Internet Draft C. DeSanti draft-desanti-imss-ipv4-over-fibre-channel-00.txt Cisco Systems Expires: April 2005 C. Carlson QLogic Corporation October 2004 Transmission of IPv4 and ARP Packets over Fibre Channel Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. 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 become aware will be disclosed, in accordance with RFC 3668. 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. Abstract This document specifies a way of encapsulating IPv4 and ARP packets over Fibre Channel, and a mechanism to perform IPv4 address resolution over Fibre Channel networks. DeSanti & Carlson Expires April 2005 [Page 1] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 Table Of Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Summary of Fibre Channel. . . . . . . . . . . . . . . . . . . 3 2.1 Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Identifiers and Login . . . . . . . . . . . . . . . . . . . . 4 2.3 FC Levels and Frame Format. . . . . . . . . . . . . . . . . . 5 2.4 Sequences and Exchanges . . . . . . . . . . . . . . . . . . . 6 3. IPv4 Capable Nx_Ports . . . . . . . . . . . . . . . . . . . . 6 4. IPv4 and ARP Encapsulation. . . . . . . . . . . . . . . . . . 6 4.1 FC Sequence Format for IPv4 Packets . . . . . . . . . . . . . 6 4.2 FC Sequence Format for ARP Packets. . . . . . . . . . . . . . 8 4.3 FC Classes of Service . . . . . . . . . . . . . . . . . . . . 8 4.4 FC Header Code Points . . . . . . . . . . . . . . . . . . . . 9 4.5 FC Network_Header . . . . . . . . . . . . . . . . . . . . . . 10 4.6 LLC/SNAP Header . . . . . . . . . . . . . . . . . . . . . . . 10 4.7 Bit and Byte Ordering . . . . . . . . . . . . . . . . . . . . 11 4.8 Maximum Transfer Unit . . . . . . . . . . . . . . . . . . . . 11 5. ARP Packet Format . . . . . . . . . . . . . . . . . . . . . . 11 6. Address Mapping for Unicast . . . . . . . . . . . . . . . . . 13 7. Address Mapping for Multicast . . . . . . . . . . . . . . . . 14 8. Sequence Management . . . . . . . . . . . . . . . . . . . . . 15 9. Exchange Management . . . . . . . . . . . . . . . . . . . . . 15 10. Interoperability with [RFC-2625]. . . . . . . . . . . . . . . 15 11. Security Considerations . . . . . . . . . . . . . . . . . . . 16 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 14. Normative References. . . . . . . . . . . . . . . . . . . . . 17 15. Informative References. . . . . . . . . . . . . . . . . . . . 18 16. Authors' Address. . . . . . . . . . . . . . . . . . . . . . . 18 A. Transmission of a Broadcast FC Sequence over FC Topologies. . 19 B. Validation of the mapping. . . . . . 20 C. Fibre Channel Bit and Byte Numbering Guidance . . . . . . . . 21 D. Changes from [RFC-2625] . . . . . . . . . . . . . . . . . . . 22 1. Introduction Fibre Channel (FC) is a high speed serial interface technology that supports several Upper Layer Protocols including Small Computer System Interface (SCSI) and IP. [RFC-2625] defined how to encapsulate IPv4 and ARP packets over Fibre Channel for a subset of Fibre Channel devices. This specification enable the support of IPv4 for a broader category of Fibre Channel devices. In addition, this specification simplifies [RFC-2625] by removing unused options and clarifying what is currently implemented. This document is an update to [RFC-2625] and, hence, obsoletes it. DeSanti & Carlson Expires April 2005 [Page 2] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 Specific limitations that this document aims to resolve are: - N_Port_Name format restriction. [RFC-2625] restricts the use of IPv4 to Fibre Channel devices having format 0x1 N_Port_Name, but many current implementations use other N_Port_Name formats. - Use of FARP. [RFC-2625] requires the support of FARP-REPLY to map N_Port_Names to N_Port_IDs, but many current implementations use other methods, such as the Fibre Channel Name Server. - Missing support for IPv4 multicast. [RFC-2625] does not specify how to transmit IPv4 packets with a multicast destination address over Fibre Channel. Warning to readers familiar with Fibre Channel: both Fibre Channel and IETF standards use the same byte transmission order. However, the bit numbering is different. See Appendix C for guidance. 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 [KEYWORDS]. 