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Friday TECHtionary.com TECH-Tip – FC-Fibre Channel protocol - Point-to-Point, Arbitrated Loop and FabricThe animated tutorial is available at http://www.techtionary.com Summary According to Alcatel, "The term switching fabric comes from the idea of criss-crossing logical pathways between ports in a switch or other similar network architectures. When every port has an independent link to every other port, the graphical depiction of such a configuration looks like woven fabric, thus the term switching fabric. The term has taken on a life of its own since it was coined and in general is a logical discussion of how the hardware in a switch, router, etc. passes information between the ports." Details In the FC-Fibre Channel protocol, three different fabric topologies: 1-Point-to-Point, 2-Arbitrated Loop and 3-Fabric. 1- PP or PTP-Point-To-Point topology (shown here) is a direct connection between two N_Ports, with at least one of the ports being a server (initiator). The topology requires no arbitration (contention-sharing) for the storage media because of separate links/circuits for transmission and reception. However, the topology is limited to two nodes making it not scalable. 2 - There are two types of FC-Fiber Channel AL-Arbitrated Loop: 1-Hub to interconnect the ports and 2-Daisy-Chain the devices. Arbitrated Loop combines the advantages of the fabric topology (support for multiple devices) with the ease-of-operation of point-to-point topology. In a FC-AL topology, devices are connected to a central hub. Like Ethernet LAN-Local Area Network Hubs, the Hub arbitrates (shares) access to devices and offers no additional functionality or intelligence to the connected devices beyond serving as a centralized connection point. In an Arbitrated Loop Hub, devices must seize control of the loop (carrier sense) and then establish a point-to-point connection with the receiving device. Once the point-to-point connection is established data is transferred. Once the transmissions have ended, devices connected by the Hub can once again "arbitrate" (share-contend) to gain control of the loop for establishing subsequent point-to-point connections. In Hub topology, there can be up to 126 nodes connected to a single link though with contention access the more the devices on network, the lower the performance. This makes is highly uncommon to attach the 126-node maximum to a single link. In an FC-AL-Fibre Channel-Arbitrated Loop Daisy-chain, the devices are connected in a series and the transmit (send port) of one device is connected to the receive port of the next device in the chain. Daisy-chain networks are ideal for small networks but not very scalable since all devices on the loop are must be operational (on) at the same time for the loop to be up and running. The failure of a single device will cause a break to the loop, and cause the entire loop to cease operation. 3 - Fabric topology consists of one or more Fibre Channel switches interconnected through one or more ports. The fabric ports are X Ports that connect to either another X Port on a different switch or to an Y Port on a node. Each switch typically contains 8, 16, 32 or 64 ports; the two largest types are sometimes called director switches. About TECHtionary.com – 303-444-6226 TECHtionary Corporation founded in 2001 and headquartered in Boulder, Colorado is the World's First and Largest Animated (rich media) Library/Magazine on Technology. Get the analysis and more than 2,603+ free tutorials on data, internet, wireless, VoIP-Voice over Internet Protocol (internet protocol telephony), PBX systems, computing, security, content, central office switching, protocols, telephony, telecommunications, networking, routing, power systems, broadband, WiFi-Wireless Fidelity and other technologies, TECHtionary.com provides "just enough – just-in-time" critical success information. TECHtionary produces web infomercials proven to "increase revenues, decrease customer support costs and increase customer satisfaction." |