PWE3 David L. Black (ed.) Internet-Draft EMC Corporation Intended status: Standard Track Linda Dunbar(ed.) Expires: August 2010 Huawei Technologies Moran Roth Ronen Solomon Corrigent Systems Munefumi Tsurusawa KDDI February 25, 2010 Encapsulation Methods for Transport of Fibre Channel frames Over MPLS Networks draft-ietf-pwe3-fc-encap-10.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on August 25, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://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 Black and Dunbar Expires August 25, 2010 [Page 1] Internet-Draft FC Encapsulation February 2010 to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the BSD License. Abstract A Fibre Channel pseudowire (PW) is used to carry Fibre Channel frames over an MPLS network. This enables service providers to take full advantage of the reliable transport of MPLS-TE/MPLS-TP to offer "emulated" Fibre Channel services. This document specifies the encapsulation of Fibre Channel PDUs within a pseudowire. It also specifies the common procedures for using a PW to provide a Fibre Channel service. The mechanisms controlling the reliable transport of Fibre Channel PW over MPLS networks can be provided by MPLS-TP. Conventions used in this document 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 0. Table of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 1.1. Transparency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 1.2. Bandwidth Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2. Reference Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 3. Encapsulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 3.1. The Control Word. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 3.2. MTU Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 3.3. Mapping of FC traffic to PW PDU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 3.4. PW failure mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4. Signaling of FC Pseudowires. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5. Timing Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6. Security Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7. Applicability Statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. IANA Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 10. Normative References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 11. Informative references. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Intellectual Property Statement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Disclaimer of Validity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Black and Dunbar Expires August 25, 2010 [Page 2] Internet-Draft FC Encapsulation February 2010 1. Introduction Fibre Channel Storage Area Networks (SAN) extension for disaster recovery has become an important potential source of network traffic. In order to meet Fibre Channel's network service requirements, such as transparency and low latency, multiple methods for encapsulating and transporting FC frames over backbone networks have been developed [FC-BB]. FC/IP, as described in [RFC3821] and [FC-BB], interconnects otherwise isolated FC SANs over IP Networks. FC/IP uses FC Frame Encapsulation, [RFC3643] to encapsulate FC frames and addresses concerns specific to tunneling FC over an IP-based network. Since such networks do not reliably deliver packets, FC/IP relies on the TCP protocol to retransmit dropped frames. Due to possible delay variation and TCP re-transmission timeouts, special timing mechanisms are required to ensure correct Fibre Channel operation over FC/IP [FC-BB]. MPLS-TP and MPLS-TE provide mechanisms for reliable transport over MPLS networks, making it possible for Fibre Channel ports to be interconnected directly over MPLS networks. A Fibre Channel pseudowire (FC PW) is a method to transparently transport FC frames over an MPLS network resulting in behavior similar to that of two FC ports are directly connected by a physical link. The result is considerably simpler control processing at both Ingress and Egress by comparison to FC/IP. This document defines the encapsulation of FC Protocol Data Units (PDU) into an MPLS pseudowire and related procedures for using PW encapsulation. The following sections describe some of the key requirements for transporting FC frames over an MPLS PSN. 1.1. Transparency Transparent emulation of an FC link is a key requirement for transporting FC frames over a carrier's network. This requires the FC PW to emulate an FC Link between two FC ports, similar to the approach defined for FC over GFPT in [FC-BB]. This results in transparent forwarding of FC frames over the MPLS PSN from both the FC Fabric and the operator's points of view. Transparency distinguishes the FC PW approach