tech-net archive


Re: IPv6 TCP sessions hangs when using PF keep state

On Monday, at 12:28, Greg Troxel wrote:
| > This means that if you initiate a TCP connection with a big MSS
| > (e.g. 1460 on a gif tunnel with a 1480 MTU), the connection will
| > eventually stall if the other part starts sending ipv6-frag packets.
| 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 :)

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 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.

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