1 csmacd =title CSMA-CD A Carrier Sense Multiple Access with Collision Detection CSMA/CD Local Area Network LAN provides high-speed communications channels for connecting computers and other digital devices located within a moderate-sized geographic area. Like other LANs, the CSMA/CD LAN falls between long-distance, low-speed networks that carry data for hundreds or thousands of kilometers, and specialized, high-speed intercommunications that are generally limited to tens of meters. The CSMA/CD LAN is intended primarily for use in such areas as office automation, distributed data processing, terminal access, distributed systems, and other situations that require economical connection to a local communication medium with sporadic traffic at high-peak data rates. The entities that constitute the CSMA-CD module are listed below. The indentation indicates the hierarchical relationships between the entities. CSMA-CD Port Station The CSMA/CD module incorporates the functions and operations defined in the Ethernet Specification V2.0 and the ISO 8802-3 IEEE 802.3 CSMA/CD Access Method and Physical Layer specification as well as parts of the ISO 8802-1 IEEE 802.1 Addressing, Internetworking, and Network Management and the ISO 8802-2 IEEE 802.2 Logical Link Control specifications. To this, the CSMA-CD module adds features often needed by users of the Data Link. A typical such Data Link user is the Network Layer. The CSMA-CD entity is the top-level entity in the hierarchy of entities belonging to the CSMA-CD module. 2 character =title Characteristic Attributes VERSION Version number of the CSMA/CD Data Link architecture specification to which the implementation conforms. You cannot modify this characteristic. 2 port =title CSMA-CD Port A CSMA-CD Port entity represents an access point to the service offered by the CSMA-CD module. A client transmits and receives data through a port. Ports are created and deleted by client use of open and close service interface procedures. 3 counters =title Counter Attributes Unless stated otherwise, counts include both normal and multicast traffic and all protocol types, service access points SAPs, and protocol identifiers. MULTICAST OCTETS RECEIVED Number of multicast data octets that were successfully received and made available to the port user. The count is the number of octets in the CSMA/CD user data field and does not include MAC medium access control, a sublayer of the CSMA/CD Data Link layer headers. Comparing this count to the octets received count yields the gross percentage of bandwidth that was consumed over time by multicast PDUs received by the port. MULTICAST OCTETS SENT Number of multicast data octets that were successfully sent through the port. The count is the number of octets in the MAC user data field, including any padding or length fields; it does not include MAC headers. Comparing this count to the octets sent count yields the gross percentage of bandwidth that was consumed over time by multicast PDUs transmitted by the port. MULTICAST PDUS RECEIVED Number of multicast PDUs that were successfully received and made available to the port user. Counted PDUs passed address and protocol filtering and were received without errors. Comparing this count to the PDUs received count yields a gross percentage of CSMA/CD usage for multicast pdus received by this port. MULTICAST PDUS SENT Number of multicast PDUs that were successfully sent through the port. Comparing this count to the PDUs sent count yields a gross percentage of CSMA/CD usage for multicast PDUs sent by this port. OCTETS RECEIVED Total number of MAC user data octets that were successfully received and made available to the port user. Counted frames passed address and protocol filtering for both individual and multicast MAC addresses and were received without errors. The count is the number of octets in the CSMA/CD user data field plus any padding, Ethernet length fields, or logical link control LLC header fields; it does not include MAC headers. Adding the octets received count to the protocol overhead calculated from the pdus received count yields the amount of CSMA/CD bandwidth consumed by frames received by the port. OCTETS SENT Total number of user data octets that were successfully sent through the port. The count is the number of octets in the MAC user data field including any padding or length fields; it does not include MAC headers. Adding the octets sent count to the protocol overhead calculated from the PDUs sent count yields the amount of CSMA/CD bandwidth consumed over time by frames sent by the port. PDUS RECEIVED Total number of PDUs that were successfully received and made available to the port user. Counted PDUs passed address and protocol filtering and were received without errors. The count provides a gross measurement of incoming CSMA/CD usage by the port. PDUS SENT Total number of PDUs that were successfully sent through the port. The count provides a gross measurement of outgoing CSMA/CD usage by the port. UNAVAILABLE USER BUFFERS Number of times that no user buffer was available at the port for an incoming frame that passed all filtering for the port. Used in conjunction with the PDUs received count, this counter can indicate the rate of user buffer receive problems. 