Fiber Channel standards were developed by the T11 Standards Committee (Technical Committee under the National Information Technology Standardization Committee). Defining Fiber Channel is a high-speed serial interface that is widely used in computers and mass storage. Compared to the SCSI interface, the Fiber Channel has the characteristics of the I / O channel and the local area network, and the fiber channel can be used as the transmission medium of the I / O channel and the local area network. However, the Fiber Channel does not include a higher transport protocol, just the usual SCSI-3 standard, which is established on SCSI-3 through the Fiber Channel. According to the National Standards Association (ANSI), Fiber Channel should support the following protocol: L Internet Protocol (IP) L Small Computer System Interface (SCSI) L High Performance Parallel Interface (HIPPI) L Other Advanced Protocols
Fiber Channel is the first network technology that is widely implemented in SAN. As a new generation of storage architecture, it integrates the advantages of network technology and channel technology. It is a high-speed, * connected to network technology, and expands the data transmission service combined with the binding.馍 馍 衿饔敕 衿 酢 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男 男搅 罅 罅 ǖ ǖ ǖ 酢 酢 阃 阃 淞 淞 鲇 淞 淞 淞 淞 淞 魇 魇 魇 魇 魇 涞 蚋 涞 蚋 蚋 蚋 蚋 蚋 蚋 蚋 蚋 锌 粤 粤 畹 畹 畹 黾 黾 黾 黾 黾 黾• BR> With Fiber Channel technology advantages, it can achieve application modes that were previously unable or difficult to implement. Its high-speed data transmission characteristics eliminate storage performance bottlenecks, is ideal for system clusters, enterprise resource planning, business intelligence, multimedia and disaster recovery. Fiber Channel will replace SCSI dominant position in storage interface solutions, and current fiber channel technology has become mainstream I / O interface technology of servers in IT systems.
Fiber Channel is the first network technology that is widely implemented in SAN. As a new generation of storage architecture, it combines the advantages of network technology and channel technology. It is a data transmission service that connects the channel technology, the connection to network technology, and the data transmission service combined together is a server and storage peripheral connection. Or leading technologies for servers and server cluster high-speed connection. The so-called channel is a high-speed information conductor, which is different from the network that it uses a lot of channel hardware technology. General channels are dedicated to flow data between two hardware devices. The so-called network is more focused on connectivity and can be flexibly increased or decreased in the network environment. By means of fiber channel technology, you can achieve application modes that are not or difficult to implement. Its high-speed data transmission characteristics eliminate storage performance bottlenecks, is ideal for system clusters, enterprise resource planning, business intelligence, multimedia and disaster recovery. Fiber Channel will replace SCSI dominant position in storage interface solutions, and current fiber channel technology has become mainstream I / O interface technology of servers in IT systems. The advantages of the Fiber Channel are as follows: l is a new multi-purpose network information infrastructure for connecting open system storage, network, video applications, and server cluster applications; L is the upper protocol (SCSI, IP, ATM, IEEE802.2, etc.) Provide a universal hardware transmission platform; L high-speed data transmission; L serial, no blocking data transmission; L is up to 10 km connection distance (1 thousand kilometers can be connected by expanders, suitable for disaster recovery applications); L multi-platform system support (Including AIX, NT, Solaris, HP / UX, UNIX, Linux, Novell, etc.); l Supports traditional environment and applications
The structural FC (Fiber Channel) structure of the Fiber Channel is defined as a multilayer functional stage, but the divided layer cannot be directly mapped to the layer of the OSI model. The five layers of the FC (fiber) channel are defined as: physical media and transmission rates, encoding methods, frame protocols, and stream control, public services, and superior protocol (ULP) interfaces. 1. FC-0 (physical interface): 1, FC-0 is the underlying standard of the physical layer. The FC-0 layer defines the physical port characteristics of the connection, including the physical characteristics, electrical characteristics, and light characteristics, transmission rates, and other connection port characteristics of the media and connector (drivers, receivers, transmitters, etc.). Most of the efforts implemented by the FC-0 layer is actually the electronic engineering work defined when designing the sender and receiver components. Physical media has fiber optic, twisted pair and coaxial cable. 