Strange kernel messages?

Grant orbman at thingysrealm.myftp.org
Tue Aug 10 13:19:29 BST 2004


Kevin O'Connor wrote:

>  
>
>>-----Original Message-----
>>From: freebsd-users-admin at uk.freebsd.org [mailto:freebsd-users-
>>admin at uk.freebsd.org] On Behalf Of Grant
>>Sent: 10 August 2004 11:44
>>To: kevin at ziptek-technologies.co.uk
>>Cc: freebsd-users at uk.freebsd.org
>>Subject: Re: Strange kernel messages?
>>
>>Kevin O'Connor wrote:
>>
>>    
>>
>>>It's just arp telling you that both nics are on the same network.
>>>This will stop arp messages being logged
>>>
>>>Sysctl net.link.ether.inet.log_arp_movements=0
>>>
>>>Of course sorting out the problem would be better, it's never a good idea
>>>      
>>>
>>to
>>    
>>
>>>run 2 completely different subnets through the same hub
>>>Regards
>>>Kevin
>>>
>>>
>>>      
>>>
>>>>-----Original Message-----
>>>>From: freebsd-users-admin at uk.freebsd.org [mailto:freebsd-users-
>>>>admin at uk.freebsd.org] On Behalf Of Grant
>>>>Sent: 10 August 2004 11:24
>>>>To: freebsd-users at uk.freebsd.org
>>>>Subject: Strange kernel messages?
>>>>
>>>>Hi,
>>>>
>>>>Got a few freebsd servers and i have noticed quite alot of these
>>>>messages on the console and in the logs.
>>>>
>>>>arp: 10.0.0.100 moved from 00:c0:4f:26:a8:83 to 00:08:c7:3b:67:93 on fxp0
>>>>arp: 10.0.0.100 moved from 00:08:c7:3b:67:93 to 00:c0:4f:26:a8:83 on fxp0
>>>>arp: 10.0.0.100 moved from 00:c0:4f:26:a8:83 to 00:08:c7:3b:67:93 on fxp0
>>>>
>>>>There is two networks one 10.0.0.0/255.0.0.0 and the second
>>>>192.168.254.0/255.255.255.0
>>>>
>>>>The ip 10.0.0.100 is a proxy/gateway running clarkconnect with dual
>>>>network cards one on 10.0.0.100 and one 192.168.254.100
>>>>
>>>>The messages only seem to show up on the freebsd boxes, there is 3 boxes
>>>>that show these messages.
>>>>
>>>>The first is 10.0.0.222 which has dual cards with the other interface at
>>>>192.168.254.1
>>>>The second box only has one card with ip of 10.0.0.60
>>>>The third box only one card again with ip 10.0.0.70
>>>>
>>>>These machines are all linked to a 24port 3Com hub... just in case that
>>>>is the problem :(
>>>>
>>>>The question is what is it ? and should i be worried at the amount i am
>>>>getting of them ? and can it be stopped ?
>>>>
>>>>Thanks
>>>>Grant.
>>>>
>>>>ps - The first box runs 4.10 and the second and third are running 5.2.1
>>>>There is some linux boxes but they dont show any of the messages.
>>>>
>>>>
>>>>------ FreeBSD UK Users' Group  -  Mailing List ------
>>>>http://listserver.uk.freebsd.org/mailman/listinfo/freebsd-users
>>>>
>>>>
>>>>        
>>>>
>>>
>>>
>>>      
>>>
>>Hey,
>>
>>Thanks for the quick reply!
>>
>>So maybe just get myself another hub and then put all the 10.0.0.0
>>network on that and leave the 192.168.254.0 on the original hub ?
>>
>>I still dont quite get why i get them though as they are on different
>>networks the subnets are different and so is the ranges... would a
>>switch help instead of a hub ?
>>
>>Thanks
>>Grant.
>>
>>
>>    
>>
>
>Ah you want to know why, this comes up every year or so.
>Lets assume fxp0 and fxp1 are on the 10.0.0.0/8 network and fxp2 and fxp3
>are on the 192.168.254.0/24 network. (Just 2 boxes in this example)
>If fxp1 says hello I'm here fxp0 gets the message and builds an arp entry 
>In the form
>IP address MAC address 
>so far no problem but you have routing enabled and that is saying if you
>want to reach the 10.0.0.0/8 network route through fxp2 or fxp3 (internal to
>the boxes) and that gives a different MAC address.You have two routes to the
>different networks one internal and the other external through the hub. So
>what is happening is you are building one arp entry for the internal route
>and then scrapping it and building a new entry from the external route. This
>is not a fault it is nothing to worry about in this case.
>
>This answer is very simplistic and is only designed to allow you to
>visualize the problem. To fully understand the problem you will need to do
>quite a bit of reading.
>
>If you wish to use a switch it will need to be layer 3 to allow it to be
>split between the two networks. Two hubs or layer 2 switches will solve it
>as well.
>Hope this helps.
>Regards
>Kevin
>
>
>  
>
Hey,

Well i think i will have to pass on getting a layer 3 switch, i just had 
a look at the price of some of them! damn! heh.

I have made a before and after diagram, the before is what it currently 
looks like with these messages popping up and the after is what i think 
would make them stop.

http://orbsrealm.com/rackmount/pub/images/before.jpeg
http://orbsrealm.com/rackmount/pub/images/after.jpg

I think thats how i could stop these messages, but i just want someone 
to kind of confirm it before i go moving cables :)

Thanks again
Grant.






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