Network Working Group S. Gringeri Internet-Draft J. Whittaker Intended status: Standards Track Verizon Expires: 21 April 2025 C. Schmutzer, Ed. B. Vasudevan P. Brissette Cisco Systems, Inc. 18 October 2024 Ethernet VPN Signalling Extensions for Bit-stream VPWS draft-schmutzer-bess-bitstream-vpws-signalling-02 Abstract 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). 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 21 April 2025. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. Gringeri, et al. Expires 21 April 2025 [Page 1] Internet-Draft Bit-stream EVPN-VPWS October 2024 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction and Motivation . . . . . . . . . . . . . . . . . 3 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Solution Requirements . . . . . . . . . . . . . . . . . . . . 6 5. Service Types . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1. Ethernet Service Types . . . . . . . . . . . . . . . . . 7 5.2. Fibre Channel Service Types . . . . . . . . . . . . . . . 8 5.3. OTN Service Types . . . . . . . . . . . . . . . . . . . . 8 5.4. TDM Service Types . . . . . . . . . . . . . . . . . . . . 9 5.5. SONET/SDH Service Types . . . . . . . . . . . . . . . . . 9 6. Reuse of existing BGP EVPN-VPWS Capabilities . . . . . . . . 10 7. BGP Bit-stream Attribute . . . . . . . . . . . . . . . . . . 11 7.1. PW Type TLV . . . . . . . . . . . . . . . . . . . . . . . 12 7.2. PLE/CEP/TDM Bitrate TLV . . . . . . . . . . . . . . . . . 12 7.3. PLE/CEP Options TLV . . . . . . . . . . . . . . . . . . . 13 7.4. TDM options TLV . . . . . . . . . . . . . . . . . . . . . 15 7.5. PLE/CEP/TDM Payload Bytes TLV . . . . . . . . . . . . . . 15 7.6. Endpoint-ID TLV . . . . . . . . . . . . . . . . . . . . . 16 8. Control Plane Operations . . . . . . . . . . . . . . . . . . 17 8.1. VPWS Setup and Teardown . . . . . . . . . . . . . . . . . 17 8.2. Misconnection Handling . . . . . . . . . . . . . . . . . 18 8.3. Failure Scenarios . . . . . . . . . . . . . . . . . . . . 18 8.3.1. Single-homed CEs . . . . . . . . . . . . . . . . . . 18 8.3.2. Multi-homed CEs . . . . . . . . . . . . . . . . . . . 19 9. Mandatory Control Word . . . . . . . . . . . . . . . . . . . 20 10. Security Considerations . . . . . . . . . . . . . . . . . . . 20 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 13.1. Normative References . . . . . . . . . . . . . . . . . . 21 13.2. Informative References . . . . . . . . . . . . . . . . . 22 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Gringeri, et al. Expires 21 April 2025 [Page 2] Internet-Draft Bit-stream EVPN-VPWS October 2024 1. Introduction and Motivation Virtual Private Wire Service (VPWS) is a widely deployed technology for providing point-to-point (P2P) services for various layer 2 and also layer 1 technologies. Initially VPWS were define in the Pseudowire Emulation Edge-to-Edge (PWE3) architecture [RFC3985] for Frame Relay, ATM, HDLC, PPP, Ethernet, TDM and SONET/SDH. How Ethernet VPWS can be signalled using Ethernet VPN has already been specified in [RFC8214]. This document is defining necessary signalling extensions for Ethernet VPN to also support the following bit-stream VPWS instance types: * TDM services using SAToP [RFC4553] * TDM services using CESoP [RFC5086] * SONET/SDH services using CEP [RFC4842] * Private line services using PLE [I-D.ietf-pals-ple] A generic VPWS reference model similar to the one defined in [RFC3985] and [I-D.ietf-pals-ple] is shown in Figure 1. Data received from CEs is encapsulated by PEs into the respective VPWS established between the attachment circuits of the local and remote PE and transmitted across the Packet Switched Network (PSN) using a PSN tunnel. CE1 & CE2 physical CE3 & CE4 physical interfaces interfaces | <------- PSN tunnels -----> | | +-----------------------------+ | | | | | +---+ v +---+ +---+ v +---+ |CE1|-----| |.......... VPWS1 ........|PE2|-----|CE3| +---+ | | +---+ +---+ |PE1| packet switched network | +---- | | +---+ +---+ |CE2|-----| |.......... VPWS2 ........