rate sub-TLV already defined in 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 .
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
PLE/CEP Options The options sub-TLV already defined in MUST be present when signaling PLE pseudowires. The format of the PLE/CEP options sub-TLV is shown in .
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
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 . 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.
Endpoint-ID The Endpoint-ID sub-TLV MAY be included to allow for misconnection detection. The format of the Endpoint-ID sub-TLV format is shown in .
Endpoint-ID sub-TLV
Type : TBD2 Length : 2-82
  • The total length in octets of the value portion of the TLV.
Endpoint Identifier :
  • Arbitrary string of variable length from 0 to 80 octets used to describe the attachment circuit to the remote PE node.
LDP Status Codes Per 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).
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 ). Similar functionality is available via use of the PW Status TLV (see ). If the latter mechanism is employed, the signaling PE sends its peer a PW Status TLV for this PW, setting the appropriate bits (see ):
  • Pseudowire Not Forwarding
  • Local Attachment Circuit (ingress) Receive Fault
  • Local Attachment Circuit (egress) Transmit Fault
  • Local PSN-facing PW (ingress) Receive Fault
  • Local PSN-facing PW (egress) Transmit Fault
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.
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 .
IANA Considerations As already indicated in section 10 of , IANA is requested to assign a PW type (value TBD1) for PLE pseudowires from the "MPLS Pseudowire Types" registry. IANA is further requested to assign a sub-TLV type (value TBD2) for the Endpoint-ID sub-TLV from the "Pseudowire Interface Parameters Sub-TLV type" registry.
Acknowledgements to be added
References Normative References Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Circuit Emulation over Packet (CEP) This document provides encapsulation formats and semantics for emulating Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) circuits and services over MPLS. [STANDARDS-TRACK] Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP) Layer 2 services (such as Frame Relay, Asynchronous Transfer Mode, and Ethernet) can be "emulated" over an MPLS backbone by encapsulating the Layer 2 Protocol Data Units (PDU) and transmitting them over "pseudowires". It is also possible to use pseudowires to provide low-rate Time Division Multiplexed and a Synchronous Optical NETworking circuit emulation over an MPLS-enabled network. This document specifies a protocol for establishing and maintaining the pseudowires, using extensions to Label Distribution Protocol (LDP). Procedures for encapsulating Layer 2 PDUs are specified in a set of companion documents. [STANDARDS-TRACK] Control Protocol Extensions for the Setup of Time-Division Multiplexing (TDM) Pseudowires in MPLS Networks This document defines extension to the Pseudowire Emulation Edge-to-Edge (PWE3) control protocol RFC 4447 and PWE3 IANA allocations RFC 4446 required for the setup of Time-Division Multiplexing (TDM) pseudowires in MPLS networks. [STANDARDS-TRACK] Private Line Emulation over Packet Switched Networks Verizon Verizon Deutsche Telekom Cisco Systems, Inc. Ciena Corporation This document describes a method for encapsulating high-speed bit- streams as virtual private wire services (VPWS) over packet switched networks (PSN) providing complete signal transport transparency. Key words for use in RFCs to Indicate Requirement Levels In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. Ethernet VPN Signalling Extensions for Bit-stream VPWS Verizon Verizon Cisco Systems, Inc. Cisco Systems, Inc. Cisco Systems, Inc. This document specifies the mechanisms to allow for dynamic signalling of Virtual Private Wire Services (VPWS) carrying bit- stream signals over Packet Switched Networks (PSN). Informative References IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3) This document allocates the fixed pseudowire identifier and other fixed protocol values for protocols that have been defined in the Pseudo Wire Edge to Edge (PWE3) working group. Detailed IANA allocation instructions are also included in this document. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. The Lightweight Directory Access Protocol (LDAP) Content Synchronization Operation This specification describes the Lightweight Directory Access Protocol (LDAP) Content Synchronization Operation. The operation allows a client to maintain a copy of a fragment of the Directory Information Tree (DIT). It supports both polling for changes and listening for changes. The operation is defined as an extension of the LDAP Search Operation. This memo defines an Experimental Protocol for the Internet community. Structure-Aware Time Division Multiplexed (TDM) Circuit Emulation Service over Packet Switched Network (CESoPSN) This document describes a method for encapsulating structured (NxDS0) Time Division Multiplexed (TDM) signals as pseudowires over packet-switching networks (PSNs). In this regard, it complements similar work for structure-agnostic emulation of TDM bit-streams (see RFC 4553). This memo provides information for the Internet community. The Twelve Networking Truths This memo documents the fundamental truths of networking for the Internet community. This memo does not specify a standard, except in the sense that all standards must implicitly follow the fundamental truths. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.