Why not use MAC ID?

Yesterday waisted a couple hours trying to get my PC to see and load a IP address to a XXXX PLC using XXX software.... way to many issues to list and to much time, so my question is if all devices have a MAC ID why would the manufactures just use that and not a IP address, every time I have issues regardless of the brand and this is not brand specific (hence the XXX) they can see the device and MAC ID but there are issues assigning a IP to the device

This would also let you see devices if your not on the same subnet... just want the stuff to work without getting stressed out and wanting to shoot my laptop with my 9

I wish it were that easy too. Bootp is a pain in the ***. I stole this answer from StackExchange.

IP addresses are explicitly not designed to be bound by hardware where as MAC addresses are. MAC addresses can be changed temporarily most of the time but each device is supposed to have a globally unique factory assigned MAC address.

Furthermore, MAC is specific to Ethernet, and while it is now the defacto Layer 2 encapsulation method, it wasn't always the case and you never know if something better will come along in the future.

Quite simply, it is a lot easier and very little overhead to do the same thing for people inside your network segment as outside your network segment.

Some other possible reasons:

You may want to use IP's to help remember what something is (the router ends with .1 kind of stuff)
You may want to run two networks on one segment that do not talk to each other (you can do that with IP via Subnets)
MAC addresses are not easy to remember.
MAC addresses are used to send Ethernet frames between two stations in the same local area network. Each station has a unique MAC address that is used to identify who is the sender (source address) and who is the receiver (destination address). But Ethernet frames can't travel between networks. One computer in a local network never sees the MAC of a computer which is on another network.

IP addresses are used to send IP packets to another station over the Internet, which is a collection of networks (hence the name "inter networks", from where Internet is derived). Contrary to MAC addresses, IP frames aren't limited to the local network. While travelling around the world, IP packets pass through many smaller networks, many of them using Ethernet (like inside your home or office LAN). When it is the case, the network stack puts the IP packet inside an Ethernet frame, using the MAC address to send to the next stop (what we call 'next hop'). The gateway strips the Ethernet header, rocering the original IP packet, and forwards it over the next network, until it reaches the destination.

It is not gonna happen.
One problem is that the MAC is in principle fixed on a device (*), so if you replace a device the MAC adress will change and it doesnt automatically connect to the same system as the device that was replaced.
*: I know that on many devices you can actually set the MAC address.

On the Profinet systems I use I really dont have a problem setting them up.
I can also see for a device that isnt setup with ist IP or Name yet if it is reachable by its MAC adress. So that helps with the initial identification and troubleshooting.

If the software you are using do not provide a facility to see if a non-setup device is reachable, then maybe a freeware like this can help: https://www.majorgeeks.com/files/details/mac_address_scanner.html

You also can't subnet MAC addresses.

geniusintraining said:

Yesterday waisted a couple hours trying to get my PC to see and load a IP address to a XXXX PLC using XXX software.... way to many issues to list and to much time, so my question is if all devices have a MAC ID why would the manufactures just use that and not a IP address, every time I have issues regardless of the brand and this is not brand specific (hence the XXX) they can see the device and MAC ID but there are issues assigning a IP to the device

This would also let you see devices if your not on the same subnet... just want the stuff to work without getting stressed out and wanting to shoot my laptop with my 9

Click to expand...

This is why Profinet uses Layer 2 for discovery, not Layer 3. The upside is that you can discover any device supporting DCP on the local network. The downside is that you can't discover across network boundaries. This is why PLC downloads still generally require IP addresses, so that you can do it across routers, VPNs, etc.

Also, TCP at the IP layer does a lot to ensure no data is lost (or at least you know about it when it is), whereas directly at the MAC layer, protocols to handle your connection for you are rarer.