|PE3|-----|CE4| +---+ +---+ +---+ +---+ ^ | | ^ | +-----------------------------+ | | | attachment attachment circuits circuits | | |<------ emulated services ------>| Gringeri, et al. Expires 21 April 2025 [Page 3] Internet-Draft Bit-stream EVPN-VPWS October 2024 Figure 1: VPWS Reference Model 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 * AIS - Alarm Indication Signal * AFI - Address Family Identifier * ATM - Asynchronous Transfer Mode * BGP - Border Gateway Protocol * CBR - Constant Bit Rate * CE - Customer Edge * CEP - SONET/SDH Circuit Emulation over Packet * CESoP - Structure-aware TDM Circuit Emulation Service over Packet Switched Network * DF - Designated Forwarder * EAD - Ethernet Auto Discovery * FC - Fibre Channel * EBM - Equipped Bit Mask * EVI - EVPN Instance * EVPN - Ethernet Virtual Private Network * HDLC - High-level Data Link Control * LDP - Label Distribution Protocol * MPLS - Multi Protocol Label Switching * MTU - Maximum Transmission Unit Gringeri, et al. Expires 21 April 2025 [Page 4] Internet-Draft Bit-stream EVPN-VPWS October 2024 * NDF - Non-Designated Forwarder * NLRI - Network Layer Reachability Information * OC - Optical Carrier * ODUk - Optical Data Unit k * PDH - Plesiochronous Digital Hierarchy * PE - Provider Edge * PLE - Private Line Emulation * PPP - Point-to-Point Protocol * PSN - Packet Switched Network * PW - Pseudo Wire * PWE3 - Pseudowire Emulation Edge-to-Edge * P2P - Point-to-Point * RTP - Realtime Transport Protocol * SAFI - Subsequent Address Family Identifier * SAToP - Structure Agnostic TDM over Packet * SDH - Synchronous Digital Hierarchy * SONET - Synchronous Optical Network * SRv6 - Segment Routing over IPv6 Dataplane * STM - Synchronous Transport Module * STS - Synchronous Transport Signal * TDM - Time Division Multiplexing * TLV - Type Length Value * UNE - Unequipped * VC - Virtual Circuit Gringeri, et al. Expires 21 April 2025 [Page 5] Internet-Draft Bit-stream EVPN-VPWS October 2024 * VPWS - Virtual Private Wire Service * VT - Virtual Tributary 4. Solution Requirements To avoid redefining PW types for [RFC8214] the notion of "PW type" from [RFC8077] is maintained and only a new PW type for [I-D.ietf-pals-ple] has been assigned by IANA. * TBD1 - Private Line Emulation (PLE) over Packet The concept of "CEP type" from [RFC5287] to distinguish different connection types that use the same PW type is adopted. In this document it is referred to as "PLE/CEP type". Two new connection types are defined in Section 7.3. To unambiguously identify the rate of an attachment circuit, also the concept of "CEP/TDM bitrate" from [RFC5287] is adopted and called "PLE/CEP/TDM bitrate" herein. The VPWS signalling requirements are as follows: * Implementations MUST support MPLS for service multiplexing and as PSN underlay. * The VPWS instance MAY be signalled as SRv6 overlay service per [RFC9252] leveraging the mechanisms specified in [RFC8986] and considering - Use of endpoint and encapsulation behaviors specified in [I-D.ietf-pals-ple] - SRv6 as underlay PSN * The use of control word MUST be signalled, as defined in [RFC4553], [RFC5086], [RFC4842] and [I-D.ietf-pals-ple]. * The PW type MUST be signalled and the PE nodes MUST validate that the PW type is identical on both endpoints. * For CEP [RFC4842] and PLE [I-D.ietf-pals-ple] the PLE/CEP type MUST be signalled and the PE nodes MUST validate that the PLE/CEP type is identical on both endpoints. Gringeri, et al. Expires 21 April 2025 [Page 6] Internet-Draft Bit-stream EVPN-VPWS October 2024 * The PLE/CEP/TDM bitrate MUST be signalled if the attachment circuit cannot be unambiguously identified from the PW type alone and the PE nodes MUST validate that the attachment circuit is identical on both endpoints. * A non-default payload size MAY be signalled. Both PE nodes MUST validate that the payload size is identical on both endpoints. * A locally configured connection identifier as defined in Section 7.6 SHOULD be sent to the remote PE node. A locally configured expected identifier MAY be used to identify a misconnection by comparing it with the identifier received from the remote PE node. * The multi-homed PE scenarios per [RFC7432] and [RFC8214] SHOULD be supported where the load-balancing mode single-active MUST be supported. Port-active load-balancing mode MAY also be supported. * Multi-homed PE scenarios non-revertive mode MUST and revertive mode SHOULD be supported in compliance to [I-D.ietf-bess-evpn-pref-df]. 