Network Working Group Luca Martini (Editor) Internet Draft Cisco Systems, Inc. Expiration Date: August 2006 Claude Kawa (Editor) Andrew Malis (Editor) Oz Communications Tellabs February 2006 Encapsulation Methods for Transport of Frame Relay Over MPLS Networks draft-ietf-pwe3-frame-relay-07.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract A frame relay pseudo wire is a mechanism that exists between a provider's edge network nodes and support as faithfully as possible frame relay services over MPLS packet switched network (PSN). This document describes the detailed encapsulation necessary to transport frame relay packets over an MPLS network. Martini, et al. [Page 1] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 Table of Contents 1 Specification of Requirements .......................... 3 2 Co-authors ............................................. 3 3 Acronyms and Abbreviations ............................. 4 4 Introduction ........................................... 4 5 Applicability Statement ................................ 6 6 General encapsulation method ........................... 6 7 Frame Relay over MPLS PSN for the One-to-One Mode ...... 7 7.1 MPLS PSN Tunnel and PW ................................. 7 7.2 Packet Format over MPLS PSN ............................ 8 7.3 The Control Word ....................................... 9 7.4 The Martini Legacy Mode Control Word ................... 10 7.5 PW packet processing ................................... 10 7.5.1 Encapsulation of Frame relay frames .................... 10 7.5.2 Setting the sequence number ............................ 11 7.6 Decapsulation of PW packets ............................ 11 7.6.1 Processing the sequence number ......................... 12 7.6.2 Processing of the Length Field by the Receiver ......... 12 7.7 MPLS Shim EXP Bit Values ............................... 13 7.8 MPLS Shim S Bit Value .................................. 13 7.9 Control Plane Details for Frame Relay Service .......... 13 7.9.1 Frame Relay Specific Interface Parameter sub-TLV ....... 13 8 Frame Relay Port Mode .................................. 14 9 Congestion Control ..................................... 14 10 IANA Considerations .................................... 15 11 Security Considerations ................................ 15 12 Full Copyright Statement ............................... 15 13 Intellectual Property Statement ........................ 16 14 Normative References ................................... 16 15 Informative References ................................. 17 16 Author Information ..................................... 18 17 Contributing Author Information ........................ 19 Martini, et al. [Page 2] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 1. Specification of Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119. Below are the definitions for the terms used throughout the document. PWE3 definitions can be found in [PWE3REQ, RFC3985]. This section defines terms specific to frame relay. - Forward direction. The forward direction is the direction taken by the frame being forwarded. - Backward direction. In frame relay it is the direction opposite to the direction taken by a frame being forwarded (see also forward direction). 2. Co-authors The following are co-authors of this document: Nasser El-Aawar Level 3 Communications, LLC Eric C. Rosen Cisco Systems Daniel Tappan Cisco Systems Thomas K. Johnson Litchfield Communications Kireeti Kompella Juniper Networks, Inc. Steve Vogelsang Laurel Networks, Inc. Vinai Sirkay Reliance Infocomm Ravi Bhat Nokia Nishit Vasavada Nokia Giles Heron Tellabs Dimitri Stratton Vlachos Mazu Networks,Inc. Chris Liljenstolpe Cable & Wireless Prayson Pate Overture Networks, Inc Martini, et al. [Page 3] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 3. Acronyms and Abbreviations BECN Backward Explicit Congestion Notification CE Customer Edge C/R Command/Response DE Discard Eligibility DLCI Data Link Connection identifier FCS Frame Check Sequence FECN Forward Explicit Congestion Notification FR Frame Relay LSP Label Switched Path LSR Label Switching Router MPLS Multiprotocol Label Switching MTU Maximum Transfer Unit NNI Network-Network Interface PE Provider Edge PSN Packet