2. Summary of Fibre Channel 2.1. Overview Fibre Channel (FC) is a gigabit speed network technology primarily used for Storage Networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards (INCITS), an American National Standard Institute (ANSI) accredited standards committee. Fibre Channel devices are called Nodes. Each Node has one or more Ports that connect to Ports of other devices. Fibre Channel may be implemented using any combination of the following three topologies: - a point-to-point link between two Ports; - a set of Ports interconnected by a switching network called a Fabric, as defined in [FC-FS]; - a set of Ports interconnected with a loop topology, as defined in [FC-AL-2]. A Node Port is more precisely called an N_Port. A Node Port that is capable of operating in a loop topology using the loop specific protocols is designated as an NL_Port. The term Nx_Port is used to generically indicate these two kinds of Node Port. A Fabric Port is more precisely called an F_Port. A Fabric Port that is capable of operating in a loop topology using the loop specific protocols is designated as an FL_Port. The term Fx_Port is used to generically indicate these two kinds of Fabric Port. DeSanti & Carlson Expires April 2005 [Page 3] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 A Fibre Channel network, built with any combination of the FC topologies described above, is a multiaccess network with broadcast capabilities. From an IPv4 point of view, a Fibre Channel network is an IPv4 Local Network. IPv4-capable Nx_Ports are what [IPv4] calls Local Network Interfaces. 2.2. Identifiers and Login Fibre Channel entities are identified by permanent 64 bit long Name_Identifiers. [FC-FS] defines several formats of Name_Identifiers. The value of the the most significant four bits defines the format of a Name_Identifier. These names are referred to in a more precise manner as follows: - an Nx_Port's Name_Identifier is called N_Port_Name; - an Fx_Port's Name_Identifier is called F_Port_Name; - a Node's Name_Identifier is called Node_Name; - a Fabric's Name_Identifier is called Fabric_Name. An Nx_Port connected to a Fibre Channel network is associated with two identifiers, its permanent N_Port_Name and a volatile 24 bit address called N_Port_ID. The N_Port_Name is used to identify the Nx_Port, while the N_Port_ID is used for communications among Nx_Ports. Each Nx_Port acquires an N_Port_ID from the Fabric by performing a process called Fabric Login or FLOGI. The FLOGI process is used also to negotiate several communications parameters between the Nx_Port and the Fabric, such as the receive data field size, which determines the maximum size of the Fibre Channel frames that may be transferred between the Nx_Port and the Fabric. Before effective communication may take place between two Nx_Ports, they must complete a process called Port Login or PLOGI. The PLOGI process provides each Nx_Port with the other Nx_Port's N_Port_Name, and negotiates several communication parameters, such as the receive data field size, which determines the maximum size of the Fibre Channel frames that may be transferred between the two Nx_Ports. Both Fabric Login and Port Login may be explicit, i.e., performed using specific FC control messages (called Extended Link Services or ELS), or implicit, in which the parameters are specified by configuration or other methods. DeSanti & Carlson Expires April 2005 [Page 4] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 2.3. FC Levels and Frame Format [FC-FS] describes the Fibre Channel protocol using 5 different levels. The FC-2 and FC-4 levels are relevant for this specification. The FC-2 level defines the FC frame format, the transport services, and control functions necessary for information transfer. The FC-4 level supports Upper Level Protocols, such as IPv4, IPv6 or SCSI. The Fibre Channel frame format is shown in figure 1. +-----+-----------+-----------+--------//-------+-----+-----+ | | | Data Field | | | | SOF | FC Header |<--------------------------->| CRC | EOF | | | | Optional | Frame | | | | | | Header(s) | Payload | | | +-----+-----------+-----------+--------//-------+-----+-----+ Fig. 1: Fibre Channel Frame Format The Start of Frame (SOF) and End of Frame (EOF) are special FC transmission words that act as frame delimiters. The CRC is 4 octets long and uses the same 32-bit polynomial used in Ethernet. The FC Header is 24 octets long and contains several fields associated with the identification and control of the Data Field. The Data Field is of variable size, ranging from 0 to 2112 octets, and includes the user data in the Frame Payload field, and Optional Headers. The currently defined Optional Headers are: - ESP_Header; - Network_Header; - Association_Header; - Device_Header. The value of the SOF field determines the FC Class of service associated with the frame. Five Classes of service are specified in [FC-FS]. They are distinguished primarily by the method of flow control between the communicating Nx_Ports and by the level of data integrity provided. A given Fabric or Nx_Port may support one or more of the following Classes of service: - Class 1: Dedicated physical connection with delivery confirmation; - Class 2: Frame multiplexed service with delivery confirmation; - Class 3: Datagram service; - Class 4: Fractional bandwidth; - Class 6: Reliable multicast via dedicated connections. Class 3 and 2 are used for storage networking