(2.1 章)
什么是SCSI 中的initator ,target和LUN ,
(2.2章)
FC如何为SCSI 提供服务,FC还为其他协议提供服务吗?
各取所需,分层构建 FC0-4
可以提供服务为NETWORK 和CHANNEL
FC的帧格式是什么样的?
FC的帧交换过程是什么样的?
什么是流控,BB EE? 为什么要流控?
fc是如何组网的 设备的连接使用什么接口 fc的接口类型只有N\F\E 吗?端口如何初始化的?
N、F、E 不止这些类型
初始化,协议如何开始工作
PRLI———PROCESS LOGIN———ESTABLISHED(FCP)
PLOGI———LOGI PORT———EXCHANGE PERMISSION
FLOGI——— LOGI FABRIC———FCID
FC的 数据帧 那么其他的帧类型是什么?做什么用的?
FC有哪些特殊的地址,都起了什么作用?是二层的定义吗?
为什么说FC有二层寻址能力?如何实现的?
FC-2 ,是可以路由的,可寻址的(与二层的MAC 不一样)
物理的—WWN
逻辑的—FCID/PID
FSPF 来计算COST
(2.5章)
VSAN是什么?和VLAN有什么关系?
SAN 的ISL 是什么东西??什么是EISL ??
什么是IVR ? 和LAN 中的IVR 对应吗?
与VLAN 共通性
链路-trunk
特别的链路-TF(TRUNK-TO-TNP )NPIV时
(2.6 章)
什么ZONE? 和VSAN 有关系吗?
VSAN -fabric-base control
ZONE- list — base control
软ZONE?和硬ZONE 是什么关系?
soft-zone configure-base WWN
har zone -ASIC -base [PORT]
(2.7章)
NPIV和NPV 的应用场景和功能是什么?
NPIV-N -PORT ID VIR 接受FLOGI/FDISC 分配FCID
NPV- N port proxy 接受FLOGI,转换为FDISC 通过上行的N-PORT proxy 接口发给NPIV 设备
ZONE 是访问控制表形式的 控制
VSAN 是 虚拟化 是架构的虚拟化——— VSAN是通过EISL 在通道里的封装 在同区域是通过FSPF寻址的 不同区域是IVR
NPIV是设备虚拟化
重点问题
FC-SCSI
FC-FRAME
FC 组网
FC 的寻址问题
FC VSAN
2 Fibre Channel topology
In Fibre Channel terms the switch connecting the devices is called Fabric. The link is the two unidirectional fibres transmitting to opposite directions with their associated transmitter and receiver. Each fibre is attached to a transmitter of a port at one end and a receiver of another port at the other end. When a Fabric is present in the configuration, the fibre may attach to a node port (N_Port) and to a port of the Fabric (F_Port).
Since Fibre channel system relies on ports logging in with each other and the Fabric, it is irrelevant whether the Fabric is a circuit switch, an active hub or a loop. The topology can be selected depending on system performance requirements or packaging options. Possible FC topologies include point-to-point, crosspoint switched or arbitrated loop (Figure 1).
Figure 1 Fibre Channel topologies
FC operates at a wide variety of speeds (133 Mbit/s, 266 Mbit/s, 530 Mbit/s, and 1 Gbits/s) and on three types of both electrical and optical media. Transmission distances vary depending on the combination of speed and media. The single mode fibre optic media using longwave laser light source gives the highest performance (10 km maximum distance at 1 Gbit/s) [2].
3 FC-0 layer
FC is structured as a set of hierarchical functions (Figure 2).
The lowest level (FC-0) defines the physical link in the system, including the fibre, connectors, optical and electrical parameters for a variety of data rates. Figure 3 shows the schematic of the Fibre Channel optical link [2].
Figure 2 Fibre Channel structure
The system bit error rate (BER) at the supported media and speeds is less than 10exp-12 [1]. The physical level is designed for the use of large number of technologies to meet the widest range of system requirements. An end-to-end communicating route may consist of different link technologies to achieve the maximal performance and price efficiency.
