Unanswered Question
Nov 23rd, 2008
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What the common root cause if we have error on the Symbol-Err,FCS-Err.

How to fix it.


----------- reading ------------

DR3#sh int gi3/1 counters errors

Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards

Gi3/7 0 2 0 783 0 0

Port Single-Col Multi-Col Late-Col Excess-Col Carri-Sen Runts Giants

Gi3/7 0 0 0 0 0 16 0

Port SQETest-Err Deferred-Tx IntMacTx-Err IntMacRx-Err Symbol-Err

Gi3/7 0 0 0 0 1104

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Giuseppe Larosa Mon, 11/24/2008 - 08:10
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Hello Sam,

Symbol errors refers to the GE physical layer: to provide some forward error correction a line code is used of type 8B/10B each 8 bits block of GE is sent inside a 10bits block on the wire.

The actual rate on the fiber is 1.25 Gbps but 0.25 Gbps is an overhead.

Symbol errors should refer to the event of not being able to recover the 8bits block.

Being a physical layer error you can try to change fiber cables and /or one GBIC of the two on the same link.

There have been two other threads about this problem, in one there was a stack of C3750.

Hope to help


Richard Burts Mon, 11/24/2008 - 08:55
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The couple of times that I have encountered symbol errors they have each turned out to be problems in the physical infrastructure. I suggest that you check the patch cables and if they test good then I would look for a problem in the fiber infrastructure.




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