ssh & select() problem on 5.3

[Claudiu Dragalia-Paraipan]

Andre Oppermann wrote:
> Peter Jeremy wrote:
> 
>> On Sun, 2004-Nov-28 18:43:47 +0200, Claudiu Dragalia-Paraipan wrote:
>>
>>> Since the problem occurs only when I connect to the firewall or to a 
>>> server behind it, I started to suspect a hardware failure. Could a 
>>> network card cause such problems ?
>>
>>
>> A couple of people have mentioned path-MTU problems.  I've also bumped
>> into this problem when playing with VLANs where one end of the VLAN
>> trunk doesn't support long frames - an oversize packet will get ignored
>> by the receiver without any error being returned.
> 
> 
> If the oversized ethernet frame makes it to the FreeBSD box it will drop
> the frame in the ethernet hardware or in ether_input() with a message. If
> you don't get a message on the console you have to look at the driver
> statistics if it got any oversized frames.
> 
> If the switches along the patch can't handle the oversized frame they will
> simply drop it.  No way to work around that.
> 


When the MTU is set to a value below 1500, for example 1450, I get this 
messages:

Nov 29 23:02:34 firewall kernel: rl0: discard oversize frame (ether type 
800 flags 3 len 1466 > max 1464)
Nov 29 23:03:00 firewall kernel: rl0: discard oversize frame (ether type 
800 flags 3 len 1514 > max 1464)

... and much many of them.
With MTU 1500 I didn't notice any such message in logs.
So, can I safely assume that the problem occurs because somewhere 
packets are simply dropped, without any warning ?




-- 
Claudiu Dragalina-Paraipan
dr.clau at gmail.com
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