applications; Class 1 and 6 are used for specialized applications in avionics. Class 3 is recommended for IPv4 (see section 4.3). DeSanti & Carlson Expires April 2005 [Page 5] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 2.4. Sequences and Exchanges An application level payload such as IPv4 is called an Information Unit at the FC-4 level of Fibre Channel. Each FC-4 Information Unit is mapped to an FC Sequence by the FC-2 level. An FC Sequence consists of one or more FC frames related by the value of the Sequence_ID (SEQ_ID) field of the FC Header. The maximum data that may be carried by an FC frame is 2112 octets. The maximum usable frame size depends on the Fabric and Nx_Port implementations and is negotiated during the Login process. Whenever an Information Unit to be transmitted exceeds this value, the FC-2 level segments it into multiple FC frames, sent as a single Sequence. The receiving Nx_Port reassembles the Sequence of frames and delivers a reassembled Information Unit to the FC-4 level. The Sequence Count (SEQ_CNT) field of the FC Header may be used to ensure frame ordering. Multiple Sequences may be related together as belonging to the same FC Exchange. The Exchange is a mechanism used by two Nx_Ports to identify and manage an operation between them. The Exchange is opened when the operation is started between the two Nx_Ports, and closed when the operation ends. FC frames belonging to the same Exchange are related by the value of the Exchange_ID fields in the FC Header. An Originator Exchange_ID (OX_ID) and a Responder Exchange_ID (RX_ID) uniquely identify the Exchange between a pair of Nx_Port. 3. IPv4 Capable Nx_Ports This specification requires an IPv4 capable Nx_Port to have the following properties: - The format of its N_Port_Name MUST be one of 0x1, 0x2, 0x5, 0xC, 0xD, 0xE, 0xF [FC-FS]; - It MUST support Class 3; - It MUST support continuously increasing SEQ_CNT [FC-FS]; - It SHOULD support a receive data field size for Device_Data FC frames of at least 1024 octets. 4. IPv4 and ARP Encapsulation 4.1. FC Sequence Format for IPv4 Packets An IPv4 packet is mapped to an Information Unit at the FC-4 level of Fibre Channel, which in turn is mapped to an FC Sequence by the FC-2 level. An FC Information Unit containing an IPv4 packet MUST carry DeSanti & Carlson Expires April 2005 [Page 6] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 the FC Network_Header [FC-FS] and the LLC/SNAP header [IEEE-LLC], resulting in the FC Information Unit format shown in figure 2. +---------------+---------------+---------------+---------------+ | | +- -+ | Network_Header | +- (16 octets) -+ | | +- -+ | | +---------------+---------------+---------------+---------------+ | LLC/SNAP header | +- (8 octets) -+ | | +---------------+---------------+---------------+---------------+ | | +- -+ / IPv4 Packet / / / +- -+ | | +---------------+---------------+---------------+---------------+ Fig. 2: FC Information Unit Mapping an IPv4 Packet The FC ESP_Header [FC-FS] MAY be used to secure the FC frames composing the FC Sequence. [AH] or [ESP] may be used to provide security at the IPv4 layer. Other types of FC Optional Header MUST NOT be used in an IPv4 FC Sequence. Typically, a Sequence consists of more than one frame. Only the first frame of the Sequence MUST include the FC Network_Header and the LLC/SNAP header. The other frames MUST NOT include them, as shown in figure 3. First Frame of an IPv4 FC Sequence +-----------+-------------------+-----------------+-------//--------+ | FC Header | FC Network_Header | LLC/SNAP header | First chunk of | | | | | the IPv4 Packet | +-----------+-------------------+-----------------+-------//--------+ Subsequent Frames of an IPv4 FC Sequence +-----------+-----------------//--------------------+ | FC Header | Additional chunk of the IPv4 Packet | +-----------+----------------//---------------------+ Fig. 3: Optional Headers in an IPv4 FC Sequence DeSanti & Carlson Expires April 2005 [Page 7] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 4.2. FC Sequence Format for ARP Packets An ARP packet is mapped to an Information Unit at the FC-4 level of Fibre Channel, which in turn is mapped to an FC Sequence by the FC-2 level. An FC Information Unit containing an ARP packet MUST carry the FC Network_Header [FC-FS] and the LLC/SNAP header [IEEE-LLC], resulting to the FC Information Unit format shown in figure 4. +---------------+---------------+---------------+---------------+ | | +- -+ | Network_Header | +- (16 octets) -+ | | +- -+ | | +---------------+---------------+---------------+---------------+ | LLC/SNAP header | +- (8 octets) -+ | | +---------------+---------------+---------------+---------------+ | | +- -+ / ARP Packet / / / +- -+ | | +---------------+---------------+---------------+---------------+ Fig. 4: FC Information Unit Mapping an ARP Packet Given the limited size of an ARP packet (see section 5), an FC Sequence carrying an ARP packet MUST be mapped to a single FC frame, that MUST include the FC Network_Header and the LLC/SNAP header. The FC ESP_Header [FC-FS] MAY be used to secure an ARP FC frame. Other types of FC Optional Header MUST NOT be used in an ARP FC frame. 