5. Service Types The following sections list all possible service types that are supported by the proposed signalling mechanisms. 5.1. Ethernet Service Types +==============+=====================+======+=========+=============+ | Service | Encapsulation | PW | PLE/CEP | PLE/CEP/TDM | | Type | Standard | Type | Type | Bitrate | +==============+=====================+======+=========+=============+ | 1000Base-X | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 1,250,000 | +--------------+---------------------+------+---------+-------------+ | 10GBASE-R | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 10,312,500 | +--------------+---------------------+------+---------+-------------+ | 25GBASE-R | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 25,791,300 | +--------------+---------------------+------+---------+-------------+ | 40GBASE-R | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 41,250,000 | +--------------+---------------------+------+---------+-------------+ | 50GBASE-R | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 51,562,500 | +--------------+---------------------+------+---------+-------------+ | 100GBASE-R | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 103,125,000 | +--------------+---------------------+------+---------+-------------+ | 200GBASE-R | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 212,500,000 | +--------------+---------------------+------+---------+-------------+ | 400GBASE-R | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 425,000,000 | Gringeri, et al. Expires 21 April 2025 [Page 7] Internet-Draft Bit-stream EVPN-VPWS October 2024 +--------------+---------------------+------+---------+-------------+ Table 1: Ethernet Service Types 5.2. Fibre Channel Service Types +==============+=====================+======+=========+=============+ | Service | Encapsulation | PW | PLE/CEP | PLE/CEP/TDM | | Type | Standard | Type | Type | Bitrate | +==============+=====================+======+=========+=============+ | 1GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 1,062,500 | +--------------+---------------------+------+---------+-------------+ | 2GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 2,125,000 | +--------------+---------------------+------+---------+-------------+ | 4GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 4,250,000 | +--------------+---------------------+------+---------+-------------+ | 8GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 8,500,000 | +--------------+---------------------+------+---------+-------------+ | 10GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 10,518,750 | +--------------+---------------------+------+---------+-------------+ | 16GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 14,025,000 | +--------------+---------------------+------+---------+-------------+ | 32GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 28,050,000 | +--------------+---------------------+------+---------+-------------+ | 64GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 57,800,000 | +--------------+---------------------+------+---------+-------------+ | 128GFC | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 112,200,000 | +--------------+---------------------+------+---------+-------------+ Table 2: Fibre Channel Service Types 5.3. OTN Service Types +==============+=====================+======+=========+=============+ | Service | Encapsulation | PW | PLE/CEP | PLE/CEP/TDM | | Type | Standard | Type | Type | Bitrate | +==============+=====================+======+=========+=============+ | ODU0 | [I-D.ietf-pals-ple] | TBD1 | 0x4 | 1,244,160 | +--------------+---------------------+------+---------+-------------+ | ODU1 | [I-D.ietf-pals-ple] | TBD1 | 0x4 | 2,498,775 | +--------------+---------------------+------+---------+-------------+ | ODU2 | [I-D.ietf-pals-ple] | TBD1 | 0x4 | 10,037,273 | +--------------+---------------------+------+---------+-------------+ | ODU2e | [I-D.ietf-pals-ple] | TBD1 | 0x4 | 10,399,525 | +--------------+---------------------+------+---------+-------------+ | ODU3 | [I-D.ietf-pals-ple] | TBD1 | 0x4 | 40,319,218 | +--------------+---------------------+------+---------+-------------+ | ODU4 | [I-D.ietf-pals-ple] | TBD1 | 0x4 | 104,794,445 | Gringeri, et al. Expires 21 April 2025 [Page 8] Internet-Draft Bit-stream EVPN-VPWS October 2024 +--------------+---------------------+------+---------+-------------+ Table 3: OTN Service Types 5.4. TDM Service Types +===============+===============+========+=========+=============+ | Service Type | Encapsulation | PW | PLE/CEP | PLE/CEP/TDM | | | Standard | Type | Type | Bitrate | +===============+===============+========+=========+=============+ | CESoPSN basic | [RFC5086] | 0x0015 | N/A | N | | mode | | | | | +---------------+---------------+--------+---------+-------------+ | CESoPSN with | [RFC5086] | 0x0017 | N/A | N | | CAS | | | | | +---------------+---------------+--------+---------+-------------+ | E1 | [RFC4553] | 0x0011 | N/A | 32 | +---------------+---------------+--------+---------+-------------+ | DS1 | [RFC4553] | 0x0012 | N/A | 24 | +---------------+---------------+--------+---------+-------------+ | DS1 octet- | [RFC4553] | 0x0012 | N/A | 25 | | aligned | | | | | +---------------+---------------+--------+---------+-------------+ | E3 | [RFC4553] | 0x0013 | N/A | 535 | +---------------+---------------+--------+---------+-------------+ | T3 | [RFC4553] | 0x0014 | N/A | 699 | +---------------+---------------+--------+---------+-------------+ Table 4: TDM Service Types 5.5. SONET/SDH Service Types +===========+=====================+========+=========+=============+ | Service | Encapsulation | PW | PLE/CEP | PLE/CEP/TDM | | Type | Standard | Type | Type | Bitrate | +===========+=====================+========+=========+=============+ | VT1.5/ | [RFC4842] | 0x0010 | 0x1 | 26 | | VC-11 | | | | | +-----------+---------------------+--------+---------+-------------+ | VT2/VC-12 | [RFC4842] | 0x0010 | 0x1 | 35 | +-----------+---------------------+--------+---------+-------------+ | VT3 | [RFC4842] | 0x0010 | 0x1 | 53 | +-----------+---------------------+--------+---------+-------------+ | VT6/VC-2 | [RFC4842] | 0x0010 | 0x1 | 107 | +-----------+---------------------+--------+---------+-------------+ | STS-Nc | [RFC4842] | 0x0010 | 0x0 | 783*N | +-----------+---------------------+--------+---------+-------------+ | VC-4-Mc | [RFC4842] | 0x0010 | 0x0 | 783_3_M | Gringeri, et al. Expires 21 April 2025 [Page 9] Internet-Draft Bit-stream EVPN-VPWS October 2024 +-----------+---------------------+--------+---------+-------------+ | Fract. | [RFC4842] | 0x0010 | 0x2 | 783 | | STS1/VC-3 | | | | | +-----------+---------------------+--------+---------+-------------+ | Fract. | [RFC4842] | 0x0010 | 0x2 | 783*4 | | VC-4 | | | | | +-----------+---------------------+--------+---------+-------------+ | Async | [RFC4842] | 0x0010 | 0x2 | 783 | | STS1/VC-3 | | | | | +-----------+---------------------+--------+---------+-------------+ | OC3/STM1 | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 155,520 | +-----------+---------------------+--------+---------+-------------+ | OC12/STM4 | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 622,080 | +-----------+---------------------+--------+---------+-------------+ | OC48/ | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 2,488,320 | | STM16 | | | | | +-----------+---------------------+--------+---------+-------------+ | OC192/ | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 9,953,280 | | STM64 | | | | | +-----------+---------------------+--------+---------+-------------+ | OC768/ | [I-D.ietf-pals-ple] | TBD1 | 0x3 | 39,813,120 | | STM256 | | | | | +-----------+---------------------+--------+---------+-------------+ Table 5: Ethernet Service Types 6. Reuse of existing BGP EVPN-VPWS Capabilities A PLE VPWS instance is identified by a pair of per-EVI ethernet A-D routes advertised by two PE nodes establishing the VPWS in accordance to [RFC8214]. The EVPN layer 2 attribute extended community defined in [RFC8214] MUST be supported and added to the per-EVI ethernet A-D route. * C bit set to 1 to indicate Control Word MUST be present. * P and B bits are set by dual-homing PEs as per [RFC8214] and [I-D.ietf-bess-evpn-pref-df] * L2 MTU MUST be set to zero and ignored by the receiver For SRv6 related aspects see Section 6.1.2 of [RFC9252]. Gringeri, et al. Expires 21 April 2025 [Page 10] Internet-Draft