Date: Thu, 22 Nov 2012 14:16:49 +0100 From: Ingo Flaschberger <if@xip.at> To: freebsd-net@freebsd.org Subject: Re: Low Bandwidth on intercontinental connections Message-ID: <50AE25C1.7050208@xip.at> In-Reply-To: <50AE1CCC.7080706@mpeters.org> References: <50ACF62C.8000408@mpeters.org> <CAOgwaMuUuJ2%2BmKqsFVp=DyVFkfm8Et%2Brnt2iEGDO8i1Kt_kDVA@mail.gmail.com> <50ad087d.1892cc0a.2cce.3bf2@mx.google.com> <50AD1012.7020209@mpeters.org> <50AD14F8.8050001@xip.at> <50ADE5E4.9090708@mpeters.org> <50AE0B12.8000309@xip.at> <50AE1CCC.7080706@mpeters.org>
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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
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