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3640 FIFO RX OVERFLOWS!!!!

About 1 month ago, I started to get these messages logged on my console:

%AMDP2_FE-3-RXOVERFLO: FastEthernet0/0 Rx FIFO Overflow

The configuration has been fine for 16 months with no problems. When these overflows occur, the input errors on fa0/0 increment signifigantly. This router is in a HSRP pair and is the passive one. When the problem started to occur, it was the active one.

The problem only occurs when I am pushing heavy outbound traffic on the active router (20MBPS) and any amount of inbound traffic on the passive one (can be anywhere from 3MBPS to 10MBPS).

I have been working with TAC for about 1 month now and still have no resolution. I have replaced the entire router, all cabling and checked line continuity and everything checks out...and I still get these errors.

Let me know if anyone has any ideas as to why this happens and what I can do to resolve it.

Thanks!

1 REPLY
New Member

Re: 3640 FIFO RX OVERFLOWS!!!!

These errors are reported by the ethernet driver when it is not able to queue an inbound frame. The ethernet chipset has a recieve and transmit queue in which to store frames before sending or processing. The queues are hardware based on the chip and cannot be changed (I am not talking about input queues, system buffers, etc). If you are receiving these messages than a few things could be happening:

1) The rate of incoming traffic is over running the interface.

2) The interface is not able to empty the rx queue fast enough. This would happen if it is not able to generate a interrupt to the CPU (the cpu is busy processing other traffic).

If you would like to send me the case number I will take a look at it for you. I can be reached at tstewart@cisco.com

Tim

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