Bit-stream EVPN-VPWS October 2024 7. BGP Bit-stream Attribute To exchange and validate bit-stream specific attachment circuit parameters during the VPWS setup, a new BGP path attribute called "BGP Bit-stream attribute" is defined. The BGP Bit-stream attribute is an optional and transitive BGP path attribute with the attribute type codepoint TBD2. The BGP Bit-stream attribute can only be attached to Ethernet Auto- Discovery (A-D) routes (Route type 1) defined in [RFC7432]. The usage for other route types and Address Family Identifier (AFI) / Subsequent Address Family Identifier (SAFI) combinations is not allowed unless specified in future specifications. The format is defined as a set of Type/Length/Value (TLV) triplets, described in the following sections and listed in Table 6. This attribute SHOULD only be included with EVPN Network Layer Reachability Information (NLRI). +==========+===============================+========+===========+ | TLV Type | Name | Length | Mandatory | +==========+===============================+========+===========+ | 1 | PW Type TLV | 3 | Y | +----------+-------------------------------+--------+-----------+ | 2 | PLE/CEP/TDM Bitrate TLV | 5 | Y | +----------+-------------------------------+--------+-----------+ | 3 | PLE/CEP Options TLV | 3 | Y 1* | +----------+-------------------------------+--------+-----------+ | 4 | TDM Options TLV | 13 | Y 2* | +----------+-------------------------------+--------+-----------+ | 5 | PLE/CEP/TDM Payload Bytes TLV | 3 | N | +----------+-------------------------------+--------+-----------+ | 6 | Endpoint-ID TLV | 0..80 | N | +----------+-------------------------------+--------+-----------+ Table 6: BGP Bit-stream attribute TLV 1* PLE/CEP only 2* TDM only For a particular PSN it is expected that the network operator will choose a common set of parameters per VPWS type, hence efficient BGP update packing as discussed in Section 12 of [RFC4277] is expected to happen. Gringeri, et al. Expires 21 April 2025 [Page 11] Internet-Draft Bit-stream EVPN-VPWS October 2024 7.1. PW Type TLV The PW Type TLV MUST be present in the BGP Bit-stream attribute to signal what type of VPWS instance has to be established. Valid PW types for the mechanisms described in this document can be found in Section 5. The PW Type TLV format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R| PW Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: PW Type TLV Type : 1 Length : 6 The total length in octets of the value portion of the TLV. Reserved / R : For future use. MUST be set to ZERO and ignored by receiver. PW Type : A 15-bit quantity containing a value that represents the type of VPWS. Assigned Values are specified in "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)" [RFC4446]. 7.2. PLE/CEP/TDM Bitrate TLV The PLE/CEP/TDM Bitrate TLV is MANDATORY but MAY be omitted if the attachment circuit type can be unambiguously derived from the PW Type carried in the PW Type TLV. The PLE/CEP/TDM Bitrate TLV format is shown in Figure 3. Gringeri, et al. Expires 21 April 2025 [Page 12] Internet-Draft Bit-stream EVPN-VPWS October 2024 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PLE/CEP/TDM Bitrate | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: PLE/CEP/TDM Bitrate TLV Type : 2 Length : 8 The total length in octets of the value portion of the TLV. Reserved : 8-bit field for future use. MUST be set to ZERO and ignored by receiver. PLE/CEP/TDM Bitrate : A four byte field denoting the data rate of the emulated service. Rules defined in [RFC5287] do apply for signalling TDM VPWS. Rules for CEP VPWS are defined in [RFC4842]. - For PLE [PLE] the bitrate MUST be set to the data rate in units of 1-kbps of the PLE payload. - Guidelines for setting the bitrate for SAToP VPWS and CESoP VPWS can be found in [RFC5287]. And for CEP VPWS in [RFC4842]. 7.3. PLE/CEP Options TLV The PLE/CEP Options TLV MUST be present when signalling CEP and PLE VPWS instances. The PLE/CPE Options TLV format is shown in Figure 4. