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FCS Rx errors

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Michael Tibbs
Occasional Contributor

FCS Rx errors

I have an ethernet gateway device (for secure entry system) connected to a port on a ProCurve 4000 which is showing a number of FCS Rx errors. I don't know if I should be concerned about it or not. The port is set to Auto, and running at 10 mb half duplex.

Here are the port stats:

Status and Counters - Port Counters - A2
Link Status : Up

Bytes Rx : 1,326,816,580 Bytes Tx : 3,778,092,352
Unicast Rx : 7,123,967 Unicast Tx : 7,984,674
Bcast/Mcast Rx : 6794 Bcast/Mcast Tx : 31,234,002

FCS Rx : 916 Drops Tx : 0
Alignment Rx : 0 Collisions Tx : 176
Runts Rx : 0 Late Colln Tx : 0
Giants Rx : 0 Excessive Colln : 0
Total Rx Errors : 916 Deferred Tx : 1633

Is there an issue that merits more investigation?
Ron Kinner
Honored Contributor

Re: FCS Rx errors

Normally you would expect to see FCS RX errors on a full duplex link that was talking to to a half duplex link. What usually happens is the full duplex side talks anytime it want to but if the Half Duplex side is transmitting when the full side starts talking then the half side stops talking immediately in mid frame if need be. The result is that the full side receives a packet that is incomplete and thus has a frame check sum error. In your case we are looking at the half side so it should not get these errors unless there is a noisy cable or bad port somewhere. Are you sure that the FCS RX errors are current and not left over from some earlier time when the port might have been set to Full? Try clearing the counters and see if they come back.

In any event it is not a major problem when you look at the percent of errors to total packets so watchful waiting is probably the best policy.