from FC/IP. An FC PW logically connects the FC port on one end of PW directly with the FC port on the other end of PW, whereas FC/IP introduces FC B_Ports at both ends of the extended FC link; each FC B_Port is logically connected to the FC port on the same side of the link extension. Black and Dunbar Expires August 25, 2010 [Page 3] Internet-Draft FC Encapsulation February 2010 1.2. Bandwidth Efficiency The bandwidth allocated to PW can be less than the rate of the attached FC port. When there is no data exchange between the two directly connected FC ports, Idle Primitive signals are continuously exchanged between the two FC ports to keep the FC Link up. In order to improve the bandwidth efficiency across the MPLS network, it is necessary for PW PE to suppress (or drop) the Idle Primitive signals generated by its adjacent FC ports. The far end PW PE regenerates Idle Primitive signals to send to its adjacent FC port as necessary, see [FC-BB]. FC link protocols may send the same FC Primitive Sequence [FC-FS-2] between two directly connected FC ports until a reply is received. To improve bandwidth efficiency, the PW PE only encapsulates a subset of the received repetitive FC Primitive Sequences to send across the PW tunnel [FC-BB]. E.g., one out of each set of four identical received primitives is sent across the MPLS network. The far end PW PE has to send the Primitive Sequences received from the WAN side, i.e. from PW tunnel, to its attached FC port continuously until a new primitive sequence or data frame is received from the WAN. Another requirement for transporting FC over an MPLS PSN is to minimize the protocol overhead to optimize the bandwidth consumed by the FC traffic. FC PW has an overhead of 16 bytes, consisting of the FC Encapsulation Header (4 bytes), the Control Word (4 bytes), the PW label (4 bytes) and the MPLS label (4 bytes). 2. Reference Model FC PW allows FC Protocol Data Units (PDUs) to be carried over an MPLS network. In addressing the issues associated with carrying a FC PDU over an MPLS network, this document assumes that a pseudowire can be provisioned statically or through signaling protocol as defined in [RFC4447]. FC PW emulates a single FC link between exactly two endpoints. This document specifies the emulated PW encapsulation for FC. Figure 1 describes the reference models which are derived from [RFC3985] to support the FC PW emulated services. FC PDUs are received by PE1's FC attachment channel, encapsulated at PE1, transported across MPLS network, decapsulated at PE2, and transmitted onward via the PE2's FC attachment channel. Black and Dunbar Expires August 25, 2010 [Page 4] Internet-Draft FC Encapsulation February 2010 |<-------------- Emulated Service ----------------->| | | | |<------- Pseudowire -------->| | | | | | | | |<-- MPLS Tunnel -->| | | | V V V V | V AC +----+ +----+ AC V +-----+ | | PE1|===================| PE2| | +-----+ | |----------|............PW1..............|----------| | | CE1 | | | | | | | | CE2 | | |----------|............PW2..............|----------| | +-----+ ^ | | |===================| | | ^ +-----+ ^ | +----+ +----+ | | ^ | | Provider Edge 1 Provider Edge 2 | | | | | | Customer | | Customer Edge 1 | | Edge 2 | | | | Native FC service Native FC service Figure 1: PWE3 FC Interface Reference Configuration The following reference model describes the termination point of each end of the PW within the PE: +-----------------------------------+ | PE | +---+ +-+ +-----+ +------+ +------+ +-+ | | |P| | | |PW ter| | MPLS | |P| | |<==|h|<=| NSP |<=|minati|<=|Tunnel|<=|h|<== From PSN | | |y| | | |on | | | |y| | C | +-+ +-----+ +------+ +------+ +-+ | E | | | | | +-+ +-----+ +------+ +------+ +-+ | | |P| | | |PW ter| | MPLS | |P| | |==>|h|=>| NSP |=>|minati|=>|Tunnel|=>|h|==> To PSN | | |y| | | |on | | | |y| +---+ +-+ +-----+ +------+ +------+ +-+ | | +-----------------------------------+ Figure 2: PW reference diagram Black and Dunbar Expires August 25, 2010 [Page 5] Internet-Draft FC Encapsulation February 2010 The Native Service Processing (NSP) function includes - suppressing the FC Idle frames received from the PE's attached FC port, - re-generating the Idle frames and send to its attached FC port when there is no FC data frames are received from PW WAN side, - selecting a subset of repetitive FC Primitive Sequences received from its attached FC port and passing them to the PW Termination Entity for both encapsulation and forwarding to the PW tunnel, and - sending the received FC Primitive Sequence received from the PW tunnel to PE's attachment FC port continuously until a new frame is received from PW tunnel. The NSP function is specified in detail by [FC-BB]. 