> Am 04.03.2016 um 19:49 schrieb Robert Mustacchi <[email protected]>:
> 
> On 3/4/16 10:13 , Dirk Steinberg wrote:
>> 
>>> Am 04.03.2016 um 18:27 schrieb Robert Mustacchi <[email protected]>:
>>> 
>>> On 3/4/16 8:32 , Dirk Steinberg wrote:
>>>> 
>>>>>> On the older Broadwell NUCs (I218) I was unable to set 
>>>>>> any MTU higher than 1500. I found that disappointing,
>>>>>> but maybe I did something wrong.
>>>>> 
>>>>> The I218 in theory supports jumbo frames. We'll need to work out a bit
>>>>> more information about what went wrong. The best starting point is to
>>>>> get the output of dladm show-linkprop -p mtu on one of the e1000g's for
>>>>> the I218.
>>>> 
>>>> [root@nuc0 ~]# dladm show-phys
>>>> LINK         MEDIA                STATE      SPEED  DUPLEX    DEVICE
>>>> e1000g0      Ethernet             up         1000   full      e1000g0
>>>> [root@nuc0 ~]# dladm show-linkprop -p mtu e1000g0
>>>> LINK         PROPERTY        PERM VALUE          DEFAULT        POSSIBLE
>>>> e1000g0      mtu             rw   1500           1500           1500-9216
>>>> 
>>>> Setting a higher MTU in a running system does not work 
>>>> (I read that this is expected, although on Linux this has always worked)
>>>> 
>>>> [root@nuc0 ~]# ifconfig e1000g0 mtu 9000
>>>> ifconfig: setifmtu: SIOCSLIFMTU: e1000g0: Invalid argument
>>>> [root@nuc0 ~]# dladm set-linkprop -p mtu=9000 e1000g0
>>>> dladm: warning: cannot set link property ‚mtu' on 'e1000g0': link busy
>>> 
>>> Yes, this is a known limitation with that driver.
>>> 
>>>> So I changed the MTU in the boot-time config in /usbkey/config:
>>>> 
>>>> # underlay_nic is the underlay for SDC fabric networking
>>>> underlay_nic=b8:ae:ed:72:8a:17
>>>> underlay0_vlan_id=4
>>>> underlay0_ip=10.88.88.2
>>>> underlay0_netmask=255.255.255.0
>>>> underlay0_mtu=9000
>>>> 
>>>> But this leads to an error in the boot-up process.
>>>> Or do I have to increase the MTU of the physical
>>>> e1000g0 as well? Since the untagged e1000g0 
>>>> is running the admin network I thought I was 
>>>> supposed to leave that at 1500…
>>> 
>>> Is this SmartOS or SDC? Is this an SDC headnode?
>> 
>> Well, this WAS supposed to be SDC, but the install failed
>> because of the smbios / UUID stuff. So I went back to 
>> SmartOS. But I kept the setup with admin untagged and all
>> other nictags with tagged VLANs. The physical box has
>> only one NIC, there is no way around this.
> 
> Okay. Well, part of the problem here is that with a lot of manual config
> file editing there's less checking here, especially with SmartOS. Using
> nictagadm(1M) will help a little bit with some of this but doesn't cover
> everything.
> 
> So every VNIC that's created in SmartOS is defined by a NIC tag. The NIC
> tag determines the maximum MTU that we can create a vnic on top of it.
> When we start up, we look at all the nic tags defined on a NIC and set
> the MTU of the physical device to the maximum of all of them. In this
> case, because there's no NIC tag defining the MTU to be 9000, that's why
> you're seeing an error.
> 
> I know in your case there's a single port, but this should be fine
> presuming that you're running a platform that contains the fix for
> OS-5146 (https://smartos.org/bugview/OS-5146 
> <https://smartos.org/bugview/OS-5146>).

Yes, I read that and thought I would be safe with my platform version.
So I should do: 

nictagadm update -p mtu=9000 underlay

Right? Is there a way to read the mtu property back from nictagadm?
Because the output from nictagadm list does not change a bit…
Where does nictagadm store the mtu?

>> BTW, it would be nice for SmartOS to be less restrictive
>> about the admin network and allow that to be a tagged VLAN
>> as well. Apart from PXE-booting (which I do not use in this case)
>> I see no argument against it and configuring the admin 
>> VLAN (2 in my case) as untagged on the access port for the
>> SmartOS server leads to more pain down the road:
>> the normal default VLAN 1 that is the usual customer facing VLAN
>> needs to be tagged if the admin VLAN 2 is untagged.
>> But adding a VLAN to SmartOS with VLAN-id 1 is not
>> supported in SmartOS and gives an error! WFT???!!
>> Why can I not use VLAN 1? Is there any way around this?
> 
> I'm not sure why off hand that's the case, but I can certainly
> understand why it's frustrating. Can you file a bug about this at
> github.com/joyent/smartos-live/issues/ 
> <http://github.com/joyent/smartos-live/issues/> and we can dig into it?

OK, I will try to file a bug report later. The problem is:

[root@nuc0 ~]# dladm create-vnic -l e1000g0 -v 1 vlan1
dladm: VLAN over ‚e1000g0' may not use default_tag ID (see dladm(1M))

I cannot find any explanation in the manpage and I do not see any
point in this limitation.

I currently have a workaround on my switch involving two access ports
with VLANs 1 and 11 respectively and BPDUs/loop detection disabled
and a patch cable for the hairpin. The hack is so ugly that I should not
even talk about it in public… and I would really like to get rid of it.

Dirk


> Robert
> 



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