3 status =title Status Attributes CLIENT Name specified by the data link user when the port was opened. ETHERNET PROTOCOL TYPES Set of Ethernet protocol types that are currently recognized for this port. LENGTH PRESENT The data link adds a length field on transmit frames, and assumes the presence of a length field and attempts to remove it on received Ethernet frames. When false, the data link does not add and remove length fields. This attribute is irrelevant for ISO 8802-3 formatted frames, which always have a length field. TRUE - The data link adds and removes length fields. FALSE - The data link does not add and remove length fields. LLC SAP ADDRESSES Set of individual and group logical link control LLC service access point SAP addresses that are currently recognized for this port. LLC SERVICE Type of LLC logical link control PDU processing that is required on the port as defined by the user when the port was opened. CLASS 1 - The data link provides class 1, type 1 service. USER-SUPPLIED - The user is responsible for handling the LLC protocol. MAC ADDRESSES Set of individual and multicast MAC medium access control addresses that are currently recognized for this port. RECEIVE MODE Type of receive mode that is currently enabled for the port. NORMAL - The port receives only those frames that meet the normal address and protocol filtering requirements requested by the user. PROMISCUOUS - The port receives all frames regardless of format and MAC address. SNAP PROTOCOL IDENTIFIERS Set of subnetwork access protocol SNAP identifiers that are currently recognized for this port. STATION Name of the station associated with this port as specified by the user when the port was opened. 2 station =title CSMA-CD Station A CSMA-CD station entity manages a CSMA/CD controller. Wherever Phase IV DECnet manages a line, DECnet-Plus manages a station. Each station corresponds to a particular logical link control LLC, medium access control MAC, and physical attachment. The station name refers to the station managed by this command. 3 character =title Charactersitics Attributes STATION BUFFERS Number of receive buffers reserved for the station. You can modify this characteristic only when the entity is disabled. 3 counters =title Counter Attributes Unless stated otherwise, counts include both normal and multicast traffic and all protocol types, service access points SAPs, and protocol identifiers. ALIGNMENT ERRORS Number of times a received frame did not contain an integral number of octets. CARRIER CHECK FAILURES Number of times the data link did not sense the receive carrier signal or detected an error in the receive carrier signal during transmission of a frame. COLLISION DETECT CHECK FAILURES Number of times the collision detect test signal was not sensed after a transmission. If this count approximates the number of frames sent, either the collision detect circuitry is not working correctly or the test signal is not implemented. DATA OVERRUNS Number of times the hardware lost one or more consecutive, partially complete, incoming frames because it could not keep up with the incoming frame rate. Used in conjunction with pdus received, this count provides a measure of hardware resource and bandwidth failures. EXCESSIVE COLLISIONS Number of times a transmission failed because the maximum allowable number of retransmission attempts all culminated in collisions. FRAME CHECK ERRORS Number of times a received frame containing an integral number of octets failed the frame check sequence FCS. FRAME SIZE ERRORS Number of times the user requested transmission of a frame outside the range of valid frame sizes. FRAMES TOO LONG Number of times a received frame exceeded the maximum length allowed by CSMA/CD medium access control. INITIALLY DEFERRED PDUS SENT Number of times a PDU was deferred by the station access algorithm on the first attempt at transmission, but was then transmitted successfully without collision. Used in conjunction with PDUs sent, this count measures the rate of CSMA/CD contention with no collisions. LATE COLLISIONS Number of times a collision was detected after the allotted time for collisions had expired. MULTICAST OCTETS RECEIVED Number of multicast data octets that were successfully received. The count is the number of octets in the CSMA/CD user data field and does not include MAC headers. Comparing this count to the octets received count yields the gross percentage of bandwidth that was consumed over time by multicast frames received by the local system. MULTICAST OCTETS SENT Number of multicast data octets that were successfully sent. The count is the number of octets in the MAC user data field, including any padding or length fields; it does not include MAC headers. Comparing this count to the octets sent count yields the gross percentage of bandwidth that was consumed over time by multicast frames transmitted by the local system. MULTICAST PDUS RECEIVED Number of multicast PDUs that were successfully received. Comparing this count to the pdus received count yields a gross percentage of CSMA/CD usage for multicast PDUs received by this system. MULTICAST PDUS SENT Number of multicast PDUs that were successfully sent. Comparing this count to the pdus sent count yields a gross percentage of CSMA/CD usage for multicast PDUs sent by this system. MULTIPLE