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PLE/CEP Options | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4: PLE/CEP Options TLV Gringeri, et al. Expires 21 April 2025 [Page 13] Internet-Draft Bit-stream EVPN-VPWS October 2024 Type : 3 Length : 6 The total length in octets of the value portion of the TLV. Reserved : 8-bit field for future use. MUST be set to ZERO and ignored by receiver. PLE/CEP Options : A two byte field with the format as shown in Figure 5 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 5: PLE/CEP Options AIS, UNE, RTP, EBM : These bits MUST be set to zero and ignored by the receiver except for CEP VPWS. Guidelines for CEP are defined in [RFC4842] 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 except for CEP VPWS. Guidelines for CEP are defined in [RFC4842] Gringeri, et al. Expires 21 April 2025 [Page 14] Internet-Draft Bit-stream EVPN-VPWS October 2024 7.4. TDM options TLV Whether when signalling TDM VPWS the TDM Options TLV MUST be present or MAY be omitted when signalling TDM VPWS instances is defined in [RFC5287]. The TDM Options TLV format is shown in Figure 6. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | TDM Options | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: TDM Options TLV Type : 4 Length : 16 The total length in octets of the value portion of the TLV. Reserved : 8-bit field for future use. MUST be set to ZERO and ignored by receiver. TDM Options : A twelve byte field with the format as defined in {Section 3.8 of RFC5287} 7.5. PLE/CEP/TDM Payload Bytes TLV The PLE/CEP/TDM Payload Bytes TLV MAY be included if a non-default payload size is to be used. If this TLV is omitted then the default payload sizes defined in [RFC4553], [RFC5086], [RFC4842] and [PLE] MUST be assumed. The format of the PLE/CEP/TDM Payload Bytes TLV is shown in Figure 7. Gringeri, et al. Expires 21 April 2025 [Page 15] Internet-Draft Bit-stream EVPN-VPWS October 2024 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PLE/CEP/TDM Payload Bytes | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7: PLE/CEP/TDM Payload Bytes TLV Type : 5 Length : 6 The total length in octets of the value portion of the TLV. Reserved : 8-bit field for future use. MUST be set to ZERO and ignored by receiver. PLE/CEP/TDM Payload Bytes : A two byte field denoting the desired payload size to be used. Rules defined in [RFC5287] do apply for signalling TDM VPWS. Rules for CEP VPWS are defined in [RFC4842]. 7.6. Endpoint-ID TLV The Endpoint-ID TLV MAY be included to allow for misconnection detection. The Endpoint-ID TLV format is shown in Figure 8. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + // Endpoint Identifier (variable) // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8: Endpoint-ID TLV Type : 6 Length : 3-83 The total length in octets of the value portion of the TLV. Gringeri, et al. Expires 21 April 2025 [Page 16] Internet-Draft Bit-stream EVPN-VPWS October 2024 Endpoint Identifier : Arbitrary string of variable length from 0 to 80 octets used to describe the attachment circuit to the remote PE node. 8. Control Plane Operations The deployment model shown in figure 3 of [RFC8214] does equally apply to the operations defined in this document. 8.1. VPWS Setup and Teardown After an attachment circuit has been configured to be part of a VPWS instance and has not declared any local defect, the PE node announces its endpoint using a per-EVI ethernet A-D route to other PEs in the PSN via BGP. The Ethernet Tag ID is set to the VPWS instance identifier and the BGP Bit-stream attribute is included to carry mandatory and optional Bit-stream specific attachment circuit parameters. Both endpoints receiving the EVPN per-EVI A-D route, validate the end to end connectivity by comparing BGP Bit-stream attributes. Upon successful validation, the VPWS instance comes up and traffic can flow through the PSN. In the scenario where the validation phase fails, the remote PE reachability information is simply ignored and dismissed as a destination candidate. The VPWS instance validation is performed as follow: * The mandatory PW type parameter MUST be identical * The mandatory PLE/CEP/TDM Bitrate parameter MUST be identical. This MAY be skipped if this parameter was not signalled because the attachment circuit rate can be unambiguously derived from the PW type [RFC5287]. * For CEP and PLE, the mandatory CEP/PLE Type parameter signalled via the CEP/PLE Options TLV MUST be identical * If the