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From: Alex Turtois on 21 Jun 2006 16:03
HI All,

Can anyone tell me please what does the following mean?

%SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
2/46 and port 2/4
%SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/47
2/48 and port 2/4
%SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
2/46 and port 2/4
%SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/47
2/48 and port 2/4
%SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
2/46 and port 2/4

Thanks,
Alex

From: SAto on 22 Jun 2006 03:01

Alex Turtois skrev:
> HI All,
>
> Can anyone tell me please what does the following mean?
>
> %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
> 2/46 and port 2/4
> %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/47
> 2/48 and port 2/4
> %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
> 2/46 and port 2/4
> %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/47
> 2/48 and port 2/4
> %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
> 2/46 and port 2/4

The flapping message means that the switch sees the host mac address
change from port 2/45 -> 2/46 -> 2/4 and back. When this happens often
the mac-address table ont he switch is "thrashed". Its may be causing
the packets destined for the mac address in question to be broadcasted
to alle ports on the switch instead.

The mac address in question is used by Windows 2000 Advanced server
with Network Load Balancing.

To fix this, you could either turn off the load balancing feature.
(which is not really network load balancing but server load balancing)
Or configure a static IP -> multicast mac address entry and turn on
igmp snooping or configure the multicast mac address to the ports which
are members of the load balancing group.

Im guessing there are seperate servers connected to the diffirent ports
but that all of them are members of the load balancing group.

Another way to "fix" this would be to change the mode from multicast to
broadcast.
But then all traffic would be broadcastet to every host on the network.

Microsoft has made some documentation on how to do this on cisco
switches.
Cant remember a url, but a search on microsoft.com should give you some
results.

Hope this is helpful.

-SAto

From: Alex Turtois on 22 Jun 2006 19:16
Sato,

thanks a lot, that really helped.

Alex


SAto írta:
> Alex Turtois skrev:
> > HI All,
> >
> > Can anyone tell me please what does the following mean?
> >
> > %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
> > 2/46 and port 2/4
> > %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/47
> > 2/48 and port 2/4
> > %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
> > 2/46 and port 2/4
> > %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/47
> > 2/48 and port 2/4
> > %SYS-4-P2_WARN: 1/Host 02:01:00:00:00:00 is flapping between port 2/45
> > 2/46 and port 2/4
>
> The flapping message means that the switch sees the host mac address
> change from port 2/45 -> 2/46 -> 2/4 and back. When this happens often
> the mac-address table ont he switch is "thrashed". Its may be causing
> the packets destined for the mac address in question to be broadcasted
> to alle ports on the switch instead.
>
> The mac address in question is used by Windows 2000 Advanced server
> with Network Load Balancing.
>
> To fix this, you could either turn off the load balancing feature.
> (which is not really network load balancing but server load balancing)
> Or configure a static IP -> multicast mac address entry and turn on
> igmp snooping or configure the multicast mac address to the ports which
> are members of the load balancing group.
>
> Im guessing there are seperate servers connected to the diffirent ports
> but that all of them are members of the load balancing group.
>
> Another way to "fix" this would be to change the mode from multicast to
> broadcast.
> But then all traffic would be broadcastet to every host on the network.
>
> Microsoft has made some documentation on how to do this on cisco
> switches.
> Cant remember a url, but a search on microsoft.com should give you some
> results.
>
> Hope this is helpful.
>
> -SAto

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