INTERNET-DRAFT David L. Black (ed.) PWE3 WG EMC Corporation Intended Status: Standard Track Linda Dunbar(ed.) Expires: July 2011 Huawei Technologies January 11, 2011 Encapsulation Methods for Transport of Fibre Channel Traffic over MPLS Networks draft-ietf-pwe3-fc-encap-14.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." 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Black and Dunbar Expires July 2011 [Page 1] Internet-Draft FC Encapsulation January 2011 This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Abstract A Fibre Channel pseudowire (PW) is used to carry Fibre Channel traffic over an MPLS network. This enables service providers to take advantage of the reliable transport of MPLS-TE/MPLS-TP to offer "emulated" Fibre Channel services. This document specifies the encapsulation of Fibre Channel traffic 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]. Table of Contents 1. Introduction...................................................3 1.1. Transparency..............................................3 1.2. Bandwidth Efficiency......................................4 1.3. Reliability...............................................4 2. Reference Model................................................5 3. Encapsulation..................................................7 3.1. The Control Word..........................................8 3.2. MTU Requirements..........................................9 3.3. Mapping of FC traffic to PW packets.......................9 3.4. PW failure mapping.......................................12 4. Signaling of FC Pseudowires...................................12 5. Timing Considerations.........................................13 6. Security Considerations.......................................14 7. Applicability Statement.......................................15 8. IANA Considerations...........................................16 9. Acknowledgments...............................................17 Black and Dunbar Expires July 2011 [Page 2] Internet-Draft FC Encapsulation January 2011 10. Normative References.........................................17 11. Informative references.......................................18 Authors' Addresses...............................................18 Contributors' Addresses..........................................18 1. Introduction Fibre Channel (FC) is a high-speed communications technology, used primarily for Storage Area Networks (SANs). Within a single site (e.g., data center), an FC-based SAN connects servers to storage systems, and FC can be extended across sites. When FC is extended across multiple sites, the most common usage is storage replication in support of recovery from disasters (e.g., flood or fire that takes a site out of operation). This is particularly the case over longer distances where network latency results in unacceptable performance for a server whose storage is not at the same site. Fibre Channel is standardized by INCITS Technical Committee T11 [T11] and multiple methods for encapsulating and transporting FC traffic over other networks have been developed [FC-BB-6]. FC/IP, as described in [RFC3821] and [FC-BB-6], 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 may not reliably deliver packets, FC/IP relies on the TCP protocol to retransmit dropped frames. Due to possible delay variation and TCP timeouts, special timing mechanisms are required to ensure correct Fibre Channel operation over FC/IP [FC-BB-6]. 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 traffic over an MPLS network resulting in behavior similar to a pair of FC ports that are directly connected by a physical FC link. The result is simpler control processing by comparison to FC/IP. This document specifies the encapsulation of FC traffic into an MPLS pseudowire and related PW procedures to transport FC traffic over MPLS PWs in conjunction with the specification of the FC portion of the FC PW in [FC-BB-6]. The following subsections describe some of the requirements for transporting FC traffic over an MPLS network. 1.1. Transparency Transparent extension of an FC link is a key requirement for transporting FC traffic over a PW. This requires the FC PW to emulate Black and Dunbar Expires July 2011 [Page 3] Internet-Draft FC Encapsulation January 2011 an FC Link between two FC ports, similar to the approach defined for FC over GFPT in [FC-BB-6]. This results in transparent forwarding of FC traffic over the MPLS network from both the FC Fabric and the network operator points of view. Transparency distinguishes the FC PW approach from FC/IP. An FC PW logically connects the FC port on the FC link attached to one end of the PW directly with the FC port on far end of the FC link attached to the other end of the PW, whereas FC/IP introduces FC B_Ports at both ends of the extended FC link; each FC B_Port is connected to an FC E_Port in an FC switch on the same side of the link extension. 