Switched Network PW Pseudo Wire PWE3 Pseudo Wire Emulation Edge to Edge POS Packet over SONET/SDH PVC Permanent Virtual Circuit QoS Quality of Service SVC Switched Virtual Circuit UNI User-Network Interface VC Virtual Circuit 4. Introduction In an MPLS or IP network, it is possible to use control protocols such as those specified in [CONTROL] to set up "Pseudo Wires" that carry the the Protocol Data Units of layer 2 protocols across the network. A number of these emulated Pseudo Wires (PW) may be carried in a single tunnel. The main functions required to support frame relay PW by a PE include: - Encapsulation of frame relay specific information in a suitable pseudo wire (PW) packet, - Transfer of a PW packet across an MPLS network for delivery to a peer PE. - Extraction of frame relay specific information from a PW packet by the remote peer PE, - Regeneration of native frame relay frames for forwarding across an egress port of the remote peer PE, - Execution of any other operations as required to support frame relay service. This document specifies the encapsulation for the emulated frame Martini, et al. [Page 4] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 relay VC over an MPLS PSN. Although different layer 2 protocols require different information to be carried in this encapsulation, an attempt has been made to make the encapsulation as common as possible for all layer 2 protocols. Other layer 2 protocols are described in separate documents. [ATM] [ETH] [PPP] The following figure describes the reference models which are derived from [RFC3985] to support the frame relay PW emulated services. |<-------------- Emulated Service ---------------->| | | | |<------- Pseudo Wire ------>| | | | | | | | |<-- PSN Tunnel -->| | | | PW End V V V V PW End | V Service +----+ +----+ Service V +-----+ | | PE1|==================| PE2| | +-----+ | |----------|............PW1.............|----------| | | CE1 | | | | | | | | CE2 | | |----------|............PW2.............|----------| | +-----+ ^ | | |==================| | | ^ +-----+ ^ | +----+ +----+ | | ^ | | Provider Edge 1 Provider Edge 2 | | | | (PE1) (PE2) | | Customer | | Customer Edge 1 | | Edge 2 | | | | Attachment Circuit (AC) Attachment Circuit (AC) native frame relay service native frame relay service Figure 1: PWE3 frame relay PVC Interface Reference Configuration Two mapping modes can be defined between frame relay VCs and pseudo wires: The first one is called "one-to-one" mapping, because there is a one-to-one correspondence between a frame relay VC and one Pseudo Wire. The second mapping is called "many-to-one" mapping or "port mode" because multiple frame relay VCs assigned to a port are mapped to one pseudo wire. The "port mode" encapsulation is identical to HDLC pseudo wire encapsulation which is described in [PPP]. Martini, et al. [Page 5] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 5. Applicability Statement Frame Relay over PW service is not intended to perfectly emulate the traditional frame relay service, but it can be used for applications that need frame relay transport service. The following are notable differences between traditional frame relay service, and the protocol described in this document: - Frame ordering can be preserved using the OPTIONAL sequence field in the control word, however implementations are not required to support this feature. - The Quality of Service model for traditional frame relay can be emulated , however this is outside the scope of this document. - A Frame Relay Port mode PW, does not process any frame relay status messages or alarms as described in [Q922] [Q933] - The frame relay BECN, and FECN bit are transparent to the MPLS network , and cannot reflect the status of the MPLS network. - Support for frame relay SVC and SPVC is outside the scope of this document. - Frame relay LMI is terminated locally in the PE connected to the frame relay attachment circuit. - The support of PVC link integrity check is outside the scope of this document. 