4.3. FC Classes of Service This specification uses FC Class 3. ARP packets MUST be encapsulated in Class 3 FC frames. IPv4 packets SHOULD use Class 3 as well. DeSanti & Carlson Expires April 2005 [Page 8] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 4.4. FC Header Code Points The fields of the Fibre Channel Header are shown in figure 5. The D_ID and S_ID fields contain respectively the destination N_Port_ID and the source N_Port_ID. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | R_CTL | D_ID | +---------------+---------------+---------------+---------------+ | CS_CTL/Prio | S_ID | +---------------+---------------+---------------+---------------+ | TYPE | F_CTL | +---------------+---------------+---------------+---------------+ | SEQ_ID | DF_CTL | SEQ_CNT | +---------------+---------------+---------------+---------------+ | OX_ID | RX_ID | +---------------+---------------+---------------+---------------+ | Parameter | +---------------+---------------+---------------+---------------+ Fig. 5: FC Header Format To encapsulate IPv4 over Fibre Channel the following code points apply. When a single value is listed without further qualification that value MUST be used: - R_CTL: 0x04 (Device_Data frame with Unsolicited Data Information Category [FC-FS]); - TYPE: 0x05 (IP over Fibre Channel); - CS_CTL/Prio: 0x00 is the default, see [FC-FS] for other values; - DF_CTL: 0x20 (Network_Header) for the first FC frame of an IPv4 Sequence, 0x00 for the following FC frames. If the FC ESP_Header is used, then 0x60 for the first FC frame of an IPv4 Sequence, 0x40 for the following FC frames; - F_CTL, SEQ_ID, SEQ_CNT, OX_ID, RX_ID: see section 8, section 9, and [FC-FS] for additional requirements; - Parameter: if Relative Offset [FC-FS] is not used, the content of this field MUST be ignored by the receiver, and SHOULD be set to zero by the sender. If Relative Offset is used, see [FC-FS]. To encapsulate ARP over Fibre Channel the following code points apply. When a single value is listed without further qualification that value MUST be used: - R_CTL: 0x04 (Device_Data frame with Unsolicited Data Information Category [FC-FS]); - TYPE: 0x05 (IP over Fibre Channel); DeSanti & Carlson Expires April 2005 [Page 9] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 - CS_CTL/Prio: 0x00 is the default, see [FC-FS] for other values; - DF_CTL: 0x20 (Network_Header). If the FC ESP_Header is used, then 0x60; - F_CTL, SEQ_ID, SEQ_CNT, OX_ID, RX_ID: see section 8, section 9, and [FC-FS] for additional requirements; - Parameter: if Relative Offset [FC-FS] is not used, the content of this field MUST be ignored by the receiver, and SHOULD be set to zero by the sender. If Relative Offset is used, see [FC-FS]. 4.5. FC Network_Header The fields of the FC Network_Header are shown in figure 6. For use with IPv4 and ARP the N_Port_Names formats MUST be one of 0x1, 0x2, 0x5, 0xC, 0xD, 0xE, 0xF [FC-FS]. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +- Destination N_Port_Name -+ | | +---------------------------------------------------------------+ | | +- Source N_Port_Name -+ | | +---------------------------------------------------------------+ Fig. 6: FC Network_Header Format 4.6. LLC/SNAP Header The fields of the LLC/SNAP Header [IEEE-LLC] are shown in figure 7. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DSAP | SSAP | CTRL | OUI | +---------------+---------------+---------------+---------------+ | OUI | PID | +---------------+---------------+---------------+---------------+ Fig. 7: LLC/SNAP Header Format DeSanti & Carlson Expires April 2005 [Page 10] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 To encapsulate IPv4 over Fibre Channel the following code points MUST be used: - DSAP: 0xAA - SSAP: 0xAA - CTRL: 0x03 - OUI: 0x000000 - PID: 0x0800 To encapsulate ARP over Fibre Channel the following code points MUST be used: - DSAP: 0xAA - SSAP: 0xAA - CTRL: 0x03 - OUI: 0x000000 - PID: 0x0806 4.7. Bit and Byte Ordering IPv4 and ARP packets are mapped to the FC-4 level using the big- endian byte ordering that corresponds to the standard network byte order or canonical form. 4.8. Maximum Transfer Unit The default MTU size for IPv4 packets over Fibre Channel is 65280 octets. This size may be reduced by manual configuration of each Nx_Port or by the Path MTU Discovery technique [PMTU], if supported. Large IPv4 packets are mapped to a Sequence of FC frames (see section 2.4). 