Network equipment failure analysis

Network equipment failure analysis

---- CRCError:
---- Meaning: indicates that there is a bad frame in data transmission. Bad frames will be discarded and retransmitted through high-level protocols.
---- Cause: Usually caused by cable or network hardware error or environmental noise. Such as network card hardware error, poor quality cable.
---- Solution: Replace the network hardware or avoid the surrounding environmental interference sources. ---- ShortFrame:
---- Meaning: It means that a frame less than the minimum frame length (64byte) is received on the device port and the frame has errors.
---- Cause: Due to noise interference, cable error and hardware error. If it happens frequently, it should be resolved.
---- Solution: Replace the network hardware or avoid the surrounding environmental interference sources. ---- Fragment:
---- Meaning: Packets with less than 64 bytes with bad frames or CRC errors.
---- Reason: The network is overburdened, mostly due to network conflicts.
---- Solution: The network burden is too heavy to cause network conflicts, and switching equipment or segmentation should be used. ---- Alignment:
---- Meaning: The received frame has reassembly error. Frame reassembly errors are frames larger than 64 bytes with CRC errors and are not integer bits in length (the number of frames cannot be divisible by 8).
---- Cause: Mostly due to cable or transceiver errors or due to mismatched connection rates.
---- Solution: If there is a frame reassembly error, it will be discarded and retransmitted. This will seriously affect the network performance, so it should be taken seriously. Replace the transceiver or transceiver cable and adjust the speed of the devices at both ends of the network cable. ---- RuntFrame:
---- Meaning: frames smaller than the minimum frame length (64byte) and having normal FCS.
---- Cause: Mostly caused by network conflicts. When the network conflict disappears, it also disappears.
---- Solution: If data frames of this type continue to appear, measures should be taken to reduce the burden on the network. ---- LongFrame:
---- Meaning: refers to the frame larger than 1518byte and smaller than 6000byte. Continuous long frames affect network performance and may cause network transmission interruption.
---- Cause: The transmission of long frames by the workstation is caused by hardware or software errors. Close to it is also "VeryLongs (also called giants)", which means that frames larger than 6000 bytes appear. The causes are similar.
---- Solution: The bad node should be removed from the network. ---- Jabber:
---- Jabber is a long frame with CRC error (more than 1518byte and less than 6000byte) or packet reassembly error.
---- Cause: It may cause packet loss on the network. Mostly due to hardware or software errors in the workstation.
---- Solution: The workstation should be carefully checked or taken off the Internet. If the adapter works properly on other computers, you should check: whether the cable connecting the nodes is too long; whether there is a mismatch between the full-duplex communication method and the switch. When the Jabber light is on, the transceiver has automatic block data transmission to reduce the burden of network traffic. ---- Collision:
---- Meaning: The data packets collide in network transmission.
---- Cause: The data packets are transmitted concurrently in the medium, usually caused by network segment congestion. Solution: HUB should be replaced with a switch or move the network equipment to other network segments to balance the communication load. ---- Latecollision:
---- Meaning: An error occurs after the 64byte frame is sent, which will affect the network performance. Such errors rarely occur in a healthy network.
---- Cause: The typical causes are: (1) Incorrect Duplex mode setting; (2) The cable is too long (the delay during signal transmission is too large); (3) The principle of 4 relays between workstations is exceeded; (4) The hardware error of the network workstation.
---- Solution: Eliminate step by step for the above reasons. ---- Excessivecollision:
---- Meaning: After collision, the frame is retransmitted. If the number of retransmission attempts exceeds 15 times, it is called Excessivecollision.
---- Cause: The network load is too heavy or the node hardware is wrong.
---- Solution: Find the hardware error of the node and replace it; switch or other means should be used to reduce the network load in the network segment. ---- CodeviolaTIon:
---- Meaning: indicates that an illegal code was received by the switch.