6. General encapsulation method The general frame relay pseudo wire packet format for carrying frame relay information (user's payload and frame relay control information) between two PEs is shown in Figure 2. Martini, et al. [Page 6] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 +-------------------------------+ | | | MPLS Transport header | | (As required) | +-------------------------------+ | Pseudo Wire (PW) Header | +-------------------------------+ | Control Word | +-------------------------------+ | FR Service | | Payload | +-------------------------------+ Figure 2 - General format of frame relay encapsulation over PSN The PW packet consists of the following fields: Control word, and Payload preceded by the MPLS Transport and pseudo wire header. The meaning of the different fields is as follows: -i. MPLS Transport header is specific to the MPLS network. This header is used to switch the PW packet through the MPLS core. -ii. PW header contains an identifier for multiplexing PWs within an MPLS tunnel. -iii. Control Word contains protocol control information for providing a frame relay service. Its structure is provided in the following sections. -iv. The contents of the frame relay service payload field depends on the mapping mode. In general it contains the layer 2 frame relay frame. 7. Frame Relay over MPLS PSN for the One-to-One Mode 7.1. MPLS PSN Tunnel and PW MPLS label switched paths (LSPs) called "MPLS Tunnels" are used between PEs and within the MPLS core network for forwarding purposes of PW packets. An MPLS tunnel corresponds to "PSN Tunnel" of Figure 1. Several "Pseudo Wires" may be nested inside one MPLS tunnel. Each PW carries the traffic of a single frame relay VC. In this case the PW header is an MPLS label called the PW label. Martini, et al. [Page 7] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 7.2. Packet Format over MPLS PSN For the one-to-one mapping mode for frame relay over an MPLS network, the PW packet format is shown in Figure 3. +-------------------------------+ | MPLS Tunnel label(s) | n*4 octets (four octets per label) +-------------------------------+ | PW label | 4 octets +-------------------------------+ | Control Word | | (See Figure 4) | 4 octets +-------------------------------+ | Payload | | (Frame relay frame | | information field) | n octets | | +-------------------------------+ Figure 3 - frame relay Over MPLS PSN Packet for the One-to-One Mapping The meaning of the different fields is as follows: - MPLS Tunnel label(s) The MPLS Tunnel label(s) corresponds to the MPLS transport header of Figure 2. The label(s) is/are used by MPLS LSRs to forward a PW packet from one PE to the other. - PW Label The PW label identifies one PW (i.e. one LSP) assigned to a frame relay VC in one direction. It corresponds to the PW header of Figure 2. Together the MPLS Tunnel label(s) and PW label form an MPLS label stack [RFC3032]. - Control Word The Control Word contains protocol control information. Its structure is shown in Figure 4. - Payload The payload field corresponds to X.36/X.76 frame relay frame information field with bit/byte stuffing, frame relay header removed, and FCS removed . It is RECOMMENDED to support a frame Martini, et al. [Page 8] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 size of at least 1600 bytes. The maximum length of the payload field MUST be agreed upon by the two PEs. This can be achieved by using the MTU interface parameter when the PW is established. [CONTROL] 7.3. The Control Word The control word defined below is REQUIRED for frame relay one-to-one mode. The control word carries certain frame relay specific information that is necessary to regenerate the frame relay frame on the egress PE. Additionally, the control word also carries a sequence number that can be used to preserve sequentiality when carrying frame relay over an MPLS network. Its structure is as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 0|F|B|D|C|Res| Length | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4 - Control Word structure for the one-to-one mapping mode The meaning of the Control Word fields (Figure 4) is as follows (see also [X36 and X76] for frame relay bits): - bits 0 to 3 In the above diagram the first 4 bits MUST be set to 0 to indicate PW data. - F (bit 4) FR FECN (Forward Explicit Congestion Notification) bit. - B (bit 5) FR BECN (Backward Explicit Congestion Notification) bit. - D (bit 6) FR DE bit (Discard Eligibility) bit. - C (bit 7) FR frame C/R (Command/Response) bit. - Res (bits 8 and 