1.2. Bandwidth Efficiency The bandwidth allocated to a PW may be less than the rate of the attached FC port. When there is no data exchange on a native FC link, Idle Primitive Signals are continuously exchanged between the two FC ports. In order to improve the bandwidth efficiency across the MPLS network, it is necessary for the FC PW PE to suppress (or drop) the Idle Primitive signals generated by its adjacent FC ports. The far end FC PW PE regenerates Idle Primitive signals to send to its adjacent FC port as required, see [FC-BB-6]. FC link control protocols require an FC port to continuously send the same FC Primitive Sequence [FC-FS-2] until a reply is received or some other event occurs. To improve bandwidth efficiency, the FC PW PE encapsulates a subset of repeated FC Primitive Sequences to send across the WAN [FC-BB-6]. For example, in a sequence of identical received primitives, only every fourth primitive may be sent across the MPLS network. The far end FC PW PE regenerates the FC link behavior by continuously sending the Primitive Sequence most recently received from the WAN until a new primitive signal, primitive sequence or data frame is received from the WAN. These two bandwidth efficiency techniques may cause changes in the FC traffic that traverses an FC PW (e.g., number of IDLE signals or number of identical Primitive Sequences), but the far end FC PW PE's regeneration of FC link behavior on the attached FC port is transparent to the FC ports connected to each PW PE. 1.3. Reliability Fibre Channel does not have a native retransmission protocol, and requires reliable delivery of frames in the absence of errors. If an FC frame cannot be delivered (e.g., is dropped or discarded as the result of an error) the typical result is an I/O operation failure. Recovery from that failure involves an I/O operation retry after what Black and Dunbar Expires July 2011 [Page 4] Internet-Draft FC Encapsulation January 2011 may be a significant delay (30 seconds and 60 seconds are typical timeout values). In addition, such retries are likely to be logged as errors indicating possible problems with FC equipment or cables. Hence, drops, errors and discards of FC frames must be very rare. In contrast to the TTL field in an IP packet, FC uses a constant delivery timeout value (R_A_TOV) for which 10 seconds is the default. Each FC frame must be delivered or discarded within that timeout period after it is sent, see Section 5. 2. Reference Model An FC PW extends a native FC link over an MPLS network. This document specifies the PW encapsulation for FC. Figure 1 describes the reference models (derived from [RFC3985]) that support the FC PW. FC traffic is 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. This document assumes that a pseudowire can be provisioned statically or via a signaling protocol as defined in [RFC4447]. |<-------------- 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 Black and Dunbar Expires July 2011 [Page 5] Internet-Draft FC Encapsulation January 2011 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 network | | |y| | | |on | | | |y| | C | +-+ +-----+ +------+ +------+ +-+ | E | | | | | +-+ +-----+ +------+ +------+ +-+ | | |P| | | |PW ter| | MPLS | |P| | |==>|h|=>| NSP |=>|minati|=>|Tunnel|=>|h|==> To network | | |y| | | |on | | | |y| +---+ +-+ +-----+ +------+ +------+ +-+ | | +-----------------------------------+ Figure 2: PW reference diagram The Native Service Processing (NSP) function includes o suppressing any FC Idle signals received from the PE's attached FC port, o re-generating FC Idle signals to send on the attached FC port when there is no other FC traffic to send, o selecting a subset of repetitive FC Primitive Sequences received from the attached FC port and passing them to the PW Termination Entity for encapsulation and forwarding to the PW tunnel (e.g., sending only every fourth, eighth or some other number of repeated identical FC Primitive Sequences), o re-sending the last received FC Primitive Sequence on the attached FC port continuously until a new packet is received from the PW WAN side, and o