Date: Sun, 18 Nov 2012 03:01:36 +0100 From: Adam Nowacki <nowakpl@platinum.linux.pl> To: freebsd-fs@freebsd.org Subject: Re: Jumbo Packet fail. Message-ID: <50A84180.9080309@platinum.linux.pl> In-Reply-To: <CACpH0Mdd7zxLmo5KLT_onRNumA0vxoa6H1Unyyu=Mvfmd4GOww@mail.gmail.com> References: <CACpH0Mdd7zxLmo5KLT_onRNumA0vxoa6H1Unyyu=Mvfmd4GOww@mail.gmail.com>
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setup ip addresses after setting the mtu or restart the interface with ifconfig em0 down up mtu gets cached in routes, see netstat -rnW On 2012-11-17 23:32, Zaphod Beeblebrox wrote: > I recently started using an iSCSI disk on my ZFS array seriously from > a windows 7 host on the network. The performance is acceptable, but I > was led to believe that using Jumbo packets is a win here. My win7 > motherboard adapter did not support jumbo frames, so I got one that > did... configured it, etc. Just in case anyone cares, the motherboard > had an 82567V-2 (does not support jumbo frames) and I added in an > intel 82574L based card. > > Similarly, I configured em0 on my FreeBSD host to have an MTU of 9014 > bytes (I also tried 9000). The hardware on the FreeBSD 9.1RC2 side > is: > > em0: <Intel(R) PRO/1000 Network Connection 7.3.2> port 0xdc00-0xdc1f > mem 0xfcfe0000-0xfcffffff,0xfcfc0000-0xfcfdffff irq 16 at device 0.0 > on pci3 > > pciconf -lv identifies the chipset as 82572EI > > Now... my problem is that the windows machine correctly advertises an > MSS of 8960 bytes in it's SYN packet while FreeBSD advertises 1460 in > the syn-ack. > > [1:42:342]root@vr:/usr/local/etc/istgt> ifconfig em0 > em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9014 > options=4019b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,VLAN_HWTSO> > ether 00:15:17:0d:04:a8 > inet 66.96.20.52 netmask 0xffffffe0 broadcast 66.96.20.63 > inet6 fe80::215:17ff:fe0d:4a8%em0 prefixlen 64 scopeid 0x5 > inet6 2001:1928:1::52 prefixlen 64 > inet 192.168.221.2 netmask 0xffffff00 broadcast 192.168.221.255 > nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> > media: Ethernet autoselect (1000baseT <full-duplex>) > status: active > > I have tested this with both ipv4 and ipv6 connections between the > win7 host and the FreeBSD server. win7 always requests the larger > mss, and FreeBSD the smaller. > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >
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