5. ARP Packet Format The Address Resolution Protocol defined in [ARP] was designed to be a general purpose protocol, and to work with many network technologies, and with many upper layer protocols. [RFC-2625] chose to use for Fibre Channel the same ARP packet format used for Ethernet networks. By doing that, [RFC-2625] restricted the use of IPv4 to Nx_Ports having N_Port_Name format 0x1. While this may have been a reasonable choice at that time, today there are Nx_Ports with N_Port_Name format other than 0x1 in widespread use. This specification accomodates Nx_Ports with N_Port_Names of format different than 0x1 by defining a Fibre Channel specific version of DeSanti & Carlson Expires April 2005 [Page 11] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 the ARP protocol, carrying both N_Port_Name and N_Port_ID as ARP HW address. IANA has registered the number 18 to identify Fibre Channel as ARP HW type. The FC ARP packet format is shown in figure 8. The length of the FC ARP packet is 40 octets. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | HW Type = 0x0012 | Protocol = 0x0800 | +---------------+---------------+---------------+---------------+ | HW Len = 12 | Proto Len = 4 | Opcode | +---------------+---------------+---------------+---------------+ | | +- -+ | HW Address of Sender | +- -+ | | +---------------+---------------+---------------+---------------+ | Protocol Address of Sender | +---------------+---------------+---------------+---------------+ | | +- -+ | HW Address of Target | +- -+ | | +---------------+---------------+---------------+---------------+ | Protocol Address of Target | +---------------+---------------+---------------+---------------+ Fig. 8: FC ARP Packet Format The following code points MUST be used with FC ARP: - HW Type: 0x0012 (Fibre Channel); - Protocol: 0x0800 (IPv4); - HW Len: 12 (Length in octets of the HW Address); - Proto Len: 4 (Length in octets of the Protocol Address); - Opcode: 0x0001 for ARP Request, 0x0002 for ARP Reply; - HW Address of Sender: the N_Port_Name and N_Port_ID of the Requester in an ARP Request, or those of the Responder in an ARP Reply; - Protocol Address of Sender: the IPv4 address of the Requester in an ARP Request, or that of the Responder in an ARP Reply; - HW Address of Target: set to zero in an ARP Request, and to the N_Port_Name and N_Port_ID of the Requester in an ARP Reply; - Protocol Address of Target: the IPv4 address of the Responder in an ARP Request, or that of the Requester in an ARP Reply. DeSanti & Carlson Expires April 2005 [Page 12] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 The format of the HW address for Fibre Channel ARP is shown in figure 9. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | +- N_Port_Name -+ | | +---------------+---------------+---------------+---------------+ | Reserved | N_Port_ID | +---------------+---------------+---------------+---------------+ Fig. 9: FC ARP HW Address Format Reserved fields MUST be set to zero when transmitting, and MUST be ignored when receiving. 6. Address Mapping for Unicast An Nx_Port has two kinds of Fibre Channel addresses: - a non-volatile 64-bit address, called N_Port_Name; - a volatile 24-bit address, called N_Port_ID. The N_Port_Name is used to uniquely identify the Nx_Port, while the N_Port_ID is used to route frames to the Nx_Port. Both FC addresses are required to resolve an IPv4 unicast address. The fact that the N_Port_ID is volatile implies that an Nx_Port MUST validate the mapping between its N_Port_Name and N_Port_ID when certain Fibre Channel events occur (see Appendix B). The procedure for mapping IPv4 unicast addresses into Fibre Channel link-layer addresses uses the FC ARP protocol, as specified in section 5 and [ARP]. A source Nx_Port that has to send IPv4 packets to a destination Nx_Port, known by its IPv4 address, MUST perform the following steps: a) The source Nx_Port should first consult its local mapping tables for a mapping . b) If such a mapping is found, and a valid Port Login is in place with the destination Nx_Port, then the source Nx_Port sends the IPv4 packets to the destination Nx_Port using the retrieved N_Port_ID as D_ID. c) If such a mapping is not found, or a valid Port Login is not in place with the destination Nx_Port, then the source Nx_Port MUST send a broadcast FC ARP Request to its connected FC network. DeSanti & Carlson Expires April 2005 [Page 13] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 Appendix A specifies how to transmit a Class 3 broadcast FC Sequence over various Fibre Channel topologies. d) When a broadcast FC ARP Request is received by the Nx_Port with the matching IPv4 address, it generates a unicast FC ARP Reply. If a valid Port Login to the Nx_Port that sent the broadcast FC ARP Request does not exist, the Nx_Port MUST perform such a Port Login, and then use it for the unicast reply. The N_Port_ID to which the Port Login is directed is taken from the N_Port_ID field of the Sender HW Address field of the received FC ARP packet. e) If no Nx_Port has the matching IPv4 address, no unicast FC ARP Reply is returned. 