FIBRE CHANNEL TECHNOLOGY

FIBRE CHANNEL

TECHNOLOGY

Data Transfer Solutionfor the 21st Century

White Paper

From Unisys Open Storage Solutions

C O N T E N T S

1 Executive Summary

1 What Is Fibre Channel?

1 Does Fibre Channel Comply with ANSI Standards?

2 Is Fibre Channel Becoming Industry Standard?

2 What Can Fibre Channel Do?

4 How Does Fibre Channel Connect Network Nodes?

7 How Is Fibre Channel Organized?

9 What Media Do I Use for Physical Connections?

10 Is Fibre Channel Being Used Successfully Today?

12 What’s the Last Word on Fibre Channel?

13 Appendix A: Fibre Channel Quick Reference Card

F I G U R E S

1 Point-to-Point

2 Switched Fabric

3 Loop

4 Fibre Channel’s Five Layers

5 The SAN Solution

T A B L E S

1 Attributes of Copper and Optical Fiber Cable

A1 Fibre Channel and Related Standards and Technical Reports

A2 FCA and FCSI Profiles and Related Documents

A3 FC-PH

A4 DF_CTL Bits for Data Frames

A5 Header Fields by Frame Group

A6 CS_CTL Bits for All Frames

A7 Parameter Field for BSY and RJT

A8 “Device” Type Field Values of FC-4 Frames

A9 F_CTL Bits for All Frames (Word 2)

A10 Reject (P_RJT, F_RJT) Reason Codes

A11 Optical Feeds and Speeds

A12 Electrical Feeds and Speeds

A13 Class Characteristics

A14 Well-Known Address Identifiers

Executive Summary

Today’s businesses are demanding the ability to find and retrieve their data instantly, and

that data is much larger than ever before because of the tremendous growth in video, multi-

media, giant software suites, and other large files. What they need is Fibre Channel.

Fibre Channel is a high-speed data transfer technology. Its primary task is to transport

data extremely fast with the least possible delay. The Fibre Channel standard supports mul-

tiple file protocols and can use either copper or optical fiber cables. This f lexibility coupled

with the range of topologies available enable customers to custom-make the Fibre Channel

solution that best fits their needs.

Fibre Channel technology has brought to the market the high-performance, low-cost

communications pathway required by the new breed of data and communications-intensive

applications commonly used in networks. This technology also solves the distance, connec-

tivity, and performance problems seen in current systems using parallel SCSI. The high-

speed transfers can reach a rate of over 1 gigabaud per second—or 10 to 250 times faster

than today’s network protocols.

Fibre Channel is positioned for entry into the mass market and is ready to be the

number one system interconnection means of the future.

What Is Fibre Channel?

Fibre Channel is a high-speed data transfer technology—an integrated standards set devel-

oped by a committee operating under the American National Standards Institute (ANSI).

Fibre Channel’s primary task is to transport data extremely fast with the least possible

delay. Fibre is a generic term referring to all supported media types, while fiber refers to

the optical fiber transmission medium.

The Fibre Channel standard is proving the most useful in interconnecting servers,

storage devices, and workstation users. Its success is based on its transfer speeds, f lexible

topology, and f lexible upper-level protocols. Fibre Channel easily handles both networking

and peripheral input/output (I/O) communication over a single channel, resulting in fewer

I/O ports and fewer unique ports—the traditional bottleneck of other server connection

technologies.

Does Fibre Channel Comply with ANSIStandards?

In 1988, the American National Standards Institute X3T9.3 committee chartered the Fibre

Channel working group to develop a practical, inexpensive, yet expandable method of

achieving high-speed data transfer among workstations, mainframes, supercomputers,

desktop computers, storage devices, and display devices. The Fibre Channel working

group was assigned full ANSI committee status in 1994.

Fibre Channel Technology 1

Is Fibre Channel Becoming Industry Standard?

Fibre Channel is gaining industry support at a blinding pace as companies recognize the

technology as a solution to their data transfer problems. The industry now provides a full

system set of products in several markets. Early adopters in key industries, such as video

pre- and post-production, are enjoying significant economic benefits from their Fibre

Channel systems.

Technology giants such as Compaq, Hewlett Packard, Tektronix, SUN, Intel, Symbios

Logic, NEC, Unisys, Digital, SGI, Microsoft, and at least 100 others now have Fibre Channel

technology tied significantly to many of their products and market strategies. With Microsoft

support, Fibre Channel appears to be a winning strategy for Windows NT suppliers as well.

Fibre Channel has become the dominant standard for information exchange, beginning

with storage networking. In the future, as with other technologies that provided an industry

paradigm shift, Fibre Channel design improvements may well come from some of the

currently smaller participants.

Though no one can be sure how and where a technology will evolve, it is certainly clear

that Fibre Channel is here to stay and has already changed data transfer technology forever.

What Can Fibre Channel Do?

