IPFC Working Group M. Rajagopal, W. Rickard, Gadzoox Networks INTERNET-DRAFT E. Rodriguez, Lucent Technologies R. Bhagwat, LightSand Communications (Expires January 14, 2001) M. Krueger, Vixel Fibre Channel Over IP (FCIP) Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026 [1]. 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/lid-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html 1. Abstract Fibre Channel(FC) is a dominant technology used in Storage Area Networks(SAN). The purpose of this draft is to specify a standard way of encapsulating FC frames over IP and to describe mechanisms that allow islands of FC SANs to be interconnected over IP-based networks running over very reliable data links. FC over IP relies on IP-based network services to provide the connectivity between the SAN islands over LANs, MANs, or WANs. While the FC over IP specification is independent of the link level transport protocol, it assumes a high bandwidth, high reliability, low loss link level transport such as Gigabit Ethernet, SONET, ATM, or DWDM. This specification treats all classes of FC frames the same -- as datagrams. 2. 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 [2]. 3. Motivation and Objectives Fibre Channel (FC) is a gigabit speed networking technology primarily used for Storage Area Networking (SAN). FC is standardized under Rajagopal, et al. [Page 1] Internet-Draft Fibre Channel over IP July 2000 American National Standard for Information Systems of the National Committee for Information Technology Standards (ANSI-NCITS) and has specified a number of documents describing its protocols, operations, and services [13]. The motivation behind connecting remote sites include disk or tape backup and live mirroring, or simply distance extension between two FC devices or FC Switch clusters (SAN islands). A fundamental assumption made in this specification is that the FC encapsulated IP packets are carried over very reliable data links and may span LANs, MANs, and WANs. This main objectives of this document are to: 1) specify the IPv4 encapsulation, mapping and routing of FC frames. 2) apply the mechanism described in 1) to a FC backbone network or generally between any two FC devices The goal of this specification is to utilize the existing IP suite of protocols and address any FC concerns such as security, data integrity (loss), and performance when running over IP-based networks. 5. FCIP Protocol 5.1 FCIP Device In this specification, the term FCIP device generally refers to any device that encapsulates FC frames into IP packets and decapsulates IP packets to regenerate FC frames. Note: In an actual implementation, the FCIP device may be a stand- alone box or integrated with an FC device such as a FC backbone switch (BBW) or integrated with any IP device such as an IP switch or an IP router. The FCIP device is a transparent translation point. The IP network is not aware of the FC payload that it is carrying. Likewise, the FC fabric and the FC end nodes are unaware of the IP-based transport. 5.2 Protocol The FCIP protocol specifies the IPv4 encapsulation, mapping and routing of FC frames and applies these mechanisms to a FC backbone network or generally between any two FC devices. The FCIP protocol is summarized below: 1. All FCIP protocol devices are peers and communicate using IP. Each FCIP device behaves like an IP end node from the perspective of the IP-based network. That Rajagopal, et al. [Page 2] Internet-Draft Fibre Channel over IP July 2000 is, these devices do not perform IP routing or IP switching but simply forward FC frames. 2. There is no requirement for an FCIP device to establish a login with a peer before communication begins. However, FCIP devices may authenticate the IP packet before accepting it using the IPSec protocols. Each IPv4 datagram is treated independently and a FCIP device receiver simply listens to the protocol value (Fibre Channel) contained in the IPv4 header. 3. Each FCIP device may be statically or dynamically configured with a list of IP addresses corresponding to all the participating FCIP devices. It is outside the scope of this specification to describe any dynamic scheme for configuring the FCIP device with an IP address or the list of IP addresses of other participating FCIP devices. 