Re: if_vlan allow to set incorrect mtu
- Reply: Zhenlei Huang : "Re: if_vlan allow to set incorrect mtu"
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Date: Mon, 06 Dec 2021 21:39:49 UTC
W dniu 8.11.2021 o 08:13, Zhenlei Huang pisze: > > >> 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 > Disabling the capabilities listed above doesn't solve the issue, but assigning mtu 8996 to VLAN children does. Reproduced on the most recent 13-STABLE (13-n248421-3b936a8c889) while testing the fix[1] To reproduce: ifconfig_igb0="mtu 9000 up" ifconfig_igb1="mtu 9000 up" ifconfig_lagg0="laggproto lacp laggport igb0 laggport igb1 -lacp_strict" vlans_lagg0="vlan0 vlan1 ..." ifconfig_vlan0="inet x.x.x.x/y" # iperf3 -R -c y.y.y.y Connecting to host y.y.y.y, port 5201 Reverse mode, remote host y.y.y.y is sending [ 5] local x.x.x.x port 52750 connected to y.y.y.y port 5201 [ ID] Interval Transfer Bitrate [ 5] 0.00-1.02 sec 0.00 Bytes 0.00 bits/sec [ 5] 1.02-2.02 sec 0.00 Bytes 0.00 bits/sec [ 5] 2.02-3.02 sec 0.00 Bytes 0.00 bits/sec [ 5] 3.02-3.55 sec 0.00 Bytes 0.00 bits/sec #ifconfig vlan0 mtu 8996 # iperf3 -R -c y.y.y.y Connecting to host y.y.y.y, port 5201 Reverse mode, remote host y.y.y.y is sending [ 5] local x.x.x.x port 49056 connected to y.y.y.y port 5201 [ ID] Interval Transfer Bitrate [ 5] 0.00-1.00 sec 118 MBytes 989 Mbits/sec [ 5] 1.00-2.00 sec 118 MBytes 990 Mbits/sec [ 5] 2.00-3.00 sec 118 MBytes 990 Mbits/sec [ 5] 3.00-3.69 sec 81.8 MBytes 989 Mbits/sec I am setting MTU to 8996 since early 13-BETA? or maybe PRERELEASE. 12-STABLE at the beginning of 2021 was fine with the default settings and MTU 9000 set for igb(4) on the same hardware. It looks like regression. Should the PR be submitted in this case? [1] https://reviews.freebsd.org/D30002 (commit 9c6432dc4bb936f0842d766d8b3b19dfcde15da2) Regards, -- Marek Zarychta