gif tunnel ipv4 over ipv4 don't work

[Andrey Smagin]

Hi All! I found next issue with gif tunnels.
gif3 work look's like mpd without tcpmssfix - google opened, but another sites waiting read forever
gif4 work fine.
all connection to internet in Box2,3 similar
I changed gif3 tunnel to vtun ethernet tunnel (tap) - it solve problem and all sites loaded good.  


Configuration
MainBox
 FreeBSD 10.0-CURRENT #45 r228164M amd64
gif3: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1500
  tunnel inet 172.17.1.200 --> 172.17.1.222
  inet6 fe80::21b:21ff:fe7b:3800%gif3 prefixlen 64 scopeid 0x19 
  inet 192.168.254.69 --> 192.168.254.70 netmask 0xfffffffc 
  nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
  options=1<ACCEPT_REV_ETHIP_VER>

gif4: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1500
  tunnel inet 172.17.1.200 --> 172.17.1.150
  inet6 fe80::21b:21ff:fe7b:3800%gif4 prefixlen 64 scopeid 0x1a 
  inet 192.168.254.73 --> 192.168.254.74 netmask 0xfffffffc 
  nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
  options=1<ACCEPT_REV_ETHIP_VER>

Box2
9.0-CURRENT FreeBSD 9.0-CURRENT #44: Tue Mar 2 2010
gif4: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1500
        tunnel inet 172.17.1.150 --> 172.17.1.200
        inet6 fe80::215:e9ff:fef1:d04d%gif4 prefixlen 64 scopeid 0x9 
        inet 192.168.254.74 --> 192.168.254.73 netmask 0xfffffffc 
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        options=1<ACCEPT_REV_ETHIP_VER>

Box3
FreeBSD 10.0-CURRENT #0 r228504M i386
gif3: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1500
        tunnel inet 172.17.1.222 --> 172.17.1.200
        inet 192.168.254.70 --> 192.168.254.69 netmask 0xfffffffc 
        inet6 fe80::215:e9ff:fe42:1ee5%gif3 prefixlen 64 scopeid 0x8 
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
        options=1<ACCEPT_REV_ETHIP_VER>