4. The reachable FC addresses behind each FCIP device and its IP address association can be statically configured or dynamically learned from any FC layer routing protocol exchanged between these devices. In the case when the FCIP device is a "border switch", the DMP routing protocol may provide this information. Routing in the IP plane and the FC plane are largely independent. The exact path (route) taken by the IP packet follows the normal procedures of any IP packet. From the perspective of the FCIP devices this communication is between only two FCIP for any given packet. 5. A FCIP device may send FC encapsulated IP packets to more than one FCIP device. However, these are treated as separate instances and are not correlated in any way in the FCIP protocol device. The FCIP device routes its packets based on the 3-byte FC destination ID (D_ID) address contained in each FC frame. 6. An IP packet may make use of the IPSec protocols to provide secure communications across the IP-based network. 7. Any re-ordering of data link frames due to MTU fragmentation will be recovered in accordance with a normal IP end node behavior. Any re-ordering of FC frames due to IP packet re-ordering will be resolved at the FC end nodes. 8. FCIP assumes that error recovery due to any data loss of IP packets will be done at the FC end nodes. FCIP is expected to run on very reliable data links making the probability of data loss due to line Bit Error Rates extremely small and no worse Rajagopal, et al. [Page 3] Internet-Draft Fibre Channel over IP July 2000 than that of a FC optic link. 9. IPv4 packets shall indicate the use of the Premium Service in the DSCP bits in the IPv4 header. 6. FCIP Encapsulation 6.1 FC Frame Format All FC frames have a standard format much like LAN 802.x protocols. However, the exact size of each frame varies depending on the size of the variable fields. The size of the variable field ranges from 0 to 2112-bytes as shown in the FC Frame Format in Fig. 1 resulting in the minimum size FC Frame of 36 bytes and the maximum size FC frame of 2148 bytes. +------+--------+-----------+----//-------+------+------+ | SOF |Frame |Optional | Frame | CRC | EOF | | (4B) |Header |Header | Payload | (4B) | (4B) | | |(24B) |<----------------------->| | | | | | Data Field = (0-2112B) | | | +------+--------+-----------+----//-------+------+------+ Fig. 1 FC Frame Format SOF and EOF Delimiters: On a FC link, SOF and EOF are called Ordered Sets and are sent as special out-of-band words constructed from the 10-bit comma character (K28.5) followed by 3 additional 10-bit data characters. On a non- Fibre Channel link the Start of Frame (SOF) and End of Frame (EOF) delimiters are both byte-encoded and 4-bytes long. On a FC link the SOF delimiter serves to identify the beginning of a frame and prepares the receiver for frame reception. The SOF contains information about the frame's Class of Service, position within a sequence, and in some cases, connection status. The EOF delimiter identifies the end of the frame and the final frame of a sequence. In addition, it serves to force the running disparity to negative. The EOF is used to end the connection in connection- oriented classes of service. It is therefore important to preserve the information conveyed by the delimiters across the IP-based network, so that the receiving FCIP device can correctly construct the FC frame in its original SOF and EOF format before forwarding it to its ultimate FC destination on the FC link. Start of Frame (SOF) and End of Frame (EOF) byte- encodings are defined in Annex A. Although, the SOF and EOF codes are 32-bits, the format makes use of a single-byte to represent each FC Ordered Set. Frame Header: Rajagopal, et al. [Page 4] Internet-Draft Fibre Channel over IP July 2000 The Frame Header is 24-bytes long and has several fields that are associated with the identification and control of the payload. Current FC Standards allow up to 3 Optional Header fields [4]: - Network_Header (16-bytes) - Association_Header (32-bytes) - Device_Header (up to 64-bytes). Frame Payload: The FC Frame Payload is transparent to the FCIP device. An FC application level payload is called an Information Unit at the FC-4 Level. This is mapped into the Frame Payload of the FC Frame. A large Information Unit is segmented using a structure consisting of FC Sequences. Typically, a Sequence consists of more than one FC frame. FCIP does not maintain any state information regarding the relationship of frames within a FC Sequence. CRC: The CRC is 4-bytes long and uses the same 32-bit polynomial used in FDDI and is specified in ANSI X3.139 Fiber Distributed Data Interface. Note: When FC frames are encapsulated into IP packets, the CRC is untouched. 