3. Encapsulation This specification provides port to port transport of FC encapsulated traffic. There are several port types defined by Fibre Channel, including: An N_port is a port on the node (e.g. host or storage device) used with both FC-P2P or FC-SW topologies. Also known as Node port. An NL_port is a port on the node used with an FC-AL topology. Also known as Node Loop port. An F_port is a port on the switch that connects to a node point- to-point (i.e. connects to an N_port). Also known as Fabric port. An F_port is not loop capable. An FL_port is a port on the switch that connects to a FC-AL loop (i.e. to NL_ports). Also known as Fabric Loop port. E_port is the connection between two fibre channel switches. Also known as an Expansion port. When E_ports between two switches form a link, that link is referred to as an inter- switch link (ISL). Black and Dunbar Expires August 25, 2010 [Page 6] Internet-Draft FC Encapsulation February 2010 Among the port types listed above, only the following FC connections (as specified in [FC-BB]) are supported by an FC PW over MPLS: - N-Port to N-Port - N-Port to F-Port - E-Port to E-Port FC Primitive Signals and FC-Port Login handling by the NSP function within the PE is defined in [FC-BB]. This FC PW specification is limited to use with FC service classes 2, 3 and F (see [FC-FS-2]). Other FC service classes (e.g., 1, 4 and 6) MUST NOT be used with an FC PW. This FC PW specification is limited to native FC attachment links that employ the 8b/10b transmission code used by FC (see [FC-FS-2]). The protocol specified in this document is not sufficient to support attached FC links that use a 64b/66b transmission code (e.g., 10GFC); such links MUST NOT be attached to an FC PW. 3.1. The Control Word The Generic PW Control Word, as defined in "PWE3 Control Word" [RFC4385] MUST be used for FC PW to facilitate the transport of short packets (by setting the Length field as detailed below), and convey the flag bit defined below. The structure of the Control Word is as follows: 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| PT |X|0 0| Length | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3 - Control Word structure for the one-to-one mapping mode The first four bits of the PW Control Word MUST be set to 0 by the ingress PE to indicate PW data. The Flags bits are in use to convey the value of two flags, as specified below. Black and Dunbar Expires August 25, 2010 [Page 7] Internet-Draft FC Encapsulation February 2010 PT - Payload Type indication. This field identifies the payload type carried within the PW PDU. The following types are defined: PT = 0: FC data frame. PT = 1: FC login frame. PT = 2: FC Primitive Sequence. PT = 6: FC Control Frame (refer to [FC-BB] for usage). X - This bit is not used by this version of the protocol. It SHOULD be set to zero by the sender and MUST be ignored by the receiver. The fragmentation bits (bits 8-9) are not used by the FC PW protocol. These bits may be used in the future for FC specific indications as defined in [RFC4385]. The length field MUST be used for packets shorter than 64 bytes. Its processing must follow the rules defined in [RFC4385]. The sequence number is not used for FC PW and MUST be set to 0 by the ingress PE, and MUST be ignored by the egress PE. Refer to section 6 for the sequencing mechanism used for FC PW. 3.2. MTU Requirements The MPLS PSN MUST be able to transport the largest Fibre Channel encapsulation frame, including the overhead associated with the tunneling protocol. The maximum frame size without PW and MPLS labels (refer to Figure 4) is 2164 bytes. The MPLS PSN SHOULD accommodate frames of up to 2500 bytes to support future expansion of FC frames. Fragmentation, described in [RFC4623], SHALL NOT be used for FC PW, therefore the network MUST be configured with a minimum MTU that is sufficient to transport the largest encapsulation frame. 3.3. Mapping of FC traffic to PW PDU FC frames and Primitive Sequences are transported over the PW. All packet types are carried over a single PW. In addition to the PW Control Word, a FC Encapsulation Header has to be included in the frame. The FC Encapsulation Header is not used in this version of the protocol. This field SHOULD be set to zero by the sender and MUST be ignored by the receiver. Black and Dunbar Expires August 25, 2010 [Page 8] Internet-Draft FC Encapsulation February 2010 Each FC frame is mapped to a PW PDU, including the Start Of Frame (SOF) delimiter, frame header, CRC field and the End Of Frame (EOF) delimiter, as shown in figure 4. The SOF and EOF frame delimiters are each encoded into a single byte as specified in [RFC3643], except the codes for delimiters that apply only to FC service class 4 (SOFi4, SOFc4, SOFn4, EOFdt, EOFdti, EOFrt, EOFrti) MUST NOT be used. The CRC in the frame is directly from FC attachment channel, so the PW PE is not required to re-calculate the CRC or to check the CRC in the received frame either. 