7. Address Mapping for Multicast By default, all best-effort IPv4 multicast or broadcast packets and ARP broadcast packets MUST be mapped to FC Sequences addressed to the broadcast N_Port_ID 0xFFFFFF and sent in FC Class 3. In this case, the Destination N_Port_Name field of the FC Network_Header MUST be set to the value 0x10-00-FF-FF-FF-FF-FF-FF. Appendix A specifies how to transmit a Class 3 broadcast FC Sequence over various Fibre Channel topologies. An Nx_Port supporting IPv4 MUST be able to map a received broadcast Class 3 Device_Data FC frame to an implicit Port Login context in order to handle IPv4 multicast or broadcast packets and ARP broadcast packets. The receive data field size of this implicit Port Login MUST be the same across all the Nx_Ports connected to the same Fabric, otherwise FC broadcast transmission does not work. In order to reduce the need for FC Sequence segmentation, the receive data field size of this implicit Port Login SHOULD be 1024 octets. This receive data field size requirement applies to broadcast Device_Data FC frames, not to ELSs. Receiving an FC Sequence carrying an IPv4 multicast or broadcast packet or an ARP broadcast packet triggers some additional processing by the Nx_Port when that IPv4 or ARP packet requires a unicast reply. In this case, if a valid Port Login to the Nx_Port that sent the multicast or broadcast packet does not exist, the Nx_Port MUST perform such a Port Login, and then use it for the unicast reply. In the case of ARP messages, the N_Port_ID to which the Port Login is directed is taken from the N_Port_ID field of the Sender HW Address field of the received ARP packet. DeSanti & Carlson Expires April 2005 [Page 14] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 8. Sequence Management FC Sequences are REQUIRED to be non-streamed. In order to avoid missing FC frame aliasing by Sequence_ID reuse, an Nx_Port supporting IPv4 is REQUIRED to use continuously increasing SEQ_CNT [FC-FS]. Each Exchange MUST start with SEQ_CNT = 0 in the first frame, and every frame transmitted after that MUST increment the previous SEQ_CNT by one. Any frames received from the other N_Port in the Exchange shall have no effect on the transmitted SEQ_CNT. 9. Exchange Management To transfer IPv4 packets, each Nx_Port MUST have a dedicated Exchange for sending data to each Nx_Port in the network and a dedicated Exchange for receiving data from each Nx_Port. An Exchange Responder is not required to assign RX_IDs. If an RX_ID of 0xFFFF is assigned, the Exchange Responder is identifying Exchanges based on S_ID / D_ID / OX_ID only [FC-FS]. When an Exchange is created between two Nx_Ports for unicast IPv4 packets, it remains active while the Nx_Ports are logged in with each other. Each FC ARP message, FC broadcast and ELS [FC-FS] SHOULD use a separate short lived Exchange. For IPv4 and FC ARP, Exchanges MUST NOT transfer Sequence Initiative, because they are used in a unidirectional mode. The Sequence Initiative bit in the F_CTL field of the FC Header [FC-FS] MUST be set to zero. The mechanism for aging or expiring exchanges based on activity, timeout, or other methods is as specified in [FC-FS]. The Exchange Originator MAY terminate Exchanges by setting the F_CTL LS bit [FC-FS]. Exchanges MAY be torn down by the Exchange Originator or Exchange Responder by using the ABTS (Abort Sequence) protocol [FC-FS]. IPv4 Exchanges SHOULD NOT be terminated by Logout, since this may terminate active Exchanges on other FC-4s [FC-FS]. 10. Interoperability with [RFC-2625] The IPv4 encapsulation defined in this document, along with Exchange and Sequence management, are exactly as defined in [RFC-2625]. Implementations following this specification should interoperate with implementations compliant to [RFC-2625] for IPv4 packet transmission and reception. DeSanti & Carlson Expires April 2005 [Page 15] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 The main difference between this document and [RFC-2625] is in the address resolution procedure. [RFC-2625] uses the Ethernet format of the ARP protocol, and requires all Nx_Ports to have a format 0x1 N_Port_Name. This specification defines a Fibre Channel format for the ARP protocol that supports all commonly used N_Port_Names. Also, this specification does not use FARP [RFC-2625]. A method by which an Nx_Port implementing this specification, and not using format 0x1 N_Port_Name, may interoperate with an [RFC-2625] implementation is by manually configuring the mapping on the involved Nx_Ports. Through this manual configuration, the ARP protocol does not need to be performed. However, issues may still arise in the IPv4 packet communication if the [RFC-2625] implementation strictly enforces the requirement for Nx_Ports to