This is a bit of a late reply but I figure I'd throw it out there for the benefit of any future inquiries. First of all, having multiple nics with IP's in the same subnet is perfectly legitimate. Let's take a look at an example -- I have a server with 4 nics and I give them the following IP's:
nic1: 192.168.1.1 / 255.255.255.0
nic2: 192.168.1.2 / 255.255.255.0
nic3: 192.168.1.3 / 255.255.255.0
nic4: 192.168.1.4 / 255.255.255.0
This is a PERFECTLY valid network configuration; but there is a challenge. It's not an "issue" or a "problem", but a challenge. This challenge is discussed in this link, but it is incomplete:
https://forums.freenas.org/index.php?threads/multiple-network-interfaces-on-a-single-subnet.20204/
If you look at that article and then follow the link from that article to the subsequent Apple article (
https://support.apple.com/en-us/HT203436), you will see the title of the document:
Multiple physical network interfaces on the same subnet may cause routing issues
the key word in this document is ROUTING. What is routing? Routing is needed when you want to access another subnet. Think of it as a street name....I live on street 192.168.1.0 and my house address is 192.168.1.1. I want to visit my friend who lives on the exact same street and his address is 192.168.1.2. I don't need directions on how to get there -- he lives on my street! But if I want to visit my concubine who happens to live on another street (192.168.77.0, for example), I need a route -- I need directions -- I need a GPS -- how do I get there?
The default gateway is what is required. The default gateway is my guide -- it guides me where I need to go to get to my mistress' address. Each computer can only have one default gateway. If you want to have more "paths" to other networks then you need to add static routes. I'm starting to babble on here because I'm drunk but he are the summarized facts:
-You can have as many nics as you want and you can put them all on the same subnet. This is a perfectly fine configuration.
-ANY other machine that is also on that SAME subnet will be able to access all those IP's, assuming of course that the service it's trying to access (cifs, nfs, apache, mysql, sql, ssh, etc) is configured to listen on those ip's.
-but any other machine which is NOT on the same subnet ------ that machine will only be able to access the interface that has a default gateway (or static route) configured.
So, if my configuration is this:
nic1: 192.168.1.1 / 255.255.255.0 GW: 192.168.1.254
nic2: 192.168.1.2 / 255.255.255.0 GW: -
nic3: 192.168.1.3 / 255.255.255.0 GW: -
nic4: 192.168.1.4 / 255.255.255.0 GW: -
then every machine on the 192.168.1.0 subnet will be able to see those ip's. It's a great way to segregate traffic (perhaps you want to dedicate one nic for backup traffic?). Regardless of whether I type \\192.168.1.1\backup, \\192.168.1.2\backup, \\192.168.1.3\backup, or \\192.168.1.4\backup, I will see the same share (assuming, of course, that samba is listening on all interfaces) but each one of those IP's will give me a full 1Gps without any kind of LACP.
however every machine which is on a different subnet will ONLY be able to see 192.168.1.1 because the others don't have a route to other networks, and you can't add multiple ROUTES to OTHER networks to interfaces on the SAME subnet. Accessing the shares would yield success to 192.168.1.1, but the other 3 would fail. Trying to create routes to those additional IP's would be a massive pain (not even sure if it's possible).
I hope this is somewhat clear.