6.2 FC Frame Mapping to IP Packet Fig.2 shows the mapping of the FC frame into an IPv4 Packet. The FC to IP mapping (and reverse) mapping is one-to-one since the maximum size of the encapsulated FC Frame along with the header fields does not exceed 2148 bytes. The minimum size FC Frame is 36 bytes resulting in a maximally minimum IP MTU size of 96 bytes. (The Maximally minimum MTU size is the IP packet with the minimum size payload and the maximum size IP headers). The maximum size FC frame is 2148 bytes resulting in a nominal IP packet size of 2168 bytes. Fig.2 shows the format of the IPv4 packet with the standard 20-byte fixed header and a 40-byte optional header. For the case of the maximum size payload of 2148 bytes, the maximum IPv4 packet size is 2208 bytes. The maximum size FC frame can cause the IP packet to be fragmented when the data link cannot support this MTU size. When an IP packet is fragmented, required parts of the header must be copied by all fragments and the option field may or may not be copied. +---------- -+---------------+-------------+ | IP Header | IP Opt. Header| FC Frame | | (20 bytes) | (40 bytes | (2148 bytes | Rajagopal, et al. [Page 5] Internet-Draft Fibre Channel over IP July 2000 | | Max) | Max) | +------------+---------------+-------------+ Fig. 2 Format of an IPv4 Payload carrying FC If IPSec is used for security it introduces its own headers and the IP packet size increase depends on the exact mode of IPSec usage (AH versus ESP, Tunnel versus Transport). However, this additional increase in the IP packet size due to IPSec headers is relatively small (see [8], [9], [10]), and the maximum size IP packet will remain within its maximum size of 65535 bytes. Adding, IPSec header may, in some cases, lead to fragmentation if it exceeds the data link MTU. IP Header Field Setting: DSCP (6 bits): The Differentiated Service Code Points (DSCP) [6] shall be set to correspond to the Premium Service. This service provides "Expedited Forwarding" at each IP hop (Per Hop Behavior (PHB)). Protocol (8 bits): This 8-bit field defines the higher level protocol that uses the service of the IP layer. In this case, this is set to the Fibre Channel Protocol Value 133 defined in [12]. Source IP Address (32 bits): This is the IP address of the ingress FCIP device that is transmitting the FC encapsulated IP packet. Destination IP Address (32 bits): This the IP address of the egress FCIP device that is receiving the FC encapsulated IP packet. FCIP specification treats all classes of FC frames the same -- as datagrams. There will be no F_BSY or F_RJT sent if a Class 2 frame is lost while in transit within the IP network. FCIP may not be suitable for transport of Class 1 traffic since these frames are treated the same way as any Class 2 or 3 frame. 6.3 Fibre Channel Bit and Byte Ordering Fibre Channel's FC-1 Level defines the method used to encode data prior to transmission and subsequently decode the data upon reception. The method encodes 8-bit bytes into 10-bit transmission characters to improve the transmission characteristics of the serial data stream. In Fibre Channel data fields are aligned on word boundaries. A word in FC is defined as 4 bytes or 32 bits. The resulting transmission word after the 8-bit to 10-bit encoding consists of 40 bits. Data words or Ordered Sets (special FC-2 Level control words) from the FC-2 Level map to the FC-1 Level with no change in order and the bytes in the word are transmitted in the Most Significant Byte first to Least Significant Byte order. The transmission order of bits within each byte is the Least Significant Bit to the Most Significant Rajagopal, et al. [Page 6] Internet-Draft Fibre Channel over IP July 2000 Bit. 7. FCIP Network 7.1 FC Backbone Switches FC Standards [3] describe the operation and interaction of FC Switches. Two distinct levels of switch interconnections are specified. Autonomous Regions (AR) are defined to allow clusters of FC Switches to be connected across a backbone network called a DMP- backbone. An AR is administratively defined with each AR encompassing one or more FC Address Domains. The DMP-backbone network is formed from one or more Backbone Switches (BSW) that run the DMP routing and switch control protocol on FC links. DMP