Date: Wed, 14 Feb 2007 13:17:09 -0500 From: Stephen Clark <Stephen.Clark@seclark.us> To: Alexander Motin <mav@alkar.net> Cc: freebsd-net@freebsd.org Subject: Re: pmtud problem Message-ID: <45D35225.2080103@seclark.us> In-Reply-To: <45D2410D.70509@alkar.net> References: <1171398196.00688135.1171386001@10.7.7.3> <1171398210.00688151.1171387801@10.7.7.3> <1171401795.00688172.1171391400@10.7.7.3> <45D2410D.70509@alkar.net>
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Alexander Motin wrote: >Stephen Clark wrote: > > >>>>if the pc sends a packet of 1460 bytes with the DF bit set shouldn't the >>>>freebsd 4.9 system >>>>send back an icmp dest unreachable - fragmentation needed and DF bit >>>>set? >>>> >>>> >>>Are you blocking icmp with a firewall filter? >>> >>> >>> >>Good question - but the answer is no. The other interesting fact is >>when I drop the mtu on >>the gre to 1412 I do see the icmp messages. >> >> > >Are you using any dummynet shapes? There is ancient bug in dummynet, >which leads to not sending of ICMPs when shape used on outgoing interface. > > > Hi Alexander, I had run into that problem before, in this case I am seing a icmp for 1420 mtu for the gre on the 4.9 side but the tun0 interface that pppoe is 1492 to allow for the ppp wrapper and I just read that the gif when using ipv4 doesn't handle pmtud - that I think is my real problem. Steve -- "They that give up essential liberty to obtain temporary safety, deserve neither liberty nor safety." (Ben Franklin) "The course of history shows that as a government grows, liberty decreases." (Thomas Jefferson)
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