Crc Error Ethernet Switch
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What Is Crc Checksum
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Input Errors On Interface Cisco Router
takes a minute: Sign up Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top What is the meaning of the CRC counter on a https://supportforums.cisco.com/discussion/10806391/crc-error-and-input-error-how-can-fix-these cisco device? up vote 22 down vote favorite 1 If the CRC counter of an interface is high, normally it's a bad sign, but why? If the count is high, what does this mean technically? What can cause this counter to go up? On which layer in the OSI model will this counter react? cisco troubleshooting share|improve this question asked May 31 '13 at 8:53 Bulki 1,41341439 Thats is perfect answer i was http://networkengineering.stackexchange.com/questions/1467/what-is-the-meaning-of-the-crc-counter-on-a-cisco-device looking for .Most helpful –user6452 Jul 8 '14 at 10:51 add a comment| 2 Answers 2 active oldest votes up vote 31 down vote accepted The counter is increasing because your frames are being corrupted. CRC is a polynomial function on the frame which returns a 4B number in Ethernet. It will catch all single bit errors and a good percentage of double bit errors. It is thus meant to ensure that the frame was not corrupted in transit. If your CRC error counter is increasing it means that when your hardware ran the polynomial function on the frame, the result was a 4B number which differed from the 4B number found on the frame itself. Ethernet frame CRC (FCS) is usually understood to be on OSI layer 2, many people claim it is layer 1 on Ethernet, but that is incorrect (only preamble, SFD and IFG are layer 1 on Ethernet). I recommend a book called Computer Networks - A systems approach on this and many other subjects. It discusses CRC in-depth around page 92 through 102. As Daniel pointed out, frames can get corrupted due to several reasons such as: duplex mismatch, faulty cabling and broken hardware. However, some level of CRC errors should be expected and the standard allows up-to 10-12 bit-error-rate on Ethernet (1 bit out of 1012
E-Series Core Switch/Router C-Series Resilient Chassis Based Switches S-Series Family of Access Switches S4810 S2410 S60 S55 S25/50N S25/50V S25P Force10 Operating System (FTOS) Force10 Management System (FTMS) Network Automation https://www.force10networks.com/CSPortal20/TechTips/0021_CRCErrors.aspx and Virtualization Open Automation Virtualization Framework Carrier Transport and Access Traverse Multiservice Transport Switch TraverseEdge Family of Multiservice Multiplexers TransAccess and Wide Bank TDM Edge Multiplexers MASTERseries Cell Site Access Aggregator Axxius 800 Cell Site Access Aggregator Adit 600 Converged Services Access Gateway Broadmore Platform Support OverviewContact SupportCustomer LoginAccount RequestDocumentationTechtips for Platforms Running FTOS Troubleshooting CRC Errors on Gigabit Ethernet Interfaces crc error Symptom The CRC counter continues to increment, as shown in the show interfaces gig output: Force10>show interface gig 0/7 GigabitEthernet 0/7 is up, line protocol is up Hardware is Force10Eth, address is 00:01:e8:07:e0:00 SFP present. Media type is ZX. Internet address is not set MTU 1554 bytes, IP MTU 1500 bytes LineSpeed 1000 Mbit ARP type: ARPA, ARP Timeout 04:00:00 Last clearing crc error ethernet of "show interface" counters 13w5d19h Queueing strategy: fifo 51040098567 packets input, 12649732603754 bytes Input 50484710883 IP Packets, 50872183339 Vlans 0 MPLS 21293513947 64-byte pkts, 16911511032 over 64-byte pkts, 1131757544 over 127-byte pkts, 2803601459 over 255-byte pkts, 5251066555 over 511-byte pkts, 3648648031 over 1023-byte pkts Received 0 input symbol errors, 0 runts, 0 giants, 0 throttles, 12783 CRC, 0 IP Checksum, 0 overrun, 0 discarded 65507855048 packets output, 50346845285803 bytes, 0 underruns Output 236700899 Multicasts, 1389966414 Broadcasts, 63881187735 Unicasts Background / Explanation The following issues have been shown to generate CRC errors: Bad fiber cable Dirty optics This condition has been seen when a connected router interface, with auto-negotiation disabled, was shut down without a link-down being detected by the Force10 system. Some third-party devices continue to power on the fiber port’s laser even though the port is in shutdown mode. Troubleshooting Steps To troubleshoot a bad fiber cable, try reducing the attenuation. To troubleshoot dirty optics, clean the optics at both ends, as described in Cleaning and Inspecting Optical Fibres. Try a different fiber cable and try connecting it to different ports. Information to Colle