Rivier College CS575: Advanced LANs Chapter 9: Fibre Channel

Chapter 9 Fiber Channel 1

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Rivier CollegeCS575: Advanced LANs

Chapter 9: Fibre Channel


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Fibre Channel Architecture, Media & Topologies

0 Fibre Channel Elements0 Fibre Channel Protocol Architecture0 Fibre Channel Transmission Media0 Fibre Channel Topologies0 Framing Protocol:

* Classes of Service* Frames, Sequences, and Exchanges* Frame Control* Frame Format


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LAN Technology Comparison


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Fibre Channel Architecture: Requirements [FCA98]

0 Full-duplex links with two fibers per link0 Performance from 100 Mbps to 3.2 Gbps on a single link results in

200 Mbps to 6.4 Gbps per link0 Support for distance up to 10 km0 Small connectors0 High-capacity utilization with distance insensitivity0 Greater connectivity than existing multidrop channels0 Broad availability (i.e., standard components)0 Support for multiple cost/performance levels, from small systems to

supercomputers0 Ability to carry multiple existing interface command sets for

existing channel and network protocols


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Fibre Channel Terms


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Fibre Channel Terms (continued)


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Fibre Channel Elements: Port Types


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Fibre Channel Network


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Fibre Channel Protocol Architecture Levels


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Fibre Channel Levels Functionality


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Structure of Fiber Optic Cables

Source: Decusatis: Handbook of Fiber Optic


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Structure of Fiber Optic Cables (concluded)

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13Fiber ChannelChapter 9

Three Types of Fibers


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Multimode Fiber



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Single Mode Fiber



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Light Source



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Fiber Optic Attenuation



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Level FC-2: Framing Protocol

0 Transmission of data between N_Ports in terms of frames0 Node and N_Port and their identifiers0 Topologies0 Classes of service provided by the fabric0 Segmentation of data into frames and reassembly0 Grouping of frames into logical entities called sequences and exchanges

0 Sequencing, flow control, and error control


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FC-3: Common Services

0 Common services across multiple N_Ports of a node.0 Stripping Service makes use of multiple N_Ports in parallel to

transmit a single information unit across multiple links simultaneously (i.e, transferring large data sets in real time, as video-imaging applications).

0 Hunt group is a set of associated N_Ports at a single node. This set is assigned an alias identifier that allows any frame sent to this alias to be routed to any available N_Port within the set. This may decrease latency by decreasing the chance of waiting for a busy N_Port.

0 Multicast delivers a transmission to multiple destinations. This includes sending to all N_Ports on a fabric (broadcast) or to a subset of the N_Ports on a fabric.


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FC-4: Mapping/ Interfaces

0 Mapping of various channel and network protocols to FC-PH.

0 Small computer system interface (SCSI) that is high-speed interface typically implemented on PCs, workstations, and servers. SCSI is used to support high-capacity and high-data-rate devices, such as disks and graphics and video equipment.

0 High-performance parallel interface (HIPPI) that is a high-speed channel standard used for mainframe/supercomputer environments. It was viewed as a possible general-purpose high-speed LAN solution, but HIPPI has been superseded by Fibre Channel.

0 Network IEEE 802 interface maps IEEE 802 MAC frames onto Fibre Channel frames.

0 Asynchronous Transfer Mode (ATM) network interface (Ch. 11).

0 Interface to Internet Protocol (Ch. 3).

0 Each FC-4 specification defines the formats and procedures for Upper-Level Protocol (ULP) level.


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Maximum Distance for Fibre Channel Media Types


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FC-0 Nomenclature


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Basic Fibre Channel Topologies


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Five Applications of Fibre Channel


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Framing Protocol: Classes of Service

0 FC-2 Framing Protocol0 Defines the rules for exchange of higher-layer information between

nodes.0 Specifies types of frames, procedures for their exchange, and

formats.0 Is similar to the data link layer functions of the OSI model.0 Classes are determine by the way communication is established

between two ports and on the flow control and error control features of the communications channel.

0 Class 1: Acknowledged Connection Service0 Class 2: Acknowledged Connectionless Service0 Class 3: Unacknowledged Connectionless Service0 Class 4: Fractional Bandwidth Connection-Oriented Service0 Class 6: Unidirectional Connection Service


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Data Frames

0 Traffic between N_Ports over Fibre Channel is in the form of a stream of frames.

0 Two general categories of frames: Data frames transfer higher-level information between source and destination N-Ports; and link control frames are used to manage frame transfer and to provide some control for FC-2 Class 1 and Class 2 services.

0 FC-4 Device Data Frame is used to transfer higher-layer data units from supported FC-4 protocols, such as IEEE 802, SCSI, and IP.

0 FC-4 Video Data Frames are transferred by N_Port directly to or from a video buffer without first directing them to an intermediate storage location.

0 Link Data Frames are used to transfer link application information between N_Ports. This type of frame supports a control function of a higher level, such as the transmission of abort sequences, echo, and termination of Class 1 connections.


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Link Control Frames

0 Link Continue (Acknowledge) Frame is used in various Fibre Channel sliding-window flow control mechanisms to report successful delivery.

0 Fibre Response Frame is used in various Fibre Channel sliding-window flow control mechanisms to report unsuccessful delivery.

0 Link Command Frame is used as a reset command to reinitialize the sliding-window scheme.


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Common Protocols defined in Fibre Channel

0 Fabric Login Protocol is executed upon initialization of an N_Port. It enables the N_Port to exchange operational and configuration information with the fabric, such as the address assigned to the N_Port, classes of service supported, and credit for buffer-to-buffer flow control.

0 N-Port Login Protocol supports the N_Port interchange of its service parameters with another N_Port BEFORE performing data transfer. Service parameters include amount of buffer space available for data transfer, total number of concurrent sequences that N_Port can support as a recipient, and supported service classes.

0 Data Transfer Protocol defines the transfer of upper-layer protocol data between N_Ports.

0 N-Port Logout Protocol is used to terminate a connection to another N_Port. This request may be used to free resources at the two N_Ports.


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Flow Control Categories in Fibre Channel

0 End-to-End Flow Control is used between two communicating N_Ports. Each of the two N_Ports in communication provides credit for a certain number of frames. This is the only type of flow control available on dedicated connections after the first frame.

0 Buffer-to-Buffer Flow Control is used between two ports connected by a single point-to point link. This type of flow control regulates traffic between an N_Port and F_Port to which it is attached.

0 The concept of credit is critical for both flow control mechanisms. Prior to communication between two N_Ports (end-to-end) and between two adjacent ports (buffer-to-buffer), each communicating port is allocated a credit during the initialization procedure.

0 The transmitting port limits the number of outstanding unacknowledged frames to the allocated credit of each type and adjusts the credit according to the responses received.

0 The Credit_Count represents the number of outstanding data frames that have been NOT acknowledged and is not permitted to exceed the corresponding maximum credit negotiated at login.


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Flow Control Mechanism in Fibre Channel


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Frame Delimiters in Fibre Channel

Rivier College CS575: Advanced LANs Chapter 9: Fibre Channel

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