The main features of Fibre Channel are that it:

• Delivers speeds that are 2.5 to 250 times faster than existing communication and I/O

interfaces

• Overcomes today’s network performance limitations regarding error detection

and recovery

• Provides low-cost and reliable performance for distance connections

• Offers f lexible protocols and topologies to best leverage existing technology

investments

• Runs multiple protocols over a single network or loop

• Allows clustering of servers

• Enables multiple servers to share storage

• Scales from small numbers of peripherals attached short distances apart to large

numbers attached many kilometers apart

Delivers Fastest Transfer SpeedsData transfer needs in all types of business are growing rapidly. Files today combine data,

sound, graphics, and even video. The size of data is exponentially larger than in past years

and decades. Information technology (IT) departments the world over need to move this

information through their networks at lightning speeds.

Fibre Channel runs at four simplex speeds (actual data throughput): 100 megabytes

per second (MB/s) (1062.5 megabaud), 50 MB/s (531.25 megabaud), 25 MB/s (265.625

megabaud), and 12.5 MB/s (132.812 megabaud). Full-duplex transfers are allowed (READ

and WRITE simultaneously), which double the above throughput rates. Currently, though,

2 White Paper

few products support full-duplex transfers. For total bandwidth, a single 100 MB/s Fibre

Channel port equals five 20 MB/s SCSI ports. Fibre Channel provides a total network

bandwidth of about one gigabit per second.

These speeds are extremely helpful in solving the problems that growing file sizes

are creating. The high-speed transfers are available because of Fibre Channel’s f lexible

topologies and protocols, which are discussed at length in the “How Does Fibre Channel

Connect Network Nodes?” section of this paper.

Overcomes Network LimitationAt the same time that Fibre Channel transports data, it also performs error detection in

low-level hardware and microcode. Because Fibre Channel’s design is hardware intensive,

it offers a lower overhead for the host system than traditional networks. One reason for this

lower overhead is that LANs are quite software intensive to allow for station management.

Station management is how each station, or network node, recognizes error conditions on

the network, then provides the error management needed to recover.

Fibre Channel hosts do not have this burden. Rather, when congestion causes a data

transfer failure, Fibre Channel retries immediately without software intervention. Only the

more complex error recovery functions are passed back to the central system. Fibre Channel

relies on the contents of the frame header to trigger actions like routing arriving data to the

right buffer. Commands and responses are routed directly to and from command buffers

while data is routed directly to the memory allocated by the task that made the request.

Provides Distance Connection and Low CostThe Fibre Channel architecture provides a range of implementation possibilities extending

from minimum cost to maximum performance. The transmission medium is isolated from

the control protocol so that each implementation may use a technology best suited to the

environment of use.

Offers Flexible Topologies and ProtocolsFibre Channel ports can be connected in three distinct topologies: point-to-point links,

switched fabric configurations, or in a loop. Both optical and copper media are supported,

working from 133 megabaud per second up to 1.062 gigabaud per second. Also, using fiber

you can achieve distances of up to 10 km. Fibre Channel supports a great many protocols,

such as:

• High Performance Parallel Interface (HIPPI)

• Single Byte Command Code Set (SBCCS, also known as the Block MUX channel)

• Small Computer System Interface (SCSI)

• Internet Protocol (IP)

• Institute of Electrical and Electronic Engineers 802 (IEEE 802)

• Asynchronous Transfer Mode (ATM)

If these network protocols use Fibre Channel for their transport system, the original

higher-level command sets and functions are retained while the lower-level physical

interface is replaced by Fibre Channel.


In addition to raw transmission speed, the use of a f lexible circuit/packet-switched

topology to connect devices is key to the high performance of Fibre Channel. Fibre Channel

is able to establish multiple simultaneous point-to-point connections. Devices attached to

a non-blocking switch do not have to contend for the transmission medium as they do in

some networks. Through its intrinsic f low control and acknowledgment capabilities, Fibre

Channel also supports connectionless traffic without suffering the congestion of the shared

transmission media used in traditional networks.

How Does Fibre Channel Connect Network Nodes?

The key to Fibre Channel performance and one of its most valuable features is its

f lexible topology, which offers three distinct interconnection choices:

Point-to-Point TopologyAs shown in Figure 1, the simplest of the three topologies is point-to-point. This method is

a single connection between two servers, or a server to storage. The point-to-point topology

uses a single, full-duplex cable between the two systems.

Point-to-point connections have several advantages. This topology has the highest

bandwidth efficiency possible because there are no devices interfering with the connection.

For the same reason, this topology has the lowest latency (delay) of all three connection

choices. Point-to-point connections are also the easiest and the least expensive way to use

the Fibre Channel technology.

The disadvantage of the point-to-point topology is that this is a very limited use of

Fibre Channel. Exactly two devices are connected—no more. In addition, both devices must

share the same data link speed and the same cabling scheme.

The best uses of point-to-point connections are when transferring extremely large

amounts of information specifically between two systems (either computer-to-computer

or computer-to-disk). When volume, cost, speed, and reliability are the mitigating factors

in data transfer, this topology may be the best choice.

Switched Fabric TopologyA switched fabric topology provides the greatest interconnection capability and largest total

aggregate throughput of the three topologies discussed. In this interconnection method,

each server or storage subsystem is connected point-to-point to a switch and receives a non-

blocking data path to any other server on the switch. This setup is equivalent to a dedicated

connection to every server. As the number of servers and storage subsystems increases to

occupy multiple switches, the switches are, in turn, connected together. Multiple connection

paths between switches are recommended to provide circuit redundancy and increase total

bandwidth. Figure 2 illustrates this connection method.

