Antonio Perez

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**HP ProCurve Switch -- Troubleshooting CRC errors**

 **Available Part Numbers:**

  J4097C HP V408 Switch,J4812A HP ProCurve 2512 Switch,J4813A HP ProCurve 2524 Switch,J4817A HP ProCurve 2312 
  Switch,J4818A HP ProCurve 2324 Switch,J4848B HP ProCurve 5372XL Switch,J4849B HP ProCurve 5348XL Switch,J4868A HP 
  V2124 Switch,J4899B HP ProCurve 2650 Switch,J4900B HP ProCurve 2626 Switch,J4903A HP ProCurve Switch 2824,J4904A 
  HP ProCurve Switch 2848,J4905A HP ProCurve Switch 3400cl-24G,J4906A HP ProCurve Switch 3400cl-48G,J8692A HP 
  E3500-24G-PoE yl Switch,J8693A HP E3500-48G-PoE yl Switch,J8697A HP E5406 zl Switch Chassis,J8698A HP E5412 zl 
  Switch Chassis,J8699A HP E5406-48G zl Switch,J8700A HP E5412-96G zl Switch,J8762A HP E2600-8-PoE Switch,J8770A HP 
  E4204 vl Switch Chassis,J8772A ProCurve Switch 4202 vl-72,J8773A HP E4208 vl Switch Chassis,J9019B HP E2510-24 
  Switch,J9020A HP E2510-48 Switch,J9021A HP E2810-24G Switch,J9022A HP E2810-48G Switch,J9029A ProCurve Switch 
  1800-8G,J9030A HP E4208-68G-4SFP vl Switch,J9077A HP V1400-8G Switch,J9078A HP V1400-24G Switch,J9079A HP V1700-8 
  Switch,J9080A HP V1700-24 Switch,J9085A HP E2610-24 Switch,J9085AZ HP E2610-24 Rack Shippable Switch,J9086A HP 
  E2610-24-PPoE Switch,J9087A HP E2610-24-PoE Switch,J9088A HP E2610-48 Switch,J9088AZ HP E2610-48 Rack Shippable 
  Switch,J9089A HP E2610-48-PoE Switch,J9137A HP E2520-8-PoE Switch,J9138A HP E2520-24-PoE Switch,J9145A HP E2910- 
  24G al Switch,J9146A HP E2910-24G-PoE+ al Switch,J9147A HP E2910-48G al Switch,J9148A HP E2910-48G-PoE+ al 
  Switch,J9049A ProCurve Switch 2900- 24G,J9050A ProCurve Switch 2900 48G,J9279A HP E2510-24G Switch,J9280A HP 
  E2510-48G Switch,J9298A HP E2520-8G-PoE Switch,J9299A HP E2520-24G-PoE Switch,J9447A HP E5406-44G-PoE+/4SFP zl 
  Switch,J9448A HP E5412-92G-PoE+/4SFP zl Switch,J9449A HP V1810-8G Switch,J9450A HP V1810-24G Switch,J9470A HP 
  E3500-24 Switch,J9471A HP E3500-24-PoE Switch,J9472A HP E3500-48 Switch,J9473A HP E3500-48-PoE Switch,J9559A HP 
  V1410-8G Switch,J9560A HP V1410-16G Switch,J9561A HP V1410-24G Switch,J9562A HP E2915-8G-PoE Switch,J9565A HP 
  E2615-8-PoE Switch
  
 **Issue Description:**

  What are CRC errors and how do I troubleshoot them?

 **Solution:**

  A Cyclic Redundancy Check (CRC) are a hash function designed to detect accidental changes to raw computer data. A 
  CRC is a short binary sequence present on each block of data. When a block of data is read or received, the 
  device repeats the calculation to check for a match. If the new CRC does not match the original CRC, then a data 
  error is logged and the device can attempt to correct the data error by re-reading or requesting the block of 
  data.

 **Excessive CRC/Alignment errors:** 
  
  A high percentage of data errors were detected on a particular switch port.

 **Possible Causes:** 

  Faulty cabling or network topology, speed duplex mismatch between ports, misconfigured NIC, malfunctioning NIC, 
  NIC driver, faulty hardware (NIC, transceiver, port).

 **Troubleshooting:**

  1. Make sure the cable, connectors, punch-down blocks, and patch panels connected to the port in question are 
  Category 5 or better and all cables connections are securely fastened.

  2. Check the directly-connected device for mismatches in speed/duplex settings.

  3. Update the NIC driver software.

  4. Verify the network topology conforms to IEEE 802.3 standards.

  5. Replace or relocate the cable to see if issue follows the connection or stays with the port.

  6. Check wiring closet components, cables, transceivers, and NICs for proper operation.

 **Best Practices:**

  Data link errors such as CRC errors, alignment errors, and runts will occur on healthy networks. How do you 
  distinguish between a reasonable number of these errors and too many? A rule of thumb is one error in 5,000. For 
  example, on average, for every 5,000 packets received you should have no more than one receive error (CRC, 
  alignment, runt, giant). Higher rates of errors will generally cause user perception of poor network performance.