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 +---------------------------------------------------------------+ | FC PW Control Word | +---------------------------------------------------------------+ | FC Encapsulation Header | +---------------+-----------------------------------------------+ | SOF Code | Reserved | +---------------+-----------------------------------------------+ | | +----- FC Data Frame ----+ | | +---------------------------------------------------------------+ | CRC | +---------------+-----------------------------------------------+ | EOF Code | Reserved | +---------------+-----------------------------------------------+ Figure 4 - FC frame (SOF/EOF/CRC/Data) encapsulation within PW PDU FC Primitive Sequences and Primitive Signals are encapsulated in a PW PDU containing the encoded K28.5 character [FC-BB], followed by the encoded 3 data characters, as shown in Figure 5. Each K28.5 - Dxx.y - Dxx.y - Dxx.y set of 4 octets represents an FC ordered set, which is either a primitive signal or a primitive sequence for the FC PW. All FC ordered sets start with a K28.5 control character, but the three following Dxx.y data characters differ depending on the ordered set. Here are a couple of ordered set examples: - Receiver Ready (R_RDY) is K28.5 - D21.4 - D10.2 - D10.2 (this FC primitive signal is used for FC link flow control). - Link Reset Response(LRR) is K28.5 - D21.1 - D31.5 - D9.2 (this FC primitive sequence is used by FC link initialization and recovery protocols). Black and Dunbar Expires August 25, 2010 [Page 9] Internet-Draft FC Encapsulation February 2010 The K28.5 10b control character received from the attached FC link is encoded for the FC PW as its 8b counterpart (0xBC). The 8b encoding is also used to encode a D28.5 data word; the receiving PW PE MUST check for presence of an 8b K28.5 value (0xBC) at the start of each ordered set (see Figure 5), MUST send that value as a 10b K28.5 character on the attached FC link, and MUST send the following 3 Dxx.y 8b values as Dxx.y 10b characters on the attached FC link (i.e., Must not send the 3 Dxx.y 8b values as the 10b Kxx.y characters on the attached FC link). A PW PDU may contain one or more encoded FC Ordered sets [FC-BB]. The length field in the FC PW Control Word is used to indicate the packet length when the PW PDU contains multiple Ordered Sets. Idle Primitive Signals can be carried over the PW in the same manner as Primitive Sequences. However, [FC-BB] requires that Idle Primitive Signals be dropped by the Ingress PE and re-generated by the egress PE to save bandwidth consumed by FC (refer to [FC-BB] for further details). 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 +---------------------------------------------------------------+ | FC PW Control Word | +---------------------------------------------------------------+ | FC Encapsulation Header | +---------------+---------------+---------------+---------------+ | K28.5 | Dxx.y | Dxx.y | Dxx.y | +---------------+---------------+---------------+---------------+ | | +---- ----+ | | +---------------+---------------+---------------+---------------+ | K28.5 | Dxx.y | Dxx.y | Dxx.y | +---------------+---------------+---------------+---------------+ Figure 5 - FC Ordered Sets encapsulation within PW PDU The egress PE extracts the Primitive Sequence or Primitive Signal from the received PW PDU. For a Primitive Sequence, the PE continues transmitting the same FC Ordered Set to its attachment FC port until a FC frame or another ordered set is received over the PW. A Black and Dunbar Expires August 25, 2010 [Page 10] Internet-Draft FC Encapsulation February 2010 Primitive Signal is sent once, except that Idle Primitive Signals are sent continuously when there is nothing else to send. FC Control frames are transported over the PW, by encapsulating each frame in a PW PDU. FC PW Control Word must have PT = 6. FC Control Frame payload is generated and terminated by the corresponding FC entity. How the FC Control Frame is generated and processed are defined in [FC-BB]. 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 +---------------------------------------------------------------+ | FC PW Control Word | +---------------------------------------------------------------+ | FC Encapsulation Header | +---------------------------------------------------------------+ | | +----- FC Control Frame ----+ | | +---------------------------------------------------------------+ Figure 6 - FC Control frame encapsulation within PW PDU 3.4. PW failure mapping PW failure mapping, which are detected through PW signaling failure, PW status notifications as defined in [RFC4447], or through PW OAM mechanisms MUST be mapped to emulated signal failure indications. Sending the FC link failure indication to its attachment FC channel is performed by the NSP, as defined by [FC-BB], and is out of the scope of this document. 