9): These bits are reserved and MUST be set to 0 upon transmission and ignored upon reception. Martini, et al. [Page 9] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 - Length (bits 10 to 15) If the Pseudo Wire traverses a network link that requires a minimum frame size (a notable example is Ethernet), padding is required to reach its minimum frame size. If the frame's length (defined as the length of the layer 2 payload plus the length of the control word) is less than 64 octets, the length field MUST be set to the PW payload length. Otherwise the length field MUST be set to zero. The value of the length field, if non-zero, is used to remove the padding characters by the egress PE. - Sequence number (Bit 16 to 31) Sequence numbers provide one possible mechanism to ensure the ordered delivery of PW packets. The processing of the sequence number field is OPTIONAL. The sequence number space is a 16 bit, unsigned circular space. The sequence number value 0 is used to indicate that the sequence number check algorithm is not used. 7.4. The Martini Legacy Mode Control Word For backward compatibility to existing implementations the following version of the control word is defined as the "martini mode CW" for frame relay. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 0|B|F|D|C|Res| Length | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 4 - Control Word structure for the frame relay martini mode Note that the "B" and "F" bits are reversed. This control word format is used for PW type "Frame Relay DLCI ( Martini Mode )" 7.5. PW packet processing 7.5.1. Encapsulation of Frame relay frames The encapsulation process of a frame relay frame is initiated when a PE receives a frame relay frame from one of its frame relay UNI or NNI interfaces. The PE generates the following fields of the control word from the corresponding fields of the frame relay frame as Martini, et al. [Page 10] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 follows: - Command/Response (C/R or C) bit: The C bit is copied unchanged in the PW Control Word. - The DE bit of the frame relay frame is copied into the D bit field. However if the D bit is not already set, it MAY be set as a result of ingress frame policing. If not already set by the copy operation, setting of this bit by a PE is OPTIONAL. The PE MUST NOT clear this bit (set it to 0 if it was received with the value of 1). - The FECN bit of the frame relay frame is copied into the F bit field. However if the F bit is not already set, it MAY be set to reflect a congestion situation detected by the PE. If not already set by the copy operation, setting of this bit by a PE is OPTIONAL. The PE MUST NOT clear this bit (set it to 0 if it was received with the value of 1). - The BECN bit of the frame relay frame is copied into the B bit field. However if the B bit is not already set, it MAY be set to reflect a congestion situation detected by the PE. If not already set by the copy operation, setting of this bit by a PE is OPTIONAL. The PE MUST NOT clear this bit (set it to 0 if it was received with the value of 1). - If the PW packet length (defined as the length of the payload plus the length of the control word) is less than 64 octets, the length field MUST be set to the packet's length. Otherwise the length field MUST be set to zero. - The sequence number field is processed if the PW uses sequence numbers. [CW] - The payload of the PW packet is the contents of ITU-T Recommendations X.36/X.76 [X36] [X76] frame relay frame information field stripped from any bit or byte stuffing. 7.5.2. Setting the sequence number For a given PW, and a pair of routers PE1 and PE2, if PE1 supports packet sequencing then the procedures in [CW] section 4.1 MUST be followed. 