2. FC-1 (transport protocol): FC-1 specifies the 8B / 10B encoding / decoding method and transport protocol according to the ANSI X3T11 standard, which takes a series of signals and encodes it as a available character data. Responsibility. The FC-1 layer uses 8B / 10B encoding method. This means that every 10bit data is transmitted, and only 8bit's frame data is actually obtained, and the other 2 bits are the check digit. The application of 8B / 10B code in reality is stable and simple. 3. FC-2 (Frame Protocol): The FC-2 layer is a fiber optic channel protocol layer, which includes important information about the data transfer structure, responsible for port definition frames and flow control. Fiber channel data frame length varies, expandable addresses. The fiber channel data frame for transmitting data is up to 2K, so it is very suitable for transmission of large capacity data. The frame header includes control information, source address, destination address, transmission sequence identification, and swap device, and the like. 64-byte Optional Framehead is used for protocol mappings when transmitting over other types of networks. Fiber Channel relies on the content of the data frame header to initiate an operation, such as sending the arrived data into a correct buffer. 4. FC-3 (Public Service): It is a general service layer of the fiber channel protocol. The FABRIC server should provide centralized resources to all connect nodes. Although there may be a server agent on each switch, all the name server agents share their information through the switch protocol to ensure that the name servers in each switch are identical to other named servers. All the behavior of the Fabric server that can implement this distributed principle is given in the FC-GS-3 definition of the Fiber Channel standard for universal services. 5. FC-4 (ULP Map): It is the highest level defined in the Fiber Channel standard, fixed mapping relationship between the underlying protocol (ULP) of the Fiber Channel and the existing standard application interface, current standard Includes all existing channel standards and network protocols, such as SCSI interfaces and IP, ATM, HIPPI, etc. The FC-4 layer is responsible for sending the frame to the FC-2 layer, where the node queries the FC-3 server to get the destination address of the frame. Next, the FC-2 layer adds the address information to the frame head and sends it to the FC-1 layer to decode, making it decomposes to be transmitted in the physical cable of the FC-0 layer.
FC0 Fiber Channel Layer 0 (FC-0): The physical part of the physical interface fiber channel network is mainly composed of cables, connectors, transceivers, used to generate and interpret signals on the network. Although the cable is seen from the name to the fiber channel seems to be implied with the fiber, the Fiber Channel is a network technology that supports a wide range of cables, including copper wires. In fact, when the remote and * characteristics are required, the fiber optic cable is much more than the copper wire. Although copper wires and fibers support Gigabit transmission, only fiber optic cables can be used when upgrading to 200MB / s, 400MB / s or 1Gb / s. 1. A key feature of the signal quality and cable any transmission medium is how to maintain it when the signal passes through it. As the distance increases, all signals will be diverged and become unclear. In other words, the signal weakens and needs to receive more time to get more time for analysis. Different cable technologies have different signal divergence features. Typically, the electronic signal in the copper cable is faster than the optical signal of the optical fiber. The frequency of the signal can also affect the signal of the signal, the frequency, the frequency is high, and the wavelength signal is low, and the signal of wavelength is fast. The internal diameter of the optical fiber also affects the quality of the signal, the larger the diameter, the stronger the signal reflection, and its harmonics also have a negative impact on the signal quality. This phenomenon is like a housing in a strong echo. If the echo is strong, it is difficult to distinguish the content of the speech. Therefore, the fiber having a small diameter reduces the reflection of the signal, thereby contributing to the quality of the signal when transmitting long distance transmission. 