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Figure 1.Point-to-Point

An obvious advantage to a switched fabric topology is the tremendous scalability it

offers. As a company’s IT needs grow, the switched fabric can continue adding connections

as needed. Because each connection is a virtual point-to-point, this topology preserves high

bandwidth requirements throughout an enterprise. Switched fabric will also match speeds

between different speed connections, providing a high level of server versatility without

performance loss. Likewise, this type of connection allows the business to match cables

throughout a diverse network. The final advantage for a very large, very complex network

is the cost savings.

For smaller networks, however, the cost of switched fabric topologies can be a disad-

vantage. Latency becomes another problem when using switches. Though the ultimate

connections are clear and fast, there can often be some delay in making the connections

between nodes due to the complexity of the system. In addition, connections are non-

deterministic, which means that two successive connections between the same ports may

take an entirely different path each time with attendant differences in latency. The result is

that sequential commands can possibly arrive out-of-order at a peripheral. Some switches

offer an option to guarantee command ordering.

A switched fabric topology would generally be the best choice for very large enter-

prises that routinely handle high volumes of complex data between local and remote

servers. It provides remarkable scalability and f lexibility, while sustaining high bandwidth

requirements.

Loop TopologyLoop topology interconnects up to 126 servers, storage subsystems, or storage devices in a

ring. In an arbitrated loop, each server arbitrates for loop access and, once granted, has a

dedicated connection between sender and receiver. The available bandwidth of the loop

is shared among all servers. The primary reason to use a loop is cost. Because no switch

is required to interconnect multiple devices, the per-connection cost is significantly less

than with the switched fabric method. The peripherals in a loop need not worry about the

possible 16 million addresses in a switched environment. With only 126 possible addresses

to deal with, peripheral costs can also be reduced. Figure 3 shows the loop method.


Figure 2.Switched Fabric

One variation on a straight loop configuration is the addition of hubs to the loop.

A hub is a hardware component with multiple ports that enables you to interconnect several

devices in the loop without breaking the loop. Using a hub will not increase the possible

number of servers or storage items in the ring, as the loop limit of 126 addresses remains

true for the hub (the hub is not normally an addressable unit). Though loop topology is

always in a ring shape, using hubs gives the ring more of a star-like shape, though it is still

a closed loop.

The reasons to use hubs in loop topology are that they allow non-disruptive expansion

to the network and allow removal-replacement of failed units while loop activity continues,

known as hot-plugging. Because hubs allow the mixing of copper and fiber cables, imple-

menting hubs in the loop allows greater distance between nodes so that the devices don’t

have to be as physically close to each other in the building. These less stringent distance

requirements and the simple configuration of hubs can help increase the f lexibility of loop

topology.

For the majority of small to medium networks, the advantages of a loop topology

outweigh any disadvantages. A loop is scalable from as few as 3 devices up to 126. Because

switches are not needed, this topology is quite cost-efficient for most enterprises. The loop

is best used to meet the scalability demands of disk storage configurations. It is in the most

demand today and will remain competitive in the future.

The disadvantages of a loop topology are most keenly felt by large networks. Loop is

rather inefficient in large configurations because only two nodes communicate at a time.

Also, large networks users can experience high latency because all the connections are

in a circle. Proposed enhancements to the Fibre Channel loop include a mode of operation

that eliminates arbitration and allows spatial reuse so that multiple “conversations” can

occur at the same time.

Another loop disadvantage is that all devices must operate at the same link speed.

Further, all devices in the loop must use the same cabling scheme, except when using

repeaters/translators or hubs. Basic physical loops have no bypass circuitry available during

power or cable interruptions, though using hubs in the loop will bypass this problem.

Finally, each additional node in the loop adds to latency.

Figure 3.Loop

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System Interface

FC-4

FC-3

FC-2

FC-1

FC-0

Upper Level Protocol

SCSI IPI-3 HIPPI Block MUX IP

Common Services

Framing Protocol/Flow Control

8B/10B Encode/Decode

266 Mbits/s 1062 Mbits/s531 Mbits/s

Despite these issues, loop connections are clearly the best choice for many network

cases. Loops are quite efficient when a network’s high bandwidth requirements are inter-

mittent. The topology is ideal for these situations. Likewise, when each node in the loop is

less than 100 meters apart, the loop topology is very effective.

How Is Fibre Channel Organized?

To allow each of the three unique topologies to work, Fibre Channel is organized into five

hierarchical functional layers and five service classes.

Functional LayersThe Fibre Channel structure is defined as a multi-layer stack of functional levels, not

unlike those used to represent network protocols. However, these layers do not map directly

to OSI layers. The five layers of the Fibre Channel standard define the physical media and

transmission rates, encoding scheme, framing protocol and f low control, common services,

and the upper-level application interfaces.

The five layers of Fibre Channel are shown in Figure 4. The user protocol transported

over Fibre Channel—such as SCSI or IP—is the upper-level protocol and is not touched by

the Fibre Channel layers.

The FC-0 layer defines the physical portions of the Fibre Channel, including the physi-

cal characteristics of the media, transmitters, receivers, and connectors that can be used; the

electrical and optical characteristics; the transmission rates; and other physical components

of the standard. This layer covers a wide range of performance and cost alternatives that

allow systems integrators to tailor installations to meet the specific customer needs.

