Cisco Crc Error List
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Cisco Support Troubleshooting Ethernet Hierarchical NavigationHOMESUPPORTTroubleshooting Ethernet Downloads Troubleshooting Ethernet Feedback cisco router crc errors Table Of Contents Troubleshooting Ethernet Ethernet and IEEE 802.3 Full-Duplex Operation cisco switch crc errors 10/100/1000 Autonegotiation Physical Connections Frame Formats Troubleshooting Ethernet show interfaces ethernet Syntax Description Command Mode cisco t1 crc errors Usage Guidelines Sample Display Troubleshooting Ethernet Ethernet was developed by Xerox Corporation's Palo Alto Research Center (PARC) in the 1970s. Ethernet was the technological basis for
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the IEEE 802.3 specification, which was initially released in 1980. Shortly thereafter, Digital Equipment Corporation, Intel Corporation, and Xerox Corporation jointly developed and released an Ethernet specification (Version 2.0) that is substantially compatible with IEEE 802.3. Together, Ethernet and IEEE 802.3 currently maintain the greatest market share of any local-area network crc error fix cisco (LAN) protocol. Today, the term Ethernet is often used to refer to all carrier sense multiple access collision detect (CSMA/CD) LANs that generally conform to Ethernet specifications, including IEEE 802.3. When it was developed, Ethernet was designed to fill the middle ground between long-distance, low-speed networks and specialized, computer-room networks carrying data at high speeds for very limited distances. Ethernet is well suited to applications on which a local communication medium must carry sporadic, occasionally heavy traffic at high peak data rates. Ethernet and IEEE 802.3 Ethernet and IEEE 802.3 specify similar technologies. Both are CSMA/CD LANs. Stations on a CSMA/CD LAN can access the network at any time. Before sending data, CSMA/CD stations "listen" to the network to see if it is already in use. If it is, the station wanting to transmit waits. If the network is not in use, the station transmits. A collision occurs when two stations listen for
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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 cisco device? up vote 22 down vote favorite 1 If the CRC counter of an interface is http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/tr1904.html 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 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 http://networkengineering.stackexchange.com/questions/1467/what-is-the-meaning-of-the-crc-counter-on-a-cisco-device 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 can flip) and it's acceptable according to the standard. In copper the signal travels by transferring state between electrons (electrons themselves are not traveling very much) and in fiber the signal travels by the photons reflecting off the walls of the fiber. There is a non-zero chance that the photon will simp
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in depth; indeed, this command is useful to obtain various interface information like drop, duplex mismatch, error, tx/rx load, … Usually, the IOS switch/router have similar "show interface" output; the differences are dictated by devices, interface and IOS. Below a show interface of a TenGigabitEthernet interface. The show is issued on a Cisco WS-C6509-E in VSS Mode with IOS version 15. Ciscozine-IOS#sh int te1/5/4 TenGigabitEthernet1/5/4 is up, line protocol is up (connected) Hardware is C6k 10000Mb 802.3, address is 0000.0000.fd90 (bia 0008.ef4a.fd90) MTU 1500 bytes, BW 10000 Kbit/sec, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 10Gb/s, media type is 10Gbase-SR input flow-control is on, output flow-control is off Clock mode is auto ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output never, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 7000 bits/sec, 8 packets/sec 5 minute output rate 10000 bits/sec, 11 packets/sec L2 Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes mcast L3 out Switched: ucast: 0 pkt, 0 bytes mcast: 0 pkt, 0 bytes 4495527 packets input, 488522378 bytes, 0 no buffer Received 4460539 broadcasts (1153347 multicasts) 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 0 multicast, 0 pause input 0 input packets with dribble condition detected 6925984 packets output, 825456963 bytes, 0 underruns 0 output errors, 0 collisions, 1 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier, 0 PAUSE output 0 output buffer failures, 0 output buffers swapped out Ciscozine-IOS# TenGigabitEthernet1/5/4 is up, line protocol is up (connected) Identify if the interface is phisically up and if the protocol is up. Hardware is C6k 10000Mb 802.3, address is 0000.0000.fd90 (bia 0008.ef4a.fd90) Identify the hardware interface and the interface mac-address; the BIA aka Burned-In (MAC) Address cannot be changed, while the "address" can be changed with the command "mac-a