2. The cable length supported by the cable length Fiber Channel is determined by the cable transmission of high quality signals. This does not mean that the line is not more insurmountable, but it does indicate that the Taihang Too long may lead to abnormal work, so it is not supported by the manufacturer. In the optical fiber, the internal diameter and signal of the cable are usually quite appropriate. The internal diameter supporting the longest transmission cable is 9um, and the signal transmitted is within 1300 nm. The laser used to generate these signals is referred to as a long wave laser. Long wave laser uses two different sizes of fibers to support signals within 780 nm. An interior diameter is 50um. Another internal diameter is 62.5um. 50 um supports transmission distances to twice the distance, but it is much shorter than 9UM cable. Basically, two types of copper cables were used in the implementation of the Fiber Channel. One is a coaxial cable, usually used in cable television; the other is a shielded twisted pair used in many local domain. However, the transfer distance of the copper cable is limited to 25m, which is much smaller than the fiber, and the various SCSI are substantially comparable. The distance limit of the copper cable makes it usually used in the data center, and of course it is also a nice selection in the subsystem. 3. There is a reaction between the speed and distance transmission speed and the supported transmission distance. The higher the transmission rate, the shorter the distance of the transmission. A potential problem that is related to SAN is that if the distance of the link exceeds the distance supported by the new technology, the existing SAN may not be able to upgrade to a higher speed device. Although standards sometimes do not support specific transmission rates on a particular distance, this does not mean that longer distance is not possible. Special fiber transmission laser and receiving devices can provide a number of distances long than those specified than the standard tissue. These products are achieved in other San vendors. 4. Cable connector Fiber Channel connector is used, one for transmitting data, and the other for receiving data. The connector on the Fiber Channel cable is a one-way insertion method, by ensuring that the signal is transmitted only in one fiber to simplify the installation and tap. The use of copper cables in the Fiber Channel is the lowest. The most common copper cable used in the Fiber Channel network is a shielded twisted pair of type 1, which consists of two pairs of wrapped two wires. One wire in the twisted pair carries the signal and the other ground. The connector of this cable is a 9-pin DS-9 connector, but only 4 of them. Fiber Channel coaxial cable uses a BNC connector, the connector of the connector and cable TV. The cable connector of the Fiber Channel is called a SC connector. These SC conners are parallel connectors, one for transmission, other for reception. The transmission connector at one end of the cable is connected to the receiving connector of the other end.
The transceiver cable and connector are passive components of I / O. Active fiber / electronic component for transmitting and receiving signals on a cable is called a transceiver. Fiber channel has different types of transceivers depending on the use of cable types and other factors, such as prices, services, and manufacturers. The transceiver is placed in the fiber optic line to access the access system, store and network hardware. They are all SAN hardware products such as host bus controller HBA (Host Bus Adapters), hubs, switches, bridges, equipment and subsystems. Another common transceiver used in the Fiber Channel is called GBIC, which is an abbreviation for Gigabit Interface Converter. The relationship between GBIC and hardware is very close, usually cannot replace another type of cable. GBIC does not necessarily support domain replacement, and the cost of generating and integrating is also very low. GBIC can integrate low-level diagnostics and management functions. FC1 Fiber Channel Layer 1 (FC-1): The data transmitted by the transmitted protocol Fiber Channel transmission is encoded by the FC-1 layer functional entity when transmitting on a physical network. The 8b / 10b coding method uses 10-bit information on a physical network to transmit 8-bit data. In essence, the encoding method is part of the mechanism to ensure data transmission integrity. The signal transmission rate in the Gigabit Baud rate and the Gigabit fiber channel may vary. The signal transmission rate of the first wave of the fiber channel is 1,0625 gigabit baud rate. Gigabit baud rate is a representation of the total bandwidth of the transmitted signal. As a measurement index, the Gigabit Baud rate includes all encoded data and data to be transmitted. Therefore, to find the actual, final transmission rate, you need to remove additional encoding bits. For Fiber Channel, the actual transmission rate is 80% of its physical layer bandwidth, which means that 1,0625 gigabit baud rate of the Fiber Channel is equivalent to 850 Mb / s. However, storage transmission is represented by bytes instead of bit. Since one byte has 8 bits, the transmission rate of 1,0625 gigabit bass is equivalent to 106MB / s. For the convenience of explanation, this value is simple to be 100Mb / s.