The Fibre Channel FC-0 layer supports a variety of physical media to address different

cabling requirements. For short-distance connections, such as attaching nodes on the same

f loor of a building, coaxial and twisted pair cables are quite effective. To connect hubs or

switches between f loors or between buildings, optical fiber cables are the best choice.

Because copper and optical fiber can use the same protocols, switches can handle both

types of cable simultaneously.

The FC-1 layer defines the 8B/10B encoding/decoding scheme used to integrate the data

with the clock information required by serial transmission techniques. Fibre Channel uses

10 bits to represent each 8 bits of upper-level data. The 10-bit transmission characters are

converted back into 8-bit bytes at the receiver. Using 10 bits for each character provides

1,024 possible encoded values rather than the 256 that 8-bit characters would allow.

Figure 4.Fibre Channel’s Five Layers


The FC-2 layer disassembles and reassembles data sequences. The layer defines some

primitive commands—ordered sets—to handle configuration management, error recovery,

and signaling between two ends of a link.

In managing a data transfer sequence, the FC-2 layer recognizes that all frames

belonging to a single transfer are uniquely identified by a sequential numbering system

from 0 through n. After a transfer, the receiver can then determine if all the frames were

received. If it recognizes that any are missing, it can determine which specific frame(s) was

not transmitted.

The FC-2 layer also manages the different classes of service, which are discussed in the

“Service Classes” section of this paper.

The FC-3 layer is intended to provide the common services required for features such

as striping to multiply bandwidth. The ANSI committee is still defining the functions in

this layer.

The FC-4 layer provides seamless integration of existing standards. This layer accom-

modates a number of other data communications protocols such as FDDI, HIPPI, SCSI-3,

and Internet Protocol (IP), as well as IBM Single Byte Command Code Set (SBCCS) of

their OEMI and EXCON Channels, Ethernet, and ATM.

As Fibre Channel is applied to other applications such as the crate-to-crate transfers

between memory buses like VME and Futurebus, many more application interfaces are

expected to be defined. In all, the Fibre Channel standard provides the capability to

support up to 255 types of protocols.

Service ClassesTo accommodate a wide range of communications needs, Fibre Channel defines five

different classes of service. Unlike FDDI and other ring-type local area networks, each

class can be used between as few as two points, and each class can be integrated within

the framework of other network protocols.

Class 1, a hard or circuit-switched connection, functions in much the same way as

today’s dedicated physical channels. When a host and device are linked using Class 1, that

path is not available to other hosts. When the time needed to make a connection is short

or data transmissions are long, Class 1 is an ideal link. Two interconnected clustered servers

could use a Class 1 hookup to ensure rapid and smooth communication.

Class 2 is a connectionless, frame-switched link that provides guaranteed delivery with

an acknowledgment of receipt. No delay is required to establish connections as in Class 1.

Also, no uncertainty exists as to whether or not delivery was achieved.

If delivery cannot be made because of congestion, a Busy frame is returned, and the

sender tries again. The sender knows to retransmit immediately without waiting for a long

time-out to expire.

As with traditional packet-switched systems, the path between the two devices is not

dedicated, allowing better use of the bandwidth of the link. Class 2 is ideal for data transfers

to and from a shared mass storage system physically located at some distance from several

individual workstations. With Class 2, however, there is a delay in the turnaround time

needed for the recipient to receive a packet and generate a response, and for the sender to

receive and understand the response on a packet-by-packet basis.

Class 3 is a connectionless service that allows data to be sent rapidly to multiple recipi-

ents, but without confirmation of receipt. This class is most practical when it takes a long

time to make a connection. By not providing confirmation, Class 3 service makes much

8 White Paper

better use of the available bandwidth by reducing overhead. However, if a single user’s

link is busy, the higher software layers must determine whether or not data has been lost.

If data is lost, then the software must retransmit the data. Class 3 service is standard for

loops because the configuration of the loop is known to all and a busy port should not

be encountered. The reduced overhead is also very attractive to peripheral designers for

whom cost is a primary concern.

Class 4 is a virtual connection service that establishes up to 256 virtual circuits to pro-

vide guaranteed fractional bandwidth service between communicating ports. The service

multiplexes frames at frame boundaries to or from one or more ports with acknowledg-

ment provided. This class is used by many video applications that need a specific bandwidth

to keep information f lowing to video screens.

Class 6 is a service that provides dedicated connections for reliable multicast. A Class

6 connection is requested by a port for one or more destination ports. Destination ports

return an acknowledgment to a multicast server, which returns an acknowledge to the con-

nection initiator, establishing a reliable multicast connection.

What Media Do I Use for PhysicalConnections?

What kinds of media are suitable for these different connections and what impact, if any,

will the media have on performance?

Fibre Channel is defined to enable systems integrators to select several speed and

distance combinations. Within each media class, the components can be selected to suit

the most important objective—economy or performance. At 100 MB/s, distance ranges

from 20 meters with electrical signals over television coaxial cables, to 10 kilometers with

long wave-length optical signals over single-mode cables.

