CRC Error's -What are they?
CRC CYCLIC REDUNDANCY CHECK
A Cyclic Redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices, to detect accidental changes in RAW data. CRC errors play a vital roll in XDSL line stability, causing corrupt or dropped data packets, resulting in dropouts (Loss of sync), LOS of your service. Which for all end users can be quite frustrating, allowing the issue to be identified so it can be resolved.
Currently, there is no set CRC maximum expectable level, but Telstra and most ISP’s around the world find 30 CRC’s P/m (Per Minute) to be executable and should not affect any service stability.
COMMON CAUSES OF CRC ERROR?
- Poor Cable connections
- Poor cabling routes
- Corrosion in Sockets
- Water/moisture in connectors/cable
- RFI (Radio Frequency Interference) caused by faulty transformers in L.E.D T.V’s monitors etc, 240 Volts home power circuits, faulty modem (neighbors)
These are just some of the known causes we find every day when troubleshooting DSL faults looking at the cause of CRC error rates, Just because a POTS (plain ordinary telephone service) line will pass within specification does not mean it will be good enough for xDSL services.
The cause of the CRC’s need to be identified, located whether within the private property or the carrier’s network, In order to establish this we use specialized equipment and conduct test at the Network Termination Device (NTD) which could be located at the 1st socket or Connect box located at the side of the house. By starting here we can quickly establish which side of the network is affected saving the customer time and money.
A lot of today’s technicians fail to fully understand the importance of testing and monitoring CRC error rates for a minimum period of 10 minutes to excluding hidden factors in xDSL testing to exclude hidden factors.