FC2 Fiber Channel Layer 2 (FC-2): Signaling Protocol Fiber Channel Port Type Node Introduction Node This term is suitable for all entities that transmit and receive data in the fiber channel network. A node can be a computer system that connects to SCSI devices, printers, scanners, and other devices, or a storage device / subsystem or a storage router / switch. In this chapter, the nodes refer to the terminal node instead of the network device because they do not initiate and receive data transmission. Port type port refers to an entry or connection point of the network. There is a one-on-one relationship between the cable and ports in the network. Each end of the cable is connected to a port. The port type of the entity determines what it can do and how it initiates and responds to network transmission. Seven port definitions are usually used in the Fiber Channel network. l N port - Connect to the system and subsystems to connect to fiber optic networks. l L port - Connect to the system and subsystems common to the ring network. L NL port - Connect to the fiber network and ring network in the system and subsystem, including through the ring to the fiber network. l F port - Connect to the exchange port of the N port. l FL port - Connect the switching port of the NL port in the ring. l E port - Connect to the exchange port of another switching port. L G port - can be a universal port of F, FL, and E ports. The N port N port represents the storage initiator and the target in the communication of the Fiber Channel SAN. They have the responsibility of managing frames. There is no traffic on the N-port network. Like other Fiber Channel ports, the N port is a strict connection device because they do not perform any logical block address or file information. The HBA or subsystem controller that implements N-port will provide some storage or file archiving functions, but the N port itself only strictly performs the connection operation. The F port F port is implemented in the Fiber Channel switch, providing a connection service for the N port connected. When a connection between the corresponding F port is established in the switch, the request from one N port is accessed by the switch is provided by the switch. The n port and the F port communicate frequently without the delivery of data. When the transmission time is not performed, the N-port sends an IDLE string to the corresponding F port on the switch. The IDLE string creates a "heartbeat" between the N port and the F port, so that the problem on the link can be discovered immediately. L The cells on the port ring network share a generic cable structure and communicate between each other, not the switch to complete the connection. Therefore, another type of port is used on the ring called the L port. The N port is designed to initiate and control communication in the fiber web, and the L port is designed to initiate and control the connection in the ring mesh. When the FL port is added to the fiber channel topology, the N nodes in the fiber network must be allowed to communicate with the L nodes in the ring network. FL ports and NL ports are used to complete this feature. The FL port is implemented in the switch and allows the switch to participate in communication with the identity of special nodes in the fiber channel ring network. Depending on the definition, the ring network retains the unique address for each FL port. The FL port is part of the public standard of the Fiber Channel. Simply put, the ports in the public looper loop and ports in the fiber network communicate with each other. There are other ways to use private technologies to connect the ring to the fiber network. NL port NL port is a port that existing N port functions and L port functions. It can initiate and manage communication between fibers and annular webs, allowing storage initiators and targets to communicate with each other. The NL port in the ring can also access the web services provided by the Fibernet. The NL port and the flt port of the switch provide the basis for building the public ring. One advantage of the NL port is that it allows the network topology to change without incurring incompatibility. The HBA and subsystem controllers with NL ports implemented for common loops can be used in fiber optic networks, or in a ring network, which can change mode of operation with the change of network configuration. The E-port is called the e-port for the switch port for communication between the switches. The e-port provides a connection to the trunk link between the switches. The e-port provides a method of building a fiber network using multiple swap mechanisms. The initiator of the N port is connected to the switch can transmit data to the target N port, which is connected to another switch through the switch between the E-port. The E port is not only used to provide an I / O path to the data between the switches, but also for transmitting information about the network service between the switches. G-port switch ports can usually be automatically configured, which is implemented by identifying the other end of the link.