3.1 Open Fibre Control
The FC-0 specifies a safety system - the Open Fibre Control system (OFC) - for SW laser data links, since the optical power levels exceed the limits defined by the laser safety standards. If an open fibre condition occurs in the link, the receiver of the Port the fibre is connected detects it and pulses its laser at a low duty cycle that meets the safety requirements. The receiver of the other port (at the other end of the fibre) detects this pulsing signal and also pulses it's transmitter at a low duty cycle. When the open fibre path is restored both ports receive the pulsing signals, and after a double handshaking procedure the connection is automatically restored within a few seconds [1].
Figure 3 FC ptical link
4 FC-1 layer
FC-1 defines the transmission protocol including serial encoding and decoding rules, special characters and error control. The information transmitted over a fibre is encoded 8 bits at a time into a 10 bit Transmission Character. The primary rationale for use of a transmission code is to improve the transmission characteristic of information across a fibre. The transmission code must be DC balanced to support the electrical requirements of the receiving units. The Transmission Characters ensure, that short run lengths and enough transitions are present in the serial bit stream to make clock recovery possible [1] [2].
4.1 FC-1 character conversion
An unencoded information byte is composed of eight information bits A,B,C,D,E,F,G,H and the control variable Z. This information is encoded by FC-1 into the bits a,b,c,d,e,i,f,g,h,j of a 10-bit Transmission Character. The control variable has either the value D (D-type) for Data characters or the value K (K-type) for special characters. Each valid Transmission Character has been given a name using the following convention: Zxx.y, where Z is the control variable of the unencoded FC-1 information byte, xx is the decimal value of the binary number composed of the bits E, D, C, B, and A, and y is the decimal value of the binary number composed of the bits H,G of the unencoded FC-1 information byte in that order. For example the name of the FC-1 Transmission Character composed of the hexadecimal "BC" special (K-type) code is K28.5.
The information received is recovered 10 bits at a time and those Transmission Characters used for data (D-type) are decoded into the one of the 256 8-bit combinations. Some of the remaining Transmission Characters (K-type) referred to as special characters, are used for protocol management functions. Codes detected at the receiver that are not D- or K- type are signaled as code violation errors [1].
4.2 Coding rules
Each data byte or special character has two (not necessarily different) transmission codes. The data bytes and special characters are encoded into these codes respectively, depending on the initial Running Disparity (RD). The RD is a binary parameter, which is calculated upon the balance of ones and zeros in the sub-blocks (the first six bits and the last four bits) of a transmission character. A new RD is calculated from the transmitted character at both the transmitter and the receiver. If the detected character has opposite RD the transmitter should have sent, (depending on the RD of the previous bit stream) the receiver indicates a disparity violation condition. A Transmission Word is composed of four contiguous transmission characters [1].
5 FC-2 Layer
The Signaling Protocol (FC-2) level serves as the transport mechanism of Fibre Channel. The framing rules of the data to be transferred between ports, the different mechanisms for controlling the three service classes (see chapter 5.7) and the means of managing the sequence of a data transfer are defined by FC-2. To aid in the transport of data across the link, the following building blocks are defined by the standard [1] :
Ordered Set
Frame
Sequence
Exchange
Protocol
5.1 Ordered Set
The Ordered Sets are four byte transmission words containing data and special characters which have a special meaning. Ordered Sets provide the availability to obtain bit and word synchronization, which also establishes word boundary alignment. An Ordered Set always begins with the special character K28.5. Three major types of Ordered Sets are defined by the signaling protocol.
The Frame delimiters (the Start-of-Frame (SOF) and End-of-Frame (EOF) Ordered Sets) are Ordered Sets which immediately precede or follow the contents of a Frame. There are multiple SOF and EOF delimiters defined for the Fabric and N_Port Sequence control.