7.6. Decapsulation of PW packets When a PE receives a PW packet, it processes the different fields of the control word in order to decapsulate the frame relay frame for transmission to a CE on a frame relay UNI or NNI. The PE performs the following actions (not necessarily in the order shown): Martini, et al. [Page 11] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 - It generates the following frame relay frame header fields from the corresponding fields of the PW packet. - The C/R bit MUST be copied in the frame relay header. - The D bit MUST be copied into the frame relay header DE bit. - The F bit MUST be copied into the frame relay header FECN bit. If the F bit is set to zero, the FECN bit may be set to one, depending on the congestion state of the PE device in the forward direction. Changing the state of this bit by a PE is OPTIONAL. - The B bit MUST be copied into the frame relay header BECN bit. If the B bit is set to zero, the BECN bit may be set to one, depending on the congestion state of the PE device in the backward direction. Changing the state of this bit by a PE is OPTIONAL. - It processes the length and sequence field, the details of which are in the following sub-sections. - It copies the frame relay information field from the contents of the PW packet payload after removing any padding. Once the above fields of a FR frame have been processed, the standard HDLC operations are performed on the frame relay frame: the HDLC header is added, any bit or byte stuffing is added as required, and the FCS is also appended to the frame. The FR frame is then queued for transmission on the selected frame relay UNI or NNI interface. 7.6.1. Processing the sequence number If a router PE2 supports receive sequence number processing, then the procedures in [CW] section 4.2 MUST be used. 7.6.2. Processing of the Length Field by the Receiver Any padding octet, if present, in the payload field of a PW packet received MUST be removed before forwarding the data. - If the Length field is set to zero then there are no padding octets following the payload field. - Else if the payload is longer then the length specified in the control word padding characters are removed based on the length field. Martini, et al. [Page 12] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 7.7. MPLS Shim EXP Bit Values If it is desired to carry Quality of Service information, the Quality of Service information SHOULD be represented in the EXP field of the PW MPLS label. If more than one MPLS label is imposed by the ingress LSR, the EXP field of any labels higher in the stack SHOULD also carry the same value. 7.8. MPLS Shim S Bit Value The ingress LSR, PE1, MUST set the S bit of the PW label to a value of 1 to denote that the PW label is at the bottom of the stack. 7.9. Control Plane Details for Frame Relay Service The PE MUST provide frame relay PVC status signaling to the frame relay network. If the PE detects a service-affecting condition for a particular DLCI, as defined in [Q933] Q.933 Annex A.5 sited in IA FRF1.1, the PE MUST communicate to the remote PE the status of the PW that corresponds to the frame relay DLCI status. The Egress PE SHOULD generate the corresponding errors and alarms as defined in [Q922] [Q933] on the egress Frame relay PVC. There are two frame relay flags to control word bit mappings described below. The legacy bit ordering scheme will be used for a PW of type 0x0001 "Frame Relay DLCI (Martini Mode)", while the new bit ordering scheme will be used for a PW of type 0x0019 "Frame Relay DLCI". The IANA allocation registry of "Pseudowire Type" is defined in [IANA] along with initial allocated values. 7.9.1. Frame Relay Specific Interface Parameter sub-TLV A separate document [CONTROL], describes the PW control, and maintenance protocol in detail including generic interface parameter sub-TLVs. The interface parameter information, when applicable, MUST be used to validate that the PEs, and the ingress and egress ports at the edges of the circuit, have the necessary capabilities to interoperate with each other. The Interface parameter TLV is defined in [CONTROL], the IANA registry with initial values for interface parameter sub-TLV types is defined in [IANA], but the frame relay specific interface parameter sub-TLV types are specified as follows: Martini, et al. [Page 13] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 - 0x08 Frame Relay Header Length Sub-TLV. An optional 16 bit value indicating the length of the FR Header expressed in octets. This OPTIONAL interface parameter Sub-TLV can have value of 2, 3, or 4, with the default being equal to 2. If this Sub-TLV is not present the default value of 2 is assumed. 