using the Alternate Simple Flow Control (ASFC) protocol for buffer management in concert with the peer PW PE's NSP function so that FC traffic is not dropped. ASFC is a simple pause/resume protocol that allows repetition of pause and resume operations; the receiver responds to the first operation in an identical sequence of operations, and ignores the rest of the sequence. The NSP function is specified in detail by [FC-BB-6]. Black and Dunbar Expires July 2011 [Page 6] Internet-Draft FC Encapsulation January 2011 3. Encapsulation This specification provides port to port transport of FC encapsulated traffic. There are several port types defined by Fibre Channel, including: o 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 a Node port. o An NL_port is a port on the node used with an FC-AL topology. Also known as a Node Loop port. o 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 a Fabric port. An F_port is not loop capable. o 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. o An E_port is a port used to connect two Fibre Channel switches. Also known as an Expansion port. When E_ports between two switches are connected to form a link, that link is referred to as an inter-switch link (ISL). Among the port types listed above, only the following FC connections (as specified in [FC-BB-6]) are supported by an FC PW over MPLS: - N_Port to N_Port, established by an FC PLOGI operation - N_Port to F_Port, established by an FC FLOGI operation - E_Port to E_Port, established by an FC ELP operation FC traffic flowing over an FC PW is subdivided into four payload types (PT) that are encoded in the PW Control Word (see Section 3.1): 1. FC login traffic (PT = 1): FC login operations and responses that establish connections between FC ports. The three FC login operations are PLOGI (Port Login), FLOGI (Fabric Login), and ELP (Exchange Link Parameters). These operations and their responses may require the NSP to allocate buffer resources, see the specification of Login Exchange Monitors in [FC-BB-6]. 2. FC data traffic (PT = 0): All FC frames other than those involved in an FC login operation. Black and Dunbar Expires July 2011 [Page 7] Internet-Draft FC Encapsulation January 2011 3. FC Primitive Sequences and Signals (PT = 2): Native FC link control operations - 4-character primitive sequences and signals that are not encapsulated in FC frames. See [FC-BB-6] and [FC-FS-2]. 4. FC PW Control (PT = 6): FC PW control operations exchanged only between the endpoints of the PW. FC PW control operations are used for ASFC flow control, ping (e.g., for round trip latency measurement) and reporting native FC link errors, see [FC-BB-6]. 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 an 8b/10b transmission code (see [FC-FS-2]). The protocol specified in this document converts a received 10b code to its 8b counterpart for PW encapsulation, and hence does not support attached FC links that use a 64b/66b transmission code (e.g., 10GFC, 16GFC); such links MUST NOT be attached to an FC PW PE. If an invalid 10b code that cannot be converted to an 8b code is received from an FC link, the PE sends an FC PW control frame to report the error, see [FC-BB-6]. 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 bits 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 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 PT - Payload Type indication. This field identifies the payload type carried by a PW packet. The following types are defined: Black and Dunbar Expires July 2011 [Page 8] Internet-Draft FC Encapsulation January 2011 PT = 0: FC data frame. PT = 1: FC login frame. PT = 2: FC Primitive Sequence(s) and/or Primitive Signal(s). PT = 6: FC PW Control Frame (refer to [FC-BB-6] 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, and MUST be processed according to the rules specified 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. 3.2. MTU Requirements The MPLS network MUST be able to transport the largest Fibre Channel frame after encapsulation, including the overhead associated with the encapsulation. The maximum FC frame size without PW and MPLS labels (refer to Figure 4) is 2164 bytes. The MPLS network SHOULD accommodate frames of up to 2500 bytes in order to support possible future increases in the maximum FC frame size. Fragmentation, described in [RFC4623], SHALL NOT be used for an FC PW, therefore the network MUST be configured with a minimum MTU that is sufficient to transport the largest encapsulated FC frame. 