is based on OSPF and the DMP backbone may consist of an arbitrary mesh network. A BSW may communicate with multiple neighbors. As specified in [3], native FC frames traverse the DMP backbone between DMP neighbors on FC links. DMP Routing Protocol messages are exchanged between BSWs on this backbone. An example network consisting of 4 ARs and a DMP FC backbone consisting of 3 links is given in Fig. 1. There is no restriction in adding other links to this network as needed. The connection between BSWs below may in fact form a fully connected mesh. _______ _______ | | | | | AR #1 |_____ _____| AR #4 | |_______| | | |_______| ___|___ ___|___ | BSW 1 |---------------------| BSW 4 | |_______| |_______| ___|___ _______ | BSW 2 |---------------------| BSW 3 | |_______| |_______| ___ ___ | | _______ | | | | | | | AR #2 |----- -----| AR #3 | |_______| |_______| Note: BSW 1 knows it is connected to BSWs 2 and 4; BSW 2 knows it is connected to BSWs 1 and 3; BSW 4 knows it is connected to BSWs 1. Fig. 1 Example Network showing DMP Backbone Switching Architecture An FCIP device provides a single logical interface to the DMP protocol connecting multiple DMP neighbors on the IP network. From the DMP routing point of view, the connection to each neighbor on the Rajagopal, et al. [Page 7] Internet-Draft Fibre Channel over IP July 2000 IP network is treated as a separate logical FC link. In FCIP, the native FC frames are first encapsulated in IP packets which then traverse the IP-based network. The IP network provides a new transport path for each emulated DMP FC link. The IP network itself may consist of any number of hops between two FCIP devices. Also, the route taken by the IP packet between any two FCIP devices is dictated by the normal IP routing. A functional and logical diagram of an IP-based DMP backbone for the example network given in Fig. 1 is shown in Fig. 2. In this figure, each BSW is logically connected to other BSWs. _______ _______ | | | | | AR #1 |--- | AR #4 | |_______| | ______ ________ ______ |_______| __|_ __ | | | | | | ___|___ | BSW 1 |---| FCIP |--| IP |--| FCIP |--| BSW 4 | |_______| |______| | Network| |______| |_______| | | -------- ______ | | ______ ______ | | | | | | _______ | BSW 2|---| FCIP |-----| |---| FCIP |---| BSW 3 | |______| |______| |______| |_______| ________ | ___|___ | | | | | | AR #2 |__| | AR #3 | |________| |_______| Fig. 2 Example Network showing an IP-based FC Backbone Switching Architecture The IP-based network has transformed the DMP backbone into a fully connected network. From the perspective of each BSW all remote BSWs therefore appear to be neighbors. The DMP routing protocol computation would make the IP based network topology appear as a fully connected mesh. The DMP routing protocol exchanges between BSWs occur transparently to the FCIP devices. Encapsulated FC frames are routed on the IP network according to the normal IP routing procedures. In this mode, the DMP routing protocol lays over the IP network and has no knowledge of the underlying IP protocol and IP routing or the underlying technology that carries the IP datagram. This concept is shown in Fig.3 Rajagopal, et al. [Page 8] Internet-Draft Fibre Channel over IP July 2000 ________ _______ | AR #1 | | AR #2 | | |-- | | |________| | ______ ________ _____ |_______| __|___ | | | | | | ____|__ | BSW 1|---| FCIP |--| IP |--|FCIP |--| BSW 2 | | | | | | Network| | | | | |______| |______| |________| |_____| |_______| <--------------> IP Routing <----------------------------------> DMP Routing Plane Note: IP Network routing may consist of multiple paths 7.2 FC Device The protocol encapsulation and mapping of the FC frame described in earlier sections applies equally to any pair of FC device (e.g. switch to switch) wishing to tunnel FC frames across an IP-based network. Any FC routing protocol exchanges may still occur transparent to the FCIP devices. 8. Security Considerations Using a wide-area, general purpose network such as an IP internet in a position normally occupied by physical cabling introduces some security problems not normally encountered in Fibre Channel storage networks. Normal media are typically protected physically from outside access; IP internets typically invite outside access. The general effect is that the security of the entire Fibre Channel internetwork is only as good as the security of the entire IP internet through which it tunnels. The following broad classes of attacks are possible: 1) Unauthorized Fibre Channel controllers can gain access to resources through normal Fibre Channel processes. 