Low Bandwidth on intercontinental connections

[Ingo Flaschberger]

Am 22.11.2012 13:38, schrieb Marc Peters:
> interesting, the MTU is way lower, than i expected. Through the VPN
> tunnel, only 1322 bytes are possible without fragmentation. ScreenOS
> adds 42 additional bytes per paket and the FreeBSD box is receiving 1364
> bytes, according to tcpdump. From the outside (only one Netscreen on the
> way), 1472 is the maximum possible size to send pakets without
> fragmentation (-D).
>
> Which MTU would you suggest to use? Shouldn't the MTU discovery of
> FreeBSD handle this correct?

should handle, yes.
Any icmp firewalls in between?

you can also try tcp mss clamping (via firewall, infos via google)

>> *) any offloading/supported used at the network-card?
> Yes:
> bce0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
> 	options=c01bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,TSO4,VLAN_HWTSO,LINKSTATE>
> 	ether ac:16:2d:b7:00:f4
> 	inet 172.16.3.10 netmask 0xffffff00 broadcast 172.16.3.255
> 	inet6 fe80::ae16:2dff:feb7:f4%bce0 prefixlen 64 scopeid 0x1
> 	nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
> 	media: Ethernet autoselect (1000baseT <full-duplex>)
> 	status: active

try to deactivate JUMBO_MTU and TSO4

>> *) try a rate-shaping queue outgoing (not really good - as shaping works
>> best on incomming interfaces):
>>     you need dummynet (and ipfw for this example):
>>    ipfw add pipe 1     all from ....
>>    ipfw pipe 1 config bw 10Mbit/s queue 50Kbytes
>>    (adjust queue size ~40ms at rated speed)
> no paketfiltering on the host itself is intended and i don't know
> anything of ipfw for a simple setup, sorry.
>
ipfw add pipe 1 all from thishostip to destinationhostip
ipfw pipe 1 config bw 10Mbit/s queue 50Kbytes

Kind regards,
     Ingo Flaschberger