3.3. Mapping of FC traffic to PW packets FC frames, Primitive Sequences, and Primitive Signals are transported over the PW. All packet types are carried over a single PW. In addition to the PW Control Word, an FC Encapsulation Header is included in the PW packet. This FC Encapsulation Header is not used in this version of the protocol; it SHOULD be set to zero by the sender and MUST be ignored by the receiver. Black and Dunbar Expires July 2011 [Page 9] Internet-Draft FC Encapsulation January 2011 Each FC frame is mapped to a PW packet, 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 that 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 obtained directly from the FC attachment channel, so that the PW PE is not required to re-calculate the CRC or to check the CRC in the received frame. The CRC will be checked by the FC port that receives the frame, ensuring that coverage is provided for data errors that occur between the PW endpoints. 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 Frame ----+ | | +---------------------------------------------------------------+ | CRC | +---------------+-----------------------------------------------+ | EOF Code | Reserved | +---------------+-----------------------------------------------+ Figure 4 - FC frame (SOF/Data/CRC/EOF) encapsulation in PW packet FC Primitive Sequences and Primitive Signals are FC ordered sets. On an 8b/10b-coded FC link, an ordered set consists of four 10b characters, starting with the K28.5 character, followed by three Dxx.y data characters. 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. A Kxx.y control character has a different 10b code from the corresponding Dxx.y data character, but uses the same 8b code (e.g., K28.5 and D28.5 both use the 8b code 0xBC). Here are two examples of ordered sets: o Idle(IDLE) is K28.5 - D21.4 - D21.5 - D21.5. This FC primitive signal is sent when the FC link is idle; it is suppressed by the FC PW NSP and not sent over the WAN. Black and Dunbar Expires July 2011 [Page 10] Internet-Draft FC Encapsulation January 2011 o Link Reset Response(LRR) is K28.5 - D21.1 - D31.5 - D9.2 (this FC primitive sequence is used as part of FC link initialization and recovery). Each ordered set is encapsulated in a PW packet containing the encoded K28.5 control character [FC-BB-6], followed by three encoded data characters, as shown in Figure 5. 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 in PW packet The K28.5 10b control character received from the PE's attached FC link is encoded for the FC PW as its 8b counterpart (0xBC). Because the same 8b value is used to encode a D28.5 data word, the receiving FC PW PE: o MUST check for presence of an 8b K28.5 value (0xBC) at the start of each ordered set (see Figure 5), and MUST send that value as a 10b K28.5 character on the attached FC link. o MUST send the following three Dxx.y 8b values as Dxx.y 10b characters on the attached FC link and MUST NOT send any of these Dxx.y 8b values as 10b Kxx.y characters on the attached FC link. A PW packet may contain one or more encoded FC Ordered sets [FC-BB- 6]. The length field in the FC PW Control Word is used to indicate the packet length when the PW packet contains multiple Ordered Sets. Idle Primitive Signals could be carried over the PW in the same manner as Primitive Sequences. However, [FC-BB-6] requires that Idle Primitive Signals be dropped by the Ingress PE and re-generated by Black and Dunbar Expires July 2011 [Page 11] Internet-Draft FC Encapsulation January 2011 the egress PE to save bandwidth consumed by FC (refer to [FC-BB-6] for further details). The egress PE extracts the Primitive Sequence or Primitive Signal from the received PW packet. For a Primitive Sequence, the PE continues transmitting the same FC Ordered Set to its attached FC port until an FC frame or another ordered set is received over the PW. A Primitive Signal is sent once, except that Idle Primitive Signals are sent continuously when there is nothing else to send. FC PW Control Frames are transported over the PW, by encapsulating each frame in a PW packet with PT=6 in the Control Word. FC PW Control Frame payloads are generated and terminated by the corresponding FC entity. FC PW Control frames are used for FC PW flow control (ASFC), ping and transmission of error indications. [FC-BB-6] specifies the generation and processing of FC PW Control Frames. 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 PW Control Frame ----+ | | +---------------------------------------------------------------+ Figure 6 - FC PW Control frame encapsulation in PW packet 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 attached FC link is performed by the NSP, as defined by [FC-BB-6]. 