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rx_address_match_errors?

Posted on 2012-04-07
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Last Modified: 2012-04-11
Hi Experts,

When I execute ethtool -S eth0, I see some values on rx_address_match_errors.
What does this thing means?

no errors found except for the rx_address_match_errors.
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Question by:d34dp00l13
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by:Mysidia
ID: 37820705
That drop counter is packets that were dropped, because the packet does not pass the Unicast or the Multicast packet filters.     In other words,  it could be a packet 'flooded out the upstream switch'  because the destination MAC address was unknown to the switch,   the Ethernet frame may have arrived at computers that are not destination.

In other words, a frame was received on the Ethernet interface,  that doesn't have a destination MAC address  matching the  computer Network card's unicast MAC address,   and  
the destination MAC address of the packet wasn't a valid multicast Ethernet address for a
multicast group the system was listening on either.
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by:d34dp00l13
ID: 37828148
Thanks Mysidia, but why does this thing hapens? And is this a sign of a network issue?
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Mysidia earned 500 total points
ID: 37830733
This is a low-level NIC statistic.   It's not really anything to be concerned about, unless you see this incrementing at a high rate.
Do you see the counter incrementing much, or does it stay at the same value?

As I mentioned above, it is completely normal for a  NIC to receive Ethernet frames not destined for it occasionally.

If it happens _too_ often,  there may be a problem.    If many non-broadcast packets are getting flooded,  the switch may not have sufficient resources to efficiently switch your LAN,  or you may have a malicious node attempting to fill up switch MAC address tables with fake entries (for example, in order to eavesdrop on other hosts by forcing their traffic to be flooded out).
Path thrashing and other mayhem can also result if there's an unintentional loop in the network.


If a switch receives a raw Ethernet frame  (a network packet) with a destination MAC address that has not been learned yet,  the switch will flood that frame out ALL  switch ports  (except the port that the frame came in on).

For example, if  some computer on your LAN has not sent any network traffic for 5  minutes or so,
its  MAC address may age out of the switch's memory.

Another host on your LAN may suddenly send a packet to that computer, for example a ping or a Netbios UDP query.  Since the destination MAC address is not on the switch's memory,  that one packet will get flooded out.

This is the most likely cause unless you see the counter running a whole lot.
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Author Closing Comment

by:d34dp00l13
ID: 37833053
Hi Mysidia, thank you for explaining it further. I learn new things from you today!

Thank you and have a good day ahead!
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