The two Primitive Signals: Idle and Receiver Ready (R_RDY) are Ordered Sets designated by the standard to have a special meaning. An Idle is a Primitive Signal transmitted on the link to indicate an operational Port facility ready for Frame transmission and reception. The R_RDY Primitive Signal indicates that the interface buffer is available for receiving further Frames.
A Primitive Sequence is an Ordered Set that is transmitted and repeated continuously to indicate specific conditions within a Port or conditions encountered by the receiver logic of a Port. When a Primitive Sequence is received and recognized, a corresponding Primitive Sequence or Idle is transmitted in response. Recognition of a Primitive Sequence requires consecutive detection of 3 instances of the same Ordered Set. The Primitive Sequences supported by the standard are Offline (OLS), Not Operational (NOS), Link Reset (LR) and Link Reset Response (LRR) [1] [2].
5.2 Frame
The basic building blocks of an FC connection are the Frames. The Frames contain the information to be transmitted (Payload), the address of the source and destination ports and link control information. Frames are broadly categorized as Data frames and Link_control frames. Data frames may be used as Link_Data frames and Device_Data frames, link control frames are classified as Acknowledge (ACK) and Link_Response (Busy and Reject) frames. The primary function of the Fabric is, to receive the Frames from the source port and route them to the destination port. It is the FC-2 layer's responsibility to break the data to be transmitted into Frame size, and reassemble the Frames.
Each Frame begins and ends with a Frame Delimiter (Figure 4) The Frame Header immediately follows the SOF delimiter. The Frame Header is used to control link applications, control device protocol transfers, and detect missing or out of order Frames. An optional header may contain further link control information. A maximum 2112 byte long field (payload) contains the information to be transferred from a source N_Port to a destination N_Port. The 4 bytes Cyclic Redundancy Check (CRC) precedes the EOF delimiter. The CRC is used to detect transmission errors. [1] [2]
这个图是示意图
Figure 4 Frame Structure [2]
5.3 Sequence
A Sequence is formed by a set of one or more related Frames transmitted unidirectionally from one N_Port to an other. Each Frame within a sequence is uniquely numbered with a Sequence Count. Error recovery, controlled by an upper protocol layer is usually performed at Sequence boundaries [2].
5.4 Exchange
An Exchange is composed of one or more nonconcurrent sequences for a single operation. The Exchanges may be unidirectional or bidirectional between two N_Ports. Within a single Exchange, only one sequence may be active at any one time, but Sequences of different Exchanges may be concurrently active.
5.5 Protocol
The Protocols are related to the services offered by Fibre Channel. Protocols may be specific to higher-layer services, although Fibre Channel provides its own set of protocols to manage its operating environment for data transfer. The following Protocols are specified by the standard [1]:
Primitive Sequence Protocols are based on Primitive Sequences (see chapter 5.1) and specified for link failure.
Fabric Login protocol: The interchanging of Service Parameters of an N_Port with the fabric.
N_Port Login protocol: Before performing data transfer, the N_Port interchanges its Service Parameters with another N_Port.
Data transfer protocol describes the methods of transferring Upper Layer Protocol (ULP) data using the Flow control management of Fibre Channel (see chapter 5.6).
N_Port Logout Protocol is performed when an N_Port requests removal of its Service Parameters from the other N_Port. This may be used to free up resources at the connected N_Port.
5.6 Flow control
保证流量不丢失,一种是BB 一种是EE
Flow control is the FC-2 control process to pace the flow of Frames between N_Ports and between an N_Port and the Fabric to prevent overrun at the receiver. Flow control is dependent upon the service classes (see chapter 5.7). Class 1 Frames use end-to-end flow control, class 3 uses only buffer-to-buffer, class 2 Frames use both types of flow control.
Flow control is managed by the Sequence Initiator (source) and Sequence Recipient (destination) Ports using Credit and Credit_CNT. Credit is the number of buffers allocated to a transmitting Port. The Credit_CNT represents the number of data frames which have not been acknowledged by the Sequence Recipient.