COLLISIONS PDUS SENT Number of times a PDU was successfully transmitted on the third or later attempt by the station access algorithm after normal collisions on previous attempts. Used in conjunction with pdus sent, this count provides a measure of CSMA/CD media contention at a level where there are collisions and the backoff algorithm no longer works efficiently. OCTETS RECEIVED Total number of MAC user data octets that were successfully received from frames that passed address and protocol filtering for both individual and multicast MAC addresses. The count is the number of octets in the CSMA/CD user data field plus any padding, Ethernet length fields, or LLC header fields; it does not include MAC headers. Adding the octets received count to the protocol overhead calculated from the pdus received count yields the amount of CSMA/CD bandwidth consumed by frames received by the local system. OCTETS SENT Total number of user data octets that were successfully sent. The count is the number of octets in the MAC user data field including any padding or length fields; it does not include MAC headers. Adding the octets sent count to the protocol overhead calculated from the pdus sent count yields the amount of CSMA/CD bandwidth consumed over time by frames sent by the local system. PDUS RECEIVED Total number of PDUs that passed address and protocol filtering and were received without errors. The count provides a gross measurement of incoming CSMA/CD usage by the local system; this information can be used in conjunction with other counters to approximate the average receive frame size or to determine the ratio of errors to successful receives. PDUS SENT Total number of PDUs successfully sent. The count provides a gross measurement of outgoing CSMA/CD usage by the local system; this information can be used in conjunction with other counters to approximate the average transmit frame size or to determine the ratio of errors to successful transmissions. RECEIVE DATA LENGTH ERRORS Number of times a frame was received with a length field value that was invalid for the number of octets actually received by medium access control. SEND DATA LENGTH ERRORS Number of times the user requested transmission of an 802.3 frame with a length field value that was not valid for the number of octets actually passed. SINGLE COLLISION PDUS SENT Number of times a PDU was successfully transmitted on the second attempt by the station access algorithm after a normal collision occurred on the first attempt. Used in conjunction with pdus sent, this count provides a measure of CSMA/CD media contention at a level where there are collisions, but the backoff algorithm still works efficiently. STATION FAILURES Number of times that the station self-testing procedures reported failure. UNAVAILABLE STATION BUFFERS Number of times a complete, fully received PDU was discarded because no station buffer was available. Used with pdus received, this count provides a measure of receive problems related to the station buffer. UNAVAILABLE USER BUFFERS Number of times no user buffer was available for an incoming frame that passed all filtering for the port. Used in conjunction with the pdus received count, this counter can indicate the rate of user buffer receive problems. UNRECOGNIZED INDIVIDUAL DESTINATION PDUS Number of times a received PDU with an individual destination MAC address was discarded because there was no port with the correct Ethernet protocol type, SNAP protocol identifier, or link logical control SAP address enabled. UNRECOGNIZED MULTICAST DESTINATION PDUS Number of times a received PDU with a multicast destination MAC address was discarded because there was no port with the correct Ethernet protocol type, SNAP protocol identifier, or link logical control SAP address enabled. 3 status =title Status Attributes ADDRESS FILTERS All individual MAC addresses currently enabled by any of the ports on the station. COMMUNICATION PORT DECnet-Plus device name for the station. HARDWARE ADDRESS Individual medium access control MAC address that was assigned during manufacture of the communications hardware that is associated with the station. MAC ADDRESS Current MAC address if any of the station. For more information about the MAC address, refer to the enable command. RECEIVE MODE Current receive mode for the station. Some stations may not support all modes. NORMAL - The station receives only those frames individual and multicast that meet the normal format, protocol, and access control requirements. ALL MULTICAST - The station receives all individual-addressed frames that meet the normal format, protocol, and address requirements, and all multicast-addressed frames regardless of their format, protocol, and address types. PROMISCUOUS - The station receives all frames individual and multicast regardless of format, Ethernet protocol type, SNAP identifier, LLC SAP address, or MAC address. STATE Operational state of the station. OFF - The station is disabled. ON - The station is enabled and available for use. FAILED - Either an attempt to enable the station failed during the self-test or the station was on and the data link determined that the station would now fail the self-test. INITIALIZING - The station is currently being initialized and tested by the data link.