8. Frame Relay Port Mode Frame relay port mode PW shares the same encapsulation as the HDLC PW, and is described in the respective document. [PPP] 9. Congestion Control As explained in [RFC3985], the PSN carrying the PW may be subject to congestion, with congestion characteristics depending on PSN type, network architecture, configuration, and loading. During congestion the PSN may exhibit packet loss that will impact the service carried by the frame relay PW. In addition, since frame relay PWs carry an variety of services across the PSN, including but not restricted to TCP/IP, they may or may not behave in a TCP-friendly manner prescribed by [RFC2914]. In the presence of services that reduce transmission rate, frame relay PWs may thus consume more than their fair share and in that case SHOULD be halted. Whenever possible, frame relay PWs should be run over traffic- engineered PSNs providing bandwidth allocation and admission control mechanisms. IntServ-enabled domains providing the Guaranteed Service (GS) or DiffServ-enabled domains using EF (expedited forwarding) are examples of traffic-engineered PSNs. Such PSNs will minimize loss and delay while providing some degree of isolation of the frame relay PW's effects from neighboring streams. It should be noted that when transporting Frame Relay, DiffServ- enabled domains may use AF (Assured Forwarding) and/or DF (Default Forwarding) instead of EF, in order to place less burden on the network and gain additional statistical multiplexing advantage. In particular, if the CIR of a Frame Relay VC is zero, then it is equivalent to a best-effort UDP over IP stream regarding congestion - the network is free to drop frames as necessary. In this case, the "DF" PHB would be appropriate in a diff-serv-TE domain. Alternatively, if the CIR of a Frame Relay VC is nonzero and the DE bit is zero in the FR header, then "AF31" would be appropriate to use, and if the CIR of a Frame Relay VC is nonzero, but the DE bit is on, then "AF32" would be appropriate [RFC3270]. Martini, et al. [Page 14] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 The PEs SHOULD monitor for congestion (by using explicit congestion notification, [VCCV], or by measuring packet loss) in order to ensure that the service using the frame relay PW may be maintained. When a PE detects significant congestion while receiving the PW PDUs, the BECN bits of the frame relay frame transmitted on the same PW SHOULD be set to notify the remote PE, and the remote frame relay switch of the congestion situation. In addition, the FECN bits SHOULD be set in the FR frames sent out the attachment circuit, to give the FR DTE a chance to adjust its transport layer advertised window if possible. If the PW has been set up using the protocol defined in [CONTROL], then procedures specified in [CONTROL] for status notification can be used to disable packet transmission on the ingress PE from the egress PE. The PW may be restarted by manual intervention, or by automatic means after an appropriate waiting time. 10. IANA Considerations This document has no IANA Actions. 11. Security Considerations PWE3 provides no means of protecting the contents or delivery of the PW packets on behalf of the native service. PWE3 may, however, leverage security mechanisms provided by the MPLS Tunnel Layer. A more detailed discussion of PW security is give in [RFC3985, CONTROL, PWE3REQ]. 12. Full Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Martini, et al. [Page 15] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 13. Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. 14. Normative References [CONTROL] Luca Martini, et al., "Pseudowire Setup and Maintenance using LDP", draft-ietf-pwe3-control-protocol-16.txt, March 2005, work in progress. [CW] "PWE3 Control Word for use over an MPLS PSN", S. Bryant, G. Swallow, D. McPherson, draft-ietf-pwe3-cw-06.txt, ( work in progress ), October 2005. [ITUG] ITU Recommendation G.707, "Network Node Interface For The Synchronous Digital Hierarchy", 1996. [RFC3032] E. Rosen, et al., RFC 3032, MPLS Label Stack encoding, January 2001. [RFC3031] E. Rosen, et al., RFC 3031, MPLS Architecture, January 2001. [IANA] "IANA Allocations for pseudo Wire Edge to Edge Emulation (PWE3)" Martini,Townsley, draft-ietf-pwe3-iana-allocation-09.txt (work in progress), April 2004 Martini, et al. [Page 16] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 [PPP] "Encapsulation Methods for Transport of PPP/HDLC Over MPLS Networks", draft-ietf-pwe3-hdlc-ppp-encap-05.txt April 2005 15. Informative References [RFC3985] Stewart Bryant, et al., PWE3 Architecture, RFC3985 [VCCV] Nadeau, T., et al."Pseudo Wire Virtual Circuit Connection Verification (VCCV)", Internet Draft draft-ietf-pwe3-vccv-08.txt, October 2005. (work in progress) [FRAG] Andrew G. Malis, et al., PWE3 Fragmentation and Reassembly, draft-ietf-pwe3-fragmentation-08.txt, February 2005, ( work in progress ). [ATM] "Encapsulation Methods for Transport of ATM Over MPLS Networks", draft-ietf-pwe3-atm-encap-05.txt April 2005 (work in progress) [ETH] "Encapsulation Methods for Transport of Ethernet Over MPLS Networks", draft-ietf-pwe3-ethernet-encap-06.txt. February 2005 (work in progress) [I233] ITU-T Recommendation I.233.1, ISDN frame relay bearer service, Geneva, October 1991. [FRF1] FRF.1.2, Frame relay PVC UNI Implementation Agreement, Frame Relay Forum, April 2000. [FRF2] FRF.2.2, Frame relay PVC UNI Implementation Agreement, Frame Relay Forum, April 2002 [FRF4] FRF.4.1, Frame relay SVC UNI Implementation Agreement, Frame Relay Forum, January 2000. [FRF10] FRF.10.1, Frame relay SVC NNI Implementation Agreement, Frame Relay Forum, January 2000. [FRF13] FRF.13, Service Level Definition Implementation Agreement, Frame Relay Forum, August 1998. [FRF14] FRF.14, Physical layer Implementation Agreement, Frame Relay Forum, December 1998. [PWE3REQ] XiPeng Xiao, et al., RFC 3916. Martini, et al. [Page 17] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 [X36] ITU-T Recommendation X.36, Interface between a DTE and DCE for public data networks providing frame relay, Geneva, 2000. [X76] ITU-T Recommendation X.76, Network-to-network interface between public data networks providing frame relay services, Geneva,2000. [Q922] ITU-T Recommendation Q.922 Specification for Frame Mode Basic call control, ITU Geneva 1995 [Q933] ITU-T Recommendation Q.933 Specification for Frame Mode Basic call control, ITU Geneva 2003 [RFC2914] S Floyd, rfc2914, "Congestion Control Principles", September 2000 [RFC3270] F. Le Faucheur, et al., rfc3270,"Multi-Protocol Label Switching (MPLS) Support of Differentiated Services",May 2002 16. Author Information Luca Martini Cisco Systems, Inc. 9155 East Nichols Avenue, Suite 400 Englewood, CO, 80112 e-mail: lmartini@cisco.com Claude Kawa OZ Communications Windsor Station 1100, de la Gauchetie`re St West Montreal QC Canada H3B 2S2 e-mail: claude.kawa@oz.com Andrew G. Malis Tellabs 90 Rio Robles Dr. San Jose, CA 95134 e-mail: Andy.Malis@tellabs.com Martini, et al. [Page 18] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 17. Contributing Author Information Kireeti Kompella Juniper Networks 1194 N. Mathilda Ave Sunnyvale, CA 94089 e-mail: kireeti@juniper.net Giles Heron Tellabs Abbey Place 24-28 Easton Street High Wycombe Bucks HP11 1NT UK e-mail: giles.heron@tellabs.com Rao Cherukuri Juniper Networks 1194 N. Mathilda Ave Sunnyvale, CA 94089 Dimitri Stratton Vlachos Mazu Networks, Inc. 125 Cambridgepark Drive Cambridge, MA 02140 e-mail: d@mazunetworks.com Chris Liljenstolpe Cable & Wireless 11700 Plaza America Drive Reston, VA 20190 e-mail: chris@cw.net Nasser El-Aawar Level 3 Communications, LLC. 1025 Eldorado Blvd. Broomfield, CO, 80021 e-mail: nna@level3.net Martini, et al. [Page 19] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 Eric C. Rosen Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA 01719 e-mail: erosen@cisco.com Dan Tappan Cisco Systems, Inc. 1414 Massachusetts Avenue Boxborough, MA 01719 e-mail: tappan@cisco.com Prayson Pate Overture Networks, Inc. 507 Airport Boulevard Morrisville, NC, USA 27560 e-mail: prayson.pate@overturenetworks.com David Sinicrope Ericsson IPI e-mail: david.sinicrope@ericsson.com Ravi Bhat Nokia e-mail: ravi.bhat@nokia.com Nishit Vasavada Nokia e-mail: nishit.vasavada@nokia.com Steve Vogelsang Laurel Networks, Inc. Omega Corporate Center 1300 Omega Drive Pittsburgh, PA 15205 e-mail: sjv@laurelnetworks.com Martini, et al. [Page 20] Internet Draft draft-ietf-pwe3-frame-relay-07.txt February 2006 Vinai Sirkay Redback Networks 300 Holger Way, San Jose, CA 95134 e-mail: sirkay@technologist.com Martini, et al. [Page 21]