Anthony Mallet <anthony.mallet%laas.fr@localhost> writes: > On Monday, at 12:28, Greg Troxel wrote: > | But, the default mtu on gif(4) is 1280. So you should not be seeing > | IPv6 fragmentation. > > However, I do see it... Not even talking about UDP, I see > fragmentation between a netbsd and solaris 10 host through a gif > tunnel. For some reason the MSS of my outgoing packets is set to 1440 > initially. I'm currently investigating :) I am seeing fragmentation too (from doing an ftp from funet.fi from a host on a lan behind a tunneling gateway). I thought that v6 by default limited itself to 1280, but now I can't remember why I think that. > Also, if you are on a host on the LAN behind the gateway, is it > possible that the host starts tcp with the correct MSS? I don't follow what you are asking. I saw outgoing SYN packets with mss 1440. That's ok, except that it's too high for the tunnel. What I don't understand is why the far side doesn't drop when it gets the packet-too-big messsage. > I have a related question: ifconfig gif0 does not show any MTU > value. Is this a bug? I can do "ifconfig gif0 mtu 1480" without error, > but I'm not sure if this is silently ignored or not. On what system/version? On a netbsd-5 system, where I did not try to set the MTU, 'ifconfig -a' included the line: gif0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1280
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