payload size was signalled via the optional PLE/CEP/TDM Payload Bytes TLV it MUST be identical and supported by the PE node. Else the default payload size MUST be assumed. If any of the previous statements is not true or any of the signal CEP/PLE or TDM options is not supported by the PE node, the VPWS instance must stay down and a appropriate defect MUST be declared. Gringeri, et al. Expires 21 April 2025 [Page 17] Internet-Draft Bit-stream EVPN-VPWS October 2024 PLE is structure agnostic for SONET/SDH service types and hence cannot validate whether a mix of SONET and SDH attachment circuits are connected (by incident) via VPWS. The detection of such misconfiguration is the responsibility of the operator managing the CE nodes. In case of multi-homed CEs the mechanisms defined in [RFC8214] apply but are limited to the single-active and port-active scenarios. Whenever the VPWS instance configuration is removed, the PE node MUST withdraw its associated per-EVI ethernet A-D route. 8.2. Misconnection Handling In circuit switched networks it is a common requirement to have the ability to check if the correct two endpoints got connected via a circuit. To confirm that the established bit-stream VPWS service is connecting the appropriate pair of attachment circuits, a Endpoint-ID string MAY be configured on each attachment circuit and communicated to the peer PE node using the Endpoint-ID TLV defined in Section 7.6. Each endpoint MAY be configured to compare the Endpoint-ID received from the peer PE node to a locally configured expected Endpoint-ID and raise a fault (defect) when the IDs don't match. When a fault is raised, the R bit in the control word must bet set to 1 (backward defect indication) for the VPWS packets sent to the peer PE node. Each endpoint MAY be configured to only compare and report mismatches, but not to raise a fault. 8.3. Failure Scenarios 8.3.1. Single-homed CEs Whenever a attachment circuit does declare a local fault the following operations MUST happen: * Operations defined in [RFC4553], [RFC5086], [RFC4842] and [I-D.ietf-pals-ple] MUST happen * The per-EVI ethernet A-D route MAY be withdrawn Whenever the CE-bound IWF does enter packet loss state the operations defined in [RFC4553], [RFC5086], [RFC4842] and [I-D.ietf-pals-ple] MUST happen. Gringeri, et al. Expires 21 April 2025 [Page 18] Internet-Draft Bit-stream EVPN-VPWS October 2024 8.3.2. Multi-homed CEs Figure 9 demonstrates a multi-homing scenario. CE1 is connected to PE1 and PE2 where PE1 is the designated forwarder while PE2 is the non designated forwarder. PSN +---------+ DF +---+ | | +---+ +---+ +--|PE1|----|---------|---|PE3|---|CE2| +---+/ +---+ | VPWS1/| +---+ +---+ |CE1| | / | +---+\ +---+ | / | +--|PE2|----|-----+ | NDF +---+ | | +---------+ Figure 9: EVPN-VPWS Multi-homing Redundancy In Figure 9 PE1 and PE2 are configured for single-active load- balancing mode. Both PEs are advertising a per-ES ethernet A-D route with the same non-zero Ethernet Segment (ES) value and the single- active bit set. This non-zero ES value is called Ethernet Segment Identifier (ESI). In this example PE1 is elected as Designated Forwarder (DF) for the shared ESI whereas PE2 is the Non-Designated Forwarder (NDF) for that segment. The signalling of primary / backup follows exactly the procedure defined in [RFC8214] where P and B bits of the layer 2 attribute extended community are used to settle proper connectivity. Upon link failure between CE1 and PE1, PE1 and PE2 follows EVPN Ethernet Segment DF Election procedures described in [RFC8214] and [I-D.ietf-bess-evpn-pref-df] for EVPN-VPWS. PE1 leverage mass- withdraw mechanism to tell PE3 to steer traffic over backup connectivity. The per-EVI ethernet A-D route advertisement remains intact. The main purpose is to keep reachability information available for fast convergence purpose. Therefore, the per-EVI ethernet A-D route MAY be withdrawn only under local fault and MUST be withdraw when the circuit is unconfigured. Port-active operation happens in the same way as single-active load- balancing mode described before but at the port level instead of being at the sub-interface level. Gringeri, et al. Expires 21 April 2025 [Page 19] Internet-Draft Bit-stream EVPN-VPWS October 2024 9. Mandatory Control Word Both Section 18 of [RFC7432] and Section 3.1 of [RFC8214] do provide guidance on when the use of control should be signalled. As the bit-stream VPWS types signalled via the mechanisms described in this document mandate a control word to be present, the use of control word MUST always be signalled independent of the underlying PSN characteristics. 