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Jan 19th, 2010
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Jan 19 20:57:46 MSK: %SIBYTE-DFC3-4-SB_EXCESS_COLL: Excessive collisions on mac 1 (count: 263)

Jan 19 20:57:46 MSK: %SIBYTE-DFC8-4-SB_EXCESS_COLL: Excessive collisions on mac 1 (count: 268)

Jan 19 20:57:46 MSK: %SIBYTE-DFC7-4-SB_EXCESS_COLL: Excessive collisions on mac 1 (count: 255)

Cisco 7609 with RSP720. Unforutantely I was unable to find this type of message on cisco.com. Does anybody know what does this exaclty mean?

P.S. All I gat is the only link http://www.cisco.com/en/US/products/hw/modules/ps2033/products_tech_note09186a008009446d.shtml#topic5



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Itzcoatl Espinosa Tue, 01/19/2010 - 12:00
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Hi Peter,

Here is the explanation of the messages.

%SIBYTE-DFC4-4-SB_EXCESS_COLL: Excessive collisions on mac 1 (count: 1)

These messages basically mean that excessive collisions have occurred on the MAC

A small number of excessive collisions is not a problem at all.  It is the nature of
bus-based Ethernet. The reason you saw the message message maybe because you have configured
the "service internal" on your switch.  If you change the configuration (no service
internal), he will not see the error message at all.

With service internal mode off, the system will only print out such message whenever the
excessive collision reaches a certain fixed threshold. In this case, the appearance of
this message may indicate a real collision case.

With the service internal mode on, the system will print out such message whenever there
is one instance of excessive collision. It may be caused by some hardware noise.  The
occasional appearance of this message with service internal mode on is a normal behavior.

I hope this information could help you.

Itzcoatl Espinosa

artur barczewski Mon, 04/18/2011 - 22:39
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thx for the explantion. But what kind of interface is mac 1 on a 6509 with SUP720?



artur barczewski Tue, 04/19/2011 - 02:25
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yes would make sense... I've got 2 messages:

1711390: Feb 21 11:04:21 GMT: %SIBYTE-DFC2-4-SB_EXCESS_COLL: Excessive collisions on mac 1 (count: 8311)

1711391: Feb 21 11:04:52 GMT: %SIBYTE-DFC1-4-SB_EXCESS_COLL: Excessive collisions on mac 1 (count: 9189)

But i would mean that the whole slot 1 and 2 had collisions on the switching matrix. This brings us back to what kind of interface it is .. maybe some kind of management interface on the slot?
Kind regards
osenevp Tue, 04/19/2011 - 03:38
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Good question...

Well, I was told that if there're not too much collisions on counters - it's OK. Otherwise - you have to do something.

artur barczewski Thu, 04/21/2011 - 07:40
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in the end i openend a TAC case:

it a collision on the out-of-band-ethernet management bus   (EOBC) for the line cards only. it is not critical. you can disable it with command no service internal.




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