2) Unauthorized agents can monitor and manipulate Fibre Channel traffic flowing over physical media used by the IP internet and under control of the agent. To a large extent, these security risks are typical of the risks facing any other application using an IP internet. They are mentioned here only because Fibre Channel storage networks are not normally suspicious of the media. Fibre Channel storage network administrators will need to be aware of these additional security risks. Security protocols and procedures used in other IP applications may also be used for FC over IP. For Virtual Private Networks , both authentication and encryption are Rajagopal, et al. [Page 9] Internet-Draft Fibre Channel over IP July 2000 generally desired, because it is important both to (1) assure that unauthorized users do not penetrate the virtual private network and (2) assure that eavesdroppers on the network cannot read messages sent over the network. IPSec provides 3 main facilities: an authentication-only function, referred to as Authentication Header (AH), a combined authentication/encryption function called Encapsulating Security Payload (ESP), and a key exchange function. Because both features are generally desirable, ESP may be more suitable than AH. The key exchange function allows for manual exchange of keys as well as an automated scheme. The IPSec specifications described in [8], [9], [10], and [11] covers these topics. It is beyond the scope of this document to discuss specific use of the IPSec protocols. Note: Use of IPSec protocol is optional. 9. Data Integrity Considerations Loss: Recovery from data loss due to IP datagram loss is made at the end FC nodes. It is expected that such data losses are rare because the mechanism assumes extremely reliable data links. 9.1 Highly Reliable Data Links Requirement The IP backbone used for FC traffic is assumed to be a highly reliable, low loss backbone-quality media. Loss takes two forms noise loss (i.e. loss due to corruption) and congestion loss. Fibre Channel traffic expects that the network the data will be transmitted across will have minimal loss. Therefore, both "loss" issues listed above need to be addressed. While most network topologies are still defined to be subject to loss, in practice, use of optics has reduced the rate of loss to almost inconsequential levels. Bit error rate (BER) is a function of the optical media. Current bit error rates are being engineered into the optical media to have the same BER as SONET networks. SONET, a commonly deployed network backbone topology, is defined in SONET standards to have a maximum bit error rate (BER) of 10^-6. In fact, a bit error rate this high is rarely, if ever, encountered today. This is due to the fact that the media being used is engineered to have very low loss rates. Copper, the lowest quality media commonly used, typically has a maximum loss rate of 10^-9 Rates for fiber are much lower. Fiber with a BER of 10^-12 is commonly deployed, and 10^-15 and 10^-18 and lower BER rates are available and being deployed today. As speeds increase, lower BER rates are being integrated with each new generation of product. BER is a function of the optics, so similar figures are available for Rajagopal, et al. [Page 10] Internet-Draft Fibre Channel over IP July 2000 WDM. In order to maintain the same or less BER as a FC network, the IP media portion of the network must have a loss rate less than or equal to that of the FC network. FC-PH [14] specifies FC networks shall have a BER of 10^-12 or less, a criteria satisfied by many optical based networks today. Additionally, to minimize loss, the network needs to be configured to ensure that packet loss due to congestion is negligible. Traditional Ethernet and Fast Ethernet networks do not satisfy this criteria, since packet loss due to congestion occurs quite frequently. Packet loss due to congestion occurs much less frequently in other types of networks, including SONET. The IP network transporting FC traffic must provide low congestion loss rates. 