The end-to-end flow control process paces the flow of Frames between N_Ports. In this case the Sequence Recipient is responsible for acknowledging the received valid data Frames by ACK Frames. When the number of receive buffers are insufficient for the incoming Frame, a "Busy", when a Frame with error is received a "Reject" Frame will be sent to the Initiator Port. (see chapter 5.2) The Sequence Initiator is responsible for managing EE_Credit_CNT. The N_Port login (see chapter 5.5) is used to establish EE_Credit.
The buffer-to-buffer flow control is managed between an N_Port and an F_Port or between N_Ports in point-to-point topology. Each port is responsible for managing BB_Credit_CNT. BB_Credit is established during the Fabric Login (see chapter 5.5). The Sequence Recipient (destination) Port signals by sending a Receiver_Ready primitive signal to the transmitting Port whether it has free receive buffers for the incoming Frames.
Figures 5-7 show the flow control management of the different service classes (see chapter 5.7) [1].
5.7 Service Classes
To ensure efficient transmission of different types of traffic, FC defines three classes of service. Users select service classes based on the characteristics of their applications, like packet length and transmission duration, and allocate the services by the Fabric Login protocol.
Class 1 is a service which provides dedicated connections, in effect providing the equivalent of a dedicated physical connection. Once established, a Class 1 connection is retained and guaranteed by the Fabric. This service guarantees the maximum bandwidth between two N_Ports, so this is the best for sustained, high throughput transactions. In Class 1, Frames are delivered to the destination Port in the same order as they are transmitted. Figure 5 shows the flow control management of a Class 1 connection.
Figure 5 Class 1 Flow Control
Class 2 is a Frame-switched, connectionless service that allows bandwidth to be shared by multiplexing Frames from multiple sources onto the same channel or channels. The Fabric may not guarantee the order of the delivery and Frames may be delivered out of order. This service class can be used, when the connection setup time is greater than the latency of a short message. Both Class 1 and Class 2 send acknowledgment Frames confirming Frame delivery. If delivery cannot be made due to congestion, a Busy frame (see chapter 5.2) is returned and the sender tries again. (Figure 6)
Figure 6 Class 2 Flow Control
Class 3 service is identical to Class 2, except that the Frame delivery is not confirmed. (Flow control is managed only on buffer level, see Figure 7) This type of transfer, known as datagram provides the quickest transmission by not sending confirmation. This service is useful for real- time broadcasts, where timeliness is key and information not received in time is valueless.
The FC standard also defines an optional service mode called intermix. Intermix is an option of Class 1 service, in which Class 1 Frames are guaranteed a special amount of bandwidth, but Class 2 and Class 3 Frames are multiplexed onto the channel, only when sufficient bandwidth is available to share the link [2] [3].
6 FC-3 Layer
The FC-3 level of the FC standard is intended to provide the common services required for advanced features such as:
Striping -To multiply bandwidth using multiple N_ports in parallel to transmit a single information unit across multiple links.
Hunt groups - The ability for more than one Port to respond to the same alias address. This improves efficiency by decreasing the chance of reaching a busy N_Port.
Multicast - Multicast delivers a single transmission to multiple destination ports. This includes sending to all N_Ports on a Fabric (broadcast) or to only a subset of the N_Ports on a Fabric. [1]
7 FC-4 Layer
FC-4, the highest level in the FC structure defines the application interfaces that can execute over Fibre Channel. It specifies the mapping rules of upper layer protocols using the FC levels below. Fibre Channel is equally adept at transporting both network and channel information and allows both protocol types to be concurrently transported over the same physical interface.
The following network and channel protocols are currently specified or proposed as FC-4s [2]:
Small Computer System Interface (SCSI)
Intelligent Peripheral Interface (IPI)
High Performance Parallel Interface (HIPPI) Framing Protocol
Internet Protocol (IP)
ATM Adaptation Layer for computer data (AAL5)
Link Encapsulation (FC-LE)
Single Byte Command Code Set Mapping (SBCCS)
IEEE 802.2
参考文档 : Introduction to Storage Area Networks
:维金百科