Optical Fiber or Copper CablesOptical fiber cable offers several advantages over copper cable, though copper is still a

viable option for many connections. Optical fiber cable has less signal attenuation and

offers reliable connection over much greater distances. Copper cable is very cost efficient,

though it is susceptible to noise. Electric ground loops that interfere with signal reception

can be caused by several copper wire network links between computers. Because fiber optic

cable uses light as the medium for data signaling, it is immune to induced electrical signals

and impulses. Because glass is an electrical insulator, fiber optic links avoid network ground

loops.


Attribute Copper Cable Optical Fiber Cable

Distance 2 to 20 meters 2 to 10,000 meters

Cable cost Lower at short distances Lower at long distances

Transceiver cost Lower than fiber Higher than copper

Installation cost Average Above average

Total cost Lower <30 meters Lower >30 meters

Electrical noise High Low

Volt immunity Low Non-existent

Ground loops High Non-existent

Single-Mode or Multimode Fiber Optic CableSingle-mode fiber optic cable is optical fiber with a small core diameter (9 µm) in which

only a single mode, the fundamental mode, is capable of propagation. (A mode is a discrete

optical wave.)

Multimode fiber optic cable is an optical wave guide whose core diameter is large

(50 or 62.5 µm) compared with the optical wavelength, and in which a large number of

modes are capable of propagation. Several hundred modes can propagate in multimode

fiber. The upper limit to the number of modes is determined by the core diameter. Single-

mode fiber cable is many times more expensive than multimode fiber cable. Therefore, it

is typically used only when distance requirements are extremely high.

Is Fibre Channel Being Used Successfully Today?

The Fibre Channel technology has already had a profound impact on many industries

and on many particular technology problems. Two such examples are the digital media

(video) industry and the network attached storage (NAS) technology.

Fibre Channel has successfully solved some daunting challenges in the area of video

editing. In today’s post-production studios, processing film and video images is typically

completed in multiple stages by a variety of people. Image processing equipment used in

one stage is generally separated from those at other stages to avoid confusion and rework.

In the past, users only had access to their local storage. When one group completed

all of its tasks on a video segment, that data had to be physically transported from one stage

of editing to the next. There was no way to share the editing stages between remote groups,

which kept each editor isolated and made data transportation cumbersome. The extremely

high bandwidth requirements of video editing made online data transfers highly risky or

even impossible.

The Fibre Channel standard of data transfer allows studios to break down the storage

and transfer barriers and allows multiple technicians to access a single, highly reliable disk

recorder. This storing, playing, editing, and caching of video becomes centralized, avoiding

the chance of error in the production process.

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Table 1.Attributes of Copperand Optical Fiber Cable

SANFC-AL(SCSI & IP)

Parallel SCSI

Storage Servers

LAN

10/100Base-T100VG

Switched EthernetToken Ring

FDDIATM

Gigabit Ethernet

Clients

Though this example is specific to one niche industry, the idea of many users accessing

a centralized data storage device is the very concept creating a boon in NAS technologies.

NAS capitalizes on the emerging trend in computing infrastructure to disaggregate comput-

er resources and functions. Whereas networks used to revolve around a single, “do-it-all”

server, modern networks have many specialized servers for different functions and processes

such as email, web connections, printing, and databases. But none of these is helping to

relieve the I/O bottleneck that the networks have had all along. Conversely, the I/O problem

is getting progressively worse as networks rely on faster servers, increased data volumes, and

now Internet growth. The next step in this evolution is to detach storage from the central-

ized servers and spin it off as a separate function like the others.

As storage begins to move into a separate network function, the I/O squeeze must

be addressed and solved for an NAS system to operate at peak efficiency. By using Fibre

Channel technology as the high-speed backbone, it becomes easy and extremely efficient

to implement both servers and storage in a storage area network (SAN) as a counterpart

and complement to the existing local area network. This SAN architecture allows storage

to grow incrementally in a building-block approach with independence and connectivity

to several servers. Expanding the Fibre Channel topology to add multiple loops or switched

fabric configurations results in almost limitless scalability.

By using a SAN, companies also relieve the host processor of its storage tasks, thereby

freeing up valuable processing cycles for application processing. SAN architecture doesn’t

share the server’s configuration constraints, such as the number of I/O channels supported,

the cost of expansion cabinets to handle additional slots, and a single host’s limit of storage

devices. A SAN lets a company scale its server and storage environments independent of one

another, while still protecting its complete IT investment.

Fibre Channel is the enabling technology that successfully creates a networked storage

device that is available to all users. The high-speed data transfers and high bandwidth capa-

bilities make it more feasible than ever to store and access massive volumes of data. Users

can have 24-hour data availability even if they are remote. NAS is a Fibre Channel success

story that is still growing each day.


Figure 5.The SAN Solution

What is the Latest Word on Fibre Channel?

Today’s customers are interested in finding and returning their data instantly, and that

data is larger than ever before because of the tremendous growth in video, multimedia,

and other large files.

Fibre Channel technology has brought to the market the high-performance, low-

cost communications pathway required by the intensive applications needed in today’s

networks. Fibre Channel also solves the distance, connectivity, and performance problems

seen in current systems using parallel SCSI.

