Assign/Choose Wich nic is used for what purpose

[Hellrazorx]

Hi all,

First, I'm an outlaw and using two different adapters on the same subnet. But I'd have the same question if I used vlans or different subnets:

First: the screenshot

So there:
- Lagg7 intended use is for internal network access. This is ''forced'' through dns resolution to 192.168.1.12.. FIne fine- Works as expected
- igb0 intended use is for offsite replication jobs and cloud syncs. This is decided by god.. Fine fine works as expected... But why...

In the screenshot, there are actually Transfers going through the network (saturating GB net 117.35mb) and another pushing through openvpn.. (7.31mb)

So yeah. I'm not sad.. everything works fine and it ran like this for more than year...
But... I feel lucky tho, and luck is the most durable fuel out there.

Is there a part I'm missing? Did I go sleepwalking and figured out something and I don't remember how I did?

thanks for any clue

 

[Patrick M. Hausen]

You cannot have two interfaces in the same subnet:

Multiple network interfaces on a single subnet

We've had a number of people over the years bring up the topic of multiple network interfaces on a single subnet. Often done by Windows administrators or storage admins, where it works to varying degrees, this is sadly not proper IP networking practice. Multiple interfaces on a single network...

www.truenas.com

You can use one interface for jails and/or VMs and one for all other TrueNAS services. Because jails and VMs all have their own network stack and in TrueNAS these are just layer 2 connections. But all TrueNAS services, sharing, replication, web UI, ... use the same IP stack, the same routes, and you cannot force them in any way to use different interfaces.

 

[sretalla]

and you cannot force them in any way to use different interfaces

I bet people think that since you can "bind" to an IP in a few of those services, that means you have locked it to a NIC... which would be wrong.

 

[Patrick M. Hausen]

You can bind services to NICs for incoming packets, but outgoing ones will always follow the system's routing table.

 

[Hellrazorx]

You cannot have two interfaces in the same subnet:

Multiple network interfaces on a single subnet

We've had a number of people over the years bring up the topic of multiple network interfaces on a single subnet. Often done by Windows administrators or storage admins, where it works to varying degrees, this is sadly not proper IP networking practice. Multiple interfaces on a single network...

www.truenas.com

You can use one interface for jails and/or VMs and one for all other TrueNAS services. Because jails and VMs all have their own network stack and in TrueNAS these are just layer 2 connections. But all TrueNAS services, sharing, replication, web UI, ... use the same IP stack, the same routes, and you cannot force them in any way to use different interfaces.

Hi,
I can't but I do, take a look at the screenshot.

But yeah I understand I cant control it

 

[Patrick M. Hausen]

Okay, you cannot have two interfaces on the same subnet and expect to control what traffic goes where or even expect consistent results from such a setup. Better?

 

[HoneyBadger]

But... I feel lucky tho, and luck is (not?) the most durable fuel out there.

Computers don't run on luck, they run on Magical Blue Smoke. ;)

Your system's routing table has decided that for this boot, this interface-up, or this phase of the moon, your OpenVPN endpoint is best reached by the .46 IP - but the rest of the 192.168.1.0/24 is best reached by the .12 IP.

How long this will work is anyone's idea. Best to set up two separate IP spaces and remove the element of chance.

 

[sretalla]

Perhaps to go back to the OP's intent here...

Are we saying that the "coin toss" between equally costed routes is done once per "interface-up" or per boot, etc. ?

I think that would sort of answer the original "why?" question.

It's a coin toss and the decision is remembered for a while. (correct me if I'm misinterpreting that)

As a general assessment, "being an outlaw" or wanting to "stick it to the 'man'" in this case only sticks it to a specific "man", in this case the OP, in the form of routing uncertainty/unpredictability between boot/interface-ups.