9.2 Requirement of Highly Reliable Links instead of TCP requirement: When an FC frame is transported over an IP network, there is a possibility of the frame getting dropped. This can happen if there is no flow control along a path within the IP network and there are no empty buffers available on one of the incoming ports along the path. In this case, there is no way for the FCIP gateway to know that the frame has been dropped. Therefore, FC layer end-to-end recovery mechanisms must deal with frame loss as there is no way for the FCIP gateway device to know when retransmission is necessary. It has been suggested by some people that FC frames be wrapped in TCP/IP instead of IP directly, so that TCP would take care of frame retransmission. However, there are two major drawbacks to this. 1. TCP, especially as typically implemented today in a software stack, tends to add significant overhead both in terms of processing power and buffer space requirements. Thus TCP's addition will cause a significant increase in resources required and result in a performance impact. 2. TCP level retransmissions may interfere with Fibre Channel level recovery. Depending on the relative value of the TCP level timeout and any FC layer timeout, it is possible for both the FC recovery and TCP recovery to process simultaneously, leading to confusion at the target device and potentially a recovery storm on the network. Specifically, let us examine the following example: a. FC layer timeout reached; end to end recovery mechanism started. I/O is retransmitted. b. FCIP gateway is holding on to one or more frames corresponding to the above I/O. c. TCP timeout is reached. Frame(s) is(are) retransmitted by the TCP on the FCIP gateway. d. Now the same I/O is being recovered at two non-cooperating Rajagopal, et al. [Page 11] Internet-Draft Fibre Channel over IP July 2000 layers. e. In addition, in an extreme case, when there is congestion within the IP network, frames may be dropped repeatedly for lack of path-wide flow control. Multiple/parallel retransmissions add to the congestion. This kind of behavior can lead to a storm. The general argument for using TCP is to recover from frame loss. However, conflicting recovery mechanisms, leading to the possibility of generating IP storms are a counter argument to use of TCP for transporting FC frames. Fragmentation: The Fibre Channel maximum transmittable unit (MTU) is 2148 bytes. It is preferable that FCIP packets encompass the FC MTU to avoid fragmentation of FCIP packets. The resulting packet size exceeds the MTU of some IP physical layers (e.g. Ethernet MTU = 1518 bytes). FCIP devices should handle fragmentation and must handle re-assembly of FCIP packets. A FCIP device may use Path MTU Discovery (RFC 1191) or an equivalent mechanism to adjust FCIP packet size to avoid fragmentation. Alternatively, the MTUs of all FC nodes may be manually set to match the path MTU of the IP network. Ordering: In an IP network, packets are not guaranteed to be delivered in the same order in which they were transmitted. Ordering is assumed to be a function of a higher layer protocol. The Fibre Channel architecture allows for out-of-order frame delivery and provides mechanisms for the destination port to reassemble a sequence with frames delivered out-of-order. FC frames in this sense are no different from IP packets. Above the sequence level, confirmation of delivery can be used to ensure the sequences within an exchange are delivered in the correct order. However, some applications may wish to prevent out-of-order arrival entirely (it should be noted that frames retransmitted as a result of busy conditions may arrive out-of-order). Any Fibre Channel mechanism that requires frames be delivered in the same order as transmitted ("Sequential delivery" service option in class 2 and 3, class 1 service, etc.) cannot be guaranteed using FC over IP. The FC Over IP specification treats all classes of FC frames alike and treats each FC frame like a datagram, and there is no support to maintain any ordering relationships that may exist between FC frames. 