The ability of Fibre Channel to support storage interconnect using SCSI commands,

data, and status—as well as transport network traffic—is providing entry to the mass

market. The resulting large sales volumes promise to drastically reduce costs, making it

possible that Fibre Channel will be the preferred interface for system interconnection. Fibre

Channel enables computing systems to transfer data at a rate of over 1 gigabaud per second,

or 10 to 250 times faster than today’s network protocols. Fibre Channel is positioned to be

the system interconnection means of the future.

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Appendix A: Fibre Channel Quick Reference Card

Project DocumentAcronym Title Number Number

FC-PH Fibre Channel Physical Interface 755-M X3.230-1994X3.230/AM1:1996

FC-PH-2 2nd-Generation Physical Interface 901-D X3.297-199x

FC-PH-3 3rd-Generation Physical Interface 1119-D

FC-AL Arbitrated Loop 960-D X3.272-1996

FC-AL-2 2nd-Generation Arbitrated Loop 1133-D

FC-FG Generic Fabric Requirements 958-D X3.289-199x

FC-SW Switch Fabric 959-D

FC-GS Generic Services 1050-D X3.288-199x

FC-GS-2 2nd-Generation Generic Services 1134-D

FC-AE Avionics Environment 2009-D

FC-AV Audio-Visual Transport Proposed

FC-BB Backbone Proposed

FC-FP Mapping of HIPPI-FP 954-M X3.254-1994

FC-LE Link Encapsulation 955-D X3.287-199x

FC-SB Mapping of Single-Byte 957-M X3.271-1996Command Code Set

SCSI-FCP SCSI-3 FC Protocol 993-R X3.269-1996

SCSI-GPP Generic Packetized Protocol 991-DT X3/TR-16-1995

FC-I3 Revision to IPI-3 Disk standard 496-R X3.291-199x

FC-I3 Revision to IPI-3 Tape standard 505-R X3.290-199x

HIPPI-FC Fibre Channel Frames on HIPPI 979-D X3.283-1996

FC-FLA Fabric Loop Attachment 1235-DT

FC-PLDA Private Loop Direct Attach 1162-DT

FC-SL Slotted Loop 1232-D

10 BIT 10-Bit Interface Technical Report 1118-DT X3/TR-18-199x

FC-CU Cu Interface Implementation Guide 1135-D

Jitter Methodology of Jitter Specification 1230-DT

DocumentOriginator Title Rev. Number

FCSI Common FC-PH Feature Sets 3.1 FCSI-101

FCSI SCSI Profile 2.2 FCSI-201

FCSI IP Profile 2.1 FCSI-202

FCSI Generic Link Module 1.0 FCSI-301

FCA N_Port to F_Port Interoperability 1.0

FCA IP Profile In development

FCA Hub Profile In development


Table A1.Fibre Channel andRelated Standards and Technical Reports

Table A2.FCA and FCSI Profilesand Related Documents

31 Byte 0 24 23 Byte 1 16 15 Byte 2 8 7 Byte 3 0

Start of Frame (SOF)

R_CTL Destination Identifier (D_ID)

CS_CTL Source Identifier (S_ID)

TYPE Frame Control (F_CTL)

SEQ_ID DF_CTL Sequence Count (SEQ_CNT)

Originator Exchange Identifier (OX_ID) Responder Exchange

Identifier (RX_ID)

Parameter

Reserved for Extended Frame Header (16 Bytes)

Reclaimed from Expiration Security Header Reserved (16 Bytes)

D_NAA Network Destination Address (high order bits)

Network Destination Address (low order bits)

S_NAA Network Source Address (high order bits)

Network Source Address (low order bits)

Validity Originator Process Associator (most significant 3 Bytes)

Originator Process Associator (least significant 4 Bytes)

Reserved Responder Process Associator (most significant 3 Bytes)

Responder Process Associator (least significant 4 Bytes)

Originator Operation Associator (most significant word)

Originator Operation Associator (least significant word)

Responder Operation Associator (most significant word)

Responder Operation Associator (least significant word)

Device Header of 16, 32, or 64 Bytes(For use of protocol mappings)

Payload Data of0 to (2112 minus length of optional headers) Bytes

CRC

End of Frame (EOF)

Bit Function Bit Function Bit Function

Extended Frame Hdr. Network Header Device Header

23 0 Absent 21 0 Absent 00 None17

1 Present (Reserved) 1 Present 01 16 Byte

Reclaimed Association Header to 10 32 Byte

22 Expiration/Security 20 0 Absent 16 11 64 Byte

Header 1 Present

14 White Paper

Table A3.FC-PH Frame

Table A4.DF_CTL Bitsfor Data Frames

Field Non-Basic Basichex Data Frame Link Service Link Service Link Control

R_CTLbits 31-28 0 FC-4 Device 2 Extended 8 C

(# in filed ➡) 4 Video 3 FC-4(Routing)

0 Uncategorized NOP ACK_1

1 Solicited Data Reserved ABTS ACK_NACK_0

2 Unsolicited Control Request RMC P_RJT

R_CTL 3 Solicited Control Reply Reserved F_RJT

bits 4 Unsolicited Data BA_ACC P_BSY

27-24 5 Data Descriptor BA_RJT F_BSY(Data)

