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Fibre Channel
Layer 4. Protocol mapping
LUN masking
Layer 3. Common services
Layer 2. Network
Fibre Channel fabric Fibre Channel zoning Registered state change notification
Layer 1. Data link
Fibre Channel 8b/10b encoding
Layer 0. Physical
FC-AL drive with SCA-2 connector.
The arbitrated loop, also known as FC-AL, is a Fibre Channel topology in which devices are connected in a one-way loop fashion in a ring topology.[1] Historically it was a lower-cost alternative to a fabric topology. It allowed connection of many servers and computer storage devices without using then very costly Fibre Channel switches. The cost of the switches dropped considerably, so by 2007, FC-AL had become rare in server-to-storage communication. It is however still common within storage systems.
It is a serial architecture that can be used as the transport layer in a SCSI network, with up to 127 devices. The loop may connect into a fibre channel fabric via one of its ports.
The bandwidth on the loop is shared among all ports.
Only two ports may communicate at a time on the loop. One port wins arbitration and may open one other port in either half or full duplex mode.
A loop with two ports is valid and has the same physical topology as point-to-point, but still acts as a loop protocol-wise.
Fibre Channel ports capable of arbitrated loop communication are NL_port (node loop port) and FL_port (fabric loop port), collectively referred to as the L_ports. The ports may attach to each other via a hub, with cables running from the hub to the ports. The physical connectors on the hub are not ports in terms of the protocol. A hub does not contain ports.
An arbitrated loop with no fabric port (with only NL_ports) is a private loop.
An arbitrated loop connected to a fabric (through an FL_port) is a public loop.
An NL_Port must provide fabric logon (FLOGI) and name registration facilities to initiate communication with other node through the fabric (to be an initiator).
Arbitrated loop can be physically cabled in a ring fashion or using a hub. The physical ring ceases to work if one of the devices in the chain fails. The hub on the other hand, while maintaining a logical ring, allows a star topology on the cable level. Each receive port on the hub is simply passed to next active transmit port, bypassing any inactive or failed ports.
Fibre Channel hubs therefore have another function: They provide bypass circuits that
prevent the loop from breaking if one device fails or is removed. If a device is removed
from a loop (for example, by pulling its interconnect plug), the hub’s bypass circuit
detects the absence of signal and immediately begins to route incoming data directly
to the loop’s next port, bypassing the missing device entirely. This gives loops at least
a measure of resiliency—failure of one device in a loop doesn’t cause the entire loop
to become inoperable.
^"What Is Fibre Channel Arbitrated Loop and How's It Working". MiniTool. 2019-09-03. Retrieved 2023-10-19.
does not contain ports. An arbitratedloop with no fabric port (with only NL_ports) is a private loop. An arbitratedloop connected to a fabric (through...
connectivity. The bandwidth is dedicated. Arbitratedloop (see FC-AL-2). In this design, all devices are in a loop or ring, similar to Token Ring networking...
the best scalability of the three FC topologies (the other two are ArbitratedLoop and point-to-point), it is the only one requiring switches, which are...
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
resolution. Fibre Channel network topologies consist of the following: ArbitratedLoop—A series of N_PORTs connected together in daisy-chain fashion. Switched...
Computer Serial Interface (SCSI) devices sf: soc+ or social Fiber Channel ArbitratedLoop (FCAL) soc: SPARC Storage Array (SSA) controllers and the control device...
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
It is a serial protocol. In disk drives usually the Fibre Channel ArbitratedLoop (FC-AL) connection topology is used. FC has much broader usage than...
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
one-dimensional, and the chain of nodes is connected to form a circular loop, the resulting topology is known as a ring. Network systems such as FDDI...
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
"walk the loop" to determine what devices are connected and then assigns each one a 7-bit "hop-count" value. Fibre Channel – ArbitratedLoop (FC-AL) initiators...
It is a serial protocol. In disk drives usually the Fibre Channel ArbitratedLoop (FC-AL) connection topology is used. FC has much broader usage than...
transmitters and receivers can be cut in half. Since a message will eventually loop all of the way around, transmission does not need to go both directions....
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
standard — Fibre Channel. The FC5000 array utilized a Fibre Channel ArbitratedLoop connection that doubled the performance of SCSI arrays at that time...
combination of control (K) codes and data (D) codes. Each device has an ArbitratedLoop Physical Address (AL_PA). These addresses are defined by an 8-bit field...
International ArbitratedLoop Physical Address, used in part of some computer systems, e.g. device numbering on Fibre Channel loops Alpa, an alternate...
Bus network Grid network Mesh network Point-to-point Ring network Arbitratedloop Star network Switched fabric Tree network Fat tree Hypertree Topology...
because in these contexts systems often use software or hardware locks to arbitrate shared resources and implement process synchronization. In an operating...
full-duplex; all earlier implementations, USB 1.0-2.0, are all half-duplex, arbitrated by the host. Low-power and high-power devices remain operational with...
hex keypad and 8-digit 7-segment LED, and a TTY (Teletype) 20 mA current loop serial interface. Pads are available for one more 2K×8 8755 EPROM, and another...
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