10. Performance Considerations Mapping the IP header DSCP bits to correspond to a Premium Service provides a preferred service at each IP Router Per Hop Behavior Rajagopal, et al. [Page 12] Internet-Draft Fibre Channel over IP July 2000 (PHB) [6]. Since FCIP protocol makes use of the layer 3 IP protocol rather than the layer 4 TCP, minimal buffering requirements are imposed on the FCIP device. However, this also means that no reliable transmission in the sense of retransmissions are supported. This aspect is important when engineering the data links between the FCIP devices. Note: We expect that technology advances in optics now have the ability to provide very large bandwidth links with very low error rates. Hence the need for a Layer 4 Transport protocol seems unnecessary. In the rare event, when an IP datagram is dropped (corrupted or due to congestion), then the FC end nodes are designed to recover from this situation. The FCIP protocol does not crack the FC Frame (except for attaching the correct byte-encoded SOF and EOF) nor does it do any FC payload processing. This allows any FC traffic to be tunneled across at high throughput rates. The case where there is no data link fragmentation, each FC frame which has a one to one mapping to an IP datagram also has a one-to- one mapping to a data link frame. This has the tendency to further improve the throughput performance. Note: Class 1 FC traffic expects a dedicated bandwidth. This specification does not address this requirement. 11. Flow Control FCIP does not provide any flow control support at the IP level. FC credit mechanism provides the required flow control at a higher level between switches. FCIP may be subject to data link level flow control when used. 12. References: [1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP 9, RFC 2026, October 1996. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [3] NCITS 321-200x (ANSI) T11/Project 1305-D/Rev4.3 "Fibre Channel Switch-Fabric-2", March 2000 (www.t11.org) [4] Fibre Channel Physical and Signaling Interface -3 (FC-PH-3), Rev. 9.3, ANSI X3.303-1998 [5] The Fibre Channel Consultant: A Comprehensive Introduction, "Robert W. Kembel", Northwest Learning Associates, 1998 [6] Nichols, K., Blake, S., Baker, F. and D. Black, " Definition Rajagopal, et al. [Page 13] Internet-Draft Fibre Channel over IP July 2000 of the Differentiated Services Field (DS Field) in the IPv4 and Ipv6 Headers", RFC 2474, December 1998. [7] NCITST11/Project 1238-D/Rev4.6 "Fibre Channel Backbone", April 17 2000 (www.t11.org) [8] Kent, S. and Atkinson, R., "Security Architecture for the Internet Protocol", RFC 2401, Nov 1998 [9] Kent, S. and Atkinson, R., "IP Authentication Header", RFC 2402, Nov 1998 [10] Kent, S. and Atkinson, R., "IP Encapsulating Security Payload (ESP)", RFC 2406, Nov 1998 [11] Maughan, D. et all, "Internet Security Association and Key Management Protocol (ISAKMP)", RFC 2408, Nov 1998 [12] http://www.isi.edu/in-notes/iana/assignments/protocol-numbers [13] http://www.t11.org [14] Fibre Channel Physical and Signaling Interphace (FC-PH), Rev 4.3, ANSI X3.230-1994. 13. Acknowledgments 14. Authors' Addresses Murali Rajagopal Gadzoox Networks, Inc. 16241 Laguna Canyon Road, Suite 100 Irvine, CA 92618 Phone: +1 949 280 6516 Fax: Email: murali@gadzoox.com Raj Bhagwat LightSand Communications, Inc. 375 Los Coches St. Milpitas, CA 95035 Phone: +1 408 941 2010 Ext 194 Fax: Email: rajb@lightsand.com Wayne Rickard Gadzoox Networks, Inc. 16241 Laguna Canyon Road, Suite 100 Irvine, CA 92618 Phone: +1 949 789 4604 Rajagopal, et al. [Page 14] Internet-Draft Fibre Channel over IP July 2000 Fax: +1 949 453 1271 Email: wayne@gadzoox.com Elizabeth G. Rodriguez Lucent Technologies 1202 Richardson Drive, Suite 210 Richardson, TX 75080 Phone: +1 972 231 0672 Fax: +1 972 671 5476 Email: egrodriguez@lucent.com Marjorie Krueger Vixel Corporation 15245 Alton Pkwy., Suite 100 Irvine, CA 92618 Phone: +1 949 450 6100 Fax: +1 949 753 9500 Email: marjorie.krueger@vixel.com Rajagopal, et al. [Page 12] Internet-Draft Fibre Channel over IP March 2000 APPENDIX A: Fibre Channel EOF and SOF Encodings A.1 Ordered Sets On a FC link, Ordered Sets (OS) are sent as special out-of-band words constructed of the 10-bit comma character (K28.5) followed by Rajagopal, et al. [Page 15] Internet-Draft Fibre Channel over IP July 2000 3 additional 10-bit data characters. The Ordered Sets defined by FC include the Frame Delimiter, Start of Frame (SOF) and End of Frame (EOF), and other Primitive Signals. When FC frames are encapsulated in an IP packet, the Byte-encoded frame format is used. The Byte-encoded frame format uses 32-bit OS Code Words to represent valid FC frame delimiter. This format uses a single-byte OS Code to represent each FC Ordered Set. FC Over IP makes use of the OS Codes defined in Annex A of [7] for the frame delimiters. SOF and EOF codes defined in the figures (see below) in this Annex are inserted into the FC frame. Primitive Signals and Primitive Sequences are stripped