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. Black and Dunbar Expires July 2011 [Page 12] Internet-Draft FC Encapsulation January 2011 The PW Type field in the PWid FEC element and PW generalized ID FEC elements MUST be set to the "FC Port Mode" value in section 7 below. 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 FC link latency between CE1 and CE2 (refer to Figure 1) be: o no more than one-half of the R_T_TOV (Receiver Transmitter Timeout Value, default value: 100 milliseconds) of the attached devices for Primitive Sequences; o no more than one-half of the E_D_TOV (Error Detect Timeout Value, default value: 2 seconds) of the attached devices for frames; and o within the R_A_TOV (Resource Allocation Timeout Value, default value: 10 seconds) of the attached fabric(s), if any. The FC standards require that the E_D_TOV value for each FC link be set so that the R_A_TOV value for the fabric is respected when the worst case latency occurs for each link, see [FC-FS-2]. 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. These three timeout values are ordered (R_T_TOV < E_D_TOV < R_A_TOV), so adherence to one-half of R_T_TOV for all FC PW traffic is sufficient. See [FC-FS-2] for definitions of the FC timeout values. The R_T_TOV is used by the FC link initialization protocol. If an FC PW's latency exceeds one-half R_T_TOV, initialization of the FC link that is encapsulated by the FC PW may fail, leaving that FC link in a non-operational state. The E_D_TOV is used to detect failures of operational FC links. If an FC PW's latency exceeds the one-half E_D_TOV requirement, the FC link Black and Dunbar Expires July 2011 [Page 13] Internet-Draft FC Encapsulation January 2011 that is encapsulated by the FC PW may fail. The usual FC response to such a link failure is to attempt to recover the FC link by initializing it. That initialization will also fail if the FC PW latency exceeds one-half R_T_TOV (a tighter requirement). The R_A_TOV is used to determine when FC communication resources (e.g., values that identify FC frames) may be reused. If an FC PW's violation of the one-half E_D_TOV requirement is sufficient to also cause the FC fabric to violate the R_A_TOV requirement, then FC reuse of frame identification values after an R_A_TOV timeout may result in multiple FC frames with the same identification values, causing incorrect Fibre Channel operation. For example, if two such frames are swapped between I/O operations, the result may be corrupted data in the I/O operations. The PING and PING_ACK FC PW control frames defined in Section 6.4.7 of [FC-BB-6] SHOULD be used to measure the current FC pseudowire latency between the CE devices. If the measured latency violates any of the timing requirements, then the FC PW PE MUST generate a WAN Down event as specified in [FC-BB-6]. 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 causes the FC link that is carried by the PW to become non- operational, halting transmission of FC traffic. However, it is not necessary to tear down the pseudowire itself in this situation (e.g., destroy the MPLS path set up by LDP). The Transparent FC-BB initialization state machine in [FC-BB-6] specifies the protocol used to attempt to recover from a 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 encapsulated 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 remains above 100ms, the initialization protocol for the FC PW will repeatedly time out in attempting to recover from the WAN Down event, preventing recovery of the FC link carried by the PW, see [FC-BB-6]. 6. Security Considerations FC PW does not change the security properties of the underlying MPLS network, rather it relies upon the network's mechanisms for encryption, integrity, and authentication as required. Black and Dunbar Expires July 2011 [Page 14] Internet-Draft FC Encapsulation January 2011 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 FC traffic between Fibre Channel ports while saving network bandwidth by removing FC Idle Signals and reducing the number of FC Primitive Sequences. o 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 FC links as specified by the FC standards. o The FC PW carries only FC data frames, FC Primitive Signals and a subset of the copies of an FC Primitive Sequence. Idle Primitive Signals are suppressed, and long streams of the same Primitive