Date: Mon, 8 Nov 2021 15:13:52 +0800 From: Zhenlei Huang <zlei.huang@gmail.com> To: Rozhuk Ivan <rozhuk.im@gmail.com> Cc: freebsd-net@freebsd.org, freebsd-hackers@freebsd.org Subject: Re: if_vlan allow to set incorrect mtu Message-ID: <F07B770B-E17F-467A-982F-4EF34F55870E@gmail.com> In-Reply-To: <20211107105130.2ccbb253@rimwks.local> References: <20211107105130.2ccbb253@rimwks.local>
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> On Nov 7, 2021, at 3:51 PM, Rozhuk Ivan <rozhuk.im@gmail.com> wrote: > > Hi! > > > Why if_vlan allow to set same MTU size or bigger as on parrent nic? > > > Setup: > - workstation with MTU 9000 and IPv4 on h/w nic > - server with MTU 9000 on h/w nic and IPv4 on vlan nic with MTU 9000 (set by defauil on iface creation) > > This setup have issue: > - big packets from server->wks - OK > - big packets from wks->server - FAIL. > > Server init sequence: > 1. Create vlans > 2. Set MTU lower than default on parent nic > > Result: vlan have bigger or same MTU as parrent nic, but parrent nic reports IFCAP_VLAN_MTU. > Probably this is if_em driver issue or iflib. > > > > This is rc.conf, vlan77 - where I got MTU 9000 and fail to receive packets: > ===================================================================================== > vlans_igb0="vlan77 vlan86 vlan87" > create_args_vlan87="vlan 87" > create_args_vlan86="vlan 86" > create_args_vlan77="vlan 77" > ifconfig_vlan87="inet 15.44.77.2 netmask 255.255.252.0 mtu 1500 down up" > ifconfig_vlan87_alias0="link 00:aa:fa:dd:44:55" > ifconfig_vlan86="DHCP mtu 1500" > ifconfig_vlan86_alias0="link 00:ff:fa:dd:44:55" > ifconfig_vlan77="inet 192.168.0.254 netmask 255.255.255.0" > ifconfig_vlan77_alias0="link 00:0f:43:48:67:fe" > ifconfig_vlan77_ipv6="inet6 2001:470:2345:555::1/64 prefixlen 64 auto_linklocal" > ifconfig_igb0="-lro -tso -vlanhwtso mtu 9000 down up" > ===================================================================================== > > > Can you please disable all vlan hardware offloading features and repeat the test again? ifconfig igb0 -vlanmtu -vlanhwtag -vlanhwfilter -vlanhwtso -vlanhwcsum
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