Link flap when adding / removing a vlan (was Re: r360902 breaks VLAN interface on if_em (82579LM))

[mike tancsa]

On 11/6/2020 2:17 PM, mike tancsa wrote:
> On 5/31/2020 5:39 PM, Lev Serebryakov wrote:
>> Hello Ian,
>>
>> Thursday, May 28, 2020, 2:45:48 AM, you wrote:
>>
>>> I noticed that my VLAN interfaces stopped working after a recent build. 
>>> tcpdump showed traffic leaving leaving and entering the interface but no 
>>> host on the network actually received any packets from this host.  A 
>>> binary search led me to r360902 and indeed the following change fixed 
>>> the issue for me:
>>  Problem is, this change will return terrible situation when adding new VLAN
>> will flap connection status.
>>
>>  It all worked before iflib: hardware VLAN filtering worked, and
>> adding/removing new VLAN didn't cause link to flap.
>>
>>  Now, with iflib, looks like we can not have all good things at once :(


Looks like this is captured in

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=240818


> Hi All,
>
> Just came across this thread as I am running into this behaviour on
> RELENG_12.  Adding a new vlan causes all vlans on the parent interface
> to flap. Not the greatest thing as it bounces a LOT of traffic
> potentially, flaps routing etc.  Is there a way around this ?
>
> This is on r367411 releng12
>
> igb0 at pci0:2:0:0:        class=0x020000 card=0x153315d9 chip=0x15338086
> rev=0x03 hdr=0x00
>     vendor     = 'Intel Corporation'
>     device     = 'I210 Gigabit Network Connection'
>     class      = network
>     subclass   = ethernet
>
> eg. just something simple like
>
> ifconfig vlan16 create 10.1.2.3/29 vlandev igb1 vlan 16
>
>  # dmesg | tail -8
> igb1: link state changed to DOWN
> vlan16: link state changed to DOWN
> vlan2049: link state changed to DOWN
> vlan15: link state changed to DOWN
> igb1: link state changed to UP
> vlan16: link state changed to UP
> vlan2049: link state changed to UP
> vlan15: link state changed to UP
>
>
>     ---Mike
>
>
>
>
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