---- Reason: In the switch used, when 100M transmission rate is used, every 4-bit code is transmitted as 5-bit code on the line. This may generate some illegal code, it should not be transmitted, if it is transmitted, it is called CodeviolaTIon. Because the signal in the network line is interfered by external signals during transmission.
---- Solution: Use shielded wires or reduce external interference signals. Especially in the 100M twisted pair wiring, run the line with the interference source. ---- DRM (DataRateMismatch):
---- Meaning: The received signal does not match the internal clock of HUB and other devices.
---- Cause: HUB or other hardware problems or network interface problems. ---- Phenomenon: Link / Traffic indicator does not light:
---- Cause: There is a problem with the network card, cable, or device port (such as HUB). Solution: Most of these phenomena are caused by network card or cable problems. The network card and cable should be carefully checked and replaced with a good network card and cable.
---- Phenomenon: PWRLED light is not on:
---- Cause: The power cord is not connected properly, and the HUB power supply is broken.
---- Solution: Connect the power supply or replace the HUB. ---- Phenomenon: ParTITIoning light is on (red):
---- Cause: It means that the network is faulty and the port is temporarily isolated when there are cable problems or conflicts are particularly frequent. (1), there is a problem with the connected cable; (2), the problem with the device port (such as HUB, repeater, transceiver port); (3), the problem with the network card; D, the termination of the cable (such as connector, terminal )problem.
---- Solution: When the error disappears, the HUB port is automatically effective. For the above different categories, you should first carefully check whether the cable connected to the device and its port are well connected; then check whether the connection of the device port, network card, and cable terminator of other connection segments is eliminated step by step The cause of the error. ---- Reset:
---- Meaning: Without turning off the power, the device will complete the configuration of the changed port again. Especially in some repeaters. ---- Link:
---- Meaning: When the port is connected to a dotted device, the indicator light is on. When the connected device is powered off or there is a problem with the connection, it goes out. ---- Receive (Rx):
---- Meaning: When the port is connected to the network and receives a data packet, the indicator light flashes continuously. ---- Translation (Tx):
---- Meaning: When the port is connected to the network and sends a data packet, the indicator light flashes continuously. ---- SQE (SignalQualityError):
---- Meaning: The "heartbeat" function, which generates a signal called "CollisionPresenceTest" (more called "HeartBeat"), detects circuit conflicts during device operation, and appears on the transceiver. When the transceiver is connected to the computer, it is set to "Enable / ON", and when it is connected to the repeater and HUB, it is set to "Disabled / OFF". ---- AUI (AttachmentUnitInterface):
---- Meaning: It is a media unit interface. It has a 15-pin (DB-15) interface specification defined by IEEE802.3 and is used to connect PCs, servers, and other devices connected to thick cables. It can also be connected to various Ethernet media (such as BNC, optical fiber) through Ethernet transceivers or MAU (MediaAccessUnit). Some HUBs and repeaters have this identifier. When the switch is turned to its end, the AUI will work. ---- MAU (MediumAttachmentUnit):
---- Meaning: It is a network device used to connect DTE to transmission medium. The Ethernet transceiver (Transceiver) is a MAU. A 10BASE-TMAU is used to connect UTP to an AUI interface (such as HUB, repeater, network card). ---- BNC (BayonetNutCouple):
---- Meaning: one of the thin cable interfaces (also T-shaped head, thin cable terminal). Some HUBs and repeaters have this identifier. When the switch is set to this end, the port is connected to the network. When there is a data packet, the corresponding indicator light flashes continuously. ---- Daisy-ChainPort:
---- Meaning: It is an MDI RJ45 port, and cascade other similar devices through straight-through. ---- MDIPort (MediumDependentInterface):
---- Meaning: MDI is one of the interfaces for UTP cable specified in the IEEE10BASE-T standard. This port connects HUB to network devices such as ROUTER, SWITCH through a direct connection. ---- MDI-XPort (MediumDependentInterface-Crossed):
---- Meaning: MDI-X is a general RJ45 port (for example, most of the ports on the HUB are of this type), it has completed the internal crossover, and the HUB can be connected to the network card of the workstation using a direct connection.

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