4. Signaling of FC Pseudowires RFC4447 specifies the use of the MPLS Label Distribution Protocol, LDP, as a protocol for setting up and maintaining pseudowires. This section describes the use of specific fields and error codes used to control FC PW. The PW Type field in the PWid FEC element and PW generalized ID FEC elements MUST be set to "FC Port Mode" as requested in section 7 below. Black and Dunbar Expires August 25, 2010 [Page 11] Internet-Draft FC Encapsulation February 2010 The Control Word is REQUIRED for FC pseudowires. Therefore the C-Bit in the PWid FEC element and PW generalized ID FEC elements MUST be set. If the C-Bit is not set the pseudowire MUST not be established and a Label Release MUST be sent with an "Illegal C-Bit" status code [RFC4447]. The Fragmentation Indicator (Parameter ID = 0x09) is specified in [RFC4446] and its usage is defined in [RFC4623]. Since fragmentation is not used in FC PW, the fragmentation indicator parameter MUST be omitted from the Interface Parameter Sub-TLV. 5. Timing Considerations Correct Fibre Channel link operation requires that the latency between CE1 and CE2 (refer to Figure 1) be: a) no more than one-half of the R_T_TOV (Receiver Transmitter Timeout Value, default value: 100 milliseconds, defined in [FC-FS]) of the attached devices for Primitive Sequences; b) no more than one-half of the E_D_TOV (Error Detect Timeout Value, default value: 2 seconds, defined in [FC-FS]) of the attached devices for frames; and c) within the R_A_TOV (Resource Allocation Timeout Value, default value: 10 seconds, defined in [FC-FS]) of the attached fabric(s), if any. An FC PW MUST adhere to these three timing requirements and MUST NOT be used in environments where high or variable latency may cause these requirements to be violated. Failure to adhere to requirement a) may result in FC link failures (e.g., FC link initialization protocol times out). Failure to adhere to requirements b) and c) may cause incorrect Fibre Channel operation, including possible corruption of stored data when Fibre Channel is used to access storage systems. The PING and PING_ACK signals defined in Section 6.4.7 of [FC-BB] MAY be used to measure the current FC pseudowire latency between the CE devices. If the measured latency violates any of the above 3 requirements, the FC PW PE MUST generate a WAN Down event as specified in [FC-BB]. The WAN Down event causes the PE to continuously send NOS (an FC primitive sequence) on the native FC link to the attached FC Port (typically an E_Port on a switch in this case). This immediately Black and Dunbar Expires August 25, 2010 [Page 12] Internet-Draft FC Encapsulation February 2010 causes the FC link that is carried by the PW to be taken down, halting transmission of FC traffic. However, it is not necessary to tear down the pseudowire itself (i.e., destroy the MPLS path set up by LDP). The state machine in Section 6.4.2 of [FC-BB] specifies the protocol used to attempt to recover from the WAN Down event (i.e., bring the WAN back up). If that protocol brings the WAN back up, FC traffic will resume and the standard FC link recovery protocol will bring the carried FC link back up. If the previous pseudowire was destroyed, attempts will be made to re-establish the path via LDP as part of recovering from the WAN Down event. If the PW round-trip latency stays above 100ms, the initialization protocol for the FC PW will repeatedly time out in attempting to recover from the WAN Down event, preventing FC recovery of the FC link carried by the PW. 6. Security Considerations FC PW does not change the security properties of the underlying MPLS PSN, rather it relies upon the PSN's mechanisms for encryption, integrity, and authentication as required. FC PW shares susceptibility to a number of pseudowire-layer attacks and implementations SHOULD use whatever mechanisms for confidentiality, integrity, and authentication are developed for PWs in general. These methods are beyond the scope of this document. The protocols used to implement security in a Fibre Channel fabric are defined in [FC-SP]. These protocols operate at higher layers of the FC hierarchy and are transparent to the FC PW. 7. Applicability Statement FC PW allows the transparent transport of point-to-point Fibre Channel ports while saving network bandwidth by removing or reducing the FC Idle Signals and Primitive Sequences. - The pair of CE devices operates as if they were directly connected