In the output below there are 38 Symbol-Errs. What do they refer to?
ROC-6509-AS-C#sh int g7/43 counters errors
Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards
Gi7/43 0 0 0 2 0 0
Port Single-Col Multi-Col Late-Col Excess-Col Carri-Sen Runts Giants
Gi7/43 0 0 0 0 0 2 0
Port SQETest-Err Deferred-Tx IntMacTx-Err IntMacRx-Err Symbol-Err
Gi7/43 0 0 0 0 38
Gig ethernet uses 10 bit encoding instead of 8 bit. These 10 bit codes are referred to as symbols. Symbol errors can occur due to dirty fibre, noisy lines or, rarer, a hardware problem.
Unless they are increasing fairly quickly or regularly they are not a cause for concern.
Clear the counters, check your connections and monitor the situation.
Hope this helps.