This type of port is called G port, which is a universal port. If the port of the other end of the link is N port, then the G port is configured to f port; if the port of the link is the E-port, the G port configured as an port; if the other end is NL port, Then the G port is configured into the FL port. The flow control of the flow control storage network in the fiber channel is the most important aspect of the connection technology of the network is its ability to manage network congestion. Most storage traffic is burst, which means it is irregular, sometimes there will be high traffic, and it is a low traffic, and it is difficult to predict. This brings challenges to exchange communication because it is impossible to know which N-port initiator wants to communicate with which N-port target. Sometimes, a conflict may also occur between N ports that communicate on the same link. If a network congestion occurs, the performance of the system is unpredictable, and the service level agreement may not be met. The Fiber Channel implements two different flow control mechanisms to manage the congestion between the N ports and the I / O path adjacent ports. The analysis of Fiber Channel flow control will be briefly described below. Buffer Credits (Buffer Credits) When there are N, L or NL ports in the Fiber Channel network, they will negotiate several parameters that affect communication methods, including how to comply with traffic control mechanisms. The fiber optic channel port is consistent on the number of available buffer credit cards for data transmission at N, L or NL ports. The buffer credit card represents a certain number of data, similar to blocks used in traditional I / O transmission. Two types of buffer credit cards, end-to-end and buffers to buffers are used in the Fiber Channel. Both will be discussed below. L-to-end traffic control When the data is sent from the transmitting end to the receiving end, the sender is subtracted from the end-to-end credit card pool. When the N, L or NL ports of the purpose receive this data, it returns a confirmation to the sender to indicate that the frame has been properly received. When the sending end port is received, the credit card pool is plus 1. In this way, when the confirmation from the destination port is received, the end-to-end credit card used by the transmitting end is added. l The flow rate of the buffer to the buffer controls another flow control in the Fiber Channel is the flow control of the buffer between the adjacent ports of the I / O path to the buffer. The flow control of the buffer to the buffer provides transmission control on a single network link. In other words, the flow control of the buffer to the buffer is managed by the L or NL port pairs in the ring and the N port and the F port. A separate credit card pool is used in the management of the flow control of the buffer to the buffer. As the end-to-end flow control, the flow control of the buffer to the buffer is completed by the send port, which uses the available credit card, and waiting for the port of the other end of the link to supplement. The receiving end sends R-RDY to the sender instead of sending a confirmation frame.
The service level Fiber Channel defines a plurality of service levels, which are used to define how n, l, nl, and f ports are interactive when transmitting data. The definition of the service level is used to classify the possibility of data transmission through the SAN. There are three categories for the original service level defined by the Fiber Channel, which is graded 1, level 2, level 3, where level 2 and grade 3 have been implemented in some commercial products. Fiber Channel Standards Tissue spent considerable time on the details of level 1, but there are very few realization in the product. There is another three service level above these three service levels, they have not been implemented in the product. The three types of original service levels are now described below: 1. Level 1 Level 1 is a connection-oriented service, which guarantees the availability of two N / NL ports. Level 1 is a link to the virtual end of the fiber to the end. Other traffic cannot interfere with the connection of level 1. The flow transmitted on the level 1 connection is reached in order on the destination port. This saves a lot of time for the destination node because it does not have to reorder the frames of the transmitted frames. As in principle, the frames of the level 1 are directly passed through the switch and immediately send to the output port of the switch without having to check whether the internal exchange connection is established. In the level 1, the internal exchange connection is always existing. The sort transfer of the level 1 is combined, and this virtual point is a low-delayed connection. The data of the fiber is quickly transmitted at a small delay. Ring does not support level 1, because shared media networks are not possible to provide a simple connection. With a virtual end-to-end connection, there is no confirmation between the switch F port and the N / NL port. This means that the flow control of the buffer to the buffer is not used for the level of service. Only the level 1 service defines the traffic control of the end-to-end. The main shortcomings of level 1 lies in that it requires a lot of resources to keep promise. Swap devices typically reuse many of the events of many events, so the proprietary connection between the switch's F port is contrary to the design principles of most switches. This may be the main reason for the level 1 is not widely implemented. Even if the level is available in a single switch, it is not known if it can pass the two Switch's e-port backed link. In order to match the definition, a proprietary backbone link is required for each level 1. Level 1 is an unrealistic dream in a plurality of (multi-switches) fibers. 