at the FCIP boundary. The frame delimiters are identified by their position. An encapsulated Byte-encoded frame must use the corresponding 32-bit OS Code Word as the first and last words in the encapsulated PDU. FC frame delimiters shall be encoded in the format shown in Table below. Table 1. Frame Delimiter Format +---+----------------+----------------+----------------+-------------- + |Wrd| <31:24> | <23:16> | <15:08> | <07:00> | +---+----------------+----------------+----------------+-------------- + |0 | OS Code | Reserved | +---+----------------+----------------+----------------+-------------- + A.2 Encoded FC Frame Delimiters The SOF OS-codes are a single byte encoding of the SOF Ordered Set. The first word in an encapsulated Byte-encoded FC frame shall map the SOF Ordered Set to the corresponding 32-bit OS Code Word. The EOF OS-codes are a single byte encoding of the EOF Ordered Set. The last word in an encapsulated Byte-encoded FC frame shall map the EOF Ordered Set to the corresponding 32-bit OS Code Word. +-----------------+----------------+ | OS-Code | Delimiter Name | | (hex) | | +-----------------+----------------+ | 0x28 | SOFf | +-----------------+----------------+ Rajagopal, et al. [Page 16] Internet-Draft Fibre Channel over IP July 2000 Rajagopal, et al. [Page 13] Internet-Draft Fibre Channel over IP March 2000 | 0x3F | SOFc1 | +-----------------+----------------+ | 0x2F | SOFi1 | +-----------------+----------------+ | 0x37 | SOFn1 | +-----------------+----------------+ | 0x3D | SOFc2 | +-----------------+----------------+ | 0x2D | SOFi2 | +-----------------+----------------+ | 0x35 | SOFn2 | +-----------------+----------------+ | 0x3E | SOFc3 | +-----------------+----------------+ | 0x2E | SOFi3 | +-----------------+----------------+ | 0x36 | SOFn3 | +-----------------+----------------+ | 0x39 | SOFc4 | +-----------------+----------------+ | 0x29 | SOFi4 | +-----------------+----------------+ | 0x31 | SOFn4 | +-----------------+----------------+ | 0x38 | SOFcf | +-----------------+----------------+ | 0x30 | SOFnf | +-----------------+----------------+ | 0x41 | EOFn | +-----------------+----------------+ | 0x42 | EOFt | +-----------------+----------------+ | 0x46 | EOFdt | +-----------------+----------------+ | 0x44 | EOFrt | +-----------------+----------------+ | 0x49 | EOFni | +-----------------+----------------+ | 0x4E | EOFdti | +-----------------+----------------+ | 0x4F | EOFrti | +-----------------+----------------+ | 0x50 | EOFa | +-----------------+----------------+ Rajagopal, et al. [Page 17] Internet-Draft Fibre Channel over IP July 2000 Appendix B: Relationship between FC over IP (FCIP, FCoverIP) and IP over FC (IPFC) IPFC describes the encapsulation of IP packets in FC frames. It is intended to facilitate IP communication over an FC network. FC over IP describes the encapsulation of FC frames in IP packets for transporting over an IP network. It gives no consideration to the type of FC frame that is being encapsulated. Therefore, the FC frame may actually contain an IP packet as described in the IP over FC specification (RFC 2625). In such a case, the encapsulated IP packet would have: IP Header FC Header IP Header Note: The two IP headers would not be identical to one another. One would have information pertaining to the final destination while the other would have information pertaining to the FCIP device. The two documents focus on different objectives. As mentioned above, implementation of FC over IP will lead to IP encapsulation within IP. While perhaps inefficient, this should not lead to issues with IP communication. One caveat: if a FC device is encapsulating IP packets in an FC frame(e.g. an IPFC device), and that device is communicating with a device running IP over a non FC media, a second IPFC device will need to act as a gateway between the two networks. This scenario is not specifically addressed by FC over IP. There is nothing in either specification preventing a single device from implementing both FC over IP and IP over FC, but this is implementation specific, and is beyond the scope of this document. Full Copyright Statement Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. Rajagopal, et al. [Page 18] Internet-Draft Fibre Channel over IP July 2000 This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. [draft-ietf-ipfc-fcoverip-02.txt] [This INTERNET DRAFT expires on January 14, 2001] Rajagopal, et al. [Page 19]