by an FC link. In particular they react to Primitive Sequences on their local ACs in the standard way. - The FC PW carries only FC data frames and a single copy of a Primitive Sequence. Idle Primitive Signals encountered between FC data frames, and long streams of the same Primitive Sequence are suppressed over the PW thus saving bandwidth. Black and Dunbar Expires August 25, 2010 [Page 13] Internet-Draft FC Encapsulation February 2010 - The PW PE MUST generate Idle Primitive Signals to the FC attachment channel when there is no frame transmitted across the MPLS network. FC PW traffic should only traverse through controlled MPLS or MPLS-TP networks. The network should enforce proper policing of incoming traffic and proper network resource/bandwidth allocation so that the FC PW delivery quality can be guaranteed. To extend FC across an uncontrolled network, FC/IP SHOULD be used instead of an FC PW. This document does not provide any mechanisms for protecting FC PW against PSN outages. As a consequence, resilience of the emulated service to such outages is dependent upon MPLS-TE/MPLS-TP network. However, the NSP MAY implement a mechanism to convey the PW status to the CE, to enable faster handling of the PSN outage. 8. IANA Considerations IANA is requested to assign a new PW type as follows: PW type Description Reference -------- -------------- ---------- 0x001F FC Port Mode [FC-encap] The above value is suggested as the next available value. [Editor's Note - is this necessary?] IANA should reserve the following Sub-TLV types which were tentatively allocated for FC PW. These Sub-TLV types were used for an FC PW Selective Retransmission protocol for FC PW, that the working group has decided to eliminate. This reservation action prevents future use of these values for other purposes, just in case there are implementations of the Selective Retransmission protocol. Parameter ID Length --------- --------- 0x12 4 0x13 4 0x14 4 0x15 4 Black and Dunbar Expires August 25, 2010 [Page 14] Internet-Draft FC Encapsulation February 2010 9. Acknowledgments This document was prepared using 2-Word-v2.0.template.dot. 10. Normative References [RFC3643] Weber, R., et al, "Fibre Channel (FC) Frame Encapsulation", RFC 3643, December 2003. [RFC3985] Bryant, S., et al, "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005. [RFC3916] Xiao, X., et al, "Requirements for Pseudo Wire Emulation Edge-to-Edge (PWE3)", RFC 3916, September 2004. [RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)", RFC 4447, April 2006. [RFC4447] Martini, L., et al, "Pseudowire Setup and Maintenance using the Label Distribution Protocol (LDP)", RFC4447, April 2006. [RFC4385] Bryant, S., et al, "Pseudowire Emulation Edge-to- Edge(PWE3) Control Word for use over an MPLS PSN", RFC4385, February 2006. [RFC4623] Malis, A., Townsley, M., "PWE3 Fragmentation and Reassembly", RFC 4623, August 2006. [FC-BB] "Fibre Channel Backbone-4" (FC-BB-4), ANSI INCITS 419:2008, August 2008. [Editor's Note: will change this reference to FC-BB-6 in a future draft version.] [BCP14] Bradner, S., "Key words for use in RFCs to Indicate requirement Levels", BCP 14, RFC 2119, March 1997. [FC-FS-2] "Fibre Channel - Framing and Signaling-2 (FC-FS-2)", ANSI INCITS 424:2007, August 2007. [FC-SP] "Fibre Channel - Security Protocols" (FC-SP), ANSI INCITS 426:2007, February 2007. Black and Dunbar Expires August 25, 2010 [Page 15] Internet-Draft FC Encapsulation February 2010 11. Informative references [RFC3821] M. Rajogopal, E. Rodriguez, "Fibre Channel over TCP/IP (FCIP)", RFC 3821, July 2004. [RFC4448] Martini, L., et al, "Encapsulation Methods for Transport of Ethernet over MPLS Networks", RFC 4448, April 2006. [RFC4842] Malis, A., et al, "SONET/SDH Circuit Emulation Over Packet (CEP)", RFC 4842, April 2007. [RFC4619] Martini, L., et al, "Encapsulation Methods for Transport of Frame Relay over MPLS Networks", RFC 4619, September 2006. [RFC4717] Martini, L., et al, "Encapsulation Methods for Transport of ATM over MPLS Networks", RFC 4717, December 2006. Authors' Addresses David L. Black EMC Corporation 176 South Street Hopkinton, MA 01748 Phone: +1 (508) 293-7953 Email: black_david@emc.com Linda Dunbar (Ed.) Huawei Technologies 1700 Alma Drive, Suite 500 Plano, TX 75075, USA Phone: +1 (972) 543-5849 Email: ldunbar@huawei.com Moran Roth Corrigent Systems 101, Metro Drive San Jose, CA 95110 Phone: +1-408-392-9292 Email: moranr@corrigent.com Ronen Solomon Corrigent Systems 126, Yigal Alon st. Tel Aviv, ISRAEL Black and Dunbar Expires August 25, 2010 [Page 16] Internet-Draft FC Encapsulation February 2010 Phone: +972-3-6945316 Email: ronens@corrigent.com Munefumi Tsurusawa KDDI R&D Laboratories Inc. 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