Info 6 Unsolicited Reserved F_BSYCategory Command (Link Control)

7 Command Status Reserved LCR

8 NTY

9 Unspecified END

Others Reserved

Type FC-4 Device 1z F_BSY(# in filed ➡) see next page 1 Extended 0 3z P_BSY

Video reserved 3 FC-4 (z-see note)others reserved

0 Abort, discard multiple Seq.

F_CTL 1 Abort, discard single Seq. Not See next

bits 5-4 2 Process policy, with ∞ buffers Meaningful page

3 Discard multiple Seq with retransmit

DF_CTL All valid None Not Meaningful

ACK, 0, 1, NParameter Relative Offset Not Meaningful BSY, RJT

(Optional) reason & action

Payload 0-2112 Bytes 0-12 Bytes 0 Byte

Notes: z in Type field is the information category of frame being busied


Simplex Camp-ON

31 0 Duplex 29 0 Not Requested31

1 Simplex 1 Requested Virtual Circuit

Stacked Connect Buffered Class 1 to Identifier

30 0 Not Requested 28 0 Not Requested 24

1 Requested 1 Requested


Table A5.Header Fieldsby Frame Group

Table A6.CS_CTL Bitsfor All Frames

31 Byte 0 24 23 Byte 1 16 15 Byte 2 8 7 Byte 3 0

Action code Reason Code Reserved VendorP_BSY and F_BSY P_BSY Unique01 Seq terminated 01 Physical busy02 Seq active 03 Resource busyOthers reserved FF Vendor Unique

F_BSY01 Fabric busy03 Nx_Port busyOthers reserved

P_RJT and F_RJT P_RJT and F_RJT01 Retry see next page02 Non-retryableOthers reserved

hex FC-4 hex FC-4 hex FC-4

04 LLC/SNAP (in order) 16 CP IPI-3 Slave 24 SNMP

05 LLC/SNAP 17 CP IPI-3 Peer 40 HIIPI-FP

08 SCSI-FCP 19 SBCCS-Chan 34 to MessageWay

09 SCSI-GPP 1A SBCCS-CU 37

11 IPI-3 Master 20 FC Services 5D Fabric Controller

12 IPI-3 Slave 21 FC-FG E0

13 IPI-3 Peer 22 FC-SW to Vendor Unique

15 CP IPI-3 Master 23 FC-AL FF

Table A7.Parameter Field for BSY and RJT

Table A8.“Device” Type FieldValues of FC-4 Frames

16 White Paper


Exchange Context X_ID Reassigned23 0 Originator 15 0 Retained Continue Seq.

1 Responder 1 Reassigned 7 00 No information

Seq. Context Invalidate X_ID to 01 Immediate22 0 Initiator 14 0 Retained 6 10 Soon

1 Recipient 1 invalidated 11 Delayed

First Sequence ACK form Abort Sequence21 0 Last or middle 13 00 No assistance 5 ACK frame

1 First sequence to 01 ACK_1 req. to 00 Continue Seq.

Last Sequence 12 10 ACK_N req. 4 01 Abort sequence20 0 First or middle 11 ACK_0 req. 10 Stop sequence

1 Last sequence 11 retransmit seqData frame (prev pg)

End Sequence Data Compression Relative Offset19 0 Cont. Sequence 11 0 Uncompressed 3 0 Not meaningful

1 Last Data Frame 1 Compressed 1 Present

End Connection Data Encryption Reserved18 0 Retain 10 0 Unencrypted 2 Exchange

1 Disconnect/Deactivate 1 Encrypted reassembly

Reclaimed Retransmit Seq. Fill Data Bytes17 Chained sequence 9 0 Original 1 00 None

1 Retransmitted to 01 One Byte

Seq. Initiative Unidirect/Remove 0 10 Two Byte16 0 Hold 8 0 Bidirect/Deactivate 11 Three Byte

1 Transfer 1 Unidirect/Remove

Code Function By Code Function By Code Function By

01 Invalid D_ID F,P 0D Invalid SEQ_ID P 19 Expiration/ PSecurity error

02 Invalid S_ID F,P 0E Invalid DF_CTL P 1A Fabric path Fnot available

03 Nx_Port F 0F Invalid P 1B Invalid VC_ID Fnot avail (temp) SEQ_CNT

04 Nx_Port F 10 Invalid P 1C Invalid F,Pnot avail (perm) Parameter field CS_CTL field

05 Class not F,P 11 Exchange error P 1D Unable to F,Psupported establish VC

06 Delimiter usage F,P 12 Protocol error P 1E Dedicated F,Perror Simplex error

07 Type not F,P 13 Incorrect length F,P 1F Invalid class F,Psupported of service

08 Invalid Link P 14 Unexpected P 20 Pre-emption FControl ACKP rejected

09 Invalid R_CTL P 15 Class invalid F 21 Pre-emption Ffield at FFFFFE not enabled

0A Invalid F_CTL P 16 Log-in required F,P 22 Multicast Ffield error

0B Invalid OX_ID P 17 Excessive Seq. P 23 Multicast Fattempted error term

0C Invalid RX_ID P 18 Establish P FF Vendor PExchange error unique error

Table A9.F_CTL Bits for AllFrames (Word 2)

