pmtud + ipnat RELENG_6_2 appears to be broken

[Stephen Clark]

Chuck Swiger wrote:

>On Jul 12, 2007, at 12:34 PM, Stephen Clark wrote:
>  
>
>>Did something change in 6.2?  If my mtu size on rl0 is 1280 it won't
>>accept a larger incoming packet.
>>    
>>
>
>Nothing changed; that is the expected behavior.
>(Modulo support for 4-byte VLAN tags.)
>
>  
>
>>kernel: rl0: discard oversize frame (ether type 800 flags 3 len  
>>1514 > max
>>1294)
>>
>>I don't think it worked this way in the past.
>>    
>>
>
>Well, it did.  :-)
>
>  
>
>>Won't this affect pmtud?
>>    
>>
>
>Nope.
>
>  
>
>>man page for ifconfig says mtu limits size of "transmission" not  
>>reception.
>>
>>    "mtu n   Set the maximum transmission unit of the interface to  
>>n, default
>>            is interface specific."
>>    
>>
>
>The MTU is actually defined in reference to a network segment such as  
>an "ethernet collision domain", and applies to all machines sending  
>traffic to that segment.  If the MTU is really 1280, nobody else  
>should be sending larger packets, and the drivers will drop any  
>larger packets they receive and generate the appropriate ICMP error....
>
>  
>
Hi Chuck,

First thanks for responding but thats the problem,
this  did't generate an icmp when the packet was dropped.

kernel: rl0: discard oversize frame (ether type 800 flags 3 len  
1514 > max
1294)

This message did not result in any icmp packet.


I was running tcpdump looking for them.

Steve

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