use N_Port_Names of format 0x1. An Nx_Port following this specification, and having a format 0x1 N_Port_Name, MAY interoperate with an [RFC-2625] implementation by using the manual configuration approach described above, or by performing the IPv4 address resolution as described below. Each implementation MUST implement the behavior described below, but the use of this behavior MUST be administratively configurable. - The Nx_Port MUST send, when IPv4 address resolution is attempted, two ARP Requests separated by a short time interval (e.g., less than one second), the first one according to the FC ARP format and the second one according to the Ethernet ARP format. The Nx_Port should then process the first ARP Reply received. If only an Ethernet ARP Reply is received, it provides the N_Port_Name of the Nx_Port having the destination IPv4 address. The N_Port_ID associated with the N_Port_Name received in an Ethernet ARP Reply may be retrieved from the S_ID field of the received ARP Reply, or by querying the Fibre Channel Name Server. - The Nx_Port MUST respond to a received Ethernet ARP Request with an Ethernet ARP Reply. - The Nx_Port MAY respond to FARP Requests [RFC-2625]. The reception of a particular format of ARP message does not imply that the sending NX_Port will continue to use the same format later. 11. Security Considerations IPv4 and ARP do not introduce any additional security concerns beyond those that already exist within the Fibre Channel protocols. Zoning techniques based on FC Name Server masking (soft zoning) do not work with IPv4, because IPv4 over Fibre Channel does not use the FC Name Server. The FC ESP_Header [FC-FS] may be used to secure the FC frames composing FC Sequences carrying IPv4 and ARP packets. All the DeSanti & Carlson Expires April 2005 [Page 16] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 techniques defined to secure IPv4 traffic may be used in a Fibre Channel Environment. 12. IANA Considerations The directory of ARP parameters should reference this document, when published, for hardware type 18. 13. Acknowledgments The authors would like to acknowledge the ANSI INCITS T11.3 Task Group members who reviewed this document. 14. Normative References [FC-FS] ANSI INCITS 373-2003, "Fibre Channel - Framing and Signaling (FC-FS)". [FC-AL-2] ANSI INCITS 332-1999, "Fibre Channel - Arbitrated Loop-2 (FC-AL-2)". [IPv4] J. Postel, "Internet Protocol", STD-5, RFC 791, September 1981. [ARP] D. Plummer, "An Ethernet Address Resolution Protocol -or- Converting Network Addresses to 48-bit Ethernet Address for Transmission on Ethernet Hardware", STD-37, RFC 826, November 1982. [RFC-2625] Rajagopal, M., Bhagwat, R., and W. Rickard, "IP and ARP over Fibre Channel", RFC 2625, June 1999. [PMTU] Mogul, J. and S. Deering, "Path MTU Discovery", RFC 1191, November 1990. [IEEE-LLC] IEEE Std 802-2001, "IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture". [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. DeSanti & Carlson Expires April 2005 [Page 17] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 15. Informative References [AH] Kent, S. and R. Atkinson, "IP Authentication Header", RFC 2402, November 1998. [ESP] Kent, S. and R. Atkinson, "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998. 16. Authors' Address Claudio DeSanti Cisco Systems, Inc. 170 W. Tasman Dr. San Jose, CA 95134 USA Phone: +1 408 853-9172 EMail: cds@cisco.com Craig W. Carlson QLogic Corporation 6321 Bury Drive Eden Prairie, MN 55346 USA Phone: +1 952 932-4064 Email: craig.carlson@qlogic.com DeSanti & Carlson Expires April 2005 [Page 18] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 A. Transmission of a Broadcast FC Sequence over FC Topologies (Informative) A.1. Point-to-Point Topology No particular mechanisms are required for this case. The Nx_Port connected at the other side of the cable receives the broadcast FC Sequence having D_ID 0xFFFFFF. A.2. Private Loop Topology An NL_Port attached to a private loop MUST transmit a Class 3 broadcast FC Sequence by using the OPN(fr) primitive signal [FC-AL-2]. a) The source NL_Port first sends an Open Broadcast Replicate (OPN(fr)) primitive signal, forcing all the NL_Ports in the loop (except itself) to replicate the frames that they receive while examining the FC Header's D_ID field. b) The source NL_Port then removes the OPN(fr) signal when it returns to it. c) The source NL_Port then sends the Class 3 broadcast FC Sequence having D_ID 0xFFFFFF. A.3. Public Loop Topology An NL_Port attached to a public loop MUST NOT use the OPN(fr) primitive signal. Rather, it MUST send the Class 3 broadcast FC Sequence having D_ID 0xFFFFFF to the FL_Port at AL_PA = 0x00 [FC-AL-2]. The Fabric propagates the broadcast to all other FC_Ports [FC-FS], including the FL_Port which the broadcast arrived on. This includes all F_Ports, and other FL_Ports. Each