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Anleitung Zusammenfassung
The ARP and RARP requests sent by bridges and routers are broadcast packets. Monitoring Hub Performance Using the SEHI100TX Hub View Multicast Packets The number of multicast packets received by this device, module, or port since the window was last opened or reset. Multicast packets are simultaneously addressed to more than one address, but fewer than all addresses. Collisions The number of collisions recorded by this device, module, or port since the window was last opened or reset. The SEHI100TX counts both receive collisions N those detected while a port is receiving data N and transmit collisions N those detected while a port is transmitting data (i.e., the port has transmitted one of the colliding packets); however, these counts are combined and a single total value is displayed. Collisions of this type (called OlegalO collisions, as opposed to the OOW collisions described below) are a natural by-product of a busy network; if you are experiencing high numbers of collisions, it may be time to redirect network traf.c by using bridges or routers. Extremely high collision rates can also indicate a data loop (redundant connections) or a hardware problem (some station transmitting without listening .rst). Total Errors The number of errors of all types recorded by this device, module, or port since the window was last opened or reset. Alignment Errors The number of misaligned packets recorded since the window was last opened or reset. Misaligned packets are those which contain any unit of bits which is less than a byte N in other words, any group of bits fewer than 8. Misaligned packets can result from a packet formation problem, or from some cabling problem that is corrupting or losing data; they can also result from packets passing through more than two cascaded multi-port transceivers (a network design which does not meet accepted Ethernet spec). CRC Errors CRC, or Cyclic Redundancy Check, errors occur when packets are somehow damaged in transit. When each packet is transmitted, the transmitting device computes a frame check sequence (FCS) value based on the contents of the packet, and appends that value to the packet. The receiving station performs the same computation; if the FCS values differ, the packet is assumed to have been corrupted and is counted as a CRC error. CRC errors can result from a hardware problem causing an inaccurate computation of the FCS value, or from some other transmission problem that has garbled the original data. The CRC error counter shows the total number of CRC errors recorded since the window was last opened or reset. OOW Collisions The number of out-of-window collisions recorded since the window was last opened or reset. OOW collisions occur when a station receives a collision signal while still transmitting, but more than 51.2 m sec (the maximum Ethernet propagation delay) after the transmission began. There are two conditions which can cause this type of error: either the networkOs physical length exceeds IEEE Monitoring Hub Performance Using the SEHI100TX Hub View 802.3 speci.cations, or a node on the net is transmitting without .rst listening for carrier sense (and beginning its illegal transmission more than 51.2 m s after the .rst station began transmitting). Note that in both cases, the occurrence of the errors can be intermittent: in the case of excessive network length, OOW collisions will only occur when the farthest stations transmit at the same time; in the case of the node which is transmitting without listening, the malfunctioning node may only fail to listen occasionally, and not all of its failures to listen will result in OOW collisions N some may simply result in collisions (if the 51.2 m s window has not yet closed), and some will get through .ne (if no one else happens to be transmitting). Runt Frames The number of received packets smaller than the minimum Ethernet frame size of 64 bytes (excluding preamble). This minimum size is tied to the maximum propagation time of an Ethernet network segment N the maximum propagation time is 51.2 m s, and it takes approximately 51.2 m s to transmit 64 bytes of data; therefore, every node on the segment should be aware that another node is transmitting before the transmission is complete, providing for more accurate collision detection. Runts can sometimes result from collisions, and, as such, may be the natural by-product of a busy network; however, they can also indicate a hardware (packet formation), transmission (corrupted data), or network design (more than four cascaded repeaters) problem. Giant Frames The number of received packets that are longer than the maximum Ethernet size of 1518 bytes (excluding preamble). Giant packets typically occur when you have a jabbering node on your network N one that is continuously transmitting, or transmitting improperly for short bursts N probably due to a bad transmitter on the network interface card. Giant packets can also result from packets being corrupted as they are ...