Table A10.Reject (P_RJT, F_RJT) Reason Codes


Optical Performance Dist.Transmitter Media MBaud Mbytes/s km

Longwave LED 62.5µm 132.8125 12.5 1.5Multimode Fiber

Longwave LASER Single-mode Fiber 2 or 10

Longwave LED 62.5µm 265.625 25 1.5Multimode Fiber

Longwave LED 50µm 1.5Multimode Fiber

Shortwave LASER 50µm 2(with OFC) Multimode Fiber

Shortwave LASER 50µm 1(with OFC) Multimode Fiber 531.25 50

Longwave LASER Single-mode Fiber 10

Shortwave LASER 50µm 0.5(with OFC) Multimode Fiber

Shortwave LASER 50µm(w/o OFC) Multimode Fiber 1062.5 100 0.5

Longwave LASER Single-mode Fiber 2 or 10

Shortwave LASER 50µm 0.3(w/o OFC) Multimode Fiber 2125 200


Shortwave LASER 50µm 0.175(w/o OFC) Multimode Fiber 4250 400


Table A11.Optical Feedsand Speeds

18 White Paper

Electrical Performance Dist.Transmitter Media MBaud Mbytes/s km

Long Video Coax (RG-6) 67

ECL Video Coax (RG-59) 56

Intra-cabinet Mini Coax (RG-179) 16

Shielded twisted pair (STP-1) 32

Twinax 37

Long Video Coax (RG-6) 132.8125 12.5 100


Inter-cabinet Mini Coax (RG-179) 42


Twinax 93



Intra-cabinet Mini Coax (RG-179) 11


Twinax 26

Long Video Coax (RG-6) 265.625 25 100




Twinax 66



Intra-cabinet Mini Coax (RG-179) 7.6


Twinax 18





Twinax 46



Intra-cabinet Mini Coax (RG-179) 5.6


Twinax 13





Twinax 33

Table A12.Electrical Feedsand Speeds


Characteristic Class 1 Class 2 Class 3 Class 4 Class 6

Dedicated Multiplexed Fractional UnidirectionalFunction Connection (Frame Datagram Guaranteed Dedicated

Switched) Bandwidth Connection

Fabric discards No No Yes No Noframes?

Communications One to One Many to Many One to Manytype btw. ports

Initial round Yes No No No Yestrip delay

Hunt group support Optional Optional Optional Optional Optional

Multicast support No No Optional No Yes

Broadcast support No No Optional No No

Stacked ConnectRequest

Dedicated Simplex

Camp-On Optional Not applicable Optional

Buffered Class 1

Unidirectional YesConnection

End-to-End Yes Yes No Yes Yesflow control

Buffer-to-Buffer Yes Yes Yesflow control

Yes, only for Yes, only forFabric can reject Only undeliverable invalid Only

frames? Connection frame activation Connectionrequest No, frame is frame request

Fabric busies frame Yes, for long- discarded frameframes? term resource No

contention

Delivery Order Yes Depends on Fabric, yes Yes Yesguaranteed? for most fabrics

Nx_Port supports Optional Optional Optional Optional, No OptionalClass of Service? for NL_Port

Fabric supports Optional Optional Optional Optional OptionalClass of Service

Topics to be included in future enhancements:

• 8 and 16 GBaud physical variants

• Asynchronous and Isochronous services

• Striping

• Mapping for many more existing and new protocols

Table A13.ClassCharacteristics

20 White Paper

Address Function Address Function

FFFFFF Broadcast Alias_ID FFFFF9 Quality of Service Facilitator

FFFFFE Fabric F_Port FFFFF8 Alias Server

FFFFFD Fabric Controller FFFFF7 Security Key Distribution Server

FFFFFC Directory Server FFFFF6 Clock Synchronization Server

FFFFFB Timer Server FFFFF5 Class 6 Multicast Server

FFFFFA Management Server 000000 Unidentified

Unisys is a registered trademark of Unisys Corporation. Intel is a registeredtrademark of Intel Corporation. Compaq is a registered trademark of CompaqComputer Corporation. Hewlett Packard is a registered trademark of Hewlett-Packard Company. Tektronix is a registered trademark of Tektronix, Inc. Sun is aregistered trademark of Sun Microsystems, Inc. Intel is a registered trademark ofIntel Corporation. Symbios Logic is a trademark of Symbios Logic, Inc. NEC is aregistered trademark of NEC Electronics, Inc. Digital is a registered trademark ofDigital Equipment Corporation. Microsoft and Windows NT are registered trade-marks of Microsoft Corporation. Other brand names, product names and trade-marks are acknowledged to be the property of their respective owners.

© 1997 Unisys Corporation.


Table A14.Well-Known Address Identifiers

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WHEN INFORMATION IS EVERYTHING

Unisys is one of a select group of companies with the broad portfolio of ser-vices, technologies and third-party alliances needed to deliver the benefits ofinformation management—helping clients use their information assets toenhance their competitiveness and responsiveness to customers.

Our expertise in information management is founded on the strengths of ourthree global businesses: consulting, outsourcing, solutions and systems inte-gration; industry-leading technologies; and comprehensive services and prod-ucts supporting distributed computing environments.

Printed in U S America 9/97