FL_Port propagates the broadcast by using the primitive signal OPN(fr), in order to prepare the loop to receive the broadcast sequence. A.4. Fabric Topology An N_Port connected to an F_Port MUST transmit the Class 3 broadcast FC Sequence having D_ID 0xFFFFFF to the F_Port. The Fabric propagates the broadcast to all other FC_Ports [FC-FS]. DeSanti & Carlson Expires April 2005 [Page 19] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 B. Validation of the mapping (Informative) B.1. Overview At all times, the mapping must be valid before use. After an FC link interruption occurs, the N_Port_ID of an Nx_Port may change, as well as the N_Port_IDs of all other Nx_Ports that have previously performed Port Login with this Nx_Port. Because of this, address validation is required after a LIP in a loop topology [FC-AL-2] or after NOS/OLS in a point-to-point topology [FC-FS]. N_Port_IDs do not change as a result of Link Reset (LR) [FC-FS], thus address validation is not required in this case. B.2. FC Layer Address Validation in a Point-to-Point Topology No validation is required after LR. In a point-to-point topology, NOS/OLS causes implicit Logout of each N_Port and after a NOS/OLS each N_Port must again perform a Port Login [FC-FS]. B.3. FC Layer Address Validation in a Private Loop Topology After a LIP [FC-AL-2], an NL_Port must not transmit any data to another NL_Port until the address of the other port has been validated. The validation consists of completing either ADISC or PDISC [FC-FS]. For a requester, this specification prohibits PDISC and requires ADISC. As a responder, an implementation may need to respond to both ADISC and PDISC for compatibility with other FC specifications. If the three FC addresses (N_Port_ID, N_Port_Name, Node_Name) of a logged remote NL_Port exactly match the values prior to the LIP, then any active Exchange with that NL_Port may continue. If any of the three FC addresses has changed, then the remote NL_Port must be logged out. If an NL_Port's N_Port_ID changes after a LIP, then all active logged in NL_Ports must be logged out. DeSanti & Carlson Expires April 2005 [Page 20] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 B.4. FC Layer Address Validation in a Public Loop Topology A FAN ELS may be sent by the Fabric to all known previously logged in NL_Ports following an initialization event. Therefore, after a LIP [FC-AL-2], NL_Ports may wait for this notification to arrive, or they may perform an FLOGI. If the F_Port_Name and Fabric_Name contained in the FAN ELS or FLOGI response exactly match the values before the LIP and if the AL_PA [FC-AL-2] obtained by the NL_Port is the same as the one before the LIP, then the port may resume all Exchanges. If not, then FLOGI must be performed with the Fabric and all logged in Nx_Ports must be logged out. A public loop NL_Port must perform the private loop validation as specified in section B.3 to any NL_Port on the local loop that has an N_Port_ID of the form 0x00-00-XX. B.5. FC Layer Address Validation in a Fabric Topology No validation is required after LR (link reset). After NOS/OLS, an N_Port must perform FLOGI. If, after FLOGI, the N_Port's N_Port_ID, the F_Port_Name, and the Fabric_Name are the same as before the NOS/OLS, then the N_Port may resume all Exchanges. If not, all logged in Nx_Ports must be logged out [FC-FS]. C. Fibre Channel Bit and Byte Numbering Guidance Both Fibre Channel and IETF standards use the same byte transmission order. However, the bit numbering is different. Fibre Channel bit numbering can be observed if the data structure heading shown in figure 10 is cut and pasted at the top of the figures present in this document. 3 2 1 0 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Fig. 10: Fibre Channel Bit Numbering DeSanti & Carlson Expires April 2005 [Page 21] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 D. Changes from [RFC-2625] - Nx_Ports with N_Port_Name format 0x2, 0x5, 0xC, 0xD, 0xE, and 0xF are supported, in addition to format 0x1; - An IPv4 capable Nx_Port MUST support Class 3; - An IPv4 capable Nx_Port MUST support continuously increasing SEQ_CNT [FC-FS]; - An IPv4 capable Nx_Port SHOULD support a receive data field size for Device_Data FC frames of at least 1024 octets; - The FC ESP_Header MAY be used; - FC Classes of services other than 3 are not supported; - A new FC ARP format is defined; - Support for FARP is removed, because it becomes useless with the new FC ARP and its usage creates interoperability issues, given that it is not uniformely implemented. DeSanti & Carlson Expires April 2005 [Page 22] INTERNET DRAFT IPv4 and ARP over Fibre Channel October 2004 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. 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Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. DeSanti & Carlson Expires April 2005 [Page 23]