2. Level 2 Level 2 is a connectionless service that provides multiple communications with a transmission frame. Multivarith communication means communication with no proprietary paths between a pair of senders and recipients. This service allows N, L, and NL ports and a series of other N, L and NL ports in the SAN. Each N, L, and NL port you want to communicate must indicate your own intent to other ports in the switch or ring to establish a connection. Although the sequencing of the frame arrives at the destination, the possibility does exist, so the communication between the level 2 must assume that the frame reordering is required. Fiber Channel frames are the same as any other network, which may be discarded or errors occurred in the transmission. Level 2 Transfer Confirmation provides a flow control of a mechanism buffer to a buffer and a point-to-point in a mechanism buffer to a buffer and a point-to-point in a transmission and receiving port. The mechanism for the flow control of the buffer to the buffer is that the receiving link port is received, and the R-RDY control statement transmitter is transmitted; the end-to-end flow control mechanism is transmitted by the receiving port to the send window. Although the ring does not have a switching port between the L or NL ports, the level 2 transmission in the ring uses both end-to-end flow control, and the flow control of the buffer to the buffer is also used. 3. Level 3 Level 3 is the most commonly used service level in the Fiber Channel network. It is a diverse, no connected datagram service. Datasheet services refer to communications that do not contain transmission confirmation. Level 3 can be considered a subset of level 2, but do not provide a mechanism for transmitting data to receive correctly. You can only use the flow control of the buffer to the buffer in the level 3 because the destination n, the NL port does not send confirmation. In other words, level 3 does not monitor transmission issues in port hardware, which means that transmission errors must be processed by high-level protocols, which will result in delays. Typically, the rating 3 error recovery is based on timeout, not an error occurs. The flow control mechanism of the level 3 is a link.
This means that when the traffic control of the buffer to the buffer allows new frames to be sent to the network, the remote connection can transmit and not discovered. Since there is no end-to-end credit card, the send port will always send frames to the network until the buffer credit card is used. In general, the level 3 lacks judgment on the status of the network, and is easier to lose frames than level 2 on the fiber optic network of network load. The topology of the Fiber Channel is to understand the working principle of the Fiber Channel device, the best entry point is the communication protocol and topology of the Fiber Channel. There are three main topologies in the fiber channel. 1. Point-to-point topology point-to-point connection is a simple connection method of a simple 100MB / s bandwidth (as shown below), which is usually used in direct connection between the fiber card and storage systems. A typical point-to-point connection configuration will include a sender (fiber card) and a target end (which can be a fiber channel port of the storage system). There is no address in the structure of point-to-point because all data is attempted to transfer to another device. Point-to-point connection uses a simple initialization process because there is no need to deal with address allocation issues. The advantage of point-to-point connection is that both devices have all bandwidth at any time. 2. Topology FC-Al topology of FC-Al (Fiber Channel Arbitration Ring) (shown below) allows users to configure 126 devices in one loop. Any device in the loop is in the process of arbitration. Other devices cannot communicate when 2 devices in the loop communicate. In a single loop connection, a node or device is invalid, it will cause the failure of the entire loop. 3. The fiber topology is connected to each node in the network connected to each node as the latitude on the fabric. Each node performs a one-to-one communication through the Fiber Channel switch with other nodes, and the connection bandwidth between each pair of nodes is 100Mb / s. In theory, 16 million nodes can be accommodated in the exchange fiber optic network.