10. Security Considerations The same Security Considerations described in [RFC8214] are valid for this document. 11. IANA Considerations This document defines a new BGP path attribute known as the "Bit- stream attribute". IANA is requested to assign the following from the "BGP Path Attributes" registry (see https://www.iana.org/assignments/bgp-parameters/bgp- parameters.xhtml#bgp-parameters-2). +=======+============+===============+ | Value | Code | Reference | +=======+============+===============+ | TBD2 | Bit-stream | this document | +-------+------------+---------------+ Table 7 This document also defines a new PW Type for PLE VPWS. IANA is requested to assign the following from the "MPLS Pseudowire Types" registry (see https://www.iana.org/assignments/pwe3-parameters/ pwe3-parameters.xhtml#pwe3-parameters-2). +=========+=============+===============+ | PW Type | Description | Reference | +=========+=============+===============+ | TBD2 | Bit-stream | this document | +---------+-------------+---------------+ Table 8 Gringeri, et al. Expires 21 April 2025 [Page 20] Internet-Draft Bit-stream EVPN-VPWS October 2024 12. Acknowledgements The authors would like to thank all reviewers, contributors and the working group for reviewing this document and providing useful comments and suggestions. 13. References 13.1. Normative References [I-D.ietf-bess-evpn-pref-df] Rabadan, J., Sathappan, S., Lin, W., Drake, J., and A. Sajassi, "Preference-based EVPN DF Election", Work in Progress, Internet-Draft, draft-ietf-bess-evpn-pref-df-13, 9 October 2023, . [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-08, 8 October 2024, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC4277] McPherson, D. and K. Patel, "Experience with the BGP-4 Protocol", RFC 4277, DOI 10.17487/RFC4277, January 2006, . [RFC4553] Vainshtein, A., Ed. and YJ. Stein, Ed., "Structure- Agnostic Time Division Multiplexing (TDM) over Packet (SAToP)", RFC 4553, DOI 10.17487/RFC4553, June 2006, . [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, April 2007, . Gringeri, et al. Expires 21 April 2025 [Page 21] Internet-Draft Bit-stream EVPN-VPWS October 2024 [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, December 2007, . [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, August 2008, . [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8214] Boutros, S., Sajassi, A., Salam, S., Drake, J., and J. Rabadan, "Virtual Private Wire Service Support in Ethernet VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017, . [RFC8986] Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer, D., Matsushima, S., and Z. Li, "Segment Routing over IPv6 (SRv6) Network Programming", RFC 8986, DOI 10.17487/RFC8986, February 2021, . [RFC9252] Dawra, G., Ed., Talaulikar, K., Ed., Raszuk, R., Decraene, B., Zhuang, S., and J. Rabadan, "BGP Overlay Services Based on Segment Routing over IPv6 (SRv6)", RFC 9252, DOI 10.17487/RFC9252, July 2022, . 13.2. Informative References [RFC1925] Callon, R., "The Twelve Networking Truths", RFC 1925, DOI 10.17487/RFC1925, April 1996, . [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, DOI 10.17487/RFC3985, March 2005, . Gringeri, et al. Expires 21 April 2025 [Page 22] Internet-Draft Bit-stream EVPN-VPWS October 2024 [RFC8077] Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP)", STD 84, RFC 8077, DOI 10.17487/RFC8077, February 2017, . Authors' Addresses Steven Gringeri Verizon United States of America Email: steven.gringeri@verizon.com Jeremy Whittaker Verizon United States of America Email: jeremy.whittaker@verizon.com Christian Schmutzer (editor) Cisco Systems, Inc. Austria Email: cschmutz@cisco.com Bharath Vasudevan Cisco Systems, Inc. Bangalore India Email: bhavasud@cisco.com Patrice Brissette Cisco Systems, Inc. Ottawa Canada Email: pbrisset@cisco.com Gringeri, et al. Expires 21 April 2025 [Page 23]