Sequence are reduced over the PW thus saving bandwidth. o The PW PE MUST generate Idle Primitive Signals to the attached FC link when there is no other traffic to transmit on the attached FC link [FC-FS-2]. o The PW PE MUST send Primitive Sequences continuously to the attached FC port, as required by the FC standards [FC-FS-2]. FC PW traffic should only traverse controlled MPLS or MPLS-TP networks. The network should enforce policing of incoming traffic and network resource/bandwidth allocation so that the FC PW delivery quality can be assured. To extend FC across an uncontrolled network, FC/IP SHOULD be used instead of an FC PW, see [RFC3821] and [FC-BB-6]. This document does not provide any mechanisms for protecting an FC PW against network outages. As a consequence, resilience of the emulated FC service to such outages is dependent upon MPLS-TE/MPLS-TP network. The NSP SHOULD use a WAN Down event (as specified in [FC-BB-6]) to convey the PW status to the CE, to enable faster network outage handling. Black and Dunbar Expires July 2011 [Page 15] Internet-Draft FC Encapsulation January 2011 8. IANA Considerations IANA is requested to assign a new MPLS Pseudowire (PW) type as follows: PW type Description Reference -------- -------------- ---------- 0x001F FC Port Mode RFC XXXX The above value is suggested as the next available value and has been reserved for this purpose by IANA. RFC Editor: Please replace RFC XXXX above with the RFC number of this document and remove this note. IANA should reserve the following Pseudowire Interface Parameters Sub-TLV Types that were tentatively allocated for FC PW and restrict them to prevent future allocation. These Sub-TLV types were used for the FC PW Selective Retransmission protocol, which the working group has decided to eliminate. This action prevents future use of these values for other purposes, just in case there are implementations of the Selective Retransmission protocol. Parameter ID Length Reference --------- --------- ---------- 0x12 4 RFC XXXX 0x13 4 RFC XXXX 0x14 4 RFC XXXX 0x15 4 RFC XXXX RFC Editor: Please replace RFC XXXX above with the RFC number of this document and remove this note. Black and Dunbar Expires July 2011 [Page 16] Internet-Draft FC Encapsulation January 2011 9. Acknowledgments Previous versions of this document were authored by Moran Roth, Ronen Solomon and Munefumi Tsurusawa (see Contributors' Addresses, below); their efforts and contributions are gratefully acknowledged. The authors would like to thank Stewart Bryant, Dave Peterson, Yaakov Stein and Alexander Vainshtein for helpful comments on this document. The protocol specified in this document is intended to be used in conjunction with the Fibre Channel pseudowire portion of the FC-BB-6 specification developed by INCITS Technical Committee T11. The authors would like to thank the members of both IETF and T11 organizations who have supported and contributed to this work. 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. [RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3)", RFC 4446, 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-6] "Fibre Channel Backbone-6" (FC-BB-6), T11 Project 2159-D, Rev 1.02, October 2010. [RFC-2119] 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. Black and Dunbar Expires July 2011 [Page 17] Internet-Draft FC Encapsulation January 2011 [FC-SP] "Fibre Channel - Security Protocols" (FC-SP), ANSI INCITS 426:2007, February 2007. 11. Informative references [RFC3821] M. Rajogopal, E. Rodriguez, "Fibre Channel over TCP/IP (FCIP)", RFC 3821, July 2004. [T11] INCITS Technical Committee T11, http://www.t11.org, visited January, 2011. Authors' Addresses David L. Black (ed.) EMC Corporation 176 South Street Hopkinton, MA 01748 Phone: +1 (508) 293-7953 Email: david.black@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 Contributors' Addresses Moran Roth Infinera Corporation 169 Java Drive Sunnyvale, CA 94089 Phone: (408) 572-5200 Email: MRoth@infinera.com Ronen Solomon Orckit-Corrigent Systems 126, Yigal Alon st. Tel Aviv, ISRAEL Phone: +972-3-6945316 Email: ronens@corrigent.com Black and Dunbar Expires July 2011 [Page 18] Internet-Draft FC Encapsulation January 2011 Munefumi Tsurusawa KDDI R&D Laboratories Inc. Ohara 2-1-15, Fujimino-shi, Saitama, Japan Phone: +81-49-278-7828 Intellectual Property Statement The IETF Trust 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 any IETF 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. 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