3Com 3C780 User Guide - Page 166

PHY Ping PMD Port Glossary 5 Physical Layer Protocol. The sublayer that describes the medium-independent portion of the OSI Physical layer and specifies the rules for encoding digital data for transmission from one FDDI station to another. It also provides the link between the PMD and the MAC layer. Packet InterNet Groper. A program used in the Internet to find out whether or not a host on the network is operational by sending it echo frames and waiting to receive the same number of frames in return. Physical Layer Medium Dependent. The sublayer in the FDDI architecture that specifies the optical fiber hardware components that create the physical link between two adjacent FDDI stations. A point of access where a physical connection is made between a device and cabling to another device, network, etc. The FDDI standard defines four port types: A, B, M, and S. Port type A (Primary IN/Secondary OUT) allows attachment to the incoming primary ring and to the outgoing secondary ring. Port type B (Secondary IN/Primary OUT) allows attachment to the outgoing primary ring and to the incoming secondary ring. Port type M (Master) allows attachment between a concentrator and a single-attach station. Uses the primary ring only. See SAS. Port type S (Slave) allows attachment between